Patent Grant
12104461
The technical field generally relates to recovering hydrocarbons from fractured reservoirs that have been hydraulically fractured and related operating methods, and more particularly frac-to-frac displacement flood operations for recovering hydrocarbons.
Recovering hydrocarbons from an underground formation can be enhanced by fracturing the formation in order to form fractures through which hydrocarbons can flow from the reservoir into a well. Fracturing can be performed prior to primary recovery where hydrocarbons are produced to the surface without imparting energy into the reservoir. Fracturing can be performed in stages along the well to provide a series of fractured zones in the reservoir. Following primary recovery, it can be of interest to inject fluids to increase reservoir pressure and/or displace hydrocarbons as part of a secondary recovery phase. Tertiary recovery can also be performed to increase the mobility of the hydrocarbons, for example by injecting mobilizing fluid and/or heating the reservoir. Tertiary recovery of oil is often referred to as enhanced oil recovery (EOR). Depending on various factors, primary recovery can be immediately followed by tertiary recovery without conducting any secondary recovery. In addition, some recovery operations include elements of pressurization and displacement as well as mobilizing of the hydrocarbons. Injecting fluids into a fractured reservoir and recovering hydrocarbons involves a number of challenges and there is a need for enhanced technologies.
A asynchronous frac-to-frac processes and systems can include a number of features for enhanced operation, such as a hybrid method where at least one cyclic valve is operated in injection and production modes to access hydrocarbons in an isolated fractured zone while at least a pair or group of valves is operated with valves in injection-only and production-only modes; implementing valves that have sliding sleeves that include one or more check-valve devices to allow only production or only injection; providing flow restrictions on the sleeves; using valves that can be remotely controlled between fully open and fully closed positions and optionally controlling the valves based on data regarding properties of the fractured zones, fluid characteristics and/or flow behavior; monitoring the asynchronous frac-to-frac operation and adjusting the groupings of valves operating in injection-only and production-only modes over time; and managing the asynchronous frac-to-frac of multiple proximal wells to avoid fluid breakthrough and optimize the overall multi-well process.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided in alternating relation along the well to enable frac-to-frac hydrocarbon recovery from fractured zones in the reservoir; wherein the production-only valves and/or the injection-only valves each comprise: a housing with a port for fluid communication therethrough; and a sliding sleeve mounted within the housing and configured to slide therein, the sliding sleeve comprising a check valve device for alignment with the port of the housing upon shifting the sliding sleeve to an aligned configuration to allow fluid flow through the check valve device in one direction.
In some implementations, the production-only valves each comprise a production check-valve device for alignment with the port of the housing to enable inflow of production fluid during a production cycle of the asynchronous frac-to-frac operation while preventing outflow of injection fluid during an injection cycle of the asynchronous frac-to-frac operation. In some implementations, the injection-only valves each comprise an injection check-valve device for alignment with the port of the housing enable outflow of injection fluid during an injection cycle of the asynchronous frac-to-frac operation while preventing inflow of production fluid during a production cycle of the asynchronous frac-to-frac operation. In some implementations, the production-only valves each comprise a production check-valve device and the injection-only valves each comprise an injection check-valve device.
In some implementations, the sliding sleeve comprises a sleeve channel providing fluid communication between a central passage of the corresponding valve and the port of the housing, and wherein the check valve device comprises a displaceable member mounted within a check valve chamber of the sleeve channel, the displaceable member being moveable between an open position and a closed position.
In some implementations, the check valve chamber of the sleeve channel is defined by a recessed region of an outer surface of the sleeve and an inner surface of the housing. In some implementations, the sleeve channel comprises axial tubular portions on either side of the check valve chamber. In some implementations, the sleeve channel comprises a second chamber in direct fluid communication with the port of the housing and one of the axial tubular portions. In some implementations, the displaceable member of the check valve device comprises an axial poppet having through-channels that provide fluid communication in the open position. In some implementations, the displaceable member of the check valve device comprises a dart around which fluid flows in the open position. In some implementations, the displaceable member of the check valve device comprises a ball. In some implementations, the sleeve channel comprises a plurality the check valve chambers arranged around a circumference of the sleeve and in parallel relation with each other, wherein each of the check valve chambers has a corresponding displaceable member therein and is in fluid communication with the central passage and with the port of the housing. In some implementations, the check valve chamber extends circumferentially around the sleeve and the displaceable member of the check valve device comprises a ring plug that extends around the check valve chamber. In some implementations, the displaceable member is configured to move axially within the check valve chamber.
In some implementations, the sliding sleeve comprises a sleeve channel providing fluid communication between a central passage of the corresponding valve and the port of the housing, and wherein the check valve device comprises a reed petal mounted with respect to the sleeve channel to be moveable between an open position and a closed position. In some implementations, the reed petal is mounted to be parallel with a longitudinal axis of the sleeve in the closed position, and to deflect radially outward toward the open position. In some implementations, the reed petal is mounted to be perpendicular with a longitudinal axis of the sleeve in the closed position. In some implementations, the reed petal is mounted to cover an end opening of the sleeve channel.
In some implementations, the sleeve comprises a first sleeve part having a sleeve port in fluid communication with the port of the housing, and a second sleeve part mounted to the first sleeve part such that the first and second sleeve parts define therebetween at least part of the sleeve channel.
In some implementations, the check valve device further comprises a biasing mechanism coupled to the displaceable member to bias the same toward the closed position. The biasing member can include a spring.
In some implementations, the check valve device comprises a displaceable member that is configured to move outwardly from a closed position to an open position.
In some implementations, the sliding sleeve comprises a sleeve channel providing fluid communication between a central passage of the corresponding valve and the port of the housing, the sleeve channel comprising a circumferential chamber extending at least partly around a circumference of the sleeve, and wherein the check valve device comprises a circumferential dart mounted within the circumferential chamber of the sleeve channel and being moveable between an open position and a closed position. In some implementations, the check valve device comprises a plurality of the circumferential chambers and corresponding circumferential darts provided therein, arranged in spaced-apart relation and stacked along the sleeve.
In some implementations, the check valve device comprises a circumferential reed valve comprising curved reed petals that extend over corresponding openings and follow a curvature of the sleeve.
In some implementations, the sliding sleeve of each valve is configured to have a first configuration, a down-shifted open configuration, and an upshifted open configuration. In some implementations, the first configuration of the sliding sleeve is a closed configuration. In some implementations, the sliding sleeve of each valve comprises a production-only check valve device configured for alignment with the port of the housing when the sleeve is shifted in one direction, and an injection-only check valve device configured for alignment with the port of the housing when the sleeve is shifted in another direction. In some implementations, the sliding sleeve of each valve further comprises flow restriction components associated with the production-only check valve device and the injection-only check valve device, respectively, to restrict a flow rate when the corresponding check valve device is open. In some implementations, the flow restriction components associated with the production-only check valve device and the injection-only check valve device are configured to provide different flow restriction.
In some implementations, the sliding sleeve of each valve further comprises a flow restriction component in fluid communication with the check valve device to restrict a flow rate when the check valve device is open. In some implementations, the flow restriction component comprises a tortuous path.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well, comprising:
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well, comprising:
In some implementations, each of the valves comprises a check valve device provided in the second-phase sleeve. In some implementations, each of the valves comprises a production-only check valve device and an injection-only check valve device provided in the second-phase sleeves. In some implementations, the check valve device comprises an axial poppet check valve, an axial dart check valve, an axial ring check valve, a circumferential dart check valve, a reed valve, or a combination thereof. In some implementations, the check valve device further comprises a biasing mechanism configured to provide a biasing force toward a closed position of the check valve device.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided in alternating relation along the well to enable frac-to-frac hydrocarbon recovery from fractured zones in the reservoir; wherein the production-only valves and/or the injection-only valves each comprise: a housing with a port for fluid communication therethrough; a flow restriction component in fluid communication with the port and configured to restrict a flow rate of fluid flowing therethrough; and a check valve device in fluid communication with the port and the flow restriction for providing one-way flow.
In some implementations, the flow restriction component comprises a tortuous path. In some implementations, the flow restriction component is provided by a sleeve that is mounted within the housing. The flow restriction component can have various other features as described herein.
In some implementations, the check valve device is provided in a sleeve channel defined by the sleeve. In some implementations, the check valve device comprises an axial poppet check valve, an axial dart check valve, a ring plug check valve, a reed check valve, or a circumferential dart check valve. In some implementations, the sleeve comprises a plurality of sleeve channels, each having a corresponding check valve provided therein. In some implementations, the sleeve is fixed with respect to the housing. In some implementations, the sleeve is slidable with respect to the housing between at least a first configuration and a second configuration. In some implementations, the check valve device is provided in the port of the housing. In some implementations, the check valve device is a radial poppet check valve.
In some implementations, the production-only valves and the injection-only valves are in fluid communication with a single well string comprising conduit sections that are interconnected together along the well, the well string providing the injection fluid during injection cycles and receiving production fluid during production cycles of the asynchronous frac-to-frac operation. In some implementations, the production-only valves are in fluid communication with a production conduit system, and the injection-only valves are in fluid communication with an injection conduit system that is fluidly isolated from the production conduit system in the well. In some implementations, the production conduit system and the injection conduit system are arranged in side-by-side relation to each other. In some implementations, the production conduit system and the injection conduit system are arranged concentrically with respect to each other.
In some implementations, both the production-only valves and the injection-only valves each comprise corresponding flow restriction components and check valve devices. Alternatively, only the injection-only valves or only the production-only valves could comprise the flow restriction components and the check valve devices.
In some implementations, the sleeve of each valve comprises a production-only check valve device configured for alignment with the port of the housing when the sleeve is shifted in one direction, and an injection-only check valve device configured for alignment with the port of the housing when the sleeve is shifted in another direction.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided in alternating relation along the well to enable frac-to-frac hydrocarbon recovery from fractured zones in the reservoir; wherein the production-only valves and/or the injection-only valves each comprise: a housing having a central passage and a housing wall with a port therethrough for fluid communication between the central passage and an exterior of the housing; and a sleeve mounted within the central passage of the housing, the sleeve comprises a sleeve channel and a check valve device cooperating with the sleeve channel for providing one-way flow therethrough, wherein the sleeve is positionable such that the sleeve channel is in fluid communication with the port of the housing and the central passage to provide fluid flow therebetween when fluid pressure enables the check valve device to move from a closed position to an open position.
In some implementations, the check valve device is an axial poppet check valve, a ring plug check valve, a reed valve such as an end or side reed valve, a circumferential dart check valve, or another types of check valve. In some implementations, the sleeve channel comprises multiple sleeve channel portions in parallel with respect to each other, each sleeve channel cooperating with a corresponding check valve device. The multiple sleeve channel portions can extend axially or circumferentially depending on the check valve construction that is used.
In some implementations, the sleeve is fixedly mounted within the housing. In some implementations, the sleeve is shiftably mounted within the housing and is shiftable between at least a non-aligned position and an aligned position in which the sleeve channel is in fluid communication with the port of the housing. The sleeves can be shifted remotely or using a downhole tool.
In some implementations, both the production-only valves and the injection-only valves comprise respective sleeves and check valve devices cooperating with the respective sleeve channels.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided in alternating relation along the well to enable frac-to-frac hydrocarbon recovery from fractured zones in the reservoir; wherein the production-only valves and/or the injection-only valves each comprise: a housing having a central passage and a housing wall within a port therethrough for fluid communication between the central passage and an exterior of the housing; and a sleeve mounted within the central passage of the housing, the sleeve comprising a flow restriction component including a tortuous path defined therein and being positionable to provide fluid communication between the port and the central passage.
In some implementations, the tortuous path comprises a groove in an outer surface of the sleeve. In some implementations, the tortuous path comprises a boustrophedonic pattern. In some implementations, the injection-only valves and the production-only valves each include a corresponding sleeve providing the tortuous path therein. In some implementations, the sleeve is fixedly mounted within the housing. In some implementations, the sleeve is shiftably mounted within the housing and is shiftable between at least a non-aligned position and an aligned position in which the tortuous path is in fluid communication with the port of the housing.
In some implementations, there is provided a hybrid process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided along the well to enable frac-to-frac hydrocarbon recovery from a first set of fractured zones in the reservoir; and concurrently with the asynchronous frac-to-frac operation, conducting a cyclical huff-and-puff operation comprising cyclically injecting injection fluid and producing production fluid from a cyclically-operated valve provided in the well in fluid communication with an isolated fractured zone that is hydraulically isolated from all other fractured zones of the reservoir.
In some implementations, the process further includes, prior to commencing the asynchronous frac-to-frac operation and the cyclical huff-and-puff operation, measuring at least one property of the fractured zones and determining: the first set of fractured zones having adjacent zone pairs that are in hydraulic communication; and the isolated fractured zone. In some implementations, the process further includes, during the asynchronous frac-to-frac operation and the cyclical huff-and-puff operation, measuring at least one property of the fractured zones and determining: the first set of fractured zones having adjacent zone pairs that are in hydraulic communication; and the isolated fractured zone.
In some implementations, if the isolated zone is determined to have become in hydraulic communication with another fractured zone, the process further comprises converting the cyclically-operated valve into an injection-only valve or a production-only valve or a closed valve.
In some implementations, if a fractured zones of the first set of fractured zones is determined to have become hydraulically isolated from the other fractured zones, further comprising converting the injection-only or production-only valve in communication with that fractured zone into a cyclically-operated valve or a closed valve.
In some implementations, the at least one property of the fractured zones comprises injectivity, pressure drop-off, or flow rates. In some implementations, multiple cyclically-operated valves are operated in respective isolated fractured zones along the well. In some implementations, each of the cyclically-operated valve, injection-only valve and/or production-only valve is in fluid communication with an adjacent fractured zone that corresponds to a single fractured stage along the well. In some implementations, each of the cyclically-operated valve, injection-only valve and/or production-only valve is in fluid communication with an adjacent fractured zone that corresponds to multiple fractured stages along the well. In some implementations, at least one of the cyclically-operated valve, the injection-only valve and/or the production-only valve is in fluid communication with an adjacent fractured zone that corresponds to multiple fractured stages along the well. In some implementations, at least one of the fractured zones is in fluid communication with multiple valves. In some implementations, prior to commencing the cyclical huff-and-puff operation, all of valves along the well are operated for the asynchronous frac-to-frac operation.
In some implementations, the process further includes, prior to commencing the asynchronous frac-to-frac operation and the cyclical huff-and-puff operation, the steps of: ceasing the primary production; deploying a tubing string down the well to run along a length thereof, the tubing string being configured for fluid flow therethrough and defining an annulus between an outer surface thereof and an outer casing of the well; deploying the valves down the well, wherein each valve is in fluid communication with the tubing string; and providing packers in the annulus to isolate each of the valves with respect to each other.
In some implementations, the cyclically-operated valve comprises a cyclical port for injection and production. In some implementations, the cyclical port is configured in a static open position during injection and production. In some implementations, the injection-only valves each comprise a housing with a port, and an injection check-valve device in fluid communication with the port, wherein the injection check-valve device is configured to allow injection fluid into the reservoir and prevents flow from the reservoir into the injection-only valve. In some implementations, the injection-only valves each comprise a sliding sleeve mounted within the housing and configured to slide therein, the sliding sleeve comprising the injection check-valve device for alignment with the port to provide a configuration for injection only. In some implementations, the production-only valves each comprise a housing and a port, and a production check-valve device in fluid communication with the port, wherein the production check-valve device is configured to allow production fluid into the valve from the reservoir and prevents flow of the injection fluid into the reservoir. In some implementations, the production-only valves each comprise a sliding sleeve mounted within the housing and configured to slide therein, the sliding sleeve comprising the production check-valve device for alignment with the port to provide a configuration for production only. In some implementations, the production-only valves and the injection-only valves have an identical construction wherein for each valve the sliding sleeve comprises the production check-valve device and the injection check-valve device located at different positions thereon, such that he sliding sleeve can be displaced to align either the production check-valve device or the injection check-valve device in order to configure the given valve as a corresponding production-only valve or injection-only valve, respectively. In some implementations, the sliding sleeves are displaceable by remote control. In some implementations, the sliding sleeves are displaceable by deploying a shifting tool downhole to engage and shift the sliding sleeve. In some implementations, the injection-only valves and the production-only valves each comprise a housing with a port; and a piston mounted within the housing and displaceable between a first position where a portion thereof occludes the port, and a second position where the first port is open for fluid communication therethrough. In some implementations, the valves each further comprise an actuator within the housing and configured to cause the piston to move between the first and second positions. In some implementations, the actuator comprises: a pump mounted within the housing and configured to move hydraulic fluid to cause the piston to move between the first and second position; a motor coupled to the pump to power the pump; and a power and control system coupled to the motor to provide power thereto and to control the motor between a first mode to cause the piston to move to the first position and a second mode to cause the piston to move to the second position, the power and control system being coupled to a command system at surface. In some implementations, each valve is configured to move only between a fully closed position corresponding to the first position and a fully open position corresponding to the second position.
In some implementations, the process further includes controlling each of the valves to be in the first position or the second position to enable the asynchronous frac-to-frac operation, such that: a first set of the valves is controlled to be in the first position during injection of the injection fluid and the second position during production of the production fluid, to provide the production-only valves; and a second set of valves is controlled to be in the first position during production of the production fluid and the second position during injection of the injection fluid, to provide the injection-only valves.
In some implementations, the production-only valves and the injection-only valves have an identical construction.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided along the well to enable frac-to-frac hydrocarbon recovery from a first set of fractured zones in the reservoir; and concurrently with the asynchronous frac-to-frac operation, conducting a cyclical huff-and-puff operation comprising cyclically injecting injection fluid and producing production fluid from a cyclically-operated valve provided in the well in fluid communication with an isolated fractured zone that is hydraulically isolated from all other fractured zones of the reservoir.
In some implementations, there is provided a hybrid process for producing hydrocarbons from a fractured reservoir via one or more wells, comprising: asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided in the one or more wells to enable hydrocarbon recovery from a first set of fractured zones in the reservoir; and concurrently cyclically injecting injection fluid and producing production fluid from a cyclically-operated valve provided in the one or more wells in fluid communication with an isolated fractured zone that is hydraulically isolated from all other fractured zones of the reservoir.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising:
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising:
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising:
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising:
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising:
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: providing a tubing string within the well and valves along the tubing string, each valve being actuatable between a fully open position and a fully closed position and being in fluid communication with a respective fractured zone of the reservoir; characterizing an injectivity of one or more of the fractured zones of the formation in accordance with sensed characteristics of an injection fluid that is injected through corresponding valves in the fully open position; based on the characterized injectivity of the one or more fractured zones, determining a first set of the valves for operation as injection-only valves, a second set of the valves for operation as production-only valves; and conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via the first set of injection-only valves and the second set of production-only valves provided along the well to enable frac-to-frac hydrocarbon recovery from the fractured zones in the reservoir.
In some implementations, the first set of valves and the second set of valves are determined to exclude any pair of valves for which the characterized injectivity indicated a hydraulic short-circuit. In some implementations, the first set of valves and the second set of valves are determined such that any pair of valves for which the characterized injectivity indicated a hydraulic short-circuit are both operated as injection-only valves or production-only valves. In some implementations, the first set of valves and the second set of valves are determined to exclude any valve for which the characterized injectivity indicated a hydraulic breakthrough. In some implementations, after conducting the asynchronous frac-to-frac operation for a first time interval, the first and second sets of valves are reversed such that the first set is operated as production-only valves and the second set is operated as production-only valves.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: providing a tubing string within the well and valves along the tubing string, each valve being actuatable between a fully open position and a fully closed position and being in fluid communication with a respective fractured zone of the reservoir; defining a first set of the valves for operation as injection-only valves and a second set of the valves for operation as production-only valves; conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via the first set of injection-only valves and the second set of production-only valves provided along the well to enable frac-to-frac hydrocarbon recovery from the fractured zones in the reservoir; and characterizing at least one property of one or more of the fractured zones of the formation in accordance with sensed characteristics. The process includes, based on the characterized property of the one or more fractured zones, determining at least one operating parameter of the asynchronous frac-to-frac operation. The operating parameter can include an operating schedule between injection and production modes; an operating flow rate or pressure of the injection fluid; an operating flow rate or pressure of the production fluid; and/or an operating mode of one or more of the valves as an injection-only valve, a production-only valve, a shut-in valve, or a cyclically operated injection-and-production valve.
In some implementations, the first set of valves is initially defined as odd-number valves along the well, and the second set of valves is initially defined as even-number valves along the well. In some implementations, the first set of valves is initially defined as even-number valves along the well, and the second set of valves is initially defined as odd-number valves along the well. In some implementations, the characterized property comprises fluid injectivity via one or more of the valves. In some implementations, the characterized property comprises pressure drop-off at one or more of the valves. In some implementations, the characterized property comprises a fluid temperature, pressure or flow property.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided along the well to enable frac-to-frac hydrocarbon recovery from a first set of fractured zones in the reservoir; wherein the production-only valves are in fluid communication with a production conduit system that receives production fluid during production cycles, and the injection-only valves are in fluid communication with an injection conduit system providing the injection fluid during injection cycles, the injection conduit system being fluidly isolated from the production conduit system in the well; for at least one transition phase between injection and production cycles, simultaneously injecting and producing via the well. In some implementations, the at least one transition phase comprises a corresponding transition phase for each transition between injection and production cycles. In some implementations, the transition phase comprises a first transition phase wherein production is decreased and injection is initiated, and a second transition phase wherein injection is decreased and production is initiated. In some implementations, the first transition phase is controlled such that the injection is initiated by flowing the injection fluid down the injection conduit system while production is ongoing, but the injection fluid does not flow through the injection-only valves until production is ceased. The overlap between the production and injection cycles can have various features, some of which are further described herein.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising: conducting an asynchronous frac-to-frac operation comprising asynchronously injecting an injection fluid into the reservoir and producing production fluid from the reservoir respectively via injection-only valves and production-only valves provided along the well to enable frac-to-frac hydrocarbon recovery from a first set of fractured zones in the reservoir; wherein the production-only valves and the injection-only valves are coupled to a closed loop hydraulic circuit; during each production cycle, operating the closed loop hydraulic circuit to open the production-only valves and close the injection-only valves; and during each injection cycle, operating the closed loop hydraulic circuit by reversing flow of hydraulic fluid therein to close the production-only valves and open the injection-only valves.
In some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising:
In some implementations, the radial poppet check valve further comprises a plug member mounted in the port and having a cavity in which the poppet member is located. In some implementations, the poppet member comprises a ball. In some implementations, the poppet member comprises a dart comprises a shank and a head. In some implementations, the fluid channel has a main portion extending through the shank and secondary portions extending from the main portion through the head and having openings therein. In some implementations, the openings of the secondary portions of the fluid channel are positioned to be spaced outward way from the sealing surface when the poppet member engages the same in the closed position.
It is noted that, in some implementations, there is provided a process for producing hydrocarbons from a fractured reservoir via a well that has been operated for primary production of hydrocarbons, comprising conducting an asynchronous frac-to-frac operation wherein the production valves and/or the injection valves have a check valve device in the housing and/or sleeve, and wherein the check valve device has one or more features as described herein. For example, the check valve device can include a radial poppet valve, an axial poppet valve, a side- or end-bending reed valve, a ring valve, a circumferential dart valve, a valve with a spring loaded sleeve, a check valve that has a member that moves radially outward to an open position, or a valve having another check valve device incorporated therein.
The present description relates to asynchronous frac-to-frac operations for recovering hydrocarbons from reservoirs that have been fractured. The asynchronous frac-to-frac processes can include various operational features and can be implemented using systems that include valves and other equipment designed to facilitate enhanced operations. In general, when referring to “fractured” reservoirs in the present description it refers to man-made fractures or “hydraulic fractures” as opposed to merely “naturally fractured” reservoirs.
In a fractured reservoir in which man-made hydraulic fractures have been created, a well can be equipped with a plurality of valves along its length, including injection-only valves and production-only valves. These valves can be the same in terms of their construction and are operated in injection-only and production-only modes, respectively; or different types of valves can be provided to enable the injection and production. The well may have been previously fractured using plug-and-perf, pinpoint, or other fracturing techniques and may have then been operated for primary production of hydrocarbons for a given period of time. There are multiple fractured zones in the reservoir along the well.
In some implementations, after primary recovery, equipment can be deployed to enable the asynchronous frac-to-frac operation. Once the equipment is deployed, the asynchronous frac-to-frac operation can begin. During an injection mode when fluid is injected into the well, the fluid is injected into some of the fractured zones via the injection-only valves while fluid injection is inhibited at the product-only valves. No production via the well occurs during the injection mode. Fluid injection is then ceased, and the well is switched to production mode. During production mode, mobilized or displaced hydrocarbons flow into the well via the production-only valves while production is inhibited via the injection-only valves. No injection into the well occurs during the production mode. It is also noted that primary recovery may in some implementations be accomplished with the same equipment used to enable the asynchronous frac-to-frac operation, as will be described in further detail below.
The asynchronous frac-to-frac operation can include a number of features for enhanced operation, such as a hybrid method where at least one cyclic valve is operated in injection and production modes to access hydrocarbons in an isolated fractured zone; implementing valves that have sliding sleeves that include check-valve devices to allow only production or only injection; using valves that can be remotely controlled between fully open and fully closed positions and controlling the valves based on data regarding properties of the fractured zones, fluid characteristics and/or flow behavior; and managing the asynchronous frac-to-frac of multiple proximal wells to avoid fluid breakthrough and optimize the overall multi-well process.
More details regarding various implementations of the asynchronous frac-to-frac processes will be described further below.
Referring to
In practice, the well 10 is initially drilled and completed (e.g., optionally with a cemented casing), subjected to multistage fracturing (e.g., plug-and-pert or other methods), and then put on primary production. Once primary production has run its course in terms of economic performance, the well can be shut in and then provided with additional completion equipment for the asynchronous frac-to-frac process. Thus, the inner conduit 16, valves 24, and packers 20 can be installed to convert the well from primary recovery to either secondary or tertiary recovery depending on the injected fluid that is used.
As shown in
Each isolated segment 22 can be the same length along the well or the can be different lengths. A given isolated segment 22 can cover a fracture stage or multiple fracture stages, and can include one valve or multiple valves along its length. To design the isolate segments 22 and the arrangement and spacing of the valves 24 in each isolated segment, the fractured reservoir can be characterized (e.g., permeability, fracture complexity).
Referring now to
In this manner, the well 10 is operated between injection and production modes where mobilizing or displacement fluid is injected through the first set of valves and then production fluid is recovered via the second set of valves. Various implementations, equipment and operating schemes leveraging this asynchronous frac-to-frac operation will be described in greater detail below.
In some implementations, the injection and production ports 32, 34 that are provided in the sleeves 30 include check-valve devices configured for one-way flow of fluids. The check-valve devices facilitate operation of the injection and production valves 24A, 24B for asynchronous frac-to-frac operations.
As shown in
Various types of check-valve devices can be used and integrated into the sliding sleeves 30. For example, the check-valve devices can include a ball check valve, diaphragm check valve, flapper valve, stop-check valve, lift-check valve, spring check valve, reed check valve, and so on. Depending on the construction and design of the valve and its sleeve as well as its function of inhibiting injection or production, different types of check-valve devices can be used. The check-valve devices can also be incorporated in various different orientations and in relation with ports having different shapes, sizes, and orientations.
The type and construction of the outflow and inflow check-valve devices can be the same or different. For example, the outflow check-valve devices can be specifically designed for the given fluid to inject and/or the injection operating conditions, whereas the inflow check-valve devices can be specifically designed for the fluids to be received from the reservoir. In frac-to-frac operations, the injection fluid is typically vapour phase and thus the outflow check-valve devices can be designed to accommodate vapor outflow while inhibiting liquid inflow. The injection fluid can be supercritical CO2, field gas (mainly methane and having relatively low miscibility in the oil in the reservoir), or enriched field gas (methane with added light components that make it more miscible in the oil). The injected fluid is preferably a compressible fluid in vapour phase. The outflow check-valve devices can thus be designed to allow flow of such fluids from the well into the fractured reservoir without detrimentally impacting desired properties of the fluid. For example, when supercritical CO2 is used, the outflow check-valve devices can be sized and configured to avoid a pressure drop that would bring the CO2 below the critical point. In addition, supercritical CO2 has a density that is similar to water while having low viscosity, and thus the outflow check-valve devices designed for water flow or similar liquid flow could be used for such an injection fluid. It is noted that the outflow check-valve devices can also be designed to provide a predetermined pressure drop depending on the injection pressure and various injection parameters for the process. Furthermore, the produced fluid is primarily liquid phase (e.g., oil with some water) and thus the inflow check-valve devices can be provided to accommodate liquid inflow while inhibiting vapor outflow. The produced fluid can also include some free gas being present in increasing amounts if the flowing bottom hole pressure depresses below the bubble point, and the inflow check-valve devices could be designed accordingly to minimize vapor inflow.
In addition, the check-valve devices can be configured based on the operating pressures within the well and within the reservoir during injection and production modes. For example, the outflow check-valve devices can be configured to allow flow only when central passage 26 pressure exceeds annulus 18 pressure (e.g., exceeds by at least certain predetermined pressure or “cracking pressure” e.g., 0.5, 1, 2, 3, 4 or 5 psi). The inflow check-valve devices can be configured to allow flow only when annulus 18 pressure exceeds central passage 26 pressure (e.g., exceeds by at least certain predetermined pressure or “cracking pressure” e.g., 0.5, 1, 2, 3, 4 or 5 psi). The check-valve devices can be designed and configured to require a certain pressure gradient between the central passage 26 and the annulus 18 to cause fluid flow. For example, some check-valve devices can be designed to require only a slight pressure gradient to enable fluid flow, while other check-valve devices can be designed to require higher pressure gradients to enable fluid flow. The inflow and outflow check-valve devices can be designed to require different pressure gradients to enable fluid flow (e.g., the minimum pressure gradient for inflow being higher than the minimum pressure gradient for outflow, or vice versa).
The check-valve devices can have various features and designs. For instance, the check valve device can have various designs and orientations and can be integrated into the other components of the injection and production valves. Some of the design features and embodiments of check valve devices will be described in more detail below in relation to
The central passage 26 pressure during injection would normally be greater than reservoir 12 pressure but would not exceed fracturing pressure of the reservoir. The central passage pressure 26 during production would be less than reservoir 12 pressure. For example, for a well with 8000 feet vertical depth having a reservoir pressure gradient of 0.5 psi per foot and a fracture gradient of 0.65 psi per foot, optimal injection pressure may fall in the range from 4,000 to 5,200 psi with a preferred value of 4,680 psi or 10% less than the upper limit of injection pressure, and optimal production pressure (also called the flowing bottom hole pressure) may fall in the range from 100 to 4000 psi, with a preferred value of about 500 psi.
Furthermore,
In addition, some or each of these valves 24 could be configured such that the sleeve 30 has other positions, such as a closed position or a fully-open position with no check-valve functionality. The sleeve 30 may be placed into other positions using a stroking tool, actuatable using an electric motor, or metered hydraulic pump, for example. It is also noted that two-position valves may be run in tandem in a zone or isolated segment, one valve being selectable between an inflow and a closed position, and the other valve selectable between an outflow and a closed position. This arrangement would allow any particular zone to be fully closed. Similarly, multiple valves having the same function may be run within a zone to provide redundancy, for example to mitigate for a damaged valve.
In addition, each, some or all of the valves could also be configured to have binary functionality. Such binary valves could have a closed position and an open position, where the open position for injection-only valves enables injection and inhibits production while the open position for production-only valves enables production and inhibits injection (e.g., via appropriate check-valve devices). In addition, multiple binary valves could be placed in a given isolated segment, each with a closed position and a functional position. For instance, in an isolated segment there could be at least one binary valve is an injection-only valve and at least one binary valve is a production-only valve, thus allowing the choice between injection or production for that segment for the asynchronous frac-to-frac operation. The isolated segment could also include at least one additional valve that is operable between a closed position and an open position, to enable other processes such as cyclic injection and production via the same valve. By providing multiple binary valves each with a different possible functionality within a same isolated segment, an operator can select the desired functionality once the properties of the fractured reservoir zones have been tested. An example system that includes multiple binary valves 24A, 24B for each segment 22 is shown in
It is also noted that various other valve constructions are possible. For example, as shown in
Another alternative example is shown in
It is also noted that multiple different types of valves could be provided for a single tubing string deployed in the well, such that one or more valves have sleeves (as in
Examples of a valve with a sleeve are described in Canadian application No. 3,079,570 (Johnson et al.), which is incorporated herein by reference; and
Examples of a valve that operates without a sleeve are described in WO 2019/183713 (Johnson & Kalantari), US 2019/0235007 (Williamson & Tajallipour) or WO 2019/148279 (Kalantari et al.); and
Turning now to
It is also noted that valve systems having certain features as described in WO 2018/161158 (Ravensbergen et al.), which is incorporated herein by reference, could be used in this type of implementation generally shown in
It is also noted that the system could be notably simplified by providing each valve to be shiftable to only one mode, either injection or production (e.g., see sleeves 30 of the valves in
Turning now to
Referring back to
When manual shifting is performed, it can be done after primary production is complete and the well is shut in to allow a work string that includes completion equipment to be fed into the well. Using the work string, the sleeves can be shifted into the desired configuration for testing the fractured zones using fluid injection and eventually to shift into the operational configuration. The downhole work string can then be removed, and the asynchronous frac-to-frac operation can be commenced with fluid injection or production. The valves can then remain in a single operational position during these operations. If the position or configuration of the valves is to be changed, then operations can be ceased, and another work string can be deployed to shift the sleeves to a modified configuration.
When the valves are installed prior to primary recovery, the manual workover operation can simply shift the valve sleeves into the desired positions prior to commencing the asynchronous frac-to-frac operation. When the valves have not been installed, the workover operations will also include installing the inner conduit, packers, and valves using a downhole work string or other equipment for this purpose. For instance, packers can be set using a setting tool or hydraulic pressure, and sleeves can be shifted using a shifting tool. The downhole work string can be deployed using coiled tubing or wireline, depending on the application and the equipment being installed.
When remote shifting is performed, deploying a work string downhole is not required for shifting the sleeves or otherwise moving components of the valve. For remote control, the valves are connected to a downhole or surface control unit electrically or by other means whereby signals can be sent to the valves for control purposes. In one example, the valve can be a flow control apparatus as described in WO 2019/183713 (Johnson & Kalantari), US 2019/0235007 (Williamson & Tajallipour) or WO 2019/148279 (Kalantari et al.), which are incorporated herein by reference.
Referring to
In this implementation, hydraulic fractures are first placed at desired locations along a well in a reservoir. The fracturing can be done using multistage fracturing techniques, e.g., using type coiled tubing shifted sleeve valves each containing two sleeves. The coiled tubing shifted sleeve valves can be of the type and design provided by NCS Multistage Inc, for example.
The valves can each include a housing with a frac port provided through the housing wall. In addition, the valves can include a first sleeve for covering and uncovering a frac port, to be used for closing the sleeve for isolation and opening the sleeve for hydraulic fracturing, primary production and unregulated injection. The valves can also include a second sleeve having one or more check-valve devices for permitting injection through the valve only while well pressure exceeds formation pressure, or a third sleeve having one or more check-valve devices for permitting production through the valve only while well pressure is less than formation pressure. In other words, each valve can include a first-phase sleeve for fracturing and production during primary production, and a second-phase sleeve that can be designed either for injection-only or production-only and thus has a check-valve device enabling either injection or production.
After hydraulic fracturing, the well is placed on production by opening only the first sleeve for up to all zones. This is the primary production phase.
After primary production, the well can then be configured for asynchronous injection and production by shifting the second-phase sleeves to regulate flow through the frac ports located in the housings.
The well is completed using an array of dual sleeve valves, each having a first-phase sleeve and a second-phase sleeve. In one implementation, the valves are arranged such that alternating valves in the array have either a second sleeve (injection-only) or a third sleeve (production-only). Thus, sleeve valves having a first and second sleeve are for injection, while sleeve valves having a first and third sleeve are for production. Second sleeves may contain a check-valve device for permitting injection outflow only while well pressure is greater than formation pressure and for preventing inflow while well pressure is less than formation pressure. Second sleeves may further contain a flow control device for regulating injection by limited-entry flow restriction in order to distribute injection fluid outflow along the length of the well. Third sleeves may contain a check-valve device for permitting production inflow only while well pressure is less than formation pressure and for preventing outflow while well pressure is greater than formation pressure. Third sleeves may further contain a flow control device for reducing the throughput of non-oil fluid phases including both or either of water and/or gas. Production sleeve valves may further contain a screen for restricting or excluding the production of formation sand or fracturing proppant.
The flow control device for the injection sleeves can include a tortuous path that induces a pressure reduction on the flow stream as a product of the flowrate, for example. Each individual interval can achieve an equilibrium condition, balanced by the reservoir injection pressure, reservoir injection flow capacity and tortuous path flow resistance on the downstream side, and by the casing injection pressure on the upstream side. With each of these factors being fixed during any particular time interval, the flowrate through any particular injection sleeve flow control device can be determined (or controlled) as a dependent governed variable of the pressure difference across the tortuous path flow resistance. The practical effect of this relationship is two-fold. Firstly, since the tortuous path flow resistance increases with pressure difference, rate of injection into intervals that are connected to parts of the reservoir having a lower flow resistance will be selectively limited, relative to other parts of the reservoir having higher flow resistance which may be disposed to the well. Secondly, the upstream casing injection pressure may be maintained at a higher value, thus increasing the injection rate into intervals disposed to parts of the reservoir having higher flow resistance. The tortuous path can be provided to have a boustrophedonic configuration, for example.
Some examples of two-sleeve valves and tortuous paths and related structures and equipment are described in WO 2018/161158 (Ravensbergen et al.) and can be adapted for use in the present technology.
A conceptual example of this type of implementation is illustrated in
This implementation can present benefits since after primary production the time, resources and infrastructure to implement the configuration in asynchronous frac-to-frac mode are less compared to retrofitting operations that can use an inner conduit and packers, as described herein. When manually-shifted sleeves are used as the production-only and injection-only sleeves 30, then after primary production a work string can be deployed to shift the sleeves into their desired positions. When remotely operated sleeves are used as the production-only and injection-only sleeves 30, then after primary production the sleeves can be shifted into their desired positions using a control system at surface, thus avoiding any additional downhole work using a work string and associated rig.
It is also noted that this implementation could be performed using valves that enable fluid communication using components other than shiftable sleeves. For example, valves using a piston-type system (e.g., see
It is also noted that the valves and asynchronous frac-to-frac process could be implemented in a well drilled into an existing waterflooded or EOR field. In this case, the valves would be installed prior to any production from that newly-drilled well. In such a case, the first production from that well may not be definable as “primary” production.
In other implementations, the well can be retrofit with appropriate equipment after primary production. A retrofit system can be provided for tubing deployment and positioning to provide the production-only and injection-only positions. A retrofit system could alternatively be configured to be autonomously controlled to provide the valves in production-only and injection-only positions.
In one implementation, hydraulic fractures are first placed at desired locations in a reservoir. The fracturing can be done using multistage fracturing techniques, e.g., using type coiled tubing shifted sleeve valves. The coiled tubing shifted sleeve valves can be of the type and design provided by NCS Multistage Inc, for example, and each valve can include a single sleeve.
After hydraulic fracturing, the well may be placed on production by any method and for any period of time. Any hydrocarbon production method could be used and may or may not involve the injection of fluid though the well or an adjacent well.
After a period of primary production, the production is stopped and an array of valves (e.g., valves that may include sleeves) is installed such that the well may be configured for asynchronous injection and production for example by shifting the sleeves into a first position or a second position to regulate flow through each valve. These new valves are sized to have a diameter that is smaller than the casing and sleeve valves that were used for the fracturing and primary recovery. Appropriate conduits and packer are also provided. An example configuration of this is shown in
In the first sleeve position injection flow can be regulated using a check-valve device for permitting injection flow through the valve only while well pressure is greater than formation pressure and for preventing inflow while well pressure is less than formation pressure. In the first sleeve position, flow may be further regulated by channeling it through a flow control device for regulating injection by limited-entry flow restriction in order to distribute injection fluid outflow along the length of the well.
In the second sleeve position, production flow is regulated using a check-valve device for permitting production flow through the valve only while well pressure is less than formation pressure and for preventing outflow while well pressure is greater than formation pressure. In the second sleeve position, production flow may be further regulated by channeling it through a flow control device to reduce the throughput of non-oil fluid phases including both or either of water and/or gas. The second sleeve position may further divert flow through a screen for restricting or excluding the production of formation sand or fracturing proppant.
Sleeve positions may be selected to configure alternating valves in the array in a production configuration and an injection configuration. Sleeve positions may be selected to configure valves in the array in any other preferred arrangement of either production configuration or injection configuration, for example to isolate a direct hydraulic short circuit between adjacent zones in which case it may be desirable to conduct injection or production at two or more adjacent zones.
In this tubing-deployed valve implementation, the valves are deployed along with an inner conduit and packers, as generally described above for
In some implementations, the valves are operated in a remote and autonomous manner. As with the above implementation, hydraulic fractures are first placed at desired locations in a reservoir using coiled tubing shifted sleeve valves or any other method. After hydraulic fracturing, the well may be placed on production by any method and for any length of time. After a period of primary production, an array of remotely controlled interval control valves (“ICVs”, for example Qumulus™ ICVs) may be installed to position each ICV in isolated communication with a zone comprising an individual hydraulic fracture or a group of adjacent hydraulic fractures to manage asynchronous injection and production by selecting the state of each individual ICV as needed to regulate flow at each zone. Examples of such ICV type valves are shown in
ICV states, whether opened or closed, may be selectable from surface. ICV states, may be selected to place alternating valves in the array in a production configuration and an injection configuration. ICV states may be selected to place alternating valves in the array in either a production configuration or an injection configuration. ICV states may be selected to place ICVs in any arrangement of either production configuration or injection configuration, for example to accommodate a direct short circuit between adjacent hydraulic fractures in which case it may be desirable to conduct injection or production in two or more adjacent zones which are not sealed outside of the completion. ICV states may be selected for each ICV in isolation of what states are selected for any of the other ICVs in the array, based on what is needed to manage the enhanced oil recovery (EOR) scheme. The ICVs may contain permanent sensors, for example to measure the pressure and temperature in the annulus at the location of the ICV.
In practice, the ICVs may be controlled using an artificial intelligence (AI) system trained on data obtained from operations in order to optimize the overall system. Various factors could be taken into consideration (e.g., measured properties, actions taken and corresponding effects, etc.) as relevant input data for Al system training, and for AI-assisted implementation of asynchronous frac-to-frac processes optionally combined with cyclic processes. The ICV array may be managed autonomously with the assistance of an AI system or another type of control system.
The array of ICVs may be installed within a single well or within multiple wells in proximity. Where ICVs are installed in multiple wells in proximity they may be used to manage injection and production collectively from the wells.
When considering the hydraulic fracture locations, hydraulic fractures subject to inter-frac flooding for waterflood or EOR may share a common well or may share a system of wells.
In some implementations, a hybrid process can be used to recover hydrocarbons via the well by performing asynchronous injection and production via some valves that communicate with through-fractures (natural fracture or hydraulic fracture) fluidly interconnected fractured zones and cyclic injection and production (also known as “huff and puff”) via other valves that communicate with fluidly isolated fractured zones. This process therefore incorporates both through-fracture displacement and cyclic fluid injection and production. It is noted that the through-fracture displacement case can benefit from the same recovery mechanisms as the cyclic fluid injection and production case, at the fluidly interconnected fracture reservoir rock surface.
More particularly, some injection zones may directly hydraulically communicate to some production zones by interconnected fast flow or high permeability pathways, for example, a natural fracture, interconnected natural fracture network or interconnected hydraulic fractures. Still other injection zones of the reservoir may be connected to a reservoir region that is isolated or contained, that is, not directly connected to other production zones by an interconnected fast flow pathway, so that fluid (e.g., gas) injected into these zones over the period of an injection cycle will remain entirely or substantially contained in the reservoir zone into which it was injected. In this case, cyclic injection may be performed into selected intervals that are connected to contained reservoir regions to conduct a cyclic injection EOR scheme (also known as “huff and puff”); while fluid is asynchronously injected into non-selected intervals to displace fluid through the fast flow pathways for recovery via the production-only valves during the subsequent production mode. It is noted that “fast” communication can be viewed in contrast to “slow” communication through the reservoir rock matrix, which is desirable for volumetrically efficient EOR.
In this hybrid setup, a portion of EOR incremental oil production would occur from the cyclic injection zones and a portion would occur from the production zones that receive injection fluid and displaced oil from interconnected fast flow pathways.
Conceptual examples of such a hybrid configuration is shown in
It is also noted that injection and production zones do not have to share the same well. By way of example,
When two adjacent wells are used, the valve arrays of the two wells could be arranged in a staggered relation to each other or directly across from each other. Various operating schemes can be implemented. For example, as shown in
An example advantage of a hybrid process is that it can facilitate operating at higher or closer-to-optimal overall injection pressures.
In some implementations, the injection fluid is a compressible fluid that is a gas or in a supercritical fluid state. For instance, the injection fluid can be a supercritical fluid, such as CO2, at reservoir conditions. The injection fluid can be relatively hot. The injection fluid can be miscible or immiscible with the oil in the reservoir. The injection fluid could be field gas or enriched field gas, methane, methane blends, nitrogen, air, ethane, light gaseous hydrocarbons, or other gases or mixtures of such gases that may be suitable for secondary or tertiary recovery. The selection of the fluid can be based on various reservoir properties. The injection fluid can also be a multiphase fluid, again depending on the EOR method being used. As mentioned above, it is noted that the valves, the check-valve devices and/or the flow control devices, as the case may be, can be designed and implemented depending on the type of injection fluid to be used.
It is also noted that depending on the type and properties of the injection fluid, the asynchronous frac-to-frac process could be considered a secondary or tertiary recovery process. An applicable type of EOR for asynchronous frac-to-frac operations in tight oil reservoirs would be miscible gas displacement, since gas pressure may be used to store energy and then release it gradually during production mode. Further, during an asynchronous frac-to-frac production cycle, the beneficial interaction of injected gas would continue at the interface between it and the reservoir fluid. In addition, particularly for light tight oil, secondary recovery using waterflood may not be feasible and therefore one could proceed straight to miscible gas EOR using asynchronous frac-to-frac following a primary production period.
Once the valves are set in their production-only and injection-only modes, the asynchronous frac-to-frac process can be conducted over a period of time. A number of variables can be monitored during the process to assess properties and performance indicators. In response to the monitoring, the asynchronous frac-to-frac process can also be adjusted if desired. For example, if two adjacent injection-only and production-only valves are experiencing a hydraulic short circuit, then one possible adjustment to mitigate this issue is to convert both valves to the same mode, i.e., both being injection-only or production-only. The hydraulic short circuit could be via a primary cement channel, a failed packer isolation, a complex hydraulic fracture in the reservoir, a natural fracture or fault in the reservoir, or a too-high permeability pathway. Other actions can also be taken in addition to grouping the short-circuited valves together to operate in a single mode, such as modifying other proximal valves to accommodate the new grouping (e.g., by converting such proximal valves from injection to production mode or vice versa). For example, if the short-circuited valves are both converted to injection-only valves, at least one other proximal valve (e.g., a valve that is adjacent to one of the short-circuited valves) can be converted from an injection valve to a production valve.
Other adjustments are also possible when a hydraulic short circuit is detected between two or more valves that are operating in different modes. For instance, one or both of the valves can be closed (e.g., one could close the injection-only valve that is the source of the hydraulic short circuit, close the production-only valve that is receiving the fluid, or both). In another example, a chemical gel, a polymer or water can be selectively placed via the injection valve to mitigate the hydraulic short circuit. In yet another example, the production valve could be intermittently closed to permit favorable relative permeability modification. In another example, one could isolate the zones and reduce injection pressure to attempt partial or full fracture closure, e.g., notably in the case of a complex hydraulic fracture or natural fault causing the hydraulic short circuit. Depending on the reason for and the location of the hydraulic short circuit, appropriate mitigation strategies can be implemented to adjust operations. In addition, different adjustments can be conducted simultaneously or concurrently (e.g., closing a valve and changing the mode of another valve), and the operation can be monitored during and/or after adjustment to assess the effectiveness of the adjustment strategy. In this manner, the asynchronous frac-to-frac process can be modulated over time to adapt to issues, such as hydraulic short circuits.
It is also noted that the asynchronous frac-to-frac process can be modulated over time to change the configuration of the production and injection valves, not necessarily in response to a hydraulic short circuit or other detected characteristics. For instance, after a given operating period, all or some of the valves of the asynchronous frac-to-frac process of one or more well can be switched between modes to “reverse” fluid flows. Thus, injection valves become production valves, and vice versa. In another example, the groupings of the valves can be changed (e.g., a series of alternating production and injection valves can be reconfigured so that there are pairs or groups of adjacent injection valves and/or production valves alternating along the well; or vice versa where a series of alternating pairs or groups of production and injection valves can be reconfigured so that there are individual adjacent injection valves and/or production valves alternating along the well). In other words, the valves can be changed from an operating pattern such as I-P-I-P-I-P-I-P to an operating pattern such as I-I-P-P-I-I-P-P; or vice versa such as I-I-I-P-P-P-I-I-P-P to I-P-I-P-I-P-I-P-I-P, for example. Various other reconfigurations are also possible where at least some valves are converted from one mode to another. It is also possible to change other variables of the asynchronous frac-to-frac process, such as fluid injection pressure, flowing bottom hole pressure, injection fluid type, and so on.
Adjustment of valves from one mode to another (e.g., injection, production, closed) can be facilitated by using remotely operated ICVs, so that the adjustments can be conducted quickly, responsively and without workover operations. Alternatively, valve adjustments can be performed via workover operations where a work string is deployed downhole to manually shift the valves.
Example embodiments of check valve devices are described in more detail below. Depending on design, the check valve device may be incorporated into the housing port or the sleeve of the valve.
Referring to
Referring to
Referring to
The poppet member 2002 can have various configurations.
In addition, the housing port and the plug member can be designed to facilitate sealing engagement of the poppet member at different locations. For example, referring to
Regarding the radial poppet check valves, each housing port around the housing wall can be provided with a corresponding check valve. In addition, the valve can also include a sleeve mounted inside the housing 28. The sleeve can include a flow restriction component, such as a tortuous path, as described elsewhere herein. The flow restriction can restrict fluid flowing into or out of the valve. The check valve can be designed in account for the level of flow restriction.
Still referring to
Referring now to
Turning now to
The sleeve 2030 can include multiple sleeve channel portions. For example, the sleeve 2030 can include circumferential portions, such as the circumferential chamber 2044 and the discharge portion 2040, as well as tubular portions 2046 such as the portions that interconnect the discharge and circumferential portions. As shown in
Referring now to
Referring to
Still referring to
The sleeve channel 2032 for the reed check valves of
The reed check valves illustrated in
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While
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It is noted that certain valve components can be designed and configured so that a given component can be assembled and used in conjunction with an injection check valve or a production check valve. As an example,
The check valve devices can be integrated with various valve implementations in different ways. It is also noted that multiple check valve devices could be integrated into a given valve, where the check valves are of the same or different type. For example, multiple check valves of the same type can be provided in a sleeve or a housing port of a give valve to operate in parallel with reach other. In addition, check valves could be provided in series with each other. Further, in some implementations, different check valves can be provided on a same valve, e.g., a radial poppet check valve could be provided in the housing port in addition to an axial poppet or ring in the sleeve that communicates with the housing port. Multiple check valve devices in a single valve can enable redundancy. For instance, serial check valves can be useful to ensure the check is maintained even in the event one of the valves becomes caught in the open position (e.g., due to debris or mechanical failures). Check valves in parallel can be useful for providing dimensions for the desired flow capacity while accounting for space considerations of the valve, since having a single checked channel may require an overly large dimensions for the target fluid flow while having multiple parallel channels each having a corresponding check valve can be provided with smaller dimensions while providing the overall size for the target fluid flow.
In addition, certain check valve types can be selected based on various factors, including the structural features of the valve, the use in a production-only valve or an injection-only valve, the operating parameters of the process including injection rates and fluid properties, and the reservoir properties. For example, in one implementation, the production-only valves can each include a check valve integrated into the housing port (e.g., radial poppet of
Furthermore, the injection-only valves can be designed and configured for the particular injection fluid and/or injection flow rates based on process design. One benefit of providing both flow restriction (e.g., via a tortuous path) and check valve functionality on each valve is that the flow restriction can facilitate distributing the fluid pressure among the injection-only valves during an injection cycle, thereby reducing preferential “over-injection” through valves communicating with fast flow or high permeability pathways of the reservoir and under-injection through the other valves. Since distribution of fluid pressure is enhanced by the flow restrictions, there is more surety that all of the valves will receive sufficient fluid pressure to move the check valves to the open position during an injection cycle. This can also facilitate the design of injection check valves since the operating windows of injection cycles can be more predictable and consistent for the injection valves. Similar benefits can also be applicable for the production-only valves in terms of distributing the inflow of the production fluid among the valves and ensuring that all of the check valves of the production-only valves are open during a production cycle.
The check valve devices can also be configured so that, in the open position, certain fluid flow is promoted while inhibiting others. For example, hydrocarbon flow can be promoted while discouraging water flow; and/or liquid flow can be promoted while discouraging gas flow. This type of phase flow control functionality can be incorporated into the check valves, or enabled by a distinct component of the system.
As mentioned above, different check valves can be used for different valve constructions. The following provides a summary for example integration of check valve devices with different valve systems.
For example, valves such as the valves shown in
Valves such as the valves shown in
Valves such as the valves shown in
In addition, the valves that include at least one check valve device as described herein can be used in the context of asynchronous frac-to-frac processes, as well as other processes. For example, the valves can be used for stimulation, production and enhanced oil recovery of oil and gas wells. The valves can be used newly completed or recompleted wells. The valves can be used for asynchronous frac-to-frac processes as well as synchronous frac-to-frac processes where appropriate completions are provided for simultaneous injection and production. The valves can also be used controlling production inflow or injection outflow in other processes for hydrocarbon mobilization, stimulation and recovery. For valves that also have constructions for fracturing, the frac fluid flow path can be separate from the production flow path (e.g., side by side controlled by position of the inner sleeve, which can be positioned in open/closed/produce positions with a three-position sleeve).
In addition, check valve devices can facilitate solutions to a number of problems. For example, embodiments of the valve assemblies with integrated check valve devices can mitigate the problem of fluid losses during production or intervention operations by preventing fluid loss out of a well bore; can mitigate the problem of production loss from a high-pressure zone or a hydrostatic column to a lower pressure zone in a well; can enable an operator to produce a well from the highest pressured area until equalizing with lower pressured areas of the well, when all intervals will contribute to production; can mitigate the problem of diverting liquid/gas/polymer (e.g., CO2 for miscible flooding) into certain portions of a well and not others, by enabling downhole mixing between hydraulic fractures and then producing oil or gas from alternating fractures; can facilitate stimulation and one or more of the following new drill wells and facilitate cemented or not cemented and one or more of the following: (i) control hydrostatic column of fluid to prevent or reduce fluid leak off in a well during stimulation and production, (ii) frac-to-frac operating with controlled injection and production in/out of specific intervals during EOR operations to improve or enhance ultimate oil recovery (UOR) (e.g., inject in to every even interval and product in every odd interval), (iii) control production flow based on fluid characteristics, (iv) control flow based on liquid or gas characteristics (viscosity, temp, oil saturation, phase, rheology). The valves can also be designed so that a first sliding sleeve can uncover a port for stimulation, a second sliding sleeve can then move into position opposite a port which contains a check valve device used to control, restrict, or stop flow in or out, and where the entire process can be reversed to go back to stimulate, inject fluid for flooding, or stop flow, if desired. Certain embodiments of the valve can be used for the following applications: cemented in place, open hole, stimulate, production, open-close, restrict or stop flow in one direction.
In some implementations, the check valve device would be designed to open under minimal flow such that the check valve is relatively sensitive to fluid activation. The check valve device can be designed so that it opens in response to a small fluid pressure and the spring is just strong enough to return the poppet to the closed position in response to zero pressure differential across the poppet. Alternatively, the check valve device could be designed without a spring and returns to the closed position when sufficient pressure is provided on that side of the valve. It is also noted that higher spring forces can facilitate re-closing of the check valve, which could provide some advantages for example in terms of reliability and debris removal. The cracking pressure of the check valve can be designed based on various parameters, and can be the same or different for valves along the well. Depending on the design, the check valve may have a closing pressure that is roughly equal to its cracking pressure or notably different. The design can depend on trade-offs between potential chattering, poppet (or other component) wear and increased flowing pressure versus low closing pressure. The flowing pressure can be additive with any uphole or downhole pressure drops. For the present application, a minimal restriction may be desired in the check valve yet sufficient to fully drive the poppet off of its seat to prevent chattering. Furthermore, if the biasing mechanisms is present, it can take various forms, such as a helical spring, a wave spring, a beam spring, a sealed air cushion, a resilient material, among others.
Further valve designs can be used in the context of the processes and system described herein. An example valve and completion system design are described in U.S. provisional application No. 63/092,656 (Werries & Powell) which is incorporated herein by reference. An example of this valve is shown in
Referring to
Another example of a valve includes a hydraulic system instead of an electrical system for actuation. Such a valve can be similar to the valve of
Another example of a valve assembly is described in U.S. provisional application No. 63/122,098 (Johnson et al.), which is incorporated herein by reference. This valve assembly has a valve sleeve that can be moved over housing ports by using an electrical cable that activates a hydraulic system so that hydraulic fluid can force the sleeve to move between open and closed positions, for example. This valve assembly can have various features similar to those of the hydraulic embodiment described above in terms of the sleeve, housing, ports, and hydraulics, although the hydraulic valve has a hydraulic connection that runs to surface instead of an electrical connection.
In some implementations, the asynchronous frac-to-frac process is operated such that production and injection never occur at the same time. In other words, production is completely ceased prior to the start of the subsequent injection cycle, and the injection is completely ceased prior to the start of the subsequent production cycle. Thus, the injection cycle and the production cycle of the process do not overlap. When using completion systems where the production and injection fluids flow through the same conduit, this type of operation would occur naturally as one cannot have flow in both directions via the same conduit at the same time. In this implementation, there may also be a gap in between production and injection cycles where no production or injection occurs as surface equipment is readied for the subsequent cycle, for example.
However, when a dual-conduit completion system is used, the asynchronous frac-to-frac process can be operated with some overlap where there is production and injection occurring simultaneously. In a dual-conduit completion system, the production and injection conduits can be provided in a side-by-side configuration, with the production conduit being in fluid communication with the production-only valves and the injection conduit being in fluid communication with the injection-only valves. Alternatively, one conduit can be provided within the other, e.g., concentrically. In a dual-conduit completion system, the overlap between production and injection cycles may be slight or more pronounced. In addition, the production and injection cycles can be operated asynchronous such that during a given production cycle there is at least a period of time where injection completely ceases, and during a given injection cycle there is at least a period of time where production completely ceases. However, the asynchronous frac-to-frac process could also be operated where injection and production never complete cease, but are rather reduced during the opposite cycle of the process. One benefit of using a dual-conduit system in asynchronous frac-to-frac operations is that each cycle can be initiated and ramped up at the same time as the preceding cycle is being ramped down, thereby enabling less downtime between cycles which can lead to faster overall recovery. For example, the injection cycle can be initiated with fluid being injected down the well and starting to flow through the injection-only valves while the preceding production cycle is winding down yet while production fluid is still flowing to surface. In addition, it may be desirable in some cases to enable heat transfer between the injection and production fluids as they pass counter-currently with respect to each other during the overlap time between cycles. In addition, by continuing a small amount of injection and production at all times, it can also be possible to detect certain events or issues more rapidly than if the injection or production were completely shut down during the opposite cycle.
Furthermore, while the methods and systems disclosed herein have been described in relation to hydrocarbon recovery operations, it is also noted that the methods and systems could be adapted for other applications, such as solution mining, geothermal operations, among others, where fluids are injected and/or produced from a subterranean formation. The methods and systems can also be adapted for recovering various types of hydrocarbons from hydrocarbon-bearing formations.
This application is a national stage application under 35 U.S.C. § 371 and claims the benefit of PCT Application No. PCT/CA2020/051780 having an international filing date of 21 Dec. 2020, which designated the United States, which PCT application claimed the benefit of U.S. Provisional Patent Application No. 62/951,307 filed 20 Dec. 2019, the disclosures of each of which are incorporated herein by reference in their entireties.
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| PCT/CA2020/051780 | 12/21/2020 | WO |
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| WO2021/119852 | 6/24/2021 | WO | A |
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