Patent Application
20140251623
Embodiments usable within the scope of the present disclosure relate, generally, to systems, methods, devices, and compositions usable within a wellbore, and more specifically, to systems and methods for fracturing a subterranean formation to stimulate production (e.g., of hydrocarbons) therefrom.
To stimulate and/or increase the production of hydrocarbons from a well, a process known as fracturing (colloquially referred to as “fracing”) is performed. In brief summary, a pressurized fluid—often water—is pumped into a producing region of a formation at a pressure sufficient to create fractures in the formation, thereby enabling hydrocarbons to flow from the formation with less impedance. Solid matter, such as sand, ceramic beads, and/or similar particulate-type materials, can be mixed with the fracturing fluid, this material generally remaining within the fractures after the fractures are formed. The solid material, known as proppant, serves to prevent the fractures from closing and/or significantly reducing in size following the fracturing operation, e.g., by “propping” the fractures in an open position The presence of open, propped fractures provides a beneficial contrast between the permeability in the fracture versus that in the adjacent subterranean reservoir. This contrast provides for a highly conductive pathway for reservoir fluids to travel, thus enhancing the productivity of the well.
Fracturing using aqueous fluids is often undesirable due to the negative effects of water on the formation. For example, clays and other formation components can swell when exposed to water, while salts and other formation components may dissolve, such that exposure to a significant quantity of water can destabilize a formation. Use of water and other aqueous fluids also generates issues regarding disposal. Specifically, aqueous fracturing fluid recovered from a well (e.g., subsequent to a fracturing operation) contains various wellbore fluids and other chemicals (e.g., additives to facilitate fracturing using the fluid), and as such, the recovered fracturing fluid must be collected and stored at the surface and disposed of in an environmentally acceptable manner, as required by numerous regulations. Such a process can add considerable time and expense to a fracturing operation, especially when considering the enormous quantities of liquid required to perform the operation.
Non-aqueous fracturing fluids have been used as an alternative, one such successful class including hydrocarbon-based fluids (e.g., crude/refined oils, methanol, diesel, condensate, liquid petroleum glass (LPG) and/or other aliphatic or aromatic compounds). Hydrocarbon-based fracturing fluids are inherently compatible with most reservoir formations, being generally non-damaging to formations while creating acceptable fracture geometry. However, due to the flammability of hydrocarbon-based fluids, enhanced safety preparations and equipment are necessary when using such fluids for wellbore operations. Additionally, many hydrocarbon-based fluids are volatile and/or otherwise unsuitable for use at wellbore temperatures and pressures, while lacking the density sufficient to carry many types of proppant. As such, it is common practice to use chemical additives (e.g., gelling agents, viscosifiers, etc.) to alter the characteristics of the fluids. An example a system describing use of liquid petroleum gas is described in U.S. Pat. No. 8,408,289, which is incorporated by reference herein in its entirety. Use of chemical additives generates waste and disposal issues similar to those encountered when performing fracturing operations using aqueous fluids.
Independent of the type of fracturing fluid and proppant used, a fracturing operation typically requires use of one or more high pressure pumps to pressurize the fracturing fluid that is pumped into a wellbore, as well as to transport fluid and/or proppant toward the wellbore. The passage of proppant through a pump can damage the pump, especially in the absence of a significant quantity of liquid in the slurry. Great care must often be taken when controlling the proportions of fluid and proppant used to create a slurry to ensure the formation of a mixture that is non-damaging to pumps and other system components, compatible with the formation, is suitable for use within the wellbore (e.g., appropriate specific gravity, stability at wellbore temperatures and pressures, etc.), and to ensure that the proppant is properly placed in the wellbore fractures.
Additionally, pumps and other such equipment are conventionally driven/powered using diesel engines, which can be responsible for significant quantities of noise, emissions, maintenance, and expense at a worksite, and which require the handling of volatile fluids to fuel and operate. Electric drive systems have been contemplated as an alternative to diesel engines; however, such systems require numerous pieces of equipment, extensive cabling and/or similar conduits, and typically utilize on-site power generation, such as a natural gas turbine. Use of turbine prime movers and similar equipment may be unsuitable when utilizing fracturing fluids that include flammable components. An exemplary electrically powered system for use in fracturing underground formations is described in published United States Patent Application 2012/0255734, which is incorporated by reference herein in its entirety.
A need exists for systems and methods for fracturing and/or stimulating a subterranean formation that can overcome issues of formation damage/compatibility, flammability, proppant delivery, and/or power supply.
Embodiments usable within the scope of the present disclosure include systems and methods usable for stimulating a formation (e.g., by forming fractures therein), by providing a first medium to the formation via a first supply subsystem, and a pressure subsystem comprising a pump usable to pressurize the first medium to a pressure sufficient to stimulate the formation. The term “first medium” is used herein to refer, generally, to any type of solid, liquid, or gas able to be flowed, e.g., through a conduit, from a source toward a formation, such through use of one or more pumps or other sources of motive force to move the medium and/or pressurize the medium for performance of a fracturing operation.
For example, in an embodiment, the first medium can include a liquid alkane, and in more specific embodiments, a non-gelled liquid alkane. The term “non-gelled” is used, herein to refer to a medium lacking conventional gellants and/or gelling agents. While in various embodiments, a non-gelled liquid alkane can be used in a chemical-free (e.g., pure) form, it should be understood that if desired, surfactants and/or other types of viscosity modification can be used to modify the first medium without departing from the scope of the present disclosure. In further embodiments, the non-gelled liquid alkane can include an alkane having from one to six carbon atoms (e.g., propane and/or a mixture of other low molecular weight alkanes).
In an embodiment, the first medium can include a halogenated hydrocarbon. While alkanes and other hydrocarbons can generate various concerns and/or difficulties due to their flammability, halogenated hydrocarbons are significantly less flammable or in many cases, non-flammable. Exemplary halogenated hydrocarbons usable within the scope of the present disclosure can include, without limitation, 1,1,1,3,3,3 hexafluoropropane; 1,1,1,2,3,3,3 heptafluoropropane; 1-methoxyheptafluoro propane; 2,3,3,3-tetraflurorpropene; 1,3,3,3-tetrafluoropropene; 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethyl-pentane; 1,1,1,4,4,4-hexafluoro-2-butene-1-methoxy; 1,1,1,2-tetrafluoroethane; or combinations thereof. In various embodiments, the first medium can include a halogenated alkene, a halogenated ether, a halogenated olefin, or combinations thereof. The halogenated hydrocarbon can constitute all or a portion of the first medium. For example, the first medium can include a non-halogenated hydrocarbon mixed with the halogenated hydrocarbon (e.g., typically 5% or less of the non-halogenated hydrocarbon by volume, though other concentrations can be used without departing from the scope of the present disclosure), such that although the first medium contains flammable components, the halogenated hydrocarbon reduces the overall flammability of the first medium.
In an embodiment, the first medium can include a foamed hydrocarbon (e.g., an alkane or another type of hydrocarbon, including, without limitation, liquefied natural gas, diesel and/or any other hydrocarbon-based fluid). A foamed hydrocarbon can include any type of hydrocarbon usable, e.g., as a fracturing fluid, mixed with a quantity of inert gas sufficient to “foam” the hydrocarbon (e.g., from 45% to 90% inert gas by volume). In an embodiment, the hydrocarbon can be mixed with a fluorosurfactant to promote foaming of the first medium.
In an embodiment, the first medium can include propylene carbonate, e.g., as a more dense and/or environmentally friendly alternative to many other hydrocarbon-based fluids. One or more water-soluble polymers, such as hydroxylpropyl cellulse ether or a similar non-ionic cellulose either, can be used to alter the viscosity and/or other characteristics of the propylene carbonate. In further embodiments, gas (e.g., nitrogen and/or carbon dioxide) can be mixed with the propylene carbonate to affect the density thereof. For example, sufficient gas can be provided to energize the first medium (e.g., up to 45% gas by volume), to foam the first medium (e.g., 45% to 90% gas by volume), or to mist the first medium (e.g., greater than 90% gas by volume).
In other embodiments, the first medium may not include a “fluid” in the conventional sense. For example, embodiments usable within the scope of the present disclosure can include use of a fluidized solid proppant, e.g., a solid material adapted to follow, substantially free of liquid, in the manner of a liquid when flowed at a threshold pressure and/or velocity, while behaving in the manner of a solid at pressures and/or velocities less than the threshold. In an exemplary embodiment, solid particulate matter, such as sand, ceramic, glass, clay, gravel, and/or other similar solid particles, can be mixed with a friction-reducing additive, such that the particles of solid matter can flow relative to one another. Without limitation, usable friction-reducing additives could include molybdenum disulfide, carbon black, graphite, fumed silica, epoxy matrix resin nanoparticles, glass bubbles, or combinations thereof. For example, the friction-reducing additive can coat and/or otherwise be interspersed between particles of solid matter, such that the solid matter can pass and/or flow relative to one another with reduced friction, e.g., behaving in a manner similar to a liquid once sufficient pressure and/or velocity is imparted thereto.
In an embodiment, a fluidized solid proppant could include a material capable of flowing in the manner of a liquid at a threshold pressure and/or velocity in the absence of an additive (such as a friction-reducing component). For example, glass bubbles and/or microspheres could be used as a fluidized solid proppant independent of or in addition to a friction-reducing additive. Alternatively or additionally, one or more solid components adapted to flow in the manner of a liquid when vibrated or pulsed could be used; for example, sand and/or similar particulate matter can be flowed toward a formation if vibrated and/or pulsed at a suitable frequency. In an embodiment, a pneumatic conveying system can be used to vibrate and/or pulse the particulate matter to facilitate movement thereof.
To facilitate intermixing of components of a fluidized solid proppant and/or a reduction in friction thereof, in various embodiments a quantity of liquid (e.g., a lubricant, a fracturing fluid, etc.) can be mixed with the fluidized solid proppant; however, a quantity insufficient to form a slurry with the proppant can be used due to the fact that the proppant, itself, can be flowed toward the formation without slurrying the proppant.
In an embodiment, the first medium can include a liquid material adapted to solidify at a threshold temperature (e.g., a foam material), such that the medium can be flowed into the formation as a liquid, then solidified (e.g., into a porous, solid material) after reaching fractures in the formation, enabling the solidified material to function as proppant. Depending on the ambient wellbore conditions (e.g., temperature), a cooling fluid could be injected to prepare the formation to receive the liquid material without premature solidification thereof.
Independent of the particular substance used as the first medium, in an embodiment the supply subsystem used to store and/or flow the first medium toward the formation can include one or more vessels adapted for containment thereof and/or for driving the first medium. For example, a vessel can be supplied with an inert gas (e.g., nitrogen or another similar gas) above and/or otherwise in association with the first medium, such that pressure of the inert gas can be used to drive the first medium from the vessel toward the formation. Alternatively or additionally, a separator (such as a bladder, a piston and/or another similar member) can be positioned in the vessel and used to drive the first medium from the vessel toward the formation, e.g., using a pressurized fluid to move the separator.
Alternatively or additionally, a vertically oriented vessel can be used, such that gravity and/or vapor pressure of the first medium can drive the first medium from the vessel toward the formation. A booster pump associated with the vessel can be used to draw the first medium from therein and feed the first medium to an additional pump (e.g., a pump used to mix the first medium with a proppant, to transport the first medium to high pressure fracturing pumps, and/or to pressurize the first medium). Use of a separate booster pump can prevent the vaporization of volatile components (e.g., low molecular weight alkanes) caused by the intake thereof at one or more of the additional pumps. In an embodiment, the vertically oriented vessel can be adapted for transport in a horizontal orientation (e.g., on a truck, trailer, and/or similar vehicle or mode of transport). In further embodiments, a vessel can include a plurality of outlets, the size and number thereof selected to flow the first medium from the vessel toward the formation at a rate sufficient to perform a desired operation (e.g., a stimulation and/or fracturing operation).
In an embodiment, a pipeline in communication with a remote source can be used to supply the first medium to the formation directly, in addition to or in lieu of one or more on-site storage vessels.
While embodiments usable within the scope of the present disclosure can be utilized for any manner of operation in which the flow of a medium relative to a formation is desired, in various embodiments, the systems and methods described herein can be used for stimulation and/or fracturing operations. In such embodiments, the first medium can include a fracturing fluid (e.g., water, hydrocarbons, and/or any of the fluids and/or media described previously). In combination with the fracturing fluid, a second supply subsystem can be used to provide a second medium that includes a proppant (potentially with lubricants and/or other additives) to the formation.
In an embodiment, the fracturing fluid can include a non-gelled liquid alkane, as described above, and the proppant can include a specific gravity, a size (e.g., a diameter) or combinations thereof adapted to provide the proppant with a substantially neutral or positive buoyancy in the fracturing fluid. As used herein, the term “substantially neutral buoyancy” can include a neutral, positive, or negative buoyancy in which the proppant does not settle at a rate sufficient to prevent use of the fracturing fluid and proppant in a fracturing operation. For example, in one embodiment, the proppant can have a specific gravity of 1.5 or less, and in a further embodiment, the proppant can have a specific gravity of 1.1 or less. Alternatively or additionally, in an embodiment, proppant particles could have a diameter of 105 microns or less to facilitate buoyancy thereof.
In an embodiment, the proppant can include a hollow material, such as glass bubbles, cenospheres, microspheres, and/or other similar materials having a structure sufficient to function as proppant while remaining generally buoyant in a fracturing fluid. In an embodiment, the proppant can include a composite material, such as a syntactic foam. In an embodiment, the proppant can include a porous material, such as an aerogel, a resin-coated aerogel, a resin-coated pumice, a ceramic foam or other type of foamed material, or combinations thereof. As used herein, a “porous material” can include particles having cylindrical and/or tubular structures (e.g., having an axial bore) through which fluid can pass. In a further embodiment, the proppant can include a porous material that is permeable to reservoir fluids, such as a filter material that permits passage of the fluid into and through particles of proppant, while the structure of the material enables the material to function as proppant. In an embodiment, the proppant material can include a crystalline material, such as zircon or other similar crystalline materials.
In an embodiment, a friction-reducing additive, such as those described above, can be combined with proppant particles to facilitate transport of the proppant, e.g., from a vessel or similar source into the fluid path of the fracturing fluid and/or a vessel containing fracturing fluid, such that the proppant can be flowed into communication with the fracturing fluid in the absence of a sufficient quantity of liquid to slurry the proppant.
Independent of the type and/or nature of the proppant used, in an embodiment, the second supply subsystem can include one or move vessels used to store and/or drive the proppant toward the formation. For example, a vertically oriented vessel can be used to enable gravity, the weight of the proppant, or combinations thereof to drive the proppant from the vessel toward the formation. Additionally or alternatively, a positive displacement pump, a centrifugal pump, other similar sources of motive force, can be used to move proppant toward the formation. In an embodiment, a positive displacement pump, for example, could be positioned in a non-horizontal orientation to facilitate intake of proppant (e.g., assisted by gravity).
In an embodiment, an inert gas (e.g., nitrogen or a similar gas) can be provided in the vessel with the proppant, and a pressure thereof can be used to drive the proppant from the vessel toward the formation. Alternatively or additionally, a separator (e.g., a piston, a bladder, and/or another similar device) in the vessel can be moved (e.g., using a pressurized fluid) and used to drive the proppant from the vessel toward the formation. In a further embodiment, a pneumatic conveying system can be used to drive proppant toward the formation (e.g., by pushing proppant within the vessel and/or pulling proppant from the vessel).
In an embodiment, a venturi nozzle can be positioned in communication with a flowpath of the fracturing fluid to reduce a pressure thereof. In doing so, proppant from the second supply subsystem can be drawn into the flowpath of the fracturing fluid. The venturi nozzle can include an elastomeric nozzle adapted to adjust (e.g., self-adjust) to provide a substantially constant pressure drop across the nozzle independent of the flow rate and/or conditions of the fracturing fluid and/or the proppant.
While embodiments usable within the scope of the present disclosure can be powered using on-site using reciprocating engines (e.g., diesel engines), coupled with turbine generators and/or similar power systems, in an embodiment, one or more system components can be configured for use with electrical power. For example, the pressure subsystem can include an electric-powered driver (e.g., an electric motor or similar source of force) in communication with and actuating the pump, while an electrical power source powers the electric-powered driver. In an embodiment, a turbine generator (e.g., a natural gas turbine or similar source) can be used to provide power to an electric motor, which in turn drives the pump. Alternatively or additionally, a grid-based power source can be used to power the electric-powered driver. In an embodiment, an electric-powered driver can be configured for selective and/or simultaneous operation using a grid-based or an on-site power source. Where a grid-based power sourced is used, in an embodiment, one or more additional transformers can be used to convert power from the grid-based power source to a desired voltage. In use, a single pump can be actuated using a single electric-powered driver or multiple electric-powered drivers, and multiple pumps can be actuated using a single electric-powered driver or multiple electric-powered drivers. Similarly, a single power source can power one or multiple electric-powered drivers, or one or multiple electric-powered drivers can be powered by multiple power sources.
A transformer can be used to alter power from the electrical power source from a first voltage to a second voltage suitable for powering the electric-powered driver. In an embodiment, a pump, an electric-powered driver, and a transformer can be positioned on a mobile vehicle. A variable frequency drive can also be included, e.g., on the mobile vehicle, in communication with the transformer and the electric-powered driver. While the above embodiment describes a single pump, electric-powered driver, transformer, and variable frequency drive situated on a mobile vehicle, it should be understood that one or multiple of each type of component described above and/or other components could be included on a vehicle without departing from the scope of the present disclosure. Other configurations of mobile vehicles can also be used without departing from the scope of the present disclosure. For example, in one embodiment a transformer, a variable frequency drive, an electric motor or other type of driver, and a pump can be situated on a single mobile vehicle. In another embodiment, a transformer and variable frequency drive can be positioned on a first mobile vehicle, while one or multiple additional vehicles, each containing one or a plurality of motors and one or a plurality of pumps, can be placed in communication with the variable frequency drive. In another embodiment, a transformer and one or multiple variable frequency drives can be positioned remote from a mobile vehicle (e.g., outside of an operational zone), while conduits can engage each variable frequency drive with one or multiple mobile vehicles, each vehicle containing one or multiple electric-powered drivers and pumps. In an embodiment, the arrangement of components can be selected such that the electrical power source can engage the transformer, and thereby, the electric-powered driver, via a single electrical conduit. In an embodiment, an electrical power source can be engaged with a transformer (and subsequently, to other associated components) via a single electric conduit, eliminating much of the cabling/conduits present at conventional worksites.
While transformers can be used, as needed, to alter the voltage of power received from one or more sources to voltages suitable for use with various system components, in an embodiment, the system components can be adapted for use with low or medium voltages.
In various embodiments, use of air moving devices may be incorporated to control the concentration of vapors (e.g., hydrocarbon-based gasses and/or similar components) proximate to pumps and/or other system components. For example, when using propane as a fracturing fluid, the accumulation of propane proximate to the pump could create a flammable condition (e.g., at a propane concentration of approximately 2.2% to 9.5% in air), while the continuous movement of air proximate to the pump would prevent accumulation of flammable components at a concentration sufficient for ignition. In an embodiment, an electric motor or similar electric-powered driver can include a fan, blower, or other type of air moving device associated therewith, and placement of the driver and/or air moving device can be selected such that the air moving device flows air proximate to the pump for dispersing gas therefrom. In an embodiment, an enclosed conduit can extend between the electric-powered driver and the pump, such that air form the air moving device flows from the driver to the pump via the conduit. Alternatively or additionally, an electric powered driver and pump can be enclosed within a single housing, such that air from the air moving device flows proximate to the pump.
In various embodiments, a drive shaft extending between the electric-powered driver and the pump can have protrusions (e.g., blades, fins, etc.) extending therefrom, such that as the air moving device flows air into contact with the protrusions, motive force is provided to the drive shaft. Alternatively, movement of the drive shaft can, itself, be used to flow air (e.g., via the protrusions) to circulate air proximate to the pump, in addition to or in lieu of an air-moving device associated with the electric-powered driver.
In the detailed description of various embodiments usable within the scope of the present disclosure, presented below, reference is made to the accompanying drawings, in which:
One or more embodiments are described below with reference to the listed Figures.
Before describing selected embodiments of the present invention in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein. The disclosure and description herein is illustrative and explanatory of one or more presently preferred embodiments of the invention and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, order of operation, means of operation, equipment structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit of the invention.
As well, it should be understood the drawings are intended illustrate and plainly disclose presently preferred embodiments of the invention to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views as desired for easier and quicker understanding or explanation of the invention. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention as described throughout the present application.
Moreover, it will be understood that various directions such as “upper”, “lower”, “bottom”, “top”, “left”, “right”, and so forth are made only with respect to explanation in conjunction with the drawings, and that the components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the inventive concept(s) herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting.
The depicted fluid addition subsystem (12) includes a plurality of tanks (18A, 18B, 18C) and/or other types of vessels usable to contain one or more fluid media usable as a fracturing fluid (e.g., to carry proppant to the well (10) and/or to form fractures in the underlying formation when pressurized). While the depicted embodiment includes tanks (18A, 18B, 18C) usable to contain liquid propane, or other low weight alkanes (e.g., having from one to six carbon atoms), it should be understood that various embodiments of the present disclosure can include use of various types of media usable in fracturing operations, as described above.
While gelled liquid petroleum gas has been used in fracturing fluids to minimize damage to formations, driven by pressure applied using inert gas (e.g., nitrogen), as described in U.S. Pat. No. 8,408,289, incorporated by reference above, embodiments usable within the scope of the present disclosure can include use of liquid propane and/or other alkanes, without the addition of gellants or other chemical additives. Additionally, to reduce or eliminate the flammability of the hydrocarbon-based fracturing fluid, in an embodiment, a halogenated hydrocarbon can be present, alone or in combination with non-halogenated hydrocarbons. For example, 1,1,1,2,3,3,3-Heptafluoropropane, or a similar halogenated hydrocarbon compound composed of an aliphatic or aliphatic derivative (e.g., ethers and/or olefins) with one or more halogen elements (e.g., fluorine, bromine, etc.) could be present in the fracturing fluid, such that the resulting fluid is fire retardant or non-flammable. A portion of the fracturing fluid could include a halogenated compound while still providing the fracturing fluid with fire retardant and/or non-flammable properties, though any quantity of halogenated compounds could be used without departing from the scope of the present disclosure. Additionally, it should be understood that heptafluoropropane is referenced as an individual exemplary embodiment; hydrofluoroalkenens, hydrofluoroethers, and other types of halogenated compounds can also be used without departing from the scope of the present disclosure. Of note, use of halongenated hydrocarbons can provide additional beneficial properties beyond non-flammability, due in part to the higher fluid density and viscosity of the halogenated compounds compared to non-halogenated hydrocarbons. Exemplary halogenated hydrocarbons usable within the scope of the present disclosure can include, without limitation: 1,1,1,3,3,3 hexafluoropropane; 1,1,1,2,3,3,3 heptafluoropropane; 1-methoxyheptafluoro propane; 2,3,3,3-tetraflurorpropene; 1,3,3,3-tetrafluoropropene; 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethyl-pentane; 1,1,1,4,4,4-hexafluoro-2-butene; 1-methoxy-1,1,1,2-tetrafluoroethane; or combinations thereof. Further, any manner of halogenated ether, alkene, and/or olefin, can be used without departing from the scope of the present disclosure.
In other embodiments, the fracturing fluid can include propylene carbonate, e.g., as an “environmentally friendly” fluid, having a density greater than other hydrocarbon fluids (e.g., a specific gravity of approximately 1.2), which can reduce hydrostatic head pressure and surface treating pressure of the fluid, resulting in lower horsepower requirements to pump the fluid. Further, propylene carbonate can be produced with recovered hydrocarbons, eliminating the need for any post-handling, processing, disposal, and/or separation operations to recover the propylene carbonate. The polar nature of propylene carbonate enables water-soluble polymers to be used in lieu of conventional additives and viscosifiers, one such water-soluble polymer including non-ionic cellulose ethers, such as hydroxylpropyl cellulose ether (sold under the trade name Klucel). Use of polymers in this manner can stabilize propylene carbonate when foamed and/or otherwise varied in density. In various embodiments, a gas (e.g., nitrogen or carbon dioxide) can be provided into the propylene carbonate to vary the density thereof. For example, up to 45% gas by volume could be provided to energize the fracturing fluid, from 45% to 90% by volume could be provided to foam the fluid, and from 90% to less than 100% by volume could be provided to mist the fluid, allowing the density of the propylene carbonate to be altered as needed (e.g., depending on formation conditions), reducing the hydrostatic head pressure of the fluid. In various embodiments, propylene carbonate can be mixed with other liquids or gasses, e.g., at the surface or as it is being moved toward the formation, e.g., to change the density and/or viscosity thereof, to enhance proppant transport characteristics (e.g., by foaming, emulsifying, and/or gelling the propylene carbonate), to reduce conduit friction pressure, to help control fluid loss, and to increase fluid efficacy during fracturing operations.
In other embodiments, the fracturing fluid can include a foamed hydrocarbon (e.g., having a quantity of gas mixed therewith). In such embodiments, a hydrocarbon can be stored in the tanks (18A, 18B, 18C), and/or a gas source (not shown) (e.g., a pressurized gas source and pump) can be configured to inject and/or mix gas into the flowpath of fluid from the tanks (18A, 18B, 18C) (e.g., downstream from the tanks), and/or into an intermediate vessel where fluid from the tanks (18A, 18B, 18C) can be mixed with the gas. A fluorosurfactant can be provided in the tanks (18A, 18B, 18C), in the gas, and/or from a separate source to facilitate stabilization of the foamed hydrocarbon.
In other embodiments, the fracturing fluid can include a fluidized solid proppant material, as described above. Fluidized solid proppant can include solid particulate matter (e.g., sand, ceramic, glass, clay, gravel, etc.), mixed with a solid or liquid friction-reducing additive (e.g., molybdenum disulfide, carbon black, graphite, fumed silica, epoxy matrix resin nanoparticles, glass bubbles, and/or silicone lubricants), to enable the solid material to flow in the manner of a liquid under sufficient pressure to impart movement thereto, while behaving in the manner of a solid in the absence of such pressure. As such, a fluidized solid proppant can be flowed, substantially in the absence of liquid (e.g., a quantity of liquid insufficient to form a slurry therewith), into a wellbore for performance of a fracturing operation, then permitted to settle and/or remain within the fractures via a cessation of pressure applied from the surface. In various embodiments, the fluidized solid proppant can include solid material (e.g., sand or similar particulate matter) that can flow in the manner of a liquid when vibrated and/or pulsed (e.g., using a pneumatic conveyance system to pulse air and/or other fluids through the proppant), with or without the addition of a friction-reducing additive.
In various embodiments, fluidized solid proppant can include materials that flow in the manner of a liquid under a threshold pressure in the absence of a friction-reducing additive. For example, “glass bubbles,” available from 3M of St. Paul, Minn., or similar microspheres or other types of particulate matter having a size, shape, surface feature, and/or other characteristic that reduces or inhibits frictional interactions with adjacent particles.
In an embodiment, the tanks (18A, 18B, 18C) can contain a liquid adapted to solidify under threshold conditions (e.g., temperature), such that the liquid can be flowed into the well (10) until it reaches a fracturing zone, then allowed to solidify within fractures. In an embodiment, binary addition of multiple components could be used. To facilitate use of such a material, the well (10) can be pre-treated using a fluid to at least temporarily cool the formation prior to flowing the liquid into the well (10), such that the material does not solidify prematurely.
In embodiments where a liquid/foamed solidifying material is used, it should be understood that the proppant supply subsystem (14) can be omitted, if desired.
The tanks (18A, 18B, 18C) are shown in communication with a fluid source (20) for supplying a first medium (e.g., propane, alkanes, and/or other types of fracturing fluid) thereto via a fill line (22). A vent line (24) is also usable, e.g., to relieve pressure from the tanks (18A, 18B, 18C) and/or otherwise facilitate flow thereto and therefrom. Each tank (18A, 18B, 18C) is shown in communication with an associated pump (26A, 26B, 26C) (e.g., a booster pump), usable to draw fracturing fluid therefrom and flow the fluid toward the well (10) via a conduit (28). A secondary fluid booster pump (30) is shown for further driving the fluid toward the well (10), through a low pressure region (32) of the conduit. While
In further embodiments, nitrogen and/or another type of inert gas could be provided in the tanks (18A, 18B, 18C) with the first medium and the pressure thereof could be altered and/or otherwise used to facilitate driving of the fracturing fluid toward the well (10). Alternatively or additionally, a bladder, piston, and/or similar type of separator (not shown) can be provided in the tanks and driven (e.g., using a pressurized fluid, hydraulic and/or pneumatic mechanisms, mechanical force, other similar means, or combinations thereof) to drive the contents of the tanks (18A, 18B, 18C) toward the well (10).
The depicted proppant addition subsystem (14) includes a plurality of proppant storage vessels (34A, 34B, 34C) (e.g., silos or another type of tank and/or container), positioned in association with a conveyor (36), which can include one or more conveyor belts, chutes, slides, pipes, or other types of conduits and/or means of conveyance usable to transport proppant from the vessels (34A, 34B, 34C) toward a hopper (38) or similar type of container. Use of vertically oriented proppant storage vessels, such as silos, can enable gravity and/or the weight of the proppant to drive proppant from the containers toward the conveyor (36) and/or toward the well (10), while also reducing the footprint presented by the containers. One exemplary proppant storage container could include a Model 424 Sand Silo, produced by Loadcraft Industries, LTD of Brady, Tex., which can include an associated transportation trailer. Proppant within the vessels (34A, 34B, 34C) can include any manner of small and/or particulate solid matter usable to retain and/or support fractures in a formation, such as sand, glass or clay beads, gravel, or other similar types of material and or particulate matter, such as crystalline material (e.g., zircon) and/or hollow glass particles (e.g., glass bubbles/microspheres, such as those made by 3M of St. Paul, Minn.), among other possible alternatives.
Depending on the type of fracturing fluid used the proppant within the vessels (34A, 34B, 34C) can have characteristics selected to facilitate buoyancy and/or transport within the fluid. For example, the proppant can be provided with a specific gravity of less than 1.5 and in an embodiment, less than 1.1, to facilitate transport in propane and/or other non-gelled alkanes, propylene carbonate, and/or other similar types of fracturing fluids. Alternately or additionally, the proppant can be provided with a size sufficiently small to promote transport, such as particles having a diameter of 105 micros or less. In various embodiments, the proppant can include hollow materials (e.g., glass bubbles, cenospheres, and/or microspheres). In various embodiments, the proppant can include a composite material, such as a syntactic foam. In various embodiments, the proppant can include a porous material, such as an aerogel, a resin-coated aerogel, a pumice, a resin-coated pumice, a ceramic foam or other foamed material, and/or a tubular-shaped (e.g., cylindrical) material having an axial bore through which fluid can flow. In various embodiments, the proppant can include a crystalline material, such as zircon.
While
A proppant pump (45) can be used to drive the proppant and lubricating fluid toward the well (10) and/or to slurry the proppant with the lubricating fluid, if desired and/or necessary. In an embodiment, the proppant pump (45) can include a positive displacement pump and/or a centrifugal pump. In a further embodiment a positive displacement pump can be provided in a non-horizontal orientation to facilitate intake of proppant from a vertically oriented vessel. As depicted in
It should be understood that the depicted proppant addition subsystem (14) is only one exemplary embodiment by which proppant can be added to a stream of fracturing fluid. In an embodiment, a venturi nozzle (47) can be positioned in communication with the flowstream of fracturing fluid, e.g., at or near the addition point (46) (e.g., upstream thereof), thereby increasing the velocity and reducing the pressure of fluid at the downstream end of the nozzle (47), such that the flow of lower-pressure fracturing fluid across and/or proximate to the addition point (46) can draw proppant through into the flowstream. A diffuser (49) can be provided downstream from the nozzle (47). An elastomeric (e.g., self-adjusting) nozzle can be used to facilitate a constant pressure drop across the nozzle, thereby facilitating control of the rate/concentration of proppant. Use of a venturi nozzle can further facilitate mixing and/or slurrying of the proppant and fracturing fluid.
In lieu of or in addition to the methods of flowing the proppant described above, in various embodiments, inert gas can be mixed with the proppant in the vessels (34A, 34B, 34C), the pressure from which can be used to facilitate driving the proppant toward the well (10). Alternatively or additionally, a separator, such as a piston or bladder, similar to that described above with regard to the tanks (18A, 18B, 18C) can be used to facilitate driving the proppant toward the well (10).
As fracturing fluid and/or proppant in the low pressure region (32) flows toward the well (10) it is pressurized by one or more high pressure fracturing pumps (70A, 70B, 70C, 70D), defining a high pressure region (72) of the conduit, such that the fluid provided into the well (10) is at a pressure sufficient to generate fractures in the formation. The depicted power subsystem (16) is usable to provide power to the high pressure pumps (70A, 70B, 70C, 70D), and/or to other system components (such as the pumps (26A, 26B, 26C, 30, 42, 45) usable to flow fracturing fluid, proppant, and/or lubricating fluid, the proppant conveyor (36), one or more valves associated with system components, and/or other similar elements).
While any number and type of high pressure pumps can be used,
Each transport vehicle (48A, 48B) is shown having a transformer (64A, 64B) positioned thereon. Use of a transformer on the vehicle, itself, enables a single respective power cable (58A, 58B) to be extended from the power source to the vehicle (48A, 48B). Conversely, use of a transformer remote from other system components would require numerous cables and/or other conduits extending from the transformer to other system components. As such, positioning of the transformers (64A, 64B) proximate to the high pressure pumps (70A, 70B, 70C, 70D) and other associated components minimizes the distance across which large numbers of cables/conduits must extend. While usable voltages can vary without departing from the scope of the present disclosure, in an embodiment, the transformers (64A, 64B) can be adapted to reduce voltage in the cables (58A, 58B) from 4,160 volts to 600 volts, for use by components associated with the high pressure pumps (70A, 70B, 70C, 70D). Specifically,
To reduce electrical noise/interference, such as when using a grid-based power source, the transformers (64A, 64B) can be adapted to convert the received power to a larger number of successive electrical phases/pulses. For example a transformer could receive and convert a three-phase source of power to a nine-phase, eighteen-pulse source of power for transmission to successive system components.
As such, the depicted power subsystem (16) is usable to reduce or eliminate conventional use of diesel engines to power high pressure fracturing pumps. Additionally, use of modular sets of components positioned on mobile trailers or similar transportable vehicles (48A, 48B) minimizes the number and length of cables and other conduits required to power each component, while also facilitating installation of each component. For example, all connections between the transformers (64A, 64B), variable frequency drives (66A, 66B, 66C, 66D), motors (68A, 68B, 68C, 68D), and high pressure pumps (70A, 70B, 70C, 70D) can generally be permanently installed, such that the vehicles (48A, 48B) can be positioned at a desired location at an operational site, then engaged with a single cable (58A, 58B), thereby powering each of the components. Further, use of modular, movable sets of components reduces the footprint of the system while enabling flexible positioning of components, as needed, depending on the position of other objects at an operational site. In an embodiment, power generation components can be placed remote from other system components, such as the fracturing fluid addition subsystem (12), which reduces risk of ignition when flammable components (e.g., propane) are used in the fracturing fluid.
While
For example,
Returning to
For example,
It should be understood that while
Conceptually,
The depicted proppant addition subsystem (110) is shown including a proppant storage vessel (112), and an additive storage vessel (114), both of which can include, for example, a silo, tank, hopper, or any other type of container or vessel usable to contain particulate solid matter. Use of vertically oriented proppant storage vessels, such as silos, can enable gravity and/or the weight of the contents within the vessels (112, 114) to drive the contents from the containers, while also reducing the footprint presented by the containers. One exemplary storage container could include a Model 424 Sand Silo, produced by Loadcraft Industries, LTD of Brady, Tex., which can include an associated transportation trailer.
The proppant storage vessel (112) can contain solid particulate matter (e.g., sand, ceramic, glass, clay, gravel, and/or other suitable materials usable as proppant), which can be flowed, pumped, and/or otherwise transferred, e.g., via a conduit (116) to a hopper (120) or other type of container. The conduit (116) can include a conveyor, chute, trough, pipe, or any other suitable means usable to transport solid particulate matter, accompanied by any manner of associated valves, doors, pumps, or other types of control mechanisms usable to regulate the passage of proppant from the proppant storage vessel (112). In an embodiment, the proppant storage vessel (112) could be positioned in direct association with the hopper (120), such that a conduit is not necessary. For example, the proppant storage vessel (112) could be positioned above the hopper (120), such that proppant could fall directly into the hopper (120).
The additive storage vessel (114) can contain a solid, friction-reducing additive, such as molybdenum disulfide, carbon black, graphite, fumed silica, epoxy matrix resin nanoparticles, glass bubbles, and/or any other solid additive or liquid additive (e.g., silicone) capable of forming a friction-reducing coating about one or more particles of proppant and/or occupying spaces between particles of proppant to reduce friction therebetween and facilitate the flow thereof. The contents of the additive storage vessel (114) can be transferred to the hopper (120) via a conduit (118), which can include any manner of conveyor, chute, trough, pipe, or other suitable means, accompanied by associated valves, doors, pumps, or other types of control mechanisms usable to regulate the passage of the additive from the additive storage vessel (114). In an embodiment, the additive storage vessel (114) could be positioned in direct association with the hopper (120), such that the conduit (118) is not necessary.
While
It should be understood that while
In other embodiments, a fluidized solid proppant could be used in the absence of a friction-reducing additive. For example, glass bubbles and/or microspheres, such as those made by 3M of St. Paul, Minn., could be used as a fluidized solid proppant, in the absence of an additional friction-reducing additive. Use of a hopper (120) could be omitted (e.g., due to the lack of a need to mix components). Alternatively or additionally, an inert gas could be provided in association with the hopper to prevent the introduction of air and/or oxygen into the system.
In still other embodiments, various types of pumps and/or other devices can be used to vibrate and/or pulse system conduits and/or vessels, as needed, to vibrate the fluidized solid proppant to reduce friction between particles thereof, allowing the proppant to flow in the manner of a liquid. For example, in an embodiment, a pneumatic conveying system could be used to project a fluid to pulse and/or vibrate sand or similar particulate matter to facilitate flow thereof.
Independent of the type of fluidized solid proppant used and/or the location and manner of preparation and/or storage thereof, the proppant storage vessel (112) is shown in fluid communication with the well (150). In the depicted embodiment, the hopper (120) is configured to dispense fluidized solid proppant via a conduit (128) (e.g., a pipe or similar member able to transport fluids to the well (150)), assisted by a booster pump (130) (e.g., a positive displacement pump or similar type of pump), to a low pressure region (132) of the conduit. As described above, the term “fluidized solid proppant” is used to describe, in general terms, solid matter (e.g., particulate matter) that flows in the manner of a liquid when transported under certain conditions (e.g., a threshold pressure and/or velocity) while functioning in the manner of a solid when stationary and/or under a pressure less than the threshold pressure. As such, the booster pump (130) and/or other associated equipment, conduits, etc., can be configured to dispense the fluidized solid proppant toward the well (150) under pressure/velocity conditions that enable the proppant to flow in the manner of a liquid, while remaining substantially free of liquid components. As described above, the fluidized solid proppant, while not wholly void of liquid, could be termed “substantially free” of liquid when the quantity of liquid mixed therewith is insufficient to form a slurry with the proppant. As described above, the booster pump (130) and/or other pumps associated with the transport of proppant could be provided in a non-horizontal orientation.
The pumping subsystem (136) is shown in communication with the low pressure region (132). Specifically, two transportable pumping units (138A, 138B) are shown, each having a high pressure fracturing pump (140A, 140B) positioned thereon. While
As the fluidized solid proppant in the low pressure region (132) flows toward the well, it is pressurized by the high pressure fracturing pumps (140A, 140B), defining a high pressure region (134) of the conduit. In an embodiment, the proppant can be provided into the well (150) at a pressure sufficient to generate fractures in the formation. The flow rate provided by the pumps (140A, 140B) can then be reduced, thereby slowing the velocity of the proppant, such that at least a portion of the proppant engages the formation and remains within the fractures, thereby maintaining and/or supporting the fractures.
Depending on the nature of the fluidized solid proppant used, in various embodiments, it may be desirable to use pressurized fracturing fluid (e.g., water, hydrocarbons, etc.) to form fractures in the formation, then displace the fracturing fluid by the provision of fluidized solid proppant into the well (150). As such,
While
In embodiments where fluid from the fluid supply subsystem (142) is used to form fractures in the formation, fluidized solid proppant can be flowed into the well (150), as described above, subsequent to the use of fracturing fluid, thereby displacing the fracturing fluid from the well (50) and engaging proppant with fractures in the formation.
In an embodiment, additional fluid (e.g., fracturing fluid or a displacement fluid from a separate source (not shown)) can be pumped into the well (150) to displace fluidized solid proppant not engaged with the formation.
Specifically,
With reference to
With reference to
With reference to
While
While various embodiments usable within the scope of the present disclosure have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention can be practiced other than as specifically described herein.
The present application claims priority to the United States Provisional Application for patent, having the Application Ser. No. 61/774,237, filed Mar. 7, 2013; the United States Provisional Application for patent, having the Application Ser. No. 61/790,742, filed Mar. 15, 2013; the United States Provisional Application for patent, having the Application Ser. No. 61/807,699, filed Apr. 2, 2013; the United States Provisional Application for patent, having the Application Ser. No. 61/870,350, filed Aug. 27, 2013; the United States Provisional Application for patent, having the Application Ser. No. 61/889,187 filed Oct. 10, 2013; and the United States Provisional Application for patent, having the Application Ser. No. 61/915,093, filed Dec. 12, 2013. Each of the above-referenced applications are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61774237 | Mar 2013 | US | |
| 61790942 | Mar 2013 | US | |
| 61807699 | Apr 2013 | US | |
| 61870350 | Aug 2013 | US | |
| 61889187 | Oct 2013 | US | |
| 61915093 | Dec 2013 | US |
