Patent Application
20200325760
Hydraulic fracturing may be used to increase hydrocarbon production from some subsurface formations. Hydraulic fracturing entails injecting fluid into a wellbore at a pressure sufficient to cause fissures in the formation surrounding the wellbore. The injected fluid may be a slurry or mixture containing any of a variety of water-, oil-, or gas-based fluids and a proppant and/or other desired additives.
In some instances, the fracturing fluid is pressurized at the surface by high-pressure pumps powered by diesel engines. In other instances, electric motors controlled by variable frequency drives are used place of the diesel engines and associated equipment. The use of electric motors greatly reduces the noise, emissions, and vibrations generated by the equipment during operation, as well as its size footprint.
Regardless of whether diesel or electric power is used to produce the pressures required for hydraulic fracturing, the pumps and associated engines tend to be bulky and heavy. In addition, a hydraulic fracturing system may include one or more of: data storage equipment, mixers, hydrators, chemical additive units, pumps, sand equipment, and the like. Thus, hydraulic fracturing equipment may be transported to hydraulic fracturing sites using heavy duty trailers, skids, or trucks capable of transporting heavy equipment.
In some embodiments, a system for fracturing a subsurface formation, may comprise a transport unit, an electric motor mounted on the transport unit, a fracking pump mounted on the transport unit and configured to be powered by the electric motor, and an oil tank mounted on the transport unit such that the motor and the pump are above the oil tank. The oil tank may have a first tank height under the pump and a second tank height under the motor and wherein the first tank height is greater than the second tank height. The system may further include at least one beam supporting the motor and at least one beam supporting the pump, and the oil tank may be formed integrally with the beams. The oil tank may be permanently secured to the beams.
In some embodiments, a system for fracturing a subsurface formation, may comprise a transport unit including a frame, an electric motor mounted on the transport unit, a fracking pump mounted on the transport unit and configured to be powered by the electric motor, and an oil tank mounted on the transport unit such that the motor and the fracking pump are above the oil tank. The tank may include a tank floor and the system may further include at least one motor support beam mounted on the frame and supporting the motor, the motor support beam including a motor mounting surface that engages the frame and a motor support surface that engages the motor, and at least one pump support beam mounted on the frame and supporting the fracking pump, each pump support beam including a pump mounting surface that engages the frame and a pump support surface that engages the fracking pump. The motor mounting surface and the pump mounting surface may define a mounting plane PM and the tank floor may lie below the mounting plane PM.
The at least one motor support beam may have an upper surface that defines a motor support plane PMS, the at least one pump support beam may have an upper surface that defines a pump support plane PPS, and the pump support plane PPS may be above the motor support plane PMS such that the bottom of the fracking pump is higher than the bottom of the motor. The oil tank may be formed integrally with the beams or permanently secured to the beams.
In still other embodiments, a system for fracturing a subsurface formation may comprise a transport unit including a frame, an electric motor mounted on the transport unit, a fracking pump mounted on the transport unit and configured to be powered by the electric motor, and an oil tank mounted on the transport unit such that the motor and the fracking pump are above the oil tank. The tank may include a tank floor and the system may further include at least one motor support beam mounted on the frame and supporting the motor and at least one pump support beam mounted on the frame and supporting the fracking pump. The oil tank, the motor support beam, and the pump support beam may be rigidly mechanically connected so as to form a single structural unit. The at least one motor support beam may include a motor mounting surface that engages the frame and a motor support surface that engages the motor and the at least one pump support beam may include a pump mounting surface that engages the frame and a pump support surface that engages the fracking pump. The motor mounting surface and the pump mounting surface may define a mounting plane PM and the tank floor may lie below the mounting plane PM. The system may include multiple motors and pumps, and each pump may be configured to be powered by an associated motor and each pump is associated with a fluid tank that extends under the pump and its associated motor. Alternatively, the system may include multiple motors and pumps, wherein each pump is configured to be powered by an associated motor and a single fluid tank provides fluid to all of the pumps.
In still other embodiments, a system for lubricating hydraulic fracturing equipment may comprise an oil pump for pumping lubricating oil, an electric motor configured to drive the oil pump, a variable frequency drive configured to control the electric motor, an oil tank, and a lubricating circuit in fluid communication with the oil pump and the oil tank. The lubricating circuit may pass through the hydraulic fracturing equipment. The variable frequency drive may vary the oil pump speed based on an input comprising at least one of oil pressure and oil temperature. The system may further include at least one of a filter, a thermostatic valve, an oil cooler, a check valve, a pressure relief valve. The thermostatic valve may control a flow of oil through the oil cooler based on oil temperature. The oil tank may be positioned beneath the hydraulic fracturing equipment. The hydraulic fracturing equipment may further include a fracking pump.
In still other embodiments, a transportable system for fracturing a subsurface formation may comprise a transport unit including wheels and a frame, a hydraulic fracturing pump unit mounted on the frame, and at least one pair of hydraulic landing legs positioned on opposite sides of the transport unit and adapted to, in conjunction with the wheels, support the transport unit. The hydraulic landing legs may be adjustable using hydraulic pressure. The system may further include a DC-powered hydraulic fluid pump in fluid communication with the hydraulic landing legs, a valve system with a switch for controlling each hydraulic landing leg, an integrated safety valve to prevent hydraulic collapse, a DC battery to provide power to the hydraulic fluid pump and valve system, and/or an in-transit battery charging system or a standby AC-powered battery charging system.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Referring initially to
As disclosed in greater detail below, it may be desirable to provide pressurized oil lubrication to some of the components of pump unit 30. Lubricating oil that has passed through the pump unit may be collected and recycled. The collected oil may be stored, along with supplemental oil if desired, in a dedicated oil tank. As further set out below, the dedicated oil tank may be configured to provide mechanical and structural support to pump unit 30.
In some instances, it may be desirable to leave trailer-mounted hydraulic fracturing components attached to the tractor throughout operations, i.e. to conduct fracturing operations without unloading the fracturing equipment from the transport unit on which it was transported to the wellsite. When the pump is diesel-driven, a tractor may be left connected to the transport unit so that the engine of the tractor may be used to start the high-pressure pump engine. In contrast, electric high-pressure pumps do not need a transport tractor in order to start or operate. Thus, in hydraulic fracturing operations in which electric high-pressure pumps are used, the trailer can be dropped and the tractor removed, thereby allowing more efficient transport fleet operations.
When a trailer is dropped, one or more landing legs are extended so that the weight of the trailer is distributed between the trailer wheels, which may be at or near the rear of the trailer, and the landing legs, which may be at or near the front of the trailer. The tractor can then be decoupled from the trailer. Because the fracturing equipment components can be very heavy, it may be difficult to operate a manual front landing leg. In particular, once the tractor has been decoupled, manual adjustment of the landing legs may be difficult or risky. In addition, in some instances, manual landing legs do not facilitate the adjustment of each leg height independently, with the result that the front of the trailer cannot be leveled side-to-side.
Therefore, in some embodiments, a leg hydraulic system 90 may be associated with each landing leg. Referring briefly to
Referring again to
Referring now to
Oil tank 42 may have an upper surface 51 and a tank floor 57. Oil tank 42 may comprise a relatively shallow section 53 and a relatively deep section 55 (shown in phantom in
In some embodiments, one or more motor support beams 52 and pump support beams 56 may each be mounted on frame 22 of transport unit 20 such that the longitudinal axis of each beam is transverse to the longitudinal axis of the transport unit 20. Motor support beams 52 and pump support beams 56 may each have a mounting surface, 52a, 56a, respectively. Mounting surfaces 52a, 56a may rest on frame 22 of transport unit 20. Motor support beams may each also have motor support surface 52b on which motor 32 may be mounted. Similarly, pump support beams may each have a pump support surface 56b on which pump 36 may be mounted. As illustrated in
In some embodiments, the shallow section 53 of oil tank 42 extends parallel to the longitudinal axis of transport unit 20 through the plane of each motor support beam 52. Likewise, the deep section 55 of oil tank 42 extends parallel to the longitudinal axis of transport unit 20 through the plane of each pump support beam 56. The upper surface 51 of oil tank 42 may be configured such that the upper surface of shallow section 53 lies below motor support plane PMS and the upper surface of deep section 55 lies below pump support plane PPS. Some or all of tank floor 57 may lie below mounting plane PM, in which case the volume of oil tank 42 that lies below mounting plane PM may be referred to an oil sump. Oil suction opening 43 may be configured to take oil from the oil sump.
In some embodiments, oil tank 42 is constructed to be functionally integral with motor support beams 52 and pump support beams 56, by which is meant that oil tank 42 may be formed integrally with beams 52, 56 or secured thereto by welds, bolts, or the like. In some embodiments, oil tank 42 may be secured permanently to beams 52, 56 and/or to frame 22 and not separated therefrom during transport and operation of the system. Oil tank 42 may itself function as a structural component in conjunction with beams 52, 56. Together oil tank 42 and beams 52, 56 form a base assembly that is stronger and more resistant to deformation than either component would be separately.
For example, in embodiments in which tank floor 57 lies below mounting plane PM as illustrated in
Thus, an advantage of the tank assembly disclosed herein is that it provides a rigid frame that is well-adapted to maintain the relative positions and coupling between the high pressure slurry pump and its motor. Minimizing movement within the coupling ensures proper shaft alignment and prevents premature wear and failure of the pump and/or motor. A rigid frame also ensures that pump/motor alignment is maintained during transport of the unit from one wellsite to another.
As illustrated, tank and beam assembly 40 may be mounted on transport unit 20. The ability to locate the tank on the trailer typically results in the selection of an oil tank with limited capacity because of the limited space to locate the tank. An integrated tank and base in accordance with the concepts disclosed herein allows for increased oil capacity, better trailer stability (because it is not located off the center line of the trailer), better gravity oil return flow from the high-pressure pump to the tank because the tank is directly below the high-pressure pump and closely coupled thereto, and better flow to the oil pump because most of the volume of the tank is above the inlet of the pump.
Further, it may be desirable to not remove the coupling during transport because realignment of the pump/motor unit may be time-consuming. Thus, if the pump and motor can remain coupled during transport, substantial time-savings may be realized. The base assembly disclosed herein is sufficiently rigid to hold the equipment in alignment and prevent any relative movement that would damage the pump/motor coupling. A hydraulic fracturing system 10 as disclosed herein can be readily transported to a well site on a transport unit 20, which may comprise a trailer or other platform or frame equipped with wheels or tracks.
In some embodiments, oil tank 42 holds lubricating oil for fracking pump 36. Lubricating oil from oil tank 42 may be pumped by a VFD-driven lube pump system.
In some embodiments, a VFD-driven lube pump system includes software control system that controls VFD 72, which in turn controls motor 74, which may be an electric motor. Motor 74 drives oil pump 76, which pumps lubricating oil through a desired lubricating circuit 80. Motor 74 and oil pump 76 may each be mounted in any suitable location on transport unit 20, including for example, on the lower outside of the trailer frame ahead of the tires and wheels. As shown in the exemplary embodiment in
Because the high-pressure fracking pump 36 requires a continuous supply of pressurized lubricating oil while fracking pump 36 is running, inconsistent delivery of lubricating oil to fracking pump 36 may affect fracking operations. The lubricating oil pressure may vary, based on oil temperature, high-pressure pump speed and other external factors. A lubricating oil pressure that is too high or too low can result in premature wear and failure of the high-pressure fracking pump. One way to control the lubricating oil system pressure is by controlling the speed of oil pump 76. In instances where the fracking pump is driven by a diesel engine, an oil pump may be driven by a power take-off on the same diesel engine and the lube oil system pressure may be controlled by varying the engine speed of the diesel engine. By contrast, in the present VFD-driven lube pump system, the lube oil system pressure can be controlled by the use of a variable frequency electric drive to vary the speed of the electric motor, which in turn can vary the speed of oil pump 76. The VFD can be controlled by software that varies the lube oil pump speed based on inputs including but not limited to oil pressure and temperature. A VFD-driven lube pump system ensures that the high-pressure fracking pump 36 always has an appropriate supply of pressurized lube oil.
Those skilled in the art will appreciate that numerous changes and modifications can be made to the embodiments of the present disclosure and that such changes and modifications can be made without departing from the spirit of said disclosure. It is, therefore, intended that the appended claims cover all such equivalent variations as fall within the true spirit and scope of said disclosure.
This application is a nonprovisional application which claims priority from U.S. provisional application No. 62/833,385, filed Apr. 12, 2019, which is incorporated by reference herein in its entirety. Technical Field/Field of the Disclosure The present disclosure relates to apparatus and methods for use in hydraulically fracturing subsurface formations.
| Number | Date | Country | |
|---|---|---|---|
| 62833385 | Apr 2019 | US |
