SUCTION AND DISCHARGE LINES FOR A DUAL HYDRAULIC
FRACTURING UNIT
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of, and claims priority to and the benefit of, co-pending U.S. Provisional Application Serial No. 62/156,301, filed May 3, 2015 and is a continuation-in-part of, and claims priority to and the benefit of co-pending U.S. Patent Application Serial No.
13/679,689, filed November 16, 2012, the full description and drawings of which are appended hereto.
BACKGROUND OF THE INVENTION
1. Field of Invention
[0002] The present disclosure relates to hydraulic fracturing of subterranean formations. In particular, the present disclosure relates to orienting piping connected to a fracturing pump so that connections in the piping are provided where the piping is oblique to a horizontal axis of the pump.
2. Description of Prior Art
[0003] Hydraulic fracturing is a technique used to stimulate production from some hydrocarbon producing wells. The technique usually involves injecting fluid into a wellbore at a pressure sufficient to generate fissures in the formation surrounding the wellbore.
Typically the pressurized fluid is injected into a portion of the wellbore that is pressure isolated from the remaining length of the wellbore so that fracturing is limited to a designated portion of the formation. The fracturing fluid slurry, whose primary component is usually water, includes proppant (such as sand or ceramic) that migrate into the fractures with the fracturing fluid slurry and remain to prop open the fractures after pressure is no longer applied to the wellbore. A
primary fluid for the slurry other than water, such as nitrogen, carbon dioxide, foam, diesel, or other fluids may be used as the primary component instead of water. A typical hydraulic fracturing fleet may include an data van unit, blender unit, hydration unit, chemical additive unit, hydraulic fracturing pump unit, sand equipment, wireline, and other equipment.
[0004] Traditionally, the fracturing fluid slurry has been pressurized on surface by high pressure pumps powered by diesel engines. To produce the pressures required for hydraulic fracturing, the pumps and associated engines have substantial volume and mass. Heavy duty trailers, skids, or trucks are required for transporting the large and heavy pumps and engines to sites where wellbores are being fractured. Each hydraulic fracturing pump usually includes power and end fluid ends, as well as seats, valves, springs, and keepers internally. Each pump is usually equipped with a water manifold (referred to as a fluid end) which contains seats, valves, and keepers internally. These parts allow the pump to draw in low pressure fluid (approximately 100 psi) and discharge the same fluid at high pressures (up to 15,000 psi or more). Traditional diesel powered hydraulic fracturing pump units only have one diesel engine, one transmission, and one hydraulic fracturing pump per unit. Recently electrical motors have been introduced to replace the diesel motors, which greatly reduces the emissions and noise generated by the equipment during operation. Because the pumps are generally transported on trailers, connections between segments of pump suction and discharge piping are generally made up in the field. Moreover, the segments having these connections extend horizontally or vertically, and which are difficult connections for operations personnel to handle. Prior turbine powered hydraulic fracturing units with two hydraulic pumps on each unit had one supply line that fed both pumps.
Also the discharge lines from both hydraulic fracturing pumps were combined into one discharge line while the unit.
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, SUMMARY OF THE INVENTION
100051 Disclosed herein is an example of a hydraulic fracturing system for fracturing a subterranean formation, and which includes a trailer having wheels, an electrically powered fracturing pump mounted on the trailer, a supply line having fracturing fluid, and a hard piped suction lead line. In another embodiment, the trailer is replaced by any platform such as a skid or a truck. Suction lead line is made up of a main segment connected to a suction inlet on the electrically powered pump and a tip segment that is angled obliquely to a portion of the main segment proximate the tip segment, an end of the tip segment is connected to an end of the main segment distal from the suction inlet, and the tip segment further having an end distal from the main segment that is connected to an end of the supply line. In one example, the pump, supply line, suction lead line, main segment, and tip segment each respectively make up a first pump, a first supply line, a first suction lead, a first main segment, and a first tip segment, this example of the hydraulic fracturing system further includes a second pump, a second supply line, a second suction lead, a second main segment, and a second tip segment, and wherein the second tip segment is angled with respect to the first tip segment. In one example, the tip segment is angled from about 22 degrees to about 45 degrees with respect to a portion of the main segment proximate the tip segment; and can optionally be angled at about 22 degrees with respect to a portion of the main segment proximate the tip segment. In one alternative, the first tip segment is angled at about 22 degrees with respect to a portion of the first main segment proximate the first tip segment, and the second tip segment is angled at about 45 degrees with respect to a portion of the second main segment proximate the second tip segment. The supply line can be a flexible line made from an elastomeric material. In one alternate embodiment, the tip segment extends away from the main segment in a direction that projects towards a surface on which the trailer is supported. In one embodiment, the supply line for a first pump is separate and distinct from the supply line for a second pump while on the unit. Boost pressure for both the first and second hydraulic fracturing pumps may come from the same blender. The system can further include a hard piped discharge lead line which is made up of a main segment connected to a discharge on the electrically powered pump, and a tip segment that is angled obliquely to a portion of the main segment proximate the tip segment, and having an end connected to an end of the main segment distal from the discharge, and further having an end distal from the main segment that is connected to an end of a discharge line. In one embodiment, the tip segment for the discharge line is parallel with a horizontal plane and is not angled down.
In an alternative where the pump, discharge line, discharge lead line, main segment, and tip segment each respectively are a first pump, a first discharge line, a first discharge lead, a first main segment, and a first tip segment, and the hydraulic fracturing system further includes a second pump, a second discharge line, a second discharge lead, a second main segment, and a second tip segment, the second tip segment is angled with respect to the first tip segment. In this example, the tip segment is angled from about 22 degrees to about 45 degrees with respect to a portion of the main segment proximate the tip segment. Optionally, the first tip segment is angled at about 22 degrees with respect to a portion of the first main segment proximate the first tip segment, and wherein the second tip segment is angled at about 45 degrees with respect to a portion of the second main segment proximate the second tip segment. In one embodiment, the tip segment for the discharge line for the first pump is parallel with a horizontal plane and is not angled down.
The tip segment for the discharge line for the first pump is offset from the discharge line for the second pump.
[0006] Another example of a hydraulic fracturing system for fracturing a subterranean formation includes an electrically powered fracturing pump mounted on a mobile platform, a lead line in fluid communication with the pump and having a tip portion that is oriented along an axis that is oblique to a horizontal axis, and a flow line connected to the tip portion and that is in fluid communication with the lead line. In one example, the axis along which the tip portion is oriented is a first axis, and wherein an angle is defined between the first axis and the horizontal axis that ranges from around 22 degrees to around 45 degrees. The pump, lead line, axis, and flow line each respectively can be referred to as a first pump, a first lead line, a first tip portion, a first axis, and a first flow line, and in this example the hydraulic fracturing system further includes a second pump, a second lead line, a second tip portion, and a second flow line, and wherein the second tip portion extends along a second axis that is oblique with the first axis and the horizontal axis. In this example, the first axis can be an at angle of around 22 degrees with respect to the horizontal axis, and wherein the second axis can be at an angle of around 45 degrees with respect to the horizontal axis. The lead line can optionally be a suction lead line, and the flow line can be a supply line, in this example the hydraulic fracturing system further includes a discharge lead line having a tip portion and a discharge line, and wherein the tip portion of the discharge lead line extends along another axis that is oblique to the horizontal axis.
-In one embodiment, the discharge lead line and tip portion are parallel with the horizontal axis of the platform and are not angled. In this example, the supply line contains fracturing fluid from a blender, and wherein the discharge line contains fracturing fluid pressurized by the pump.
[0007] Another example of a hydraulic fracturing system for fracturing a subterranean formation includes a trailer, a first electrically powered pump mounted on the trailer and having a suction lead line with an end connected to a supply line and that is angled in a range of from around 22 degrees to around 45 degrees with respect to a horizontal axis, and having a discharge lead line with an end connected to a discharge line that is angled in a range of from around 22 degrees to around 45 degrees with respect to the horizontal axis, and a second electrically powered pump mounted on the trailer and having a suction lead line with an end connected to a supply line and that is angled in a range of from around 22 degrees to around 45 degrees with respect to the horizontal axis, and having a discharge lead line with an end connected to a discharge line that is angled in a range of from around 22 degrees to around 45 degrees with respect to the horizontal axis. In one embodiment, the discharge line is not angled and is parallel with the horizontal axis of the trailer.
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[0008] 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:
[0009] FIG. 1 is a schematic of an example of a hydraulic fracturing system.
[0010] FIGS. 2 and 3 are side views of examples of piping for a fracturing pump having connections in obliquely oriented segments of the piping.
[0011] FIG. 4 is an end perspective view of an example of an example fracturing pumps on a trailer having separate and distinct suction and discharge piping.
[0012] While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
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DETAILED DESCRIPTION OF INVENTION
[0013] 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 the cited magnitude.
In an embodiment, usage of the term "substantially" includes +/- 5% of the cited magnitude.
[0014] 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.
[0015] Figure 1 is a schematic example of a hydraulic fracturing system 10 that is used for pressurizing a wellbore 12 to create fractures 14 in a subterranean formation 16 that surrounds the wellbore 12. Included with the system 10 is a hydration unit 18 that receives fluid from a fluid source 20 via line 22, and also selectively receives additives from an additive source 24 via line 26. Additive source 24 can be separate from the hydration unit 18 as a stand-alone unit, or can be included as part of the same unit as the hydration unit 18. The fluid, which in one example is water, is mixed inside of the hydration unit 18 with the additives.
In an embodiment, the fluid and additives are mixed over a period of time to allow for uniform distribution of the additives within the fluid. In the example of Figure 1, the fluid and additive mixture is transferred to a blender unit 28 via line 30. A proppant source 32 contains proppant, which is delivered to the blender unit 28 as represented by line 34, where line 34 can be a conveyer.
Inside the blender unit 28, the proppant and fluid/additive mixture are combined to form a fracturing slurry, which is then transferred to a fracturing pump system 36 via line 38; thus fluid in line 38 includes the discharge of blender unit 28 which is the suction (or boost) for the fracturing pump system 36. Blender unit 28 can have an onboard chemical additive system, such
- 7 -as with chemical pumps and augers. Optionally, additive source 24 can provide chemicals to blender unit 28; or a separate and standalone chemical additive system (not shown) can be provided for delivering chemicals to the blender unit 28. In an example, the pressure of the slurry in line 38 ranges from around 80 psi to around 100 psi. The pressure of the slurry can be increased up to around 15,000 psi by pump system 36. A motor 39, which connects to pump system 36 via connection 40, drives pump system 36 so that it can pressurize the slurry. In one example, the motor 39 is controlled by a variable frequency drive ("VFD"). In one embodiment, a motor 39 may connect to a first pump system 36 via connection 40 and to a second pump system 36 via a second connection 40. After being discharged from pump system 36, slurry is pumped into a wellhead assembly 41; discharge piping 42 connects discharge of pump system 36 with wellhead assembly 41 and provides a conduit for the slurry between the pump system 36 and the wellhead assembly 41. In an alternative, hoses or other connections can be used to provide a conduit for the slurry between the pump system 36 and the wellhead assembly 41.
Optionally, any type of fluid can be pressurized by the fracturing pump system 36 to form injection fracturing fluid that is then pumped into the wellbore 12 for fracturing the formation 14, and is not limited to fluids having chemicals or proppant.
[0016] An example of a turbine 44 is provided in the example of Figure 1 and which receives a combustible fuel from a fuel source 46 via a feed line 48. In one example, the combustible fuel is natural gas, and the fuel source 46 can be a container of natural gas or a well (not shown) proximate the turbine 44. Combustion of the fuel in the turbine 44 in turn powers a generator 50 that produces electricity. Shaft 52 connects generator 50 to turbine 44. The combination of the turbine 44, generator 50, and shaft 52 define a turbine generator 53. In another example, gearing can also be used to connect the turbine 44 and generator 50. An example of a micro-grid 54 is further illustrated in Figure 1, and which distributes electricity generated by the turbine generator 53. Included with the micro-grid 54 is a transformer 56 for stepping down voltage of the electricity generated by the generator 50 to a voltage more compatible for use by electrical powered devices in the hydraulic fracturing system 10. In another example, the power generated by the turbine generator and the power utilized by the electrical powered devices in the hydraulic fracturing system 10 are of the same voltage, such as 4160 V so that main power transformers are not needed. In one embodiment, multiple 3500 kVA dry cast coil transformers are utilized.
Electricity generated in generator 50 is conveyed to transformer 56 via line 58. In one example,
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, transformer 56 steps the voltage down from 13.8 kV to around 600 V. Other step down voltages can include 4,160 V, 480 V, or other voltages. The output or low voltage side of the transformer 56 connects to a power bus 60, lines 62, 64, 66, 68, 70, and 72 connect to power bus 60 and deliver electricity to electrically powered end users in the system 10. More specifically, line 62 connects fluid source 20 to bus 60, line 64 connects additive source 24 to bus 60, line 66 connects hydration unit 18 to bus 60, line 68 connects proppant source 32 to bus 60, line 70 connects blender unit 28 to bus 60, and line 72 connects motor 39 to bus 60.
In an example, additive source 24 contains ten or more chemical pumps for supplementing the existing chemical pumps on the hydration unit 18 and blender unit 28. Chemicals from the additive source 24 can be delivered via lines 26 to either the hydration unit 18 and/or the blender unit 28. In one embodiment, the elements of the system 10 are mobile and can be readily transported to a wellsite adjacent the wellbore 12, such as on trailers or other platforms equipped with wheels or tracks.
[0017] Figure 2 shows in a side view a schematic example of a portion of the hydraulic fracturing system 10 of Figure 1 and which includes a pair of pumps 80, 82 mounted on a trailer 84. In another embodiment, the platform 84 may be a truck or one or more skids. The pumps 80, 82 and trailer 84 make up one example of a fracturing pump system 36 and which is used for pressurizing fracturing fluid that is then transmitted to the wellhead assembly 41 of Figure 1.
Trailer 84 is shown mounted on a surface 85, which can be any surface proximate wellhead assembly 41 (Figure 1), such as a paved or unpaved road, a pad (formed from concrete or a mat), gravel, or the Earth's surface. As shown, surface 85 is generally parallel with a horizontal axis Ax which provides one example of a reference axis for comparing relative angles thereto.
Further included with the fracturing pump system 36 of Figure 2 is a suction lead line 86 which is substantially supported on top of trailer 84. In the illustrated example, lead line 86 is hard piped, e.g., formed from metal or other generally non-pliable material.
Suction lead line 86 provides a conduit for fracturing fluids supplied from the blender unit 28 and to the suction inlets 87 provided on pump 80. While three suction inlets 87 are shown on pump 80, any number of inlets may be provided depending on the design and application of pump 80.
Another suction lead line 88 is provided on trailer 84 which connects to suction inlets 89 formed on pump 82, suction lead line 88 is also hard piped. Suction lead lines 86, 88 respectively couple to supply lines 90, 92, both of which carry fracturing fluid from blender unit 28 and across the distance
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, between blender unit 28 and fracturing pump system 36. In one example supply lines 90, 92 are generally flexible and include elastomeric material. Connections 94, 96 provide a coupling between the suction lead lines 86, 88 and supply lines 90, 92. Connections 94, 96 can be flanged or threaded and may include any different number of connections that are appropriate for use in a field application, such as compression fittings, threaded unions, hammer lug unions, and the like.
Fracturing fluid 97 is shown stored within tub 98 which is part of the blender unit 28 and as described above provides a place for preparing fracturing fluid to be used in a fracturing environment. Fracturing fluid 97 is directed from tub 98 through piping 99 to a discharge pump 100 which pressurizes or boosts fracturing fluid 97 for transmitting the fracturing fluid 97 to the fracturing pump system 36. Piping 101 attached to a discharge end of pump 100 directs the pressurized fracturing fluid to a manifold 102. Connections 1031, formed on manifold 102 attach to supply lines 104, which are similar to supply lines 90, 92 and that direct the fracturing fluid to pumps (not shown). Pumps connected to supply lines 1041, are similar to pumps 80, 82, and are also part of the fracturing pump system 36.
100181 Suction lead lines 86, 88 of Figure 2 each include main segments 105, 106; which make up portions of the suction lead lines 86, 88 on the trailer 84 and distal from the supply lines 90, 92. Suction lead lines 86, 88 also include tip segments 108, 110, which include portions of the suction lead lines 86, 88 that connect to ends of main segments 105, 106 respectively, and that are proximate to and connect with the supply lines 90, 92. As shown, tip segments 108, 110 are shown extending along axes Axi, Ax2 that are oblique with respect to horizontal axis Ax. By obliquely angling the tip segments 108, 110, operations personnel experience significantly less difficulty in connecting the supply lines 90, 92 to the suction lead lines 86, 88. When connecting/disconnecting a supply line 90, 92 from an obliquely angled tip segment 108, 110 allows operations personnel to hold the portion of the supply lines 90, 92 spaced away from the suction leads 86, 88 vertically lower than the end at the connection 94, 96;
which is a more natural and less cumbersome orientation for operations personnel. The angled connections also generate less stress on the supply lines 90, 92 which may lengthen their life and minimize failures The angled holding of the supply lines 90, 92 is in contrast to the generally horizontal or vertical orientations of ends of traditional suction lead lines, which requires that the rearward portions of the supply lines 90, 92 at the same vertical level as the ends at the connections 94, 96.
-10-[0019] In one non-limiting example, axis Axi is at an angle Eli of around 22 with respect to horizontal axis Ax. Optionally, axis Ax2 is at an angle D2 of around 45 with respect to horizontal axis Ax. An additional advantage is realized by offsetting the angles of the adjacent tip segments 108, 110 as not only can personnel realize the advantage of the non-horizontal orientation of these tip segments 108, 110 when attaching or moving the supply lines 90, 92, but angularly offsetting the adjacent tip segments 108, 110 reduces interference of operation between these two tip segments 108, 110. It should be pointed out, however, that the axes Axi, Ax2 along which the tip segments 108, 110 are oriented can range between around 22 and up to around 45 from the horizontal axis Ax. Additionally, the offset angles between axes Axi, Ax2 and horizontal axis Ax can be less than 22 . In Figure 2, tip segments 108, 110 are shown projecting along a path that intersects with surface 85. However, embodiments exist wherein one or both of tip segments 108, 110 extend along a path that projects away from surface 85.
[0020] Further shown in Figure 2 is a discharge lead line 112 which is shown connecting to a discharge 113 mounted on a high pressure side of pump 80. A discharge line 114 is shown connecting to a discharge 115 mounted on the high pressure side of pump 82.
Referring now to the example of Figure 3, shown is that discharge lead lines 112, 114 each include main segments 116, 118 and which are primarily mounted on trailer 84. The ends of the discharge lead lines 102, 114 distal from pumps 80, 82 are angled to define tip segments 120, 122 which as shown are oriented respectively along axes Ax3, Ax4. Like axes Axi, Ax2 of Figure 2, axes Ax3, Ax4 of Figure 3 project at angles with respect to horizontal axis Ax that are oblique. More specifically, Ax3 is shown at an angle of 113 with respect to horizontal axis Ax, and axis Ax4 is at an angle of 114 with respect to horizontal axis Ax. Similar to the tip segments 108, 110 of Figure 2, obliquely angling of the tip segments 120, 122 provides an easier connection and disconnection of discharge lines 124, 126 shown respectively coupled to the ends of the tip segments 120, 122.
Connections 128, 130 are illustrated that provide connection between the discharge lines 124, 126 and tip segments 120, 122. In one optional embodiment, tip segments 108, 110, 120, 122 extend across the outer periphery of the upper surface of trailer 84. Example connections 128, 130 include flange connections, threaded connections, unions, hammer unions, quick disconnect connections, and the like. In one embodiment, the ends of the two discharge lead lines for the first pump and the second pump are parallel to the horizontal plane and are offset from each other.
- 11 -., [0021] Further shown in the example of Figure 4 are hydraulic fracturing pumps 80, 82 mounted on trailer 84. In the illustrated embodiment, suction line 88 and the discharge line 114 fluidly connected to pump 80 and are routed underneath the fluid end of pump 82.
Further in this example, the discharge tip segments 120, 122 are offset from one another, but are oriented along paths that are generally parallel with the trailer 84 and surface 85 on which trailer 84 is supported. As shown, the discharge lead lines 112, 114 and respective tip segments 120, 122 remain separate from one another so that pressurized slurry from the pumps 80, 82 remains in separate conduits while on and adjacent trailer 84. Lines 86, 88 and associated tip segments 108, 110 are also kept apart from one another while on and adjacent trailer 84 As indicated above, separating these fluid flow lines, especially proximate the pumps 80, 82 reduces vibration in the hardware coupled with the pumps 80, 82, and flow lines carrying slurry to and from the pumps 80, 82.
[0022] 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. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.
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SYSTEM FOR PUMPING HYDRAULIC FRACTURING FLUID USING ELECTRIC
PUMPS
BACKGROUND OF THE INVENTION
1. Field of the Invention 100011 This technology relates to hydraulic fracturing in oil and gas wells.
In particular, this technology relates to pumping fracturing fluid into an oil or gas well using pumps powered by electric motors.
2. Brief Description of Related Art [0002] Hydraulic fracturing has been used for decades to stimulate production from conventional oil and gas wells. The practice consists of pumping fluid into a wellbore at high pressure. Inside the wellbore, the fluid is forced into the formation being produced. When the fluid enters the formation, it fractures, or creates fissures, in the formation. Water, as well as other fluids, and some solid proppants, are then pumped into the fissures to stimulate the release of oil and gas from the formation.
[0003] Fracturing rock in a formation requires that the fracture fluid be pumped into the wellbore at very high pressure. This pumping is typically performed by large diesel-powered pumps.
Such pumps are able to pump fracturing fluid into a wellbore at a high enough pressure to crack the formation, but they also have drawbacks. For example, the diesel pumps are very heavy, and thus must be moved on heavy duty trailers, making transport of the pumps between oilfield sites expensive and inefficient. In addition, the diesel engines required to drive the pumps require a relatively high level of expensive maintenance. Furthermore, the cost of diesel fuel is much higher than in the past, meaning that the cost of running the pumps has increased.
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[0004] What is needed therefore, is a pump system for hydraulic fracturing fluid that overcomes the problems associated with diesel pumps.
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SUMMARY OF THE INVENTION
[0005] Disclosed herein is a system for hydraulically fracturing an underground formation in an oil or gas well to extract oil or gas from the formation, the oil or gas well having a wellbore that permits passage of fluid from the wellbore into the formation. The system includes a plurality of electric pumps fluidly connected to the well, and configured to pump fluid into the wellbore at high pressure so that the fluid passes from the wellbore into the formation, and fractures the formation. The system also includes a plurality of generators electrically connected to the plurality of electric pumps to provide electrical power to the pumps. At least some of the plurality of generators can be powered by natural gas. In addition, at least some of the plurality of generators can be turbine generators.
[0006] In one embodiment, the system further includes an A/C console and a variable frequency drive that controls the speed of the pumps. Furthermore, the electric pumps, as well as the electric generators, can be mounted on vehicles, and can be ported from one well to another. The vehicles can be trucks and can have at least five axles.
[0007] Further disclosed herein is a system for fracturing a rock formation in an oil or gas well by pumping hydraulic fracturing fluid into the well that includes a pump, an electric motor, a variable frequency drive, and a natural gas powered electric generator. The pump is configured for pumping the hydraulic fracturing fluid into the well, and then from the well into the formation, and is capable of pumping the hydraulic fracturing fluid at high pressure to crack the formation. The electric motor can have a high-strength steel or steel alloy shaft attached to the pump and configured to drive the pump. The variable frequency drive can be connected to the electric motor to control the speed of the motor. In addition, the natural gas powered generator,
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which can be a turbine generator, can be connected to the electric motor and provide electric power to the electric motor.
[0008] In one embodiment, the pump can be a triplex or a quinteplex pump, optionally rated at about 2250 hydraulic horsepower or more. In addition, the pump can also have 4.5 inch diameter plungers with an eight inch stroke. In another embodiment, the electric motor can have a maximum continuous power output of about 1500 brake horsepower, 1750 brake horsepower, or more, and a maximum continuous torque of about 8750 lb-ft or more.
Furthermore, the electric motor can have a high temperature rating of about 1100 degrees C or more, and a shaft composed of 4340 alloy steel.
[0009] In another embodiment, variable frequency drive can frequently perform electric motor diagnostics to prevent damage to the electric motor if it becomes grounded or shorted. In addition, the variable frequency drive can include power semiconductor heat sinks having one or more thermal sensors monitored by a microprocessor to prevent semiconductor damage caused by excessive heat.
[0010] Also disclosed herein is a system for hydraulically fracturing an underground formation in an oil or gas well to extract oil or gas from the formation, the oil or gas well having a wellbore that permits passage of fluid from the wellbore into the formation. The system includes a trailer for attachment to a truck. Two or more electric pumps can be attached to the trailer and are fluidly connected to the well, the electric pumps configured to pump fluid into the wellbore at high pressure so that the fluid passes from the wellbore into the formation, and fractures the formation. One or more electric motors are attached to the electric pumps to drive the pumps.
The electric motors can also be attached to the trailer. A natural gas powered generator is provided for connection to the electric motor to provide electric power to the electric motor. The
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system of claim can further include a variable frequency drive attached to the trailer and connected to the electric motor to control the speed of the motor. In addition, the system can include a skid to which at least one of the electric pumps, the one or more electric motors, and the variable frequency drives are attached.
100111 Also disclosed herein is a process for stimulating an oil or gas well by hydraulically fracturing a formation in the well. The process includes the steps of pumping fracturing fluid into the well with an electrically powered pump at a high pressure so that the fracturing fluid enters and cracks the formation, the fracturing fluid having at least a liquid component and a solid proppant, and inserting the solid proppant into the cracks to maintain the cracks open, thereby allowing passage of oil and gas through the cracks. The process can further include powering the electrically powered pump with a natural gas generator, such as, for example, a turbine generator.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present technology will be better understood on reading the following detailed description of nonlimiting embodiments thereof, and on examining the accompanying drawing, in which:
[0013] Fig. 1 is a schematic plan view of equipment used in a hydraulic fracturing operation, according to an embodiment of the present technology; and [0014] Fig. 2 is a schematic plan view of equipment used in a hydraulic fracturing operation, according to an alternate embodiment of the present technology.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] The foregoing aspects, features, and advantages of the present technology will be further appreciated when considered with reference to the following description of preferred embodiments and accompanying drawing, wherein like reference numerals represent like elements. In describing the preferred embodiments of the technology illustrated in the appended drawing, specific terminology will be used for the sake of clarity. However, the technology is not intended to be limited to the specific terms used, and it is to be understood that each specific term includes equivalents that operate in a similar manner to accomplish a similar purpose.
[0016] Fig. 1 shows a plan view of equipment used in a hydraulic fracturing operation.
Specifically, there is shown a plurality of pumps 10 mounted to pump vehicles 12. The pump vehicles 12 can be trucks having at least five axles. In the embodiment shown, the pumps 10 are powered by electric motors 14, which can also be mounted to the pump vehicles 12. The pumps are fluidly connected to the wellhead 16 via the missile 18. As shown, the pump vehicles 12 can be positioned near enough to the missile 18 to connect fracturing fluid lines 20 between the pumps 10 and the missile 18. The missile 18 is then connected to the wellhead 16 and configured to deliver fracturing fluid provided by the pumps 10 to the wellhead 16.
[0017] In some embodiments, each electric motor 14 can be capable of delivering about 1500 brake horsepower (BHP), 1750 BHP, or more, and each pump 10 can optionally be rated for about 2250 hydraulic horsepower (HHP) or more. In addition, the components of the system, including the pumps 10 and the electric motors 14, can be capable of operating during prolonged pumping operations, and in temperature in a range of about 0 degrees C or less to about 55 degrees C or more. In addition, each electric motor 14 can be equipped with a variable
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frequency drive (VFD), and an A/C console, that controls the speed of the electric motor 14, and hence the speed of the pump 10.
[0018] The electric motors 14 of the present technology can be designed to withstand an oilfield environment. Specifically, some pumps 10 can have a maximum continuous power output of about 1500 BHP, 1750 BHP, or more, and a maximum continuous torque of about 8750 lb-ft or more. Furthermore, electric motors 14 of the present technology can include class H insulation and high temperature ratings, such as about 1100 degrees C or more. In some embodiments, the electric motor 14 can include a single shaft extension and hub for high tension radial loads, and a high strength 4340 alloy steel shaft, although other suitable materials can also be used.
[0019] The VFD can be designed to maximize the flexibility, robustness, serviceability, and reliability required by oilfield applications, such as hydraulic fracturing.
For example, as far as hardware is concerned, the VFD can include packaging receiving a high rating by the National Electrical Manufacturers Association (such as nema 1 packaging), and power semiconductor heat sinks having one or more thermal sensors monitored by a microprocessor to prevent semiconductor damage caused by excessive heat. Furthermore, with respect to control capabilities, the VFD can provide complete monitoring and protection of drive internal operations while communicating with an operator via one or more user interfaces. For example, motor diagnostics can be performed frequently (e.g., on the application of power, or with each start), to prevent damage to a grounded or shorted electric motor 14. The electric motor diagnostics can be disabled, if desired, when using, for example, a low impedance or high-speed electric motor.
[0020] In some embodiments, the pump 10 can optionally be a 2250 HHP triplex or quinteplex pump. The pump 10 can optionally be equipped with 4.5 inch diameter plungers that have an = CA 02928707 2016-05-03 APPENDIX
eight (8) inch stroke, although other size plungers can be used, depending on the preference of the operator. The pump 10 can further include additional features to increase its capacity, durability, and robustness, including, for example, a 6.353 to 1 gear reduction, autuofrettaged steel or steel alloy fluid end, wing guided slush type valves, and rubber spring loaded packing.
[0021] In addition to the above, certain embodiments of the present technology can include a skid (not shown) for supporting some or all of the above-described equipment.
For example, the skid can support the electric motor 14 and the pump 10. In addition, the skid can support the VFD. Structurally, the skid can be constructed of heavy-duty longitudinal beams and cross-members made of an appropriate material, such as, for example, steel. The skid can further include heavy-duty lifting lugs, or eyes, that can optionally be of sufficient strength to allow the skid to be lifted at a single lift point.
[0022] Referring back to Fig. 1, also included in the equipment is a plurality of electric generators 22 that are connected to, and provide power to, the electric motors 14 on the pump vehicles 12. To accomplish this, the electric generators 22 can be connected to the electric motors 14 by power lines (not shown). The electric generators 22 can be connected to the electric motors 14 via power distribution panels (not shown). In certain embodiments, the electric generators 22 can be powered by natural gas. For example, the generators can be powered by liquefied natural gas. The liquefied natural gas can be converted into a gaseous form in a vaporizer prior to use in the generators. The use of natural gas to power the electric generators 22 can be advantageous because, where the well is a natural gas well, above ground natural gas vessels 24 can already be placed on site to collect natural gas produced from the well.
Thus, a portion of this natural gas can be used to power the electric generators 22, thereby reducing or eliminating the need to import fuel from offsite. If desired by an operator, the APPENDIX
electric generators 22 can optionally be natural gas turbine generators, such as those shown in Fig. 2.
[0023] Fig. 1 also shows equipment for transporting and combining the components of the hydraulic fracturing fluid used in the system of the present technology. In many wells, the fracturing fluid contains a mixture of water, sand or other proppant, acid, and other chemicals.
Examples of fracturing fluid components include acid, anti-bacterial agents, clay stabilizers, corrosion inhibitors, friction reducers, gelling agents, iron control agents, pH adjusting agents, scale inhibitors, and surfactants. Historically, diesel has at times been used as a substitute for water in cold environments, or where a formation to be fractured is water sensitive, such as, for example, clay. The use of diesel, however, has been phased out over time because of price, and the development of newer, better technologies.
[0024] In Fig. 1, there are specifically shown sand transporting vehicles 26, an acid transporting vehicle 28, vehicles for transporting other chemicals 30, and a vehicle carrying a hydration unit 32, such as, for example, a water pump. Also shown are fracturing fluid blenders 34, which can be configured to mix and blend the components of the hydraulic fracturing fluid, and to supply the hydraulic fracturing fluid to the pumps 10. In the case of liquid components, such as water, acids, and at least some chemicals, the components can be supplied to the blenders 34 via fluid lines (not shown) from the respective component vehicles, or from the hydration unit 32. In the case of solid components, such as sand, the component can be delivered to the blender 34 by a conveyor belt 38. The water can be supplied to the hydraulic unit 32 from, for example, water tanks 36 onsite. Alternately, the water can be provided by water trucks.
Furthermore, water can be provided directly from the water tanks 36 or water trucks to the blender 34, without first passing through the hydration unit 32.
APPENDIX
[0025] Pump control and data monitoring equipment 40 can be mounted on a control vehicle 42, and connected to the pumps 10, electric motors 14, blenders 34, and other downhole sensors and tools (not shown) to provide information to an operator, and to allow the operator to control different parameters of the fracturing operation. For example, the pump control and data monitoring equipment 40 can include an A/C console that controls the VFD, and thus the speed of the electric motor 14 and the pump 10. Other pump control and data monitoring equipment can include pump throttles, a pump VFD fault indicator with a reset, a general fault indicator with a reset, a main estop, a programmable logic controller for local control, and a graphics panel. The graphics panel can include, for example, a touchscreen interface.
[0026] Referring now to Fig. 2, there is shown an alternate embodiment of the present technology. Specifically, there is shown a plurality of pumps 110 which, in this embodiment, are mounted to pump trailers 112. As shown, the pumps 110 can optionally be loaded two to a trailer 112, thereby minimizing the number of trailers needed to place the requisite number of pumps at a site. The ability to load two pumps 110 on one trailer 112 is possible because of the relatively light weight of the electric pumps 110 compared to other known pumps, such as diesel pumps. In the embodiment shown, the pumps 110 are powered by electric motors 114, which can also be mounted to the pump trailers 112. Furthermore, each electric motor 114 can be equipped with a VFD, and an A/C console, that controls the speed of the motor 114, and hence the speed of the pumps 110.
[0027] In addition to the above, the embodiment of Fig. 2 can include a skid (not shown) for supporting some or all of the above-described equipment. For example, the skid can support the electric motors 114 and the pumps 110. In addition, the skid can support the VFD. Structurally, the skid can be constructed of heavy-duty longitudinal beams and cross-members made of an , APPENDIX
appropriate material, such as, for example, steel. The skid can further include heavy-duty lifting lugs, or eyes, that can optionally be of sufficient strength to allow the skid to be lifted at a single lift point.
[0028] The pumps 110 are fluidly connected to a wellhead 116 via a missile 118. As shown, the pump trailers 112 can be positioned near enough to the missile 118 to connect fracturing fluid lines 120 between the pumps 110 and the missile 118. The missile 118 is then connected to the wellhead 116 and configured to deliver fracturing fluid provided by the pumps 110 to the wellhead 116.
[0029] Still referring to Fig. 2, this embodiment also includes a plurality of turbine generators 122 that are connected to, and provide power to, the electric motors 114 on the pump trailers 112. To accomplish this, the turbine generators 122 can be connected to the electric motors 114 by power lines (not shown). The turbine generators 122 can be connected to the electric motors 114 via power distribution panels (not shown). In certain embodiments, the turbine generators 122 can be powered by natural gas, similar to the electric generators 22 discussed above in reference to the embodiment of Fig. 1. Also included are control units 144 for the turbine generators 122.
[0030] The embodiment of Fig. 2 can include other equipment similar to that discussed above.
For example, Fig. 2 shows sand transporting vehicles 126, acid transporting vehicles 128, other chemical transporting vehicles 130, hydration units 132, blenders 134, water tanks 136, conveyor belts 138, and pump control and data monitoring equipment 140 mounted on a control vehicle 142. The function and specifications of each of these is similar to corresponding elements shown in Fig. 1.
= , .., APPENDIX
[0031] Use of pumps 10, 110 powered by electric motors 14, 114 and natural gas powered electric generators 22 (or turbine generators 122) to pump fracturing fluid into a well is advantageous over known systems for many different reasons. For example, the equipment (e.g.
pumps, electric motors, and generators) is lighter than the diesel pumps commonly used in the industry. The lighter weight of the equipment allows loading of the equipment directly onto a truck body. In fact, where the equipment is attached to a skid, as described above, the skid itself can be lifted on the truck body, along with all the equipment attached to the skid, in one simple action. Alternatively, and as shown in Fig. 2, trailers 112 can be used to transport the pumps 110 and electric motors 114, with two or more pumps 110 carried on a single trailer 112. Thus, the same number of pumps 110 can be transported on fewer trailers 112. Known diesel pumps, in contrast, cannot be transported directly on a truck body or two on a trailer, but must be transported individually on trailers because of the great weight of the pumps.
[0032] The ability to transfer the equipment of the present technology directly on a truck body or two to a trailer increases efficiency and lowers cost. In addition, by eliminating or reducing the number of trailers to carry the equipment, the equipment can be delivered to sites having a restricted amount of space, and can be carried to and away from worksites with less damage to the surrounding environment. Another reason that the electric pump system of the present technology is advantageous is that it runs on natural gas. Thus, the fuel is lower cost, the components of the system require less maintenance, and emissions are lower, so that potentially negative impacts on the environment are reduced.
[0033] In practice, a hydraulic fracturing operation can be carried out according to the following process. First, the water, sand, and other components are blended to form a fracturing fluid, which is pumped down the well by the electric-powered pumps. Typically, the well is designed APPENDIX
so that the fracturing fluid can exit the wellbore at a desired location and pass into the surrounding formation. For example, in some embodiments the wellbore can have perforations that allow the fluid to pass from the wellbore into the formation. In other embodiments, the wellbore can include an openable sleeve, or the well can be open hole. The fracturing fluid can be pumped into the wellbore at a high enough pressure that the fracturing fluid cracks the formation, and enters into the cracks. Once inside the cracks, the sand, or other proppants in the mixture, wedges in the cracks, and holds the cracks open.
[0034] Using the pump control and data monitoring equipment 40, the operator can monitor, gauge, and manipulate parameters of the operation, such as pressures, and volumes of fluids and proppants entering and exiting the well. For example, the operator can increase or decrease the ratio of sand to water as the fracturing process progresses and circumstances change.
[0035] This process of injecting fracturing fluid into the wellbore can be carried out continuously, or repeated multiple times in stages, until the fracturing of the formation is optimized. Optionally, the wellbore can be temporarily plugged between each stage to maintain pressure, and increase fracturing in the formation. Generally, the proppant is inserted into the cracks formed in the formation by the fracturing, and left in place in the formation to prop open the cracks and allow oil or gas to flow into the wellbore.
[0036] While the technology has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the technology. Furthermore, it is to be understood that the above disclosed embodiments are merely illustrative of the principles and applications of the present technology. Accordingly, numerous modifications can be made to the illustrative APPENDIX
embodiments and other arrangements can be devised without departing from the spirit and scope of the present technology as defined by the appended claims.