The present disclosure relates to controlling downhole systems with wireless telemetry.
Lift systems for unloading liquids from a well include pumps, such as electrical submersible pumps (“ESP”), which pressurize the liquid downhole and propel it up production tubing that carries the pressurized fluid to surface. Sucker rods and plunger lift pumps are also sometimes employed for lifting liquid from a well. In wells having an appreciable amount of gas mixed with the liquid a two-phase fluid may form and gas is sometimes separated from the fluid upstream of the ESP and routed to surface separately from the pressurized liquid. In some instances, compressor pumps are employed to pressurize the two-phase fluid to lift it to surface. A gas lift system is another type of artificial lift system, and that injects a lift gas, typically from surface, into production tubing installed in the well. The lift gas is usually directed into an annulus between the production tubing and sidewalls of the well, and from the annulus into the production tubing. Gas lift is commonly employed when pressure in a formation surrounding the well is insufficient to urge fluids to surface that are inside of the production tubing. By injecting sufficient lift gas into the production tubing, static head pressure of fluid inside the production tubing is reduced to below the pressure in the formation, so that the formation pressure is sufficient to push the fluids inside the production tubing to surface. Fluids that are usually in the production tubing are hydrocarbon liquids and gases produced from the surrounding formation. Sometimes these fluids are a result of forming the well or a workover and have been directed into the production tubing from the annulus.
The lift gas is typically transported to the well through a piping circuit on surface that connects a source of the lift gas to a wellhead assembly mounted over the well. Usually, valves are mounted at various depths on the production tubing for regulating the flow of lift gas into the production tubing from the annulus. Some types of these valves automatically open and close in response to designated pressures in the annulus and/or tubing. An injection pressure operated (“IPO”) gas lift valve is one type of automatic valve for injecting lift gas into production tubing. IPO valves are usually designed to close in response to pressure in the annulus, and with staggered closing pressures so the lowermost valve is set to close at the lowest annulus pressure. Production pressure operated (“PPO”) gas lift valves are another type of automatic valve used for gas lift injection. PPO valves have staggered set pressures; but operate in response to pressure inside the production tubing rather than in the annulus, and with the lowermost valve closing at the highest set pressure. Another type of valve is motor operated and controlled by signals delivered from a remote location. IPO and PPO gas lift systems are not controlled from surface, are unpredictable, and typically require being pulled from the well to adjustments to optimize the system. Current surface-controlled gas lift systems require a physical communications line to the surface, either hydraulic or electric, in order to be in continuous communication with the surface.
Disclosed herein is an example of a computer implemented method of operating a well system, which includes controlling operation of a lift gas valve unit that is disposed inside of a wellbore based on wireless communication received proximate the lift gas valve unit, monitoring inside the wellbore for a designated condition within the wellbore, and upon sensing the designated condition, autonomously controlling operation of the lift gas valve unit from within the wellbore. The designated condition includes a downhole operating scenario, such as, a suspension of the wireless communication, a reduction of pressure within production tubing in the wellbore indicating a loss of fluid production from the wellbore, pressure in the annulus indicating a blow down, an instruction received, and if pressure in the production tubing is greater than or substantially equal to pressure in an annulus outside the production tube in excess of a designated period of time. Examples of autonomously controlling operation of the lift gas valve unit include injecting lift gas based on pressure inside of production tubing in the wellbore, injecting lift gas based on pressure in an annulus outside the wellbore, unloading liquid from within the wellbore, communicating with sensors inside the wellbore, and combinations thereof. Autonomously controlling operation of the lift gas valve unit further optionally includes controlling the injection of lift gas based on pressure inside of production tubing in the wellbore, controlling the injection of lift gas based on pressure in an annulus outside the wellbore, and combinations thereof. In this example, controlling operation of the lift gas valve unit is based on information received from the sensors. In an alternative, monitoring is performed proximate the lift gas valve unit. In one example, the method further includes removing the lift gas valve unit from within the wellbore, installing a replacement lift gas valve unit in the wellbore having logics for autonomous operation, and communicating wirelessly with the replacement lift gas valve unit. In alternatives, the method further includes resuming control of operation of the lift gas valve unit based on wireless communication.
Also disclosed herein is an example of a non-transitory computer readable storage medium having executable code stored thereon for controlling an injection of lift gas into a wellbore, the executable code having instructions causing a processor inside a wellbore to perform operations including, monitoring for a designated condition within the wellbore, and controlling operation of a lift gas valve unit from within the wellbore when the designated condition is identified. Examples of the designated condition include a downhole operating scenario, such as, a suspension of the wireless communication, a reduction of pressure within production tubing in the wellbore indicating a loss of fluid production from the wellbore, pressure in the annulus indicating a blow down, an instruction received, and if pressure in the production tubing is greater than or substantially equal to pressure in an annulus outside the production tube in excess of a designated period of time. Examples of autonomously controlling operation of the lift gas valve unit include injecting lift gas based on pressure inside of production tubing in the wellbore, injecting lift gas based on pressure in an annulus outside the wellbore, unloading liquid from within the wellbore, communicating with sensors inside the wellbore, and combinations thereof. Autonomously controlling operation of the lift gas valve unit further optionally includes controlling the injection of lift gas based on pressure inside of production tubing in the wellbore, controlling the injection of lift gas based on pressure in an annulus outside the wellbore, and combinations thereof. Monitoring is optionally performed proximate the lift gas valve unit. The lift gas valve unit optionally includes a first lift gas valve unit, and wherein the executable code further includes instructions causing the processor to control a second lift gas valve unit. In an example, the executable code comprising instructions is updated by a wireless signal that is received in the wellbore.
An example of a well system is disclosed also, and that includes a communication system that provides selective communication between surface and inside a wellbore that intersects a subterranean formation, a processor in communication with the communication system, the processor disposed on surface outside the wellbore, and a valve station disposed in the wellbore. The valve station of this example includes a valve actuator, a valve member coupled with the valve actuator and selectively moveable in response to an operation of the valve actuator, and a valve controller in operational communication with the valve actuator and programmable with commands for autonomous operation of the valve actuator when out of communication with the processor. The communication system optionally includes wireless telemetry. In an alternative, the valve station is a first valve station, the well system further has a tubing encased conductor and a second valve station in communication with the first valve station via the tubing encased conductor. In an embodiment, one or more of the first and second valve stations are mounted on a tailpipe that depends from a straddle packer disposed in production tubing mounted in the wellbore. Examples of a valve member include a gas lift valve, an interval control valve, an inflow control device, and an outflow control device.
Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
While subject matter is described in connection with embodiments disclosed herein, it will be understood that the scope of the present disclosure is not limited to any particular embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents thereof.
The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term “about” includes +/−5% of a cited magnitude. In an embodiment, the term “substantially” includes +/−5% of a cited magnitude, comparison, or description. In an embodiment, usage of the term “generally” includes +/−10% of a cited magnitude.
It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation.
The present disclosure involves controlling a gas lift valve from the surface-controlled without a wired connection to the surface. This is an improvement over current surface-controlled gas lift systems that require a physical communications line to the surface, either hydraulic or electric. The present disclosure also provides an improvement over current IPO and PPO gas lift systems that are unpredictable and require being pulled from the well to adjustments to optimize the system, and is applicable for retrofit applications or those in which there are limited wellhead penetrations.
In examples of the system and method described herein, limited and discontinuous wireless communication is used to optimize and operate wells with surface-controlled gas lift systems. This is accomplished by automating some of the downhole behaviors and adjusting those behaviors from the surface. There are more complexities to consider, and those will be discussed later in this disclosure.
An example is to imitate the behavior of an IPO or a PPO gas lift valve. Each of these is set up at the surface before installation to open and close at certain pressures. This is typically accomplished by either adjusting a spring or gas charge, and the setpoints can change with temperature as well as the pressure opposite of its control pressure. Some problems include: (1) IPOs are supposed to open/close based on annulus pressure, but tubing pressure has some effect on the actual open/close pressures. (2) PPOs are supposed to open/close based on tubing pressure, but annulus pressure has some effect on the actual open/close pressures. (3) Gas lift valves Open % changes with absolute and differential pressures; may not be ideal. (4) Gas lift valves have some hysteresis, but not adjustable or ideal. (5) Gas lift valves are prone to chatter. (6) IPOs require a well design with a pressure reduction as injection passes each stage to make sure the valves close as gas is injected deeper into the well.
In current surface-controlled gas lift valves, the user at the surface can watch pressure and temperature data coming from downhole gas lift valves and make appropriate adjustments at the surface. This requires real time monitoring and control of the downhole components.
Many forms of telemetry exist to communicate from the bottom of a well to the surface. Some methods are more energy intensive and some less. Some are slower and others faster. Some with have a limited scope and some broader. In general, more energy intensive systems can travel through more complex mediums and can communicate data faster, less energy intensive systems are limited to simple mediums and transmit data slower.
For instance, cellular phones can transmit data very fast, but they are traveling through open air. If instead those signals had to travel through water, the data rate and electromagnetic signal would require much more power and be much slower. It is true that the same mode of communication is not required in both directions. For instance, a transmitter at the surface can have much more power than a transmitter downhole. Or in some situations, the downhole components may have the ability to add a pressure signal to the flow stream inside of the tubing. Furthermore, the data rates can change at various points in the well's life based on the flow and compositions of the fluids in the tubing and annulus. Additionally, all communication will be lost at some points in the well's life. The present disclosure utilizes some of the positive characteristics of an IPO or PPO valve, which are intended to operate automatically in response to downhole pressure and temperature, while still allowing an operator to adjust their behavior using limited and intermittent communication. Furthermore, it allows for a mechanism to reset functionality if the settings are adjusted beyond acceptable limits.
Known surface control systems have been proven in dozens of applications over the prior decade, but they require relatively fast closed loop control. Wireless communications schemes are readily available for communication between surface and downhole. However, they have limitations with respect to data rate, available mediums, available power, and distance. Some of the more available wireless technologies are only good for certain well scenarios, such as flowing during production. When production stops, these cease to be valid. The present disclosure allows the best features of surface control gas lift to be realized wirelessly despite the shortcomings of wireless technologies and the lack of communication at various stages in the life of the well.
The present disclosure relates to gas lifted wells that are controlled and optimized from the surface without need for a dedicated signal or control line to the surface. Surface control has thus far required a communication conduit to adjust downhole equipment from the surface and communicate information from downhole sensors back to the surface. This closed loop communication allows wells to be optimized taking into account feedback from downhole sensor or other decision making tools. This feedback loop required for surface control of downhole systems can happen very quickly with mechanical or electrical communication conduits, such as an electric or hydraulic lines between the surface system and the downhole components.
Instead of hard wired electrical or hydraulic lines, this system utilizes wireless communication. This disclosure is independent of the form of wireless communication. Instead, it accounts for the fact that some forms of low power wireless communication are quite slow. For a closed loop surface-controlled gas lift system to date, data must travel from the surface to the downhole equipment as well as from the downhole equipment up to the surface. A disruption of either can negatively affect production.
Because there is more power available at the surface, some forms of communication may transmit data downhole more quickly than data is transmitted back to the surface. In other scenarios, there might be significant power limitations restricting how quickly the downhole system can take readings to detect a pressure signal. If there is limited bandwidth in either leg of the closed loop, it can affect how well the system can optimize or even operate in a gas lifted well.
Furthermore, wells change over time. The fluids and phases change in both the tubing and annulus, the pressures diminish, flow slows, and wells are shut in. Different types of wireless telemetry may be optimal for each of these various stages, and those that are most universal can also have the slowest data rate. There may even be situations in which the chosen wireless communication method cannot communicate at all, such as shut-in. All situations over the life of the well are considered.
Some aspects of gas lift completions may offer advantages over other flow control intelligent completions when it comes to wireless technology. Regarding power for example, high pressure gas provides energy for power generation that needs to be shed anyway; and concerning telemetry, unloading valves can include repeaters to receive and retransmit a signal. However, some gas lift scenarios complicate wireless telemetry downhole. Varied combinations of shut-in, multiphase flow in the tubing, compressible and then incompressible fluids in the annulus, and salinity all complicate, slow, and block many forms of telemetry.
Non-Surface-Controlled Conventional Gaslift Equipment (IPOs and PPOs):
Conventional gas lift valves (IPOs and PPOs) do not require a feedback loop. Each reacts to downhole pressure and temperatures in a prescribed manner. However, they have problems such as multi-pointing, requiring unique calibration before running in hole that cannot be changed as the well changes, losing their calibration over time, not fully utilizing the pressure available at the surface, not being adjustable if the well parameters are not fully understood, cannot be optimized for the life of the well, etc. Therefore, conventional gas lift valves cannot provide an optimized production solution. To elaborate on wells with IPOs, they are each adjusted to close at subsequently lower pressures with each deeper IPO in the production string. Furthermore, there is a margin of error in setting these due to variations in temperatures, pressures, depths, densities, leakage, and other factors that might change over time. A safety factor usually is included in the set pressures to guarantee that valves will close and injection will work its way down the well as the density is reduced in the tubing. The net effect of the safety factory is to reduce the injection pressure available at the bottom of the well. This leads to reduced injection depth, less drawdown of the formation, and less production. PPOs also have their own problems. They can chatter, multipoint, allow reduced amounts of injected gas, and offer no feedback as to the depth of injection.
Surface-Controlled Gaslift:
Gas lift is a form of artificial lift technology that has been utilized for over 150 years. Relatively little significant development has occurred over the last quarter of that time, but surface-controlled gaslift is quickly bringing gas lift into a new era by enabling real time control and monitoring without intervention. Surface control of gas lift provides advantages that might not be immediately obvious, such as increased production, reduced Greenhouse Gas emissions, improved safety, better understanding of the reservoir, and increased ultimate recovery.
As the acceptance of digital intelligent artificial lift (“DIAL”) and other intelligent completion technologies has grown over previous decades, so have the technological demands placed on them. Most widespread intelligent flow control systems have been almost exclusively dependent on hydraulic power as the motive force until recently. With the advent of more robust and proven electronics, technology is starting to shift towards electric systems for flow control. This electrical control has been essential for gas lift because multiple stations with multiple choke sizes can be controlled quickly with a single communication conduit downhole.
Drivers for Wireless Control:
The shift towards electric intelligent completions and gas lift has brought with it interest in wireless control of downhole systems. Wireless motoring systems have been installed in wells for decades and have a great track record for some specific scenarios, but flow control and varying well conditions bring additional complications to gas lift; such as (1) increased power requirements; (2) reduced production if a power harvester uses downhole flow for power generation; and (3) varied mediums can reduce communication depth, data rates, and reliability. In general, surface control gas lift system provides a great opportunity for new wells. However, there are thousands of older wells all of which require retrofit. Though these wells have various configurations, a wireless solution would enable control in many of them.
The following is a non-exhaustive list of examples of wireless communications that do not require EM waves. Ships and submarines use sonar to transmit through the ocean, which works well in expansive incompressible fluids. Measurement While Drilling (MWD) systems use distinct pressure pulses, which work well for incompressible liquids with significant energy. Some downhole gauge systems use acoustic signals through the tubing or casing, which can work well for shorter distances. Inductive systems have been utilized for extremely short distance. Others have used pressure perturbations, and some systems even pump or drop down RFID chips to send commands downhole. There are examples of noisemakers that are electrically regulated but amplified by flow to send a signal.
Each of these types of telemetry are well suited for specific environments. Some are good for gas, some are good to get through metal, some are good for short range, some are good for formations without salinity, others might be acceptable for some distance through saline fluids. Further, the range of data rates can vary from bits per day to megabits per second. The key is finding the communication scheme that is right for any particular situations. Sometimes that can include a combination of technologies for different locations or phases of a well. For instance, a well might use TEC for a main bore and inductive technology for the short hop to a multilateral zone.
Some environmental considerations that tend to determine the ideal form of telemetry for given conditions are salinity, gas liquid, multi-phase, compressibility, solids, ferromagnetic or conductive material, formation (if traveling outside of wellbore), and depth. Complicating things further, some of these factors might change over the life and stages of a gas lifted well. These stages are included in Table 1 and Table 2 below.
Also considered is that at some points in a well's life, communication may not be available at all. In such situations it is often desired to ensure that the system can be brought online and oil production and optimization resumed when desired.
Stages of a Gaslifted Well:
As previously mentioned, there are many stages in the life of a well. Types of wireless telemetry that best fits some set of stages might not work well in other stages. In some situations, they type of telemetry available for some stages might not be feasible with the limited power available. In the present disclosure is a wireless surface-controlled gas list system that is operational in all stages in a well's life despite limited band-with and delayed communications, loss of communication (temporary or permanent), These stages of a well's life to be considered are included in Table 1 and Table 2. These are separated into: (1) Production Stages: the stages of well production in which the well spend most of its life; and (2) Transitory Stages: the stages in which the well is transitioning (unloading, shut in, blowing down the annulus, etc).
Power for a Wireless Solution:
Any wireless solution requires power to receive and interpret information and commands, take readings of its environment, actuate downhole mechanisms, and transmit information. This power can come from electrical storage downhole, electrical power generated downhole, mechanical or chemical energy storage, or a combination of the above.
Furthermore, any power system should consider the phase of a well's life to which it applies. If the well will be under constant production, perhaps no downhole power storage is required. If instead a well will sit dormant for long periods of time, more power storage will be required. There might even be cases where some portions of the same well might have different power requirements than other portions.
As with telemetry, Table 1 and Table 2 provide examples for determining relevant technologies over the life of the well once the project has been better defined and is underway.
Electrical Storage:
Batteries provide a very practical form of electrical storage downhole, but have limitations, of life span, size, and temperature ratings. Life and size go hand-in-hand. The battery's stored energy will drain with usage and time, but more batteries can be added to increase the energy capacity. However, that also increases the size of the overall package. When utilizing batteries downhole, temperature can also be a big factor. In the past it has been a struggle for batteries to operate for lengthy periods of time at temperature, but significant research has been going into battery technology of late. Options which include replacing battery packs via slickline or wireline have also been discussed in the industry.
Power Generation:
Electrical energy can be generated downhole for storage or immediate use. Dozens of ideas for downhole power generation have been researched and tested over the years including combinations of mechanical rotation, mechanical waves, thermoelectric, piezoelectric, and just about anything else that can be imagined.
Practical solutions for downhole power generation include a fluid or gas driven rotating device (such as a turbine) and a mechanical to electrical conversation device (such as an alternator). In general, devices such as downhole turbines are thought to have a limited life due to debris and general wear. Therefore, such devices have also been designed in formats such that moving parts can be removed and replaced via wireline when needed. Another shortcoming of any type of rotating device being driven by downhole fluids is the inherent restriction which reduces production potential. Some designs have provided a bypass when not needed or variable fins, both of which add complexity.
Mechanical and Chemical Energy Storage:
Power can also be stored via mechanical or chemical means. For downhole completion tools, mechanical energy storage has typically been in the form of atmospheric chambers and chemical energy storage in the form of power charges. In general both of these are used as motive forces rather than for communications, and both only supply a limited number of actuations. A rechargeable option includes a compressible fluid or one that energizes a hydraulic chamber with a piston acting against a spring.
Combinations of Power Storage and Generation:
Engineering considerations for power include storage and operating temperatures, mechanical envelope, using non-electric energy storage, lifetime, power requirements, fluid type, solids production, available flow, and available pressure differential. In examples, power is supplied downhole using downhole power generation and energy storage, and that considers requirements over the applicable stages of a well's life. In examples, the complete system is operated using battery power alone, which can be replaced by changing the batteries, some combination of downhole components, or the entire downhole assembly.
Mechanical Installation:
The mechanical system is optionally installed initially along with the production string or afterwards as a retrofit assembly. Installation with the production string is straight forward, and there are several options that will be mentioned for retrofit. As previously mentioned, examples of applying this disclosure include use in retrofit completions. Included is a straddle system along with a system meant to fit into standard side pocket mandrels. Hanging a system off of an anchor is another option. A through tubing straddle is a commercially available set of packers for sealing off an opening in a piece of tubing or casing. Auxiliary downhole components are optionally installed between these packers or below the anchor, in this case would include at least a power source, gas lift valve, and form of telemetry. Examples of these straddles include the BB and BR Straddles that are commercially available from Halliburton (www.halliburton.com).
A difference between these two solutions is the mechanical envelope. A straddle or anchor solution would offer more room for electronics, actuators, and batteries. Example visual summaries of each of these systems' installations are shown in
Another option utilizes a straddle to hold the power sources and use a lower tailpipe to hang off the gas lift valves. An advantage to such a system is that there is one power harvester through which all of the gas flow passes, and all of the other sections could share power via power generation and storage in this section (
Surface-controlled gas lift valves are available today. However, they require a form of communication from the surface to downhole equipment. Conventional gas lift systems with IPOs and PPOs are also available and require no communication, but they cannot be adjusted over time nor provide optimized production without intervention. Furthermore, they inherently limit production because they do not allow the full pressure available at the surface to maximize the depth of gas injection to the maximum possible depth.
The present disclosure provides an optimized solution while eliminating a mechanical or electrical conduit to the surface and allows for the use of slow telemetry that might not otherwise allow for fast enough closed loop control to meet the needs of a gas lift system. Surface-controlled gas lift with a hydraulic conduit or electrical line are used for optimized gas lift. However, the electrical line and/or hydraulic conduit limits its ability to be installed in retrofit applications or new completions which might now allow such electrical or hydraulic conduits. Conventional gas lift valves do not require an electrical or hydraulic conduit for control or feedback, but they also cannot be adjusted without pulling the completion. Furthermore, they inherently do not provide an optimized solution as they cannot allow gas to be injected at the deepest for a given available surface gas pressure. As previously discussed, wireless systems are also available, but many are too slow to allow for an efficient real time closed loop gas lift control system. Furthermore, they are not functional for all of the well stages listed in Table 1 and Table 2 above.
Examples of the system and method disclosed herein provides a gas lift system that is selectively autonomous, so that it can make its own decisions and take actions regarding closing, opening, or a variable choke rate of a valve through which lift gas is injected into a well. Similarly, in embodiments the system is imbued with means for operating autonomously when designated conditions are sensed in the well and otherwise act under the control of an operator or system processor. For the purposes of discussion herein, operating autonomously at certain times and at other times operation being controlled, is referred to as semi-autonomous. Examples of designated conditions include when communication between surface and downhole is suspended. Examples of operating autonomously include obtaining conditions in the well and imitating how an IPO (or PPO) valve would operate under the same or similar conditions in the well. In examples, the step of imitating includes use of a controller and/or processor downhole programmed to analyze wellbore conditions and identify a resulting action or operation of an IPO (or PPO) valve. The system can use downhole tubing pressure, annulus pressure, and temperature to make such decisions on its own, but the parameters affecting how it makes those decisions can be adjusted from the surface. Because real time decisions are being made downhole at the valves rather than the surface, the decisions can be made more quickly regardless of the potential use of a slow telemetry system. Instead, the telemetry system is used to adjust the parameters by which those decisions are made. Furthermore, the system does not require the same pressure reduction per station as required by conventional IPO systems (which are by far the most common systems used to date). Instead, the surface system can command downhole valves to lock open or closed at various points in the wells life to allow full surface pressure to be utilized and increase the depth of injection. The present disclosure provides the ability to install downhole gas lifted valves in a well that do not require electrical or hydraulic control lines. This allows these valves to be utilized in retrofit gas lift systems as well as completions that do not have the facility to provide well head penetrations for electrical or hydraulic conduits.
An advantage of the present disclosure is that well operations continue over a period of time when some types of communications are not operative at certain points in the well's life, such as when the well is shut in or when the well has various sets of fluids in its tubing or annulus. Some types of telemetry can communicate regardless of the well status. However, the system is programmable to act independently at times when the chosen communication system is unavailable until such a time that the communication can be regained. There are numerous systems available capable to provide communication between downhole tools and surface. An inexhaustive list of the technologies include electromagnetic signals, pressure pulses, pressure perturbations, acoustic signals in tubing, and even RFID chips. Some of these systems communicate one way and others communicate in two directions. However, none of these include a system with downhole equipment that can make its own decision as to when to provide an actuation, that decision being made using parameters of which can be adjusted from the surface.
The installation and means of conveyance are not critical nor are the types of downhole completion or workover equipment used. It can be installed on straddles, on an anchor, in a side pocket, or anything else appropriate. An advantage of the disclosed system and method is the wireless surface control of a downhole flow control system with limited or intermittent telemetry.
In one embodiment, this system includes individual surface-controlled gas lift stations and a processor with independent decision making ability that is optionally based on parameters related to pressures (tubing and annulus), temperatures, and any other sensor data available. Time is also a consideration. If the gas lift station has not received signals for some amount of time or infers that there is no production, it can act based on that each station has the ability to send and/or receive data and/or commands to/from the surface. The parameters controlling the actions of each gas lift station are selectively adjusted with commands from the surface. Additionally, each gas lift station is optionally, battery operated, has a power harvesting system, or both; equipped with one or more forms of telemetry; in communication with other gas lift stations so that signals sent by one gas lift station is receivable by another station.
To explain when a well operator might want to adjust the parameters of the semi-autonomous gas lift valve, some details are optionally considered regarding an IPO's operation. IPOs are carefully calibrated to open and close at a certain injection pressure. They begin to open when there is a high hydrostatic pressure in the annulus. Then they close as the well is unloaded and pressure drops in the tubing and annulus. This means that the available injection pressure at the surface needs to be well defined and not change over time. Sometimes there are situations where higher injection pressures may be available after an initial installation. Ideally, that additional injection pressure could be used to inject gas deeper in the production string and increase drawdown. Unfortunately, an IPO in the string eliminates the ability to utilize that extra gas pressure because an increase in annulus pressure will just cause an upper DIAL Unit to open and bypass the deeper IPOs and DIAL Units. In such a scenario, a signal could be sent down to the upper semi-autonomous gas lift valves to lock closed. Once locked, the surface injection pressure can be increased providing more pressure to the lower valves and deeper injection. Another option would be to send down a signal adjusting the operating parameters to a higher pressure. Once these upper semi-autonomous valves have locked closed or their values changed, another challenge can present itself. If the well is subsequently shut in and communications are interrupted, there may no longer be a way to unload the well to restart production since the upper valves may be locked shut or their parameters adjusted such that they cannot open with the available surface pressure. In such cases, a safety feature can be included to reset to conservative parameters under various situations such as: (1) senses no pressure in the annulus; (2) senses the same pressure in tubing and annulus for some amount of time; (3) senses more pressure in tubing than annulus; (4) receives some alternate type of communication applicable while shut in (large pressure pulse such as from an explosion or impact or implosion, or combination thereof, pump down RFID ball or tracer, etc.); (5) lack of a periodic signal to maintain the current set parameters; (6) something similar to the above; or some combination of the above.
To reiterate, some telemetry scenarios that are most applicable to gas lift wells might not be available during a temporary shut-in. Some examples for such situations might be a combination of one or more of the following, for example, if some valves have been locked closed, they can be reset by some non-production scenario, such as tubing pressure dropping or annulus pressure being blown down. That would open the valves and allow production to be restarted despite there being no communication. Another option is for the system to require a periodic signal from the telemetry system to maintain the adjusted parameters. If that signal is not received, the system would resort to the base parameters set for each surface-controlled semi-autonomous gas lift station. Another form of telemetry could be included for non-flowing situations (drop or pump something down tubing, pressure pulse, EM pulses, etc.). If tubing and annulus pressure are the same for some amount of time, the parameters would reset. An optional form of resetting to default values includes using available sensors, such as using pressure values to infer shut in or the lack of a signal to reset the adjusted parameters. In an example of resetting, operational parameters of the gas lift station are adjusted so that there is production from the well, or the well is capable of production. In some scenarios resetting involves the gas lift station identifying that the well is non-operational, such as due to a pressure setting in the gas lift station that either prevents an injection of lift gas, or allows an injection of lift gas that interferes with production from within the well (e.g., a gas lift station at a shallow location that is locked or in a failsafe mode to be full open or fully closed and prevents production from deeper in the well).
In alternatives, each gas lift valve does not act independently. For instance, they can be electrically connected to each other, and communicate to surface via a single wireless system. In this case, all units could share battery power or even energy harvesting when applicable as well as communicate directly with each other. There could also be a single logic module to direct the individual gas lift valves.
Another option would be to include the ability for individual semi-autonomous valves to receive signals (wireless or hard wired) from each other and act accordingly. The main adjustment typically available before an IPO installation is the test rack-opening pressure. However, there are variations in when the valves open, how much they open at certain pressures in the tubing and/or annulus, the differential pressure between the tubing and annulus, and the temperature. This is also true of when the valve closes. An example of the decision-making process described herein includes the portions of this IPO operation that are advantageous and leave off the portions that are deleterious.
This technology is also applicable to different sorts of downhole systems such as Interval Control Valves (ICVs), Inflow Control Devices (ICDs), Outflow Control Devices (OCDs), etc. In each of these, there would default operational values and instruction that could be overridden or adjusted by communications from the surface though they might not be the same as those for gas lift valves.
In an alternative, a low rate telemetry is used to optimize a well by moving some of the logic to semi-autonomous downhole units. Embodiments of a low rate telemetry include transmitting and/or receiving a data point per hour, per day, or slower; and examples of a data point include an instructional command, a response to a query for information (e.g., temperature, pressure, flow rate, etc.), or a signal acknowledging receipt of a communication. This means that despite low feedback rates on well conditions, the system is self-adjustable when there are sudden changes in injection pressure, reservoir pressure, injection rate, etc. At the same time, long term control parameter adjustments can be made to account for longer term changes in the reservoir such as depletion, change in water cut, or gas production. Furthermore, there are ways to reset these values to defaults in situations where communication is lost and the system needs to reset.
In an example embodiment this system includes: individual gas lift stations; operates on batteries; and acts like an idealized virtual IPO (each will have its own processor and can make decisions independently based on parameters related to pressures (tubing and annulus), temperatures, and any other sensor data available). The parameters controlling the actions of each downhole valve are selectively adjustable by commands from the surface. Examples include opening/closing pressures in tubing/annulus, amount of time pressures are at given levels before an action happens, or the amount it opens. The semi-autonomous valves can be reset to conservative values. For instance, it can reset if the valve has not received signals for some amount of time, infers that there are no communications, or determines the well is shut in. Each station has the ability to receive and possibly send data and/or commands to/from the surface, even if such information is slow and sporadic.
Another variation includes a series of stations connected via electric lines but with no communications conduit to the surface. In this situation stations could communicate with each other via the TEC but together would communicate to the surface with a wireless telemetry system. One generator and/or battery pack could be used to supply all stations. Though they would be programmed with logic not identical to PPOs, this is also applicable to ICVs, ICDs, OCDs, Circ Valves, etc.
In an alternative, when the wellbore is in a communication mode communication occurs between the surface and downhole valve, and when in a non-communication mode the downhole valve is out of communication with surface. In examples, the wellbore is in a communication mode when the wellbore is not producing, e.g., when no fluid is flowing in or being produced from the wellbore (such as when the wellbore is shut in). Alternatively, the wellbore is in a communication mode when the wellbore is producing, e.g., when fluid is flowing within or from the wellbore. In a further alternative, the wellbore is in a communication mode only when the wellbore is not producing or is shut-in, or only when the well is producing or not shut in. In an embodiment, operation of the downhole valve or of the wellbore does not change instantaneously with a change between a communication mode and a non-communication mode. Instead, a delay occurs, such as to allow for adjustments of the downhole valve when updated instructions or parameters are received downhole upon the change of a communication mode. In a non-limiting example of such a delay, the downhole valve operation is based on previously received parameters. Optionally, the downhole valve continues to operate based on the previously received parameters until an operational stage is completed, such as unloading of the wellbore (determined by time, pressures, temperatures, or some other signal) at which point the new parameters take effect. These parameters could adjust the open/close behavior of a valve or even lock the valve opened or closed. Further optionally, the data (e.g., pressure and temperature) is stored and sent when the wellbore is in a communication mode.
Referring now to
The lift gas is injected into the wellbore 12 from a lift gas system 32, which includes a source of lift gas 34, such as a tank of natural gas, an adjacent well, or a transmission line, and an injection line 36 shown having an end distal from the tank 34 inside the wellbore 12. Optionally included with the system 10 are automatic gas lift valves 381, 2 inside the annulus 24 and having exit ports inside the production tubing 20 for delivering lift gas 26 into the production tubing 20. In embodiments gas lift valves 381, 2 are IPO and/or PPO type valves. Sensors 40, 42 are also in the wellbore 12, which sense conditions within the annulus 24, production tubing 26, or both. Example conditions include temperature, pressure, or both. In the example shown, sensors 40, 42 are in signal communication with a controller 44 on surface, and alternatively, are in wireless communication with one or more of the gas lift valve units 221-n. Communication lines 46,48, which in an example are elongated conducting members, are shown having ends connected with controller 44. In embodiments, the processor 44 is part of an information handling system, and further includes memory accessible by the processor, nonvolatile storage area accessible by the processor, and logics for performing each of the steps described herein. Opposing ends of one or both of lines 46, 48 are in communication with a modem 50 shown included with wellhead assembly 28, and alternative locations for modem 50 include, on surface and inside wellbore 12, such as proximate wellhead assembly 28. Ends of lines 46, 48 distal from controller 44 are optionally in communication with sensors 40, 42. Controller 44 is in selective wireless communication with one or more of valve units 221-n via modem 50 and one or more of lines 46, 48. Examples of wireless communication include electromagnetic waves, acoustic waves, fluid pressure pulses, electrical signals through casing, acoustic signals through tubing, radio frequency identification (“RFID”), etc., and in the form of digital or analog data. For the purposes of discussion herein, wireless communication that transmits signals between the valve units 221-n and controller 44 at a rate and capacity for closed loop operation of the valve units 221-n is deemed high quality transmission.
Referring now to
An advantage of one or more of valve units 221-n being in wireless communication with surface is that replacement does not require disconnection or reconnection of any hardwire communication lines. An example of replacing a one or more of the valve units 221-n is shown in a side sectional schematic view in
Alternatively, and as shown in a side sectional view in
In a non-limiting example of operation, lift gas 26 (
Referring now to
The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. Optionally, wireless signals are transmitted to one or more of the gas lift valve units 221-n with commands to lock the valve in an open configuration, a closed configuration, or a choke configuration. Alternatively, the autonomous operation of one or more of the gas lift valve units 221-n depends on the type of designated condition identified by the processing system 100 (or controller 62). For example, a designated condition of loss of communication could result in a “safe mode” autonomous operation in which the valve assembly 52 (
This application claims priority to and the benefit of co-pending U.S. Provisional Application Ser. No. 63/397,459, filed Aug. 12, 2022, the full disclosure of which is incorporated by reference herein in its entirety and for all purposes.
Number | Date | Country | |
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63397459 | Aug 2022 | US |