(19) United States
`(12) Patent Application Publication (Η» Pub. No.: US 2013/0306322 Al
`Sanborn et al.
`Nov. 21,2013
`(43) Pub. Date:
`
`US 20130306322A1
`
`(54) SYSTEM AND PROCESS FOR EXTRACTING
`OIL AND GAS BY HYDRAULIC
`FRACTURING
`
`(71) Applicant: GENERAL ELECTRIC COMPANY,
`Schenectady, NY (US)
`
`(72)
`
`Inventors: Stephen Duane Sanborn, Copake, NY
`(US); David Kamensky, West Chester,
`OH (US); John Andrew Westerheide,
`Houston, TX (US); Christopher
`Edward Wolfe, Niskayuna, NY (US);
`Hareesh Kumar Reddy Kommepalli,
`Schenectady, NY (US)
`(73) Assignee: GENERAL ELECTRIC COMPANY,
`Schenectady, NY (US)
`.: 13/708,206
`Appl.No
`(21)
`(22) Filed:
`Dec. 7, 2012
`
`Related U.S. Application Data
`(60) Provisional application No. 61/649,563, filed on May
`21, 2012.
`
`Publication Classification
`
`(51) Int.Cl.
`E21B 43/26
`(52) U.S. Cl.
`CPC .......................................... E2IB 43/26 (2013.01)
`USPC ............................................................. 166/308.1
`
`(2006.01)
`
`(57)
`
`ABSTRACT
`
`A fracturing system is described. The system includes an
`electric motor-driven pumping sub-system, configured to
`pump a pressurized fracturing fluid into at least one wellbore,
`under high pressure conditions sufficient to increase the
`downhole pressure of the wellbore, to exceed that of the
`fracture gradient of the solid matter surrounding the wellbore.
`The system also includes an electric power generation sub-
`system that provides energy to the pumping sub-system. The
`electric power generation sub-system includes a multitude of
`electric motors that are powered by a single electrical feed
`source. A related process for extracting hydrocarbons from a
`reservoir rock formation by the fracturing operation is also
`described.
`
`ΠΙΊΙΊΠΠΠΓΊΠΠΠ
`
`SAND CONTAINERS |
`
`LIBERTY EXHIBIT 1047, Page 1
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`Patent Application Publication Nov. 21, 2013 Sheet 1 of 2
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`US 2013/0306322 Al
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`LIBERTY EXHIBIT 1047, Page 2
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`Patent Application Publication Nov. 21, 2013 Sheet 2 of 2
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`US 2013/0306322 Al
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`US 2013/0306322 Al
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`1
`
`Nov. 21,2013
`
`SYSTEM AND PROCESS FOR EXTRACTING
`OIL AND GAS BY HYDRAULIC
`FRACTURING
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`[0001] This Application claims the benefit of U.S. Provi-
`sional Application No. 61/649,563, filed May 21, 2012,
`which is herein incorporated in its entirety by reference.
`
`TECHNICAL FIELD
`[0002] This invention relates generally to the extraction of
`hydrocarbons from reservoir rock formations. In some spe-
`cific embodiments, the invention relates to a portable and
`modular system that can be transported to an oil or gas field,
`and used to stimulate production from an oil or gas well.
`
`BACKGROUND OF THE INVENTION
`[0003] Hydraulic fracturing or “fracing” is a process for
`increasing the flow of oil or gas from a well. It is usually
`carried out by pumping specific types of liquids into a well,
`under pressures that are high enough to fracture the rock. A
`network of interconnected fractures are formed, and they
`serve as pore spaces for the movement of oil and natural gas
`to the wellbore. When used in combination with techniques
`such as horizontal drilling, hydraulic fracturing is capable of
`converting previously-unproductive rock formations into
`large natural gas fields, for example.
`[0004] A hydraulic fracture is typically formed by pumping
`the fracturing fluid into the wellbore at a rate sufficient to
`create a downhole pressure that exceeds the fracture gradient
`of the surrounding rock. The rock cracks, and the fracture
`fluid continues farther into the rock, extending the crack into
`the depth of the well. Often, a proppant (as discussed below)
`is added into the injected fluid, to prevent the fractures from
`closing when the injection is stopped. The fracture that
`remains open is permeable enough to allow the flow of the
`desired gas or oil to the well, and eventually, to the surface for
`collection. The fracturing technique can be especially pro-
`ductive in the case of wells formed by horizontal drilling.
`These types of wells are formed by drilling holes that are
`substantially lateral, i.e., parallel with the rock layer that
`contains the fuels to be extracted. The lateral wells can have
`tremendous lengths, e.g., up to about 10,000 feet, after an
`initial, vertical depth into the rock formation.
`[0005] Hydraulic fracturing equipment that is used in oil
`and natural gas fields includes a large number of components.
`Blenders, high-volume fracturing pumps, monitoring units,
`material tanks, hoses, electronics systems, and power units
`are just some of the components required for these operations.
`In a typical fracturing operation currently practiced, a large
`number of tractor trailers are used to support individual sets of
`diesel engines and fracturing pumps, along with associated
`equipment, such as transmission systems. Asoneexample, 16
`tractor trailers may support 16 diesel-powered, 2000 hp frac-
`turing pumps. (Two of the engine/pump sets are typically
`employed for back-up purposes). High-capacity, high-power
`hydraulic pumps (e.g., triplex or quintuplex types) are com-
`mercially available from a number of sources. Collectively,
`the pumps provide sufficient pressure into one or more well-
`bores, to allow for the injection and movement of the slurry
`(water, proppants, and chemical additives), through thou-
`sands of feet of earth and rock. Fracturing equipment needs to
`
`be designed to operate over a wide range of pressures and
`injection rates, and can operate at about 100 Mpa (15,000 psi)
`orhigher; and 265 L/s (100 barrels per minute), or higher. The
`power needed for these operations can exceed 20-30 mega-
`watts.
`[0006] A number of drawbacks are associated with most of
`the current types of fracturing equipment and systems. For
`example, the mechanical collection of many diesel engines
`and many pumps can lead to high inefficiencies in the overall
`pumping operation. Part of this inefficiency is due to mainte-
`nance requirements for each of a multitude of engines, and the
`potential for engine break-downs.
`[0007] The use of large amounts of diesel fuel can also
`require extra safeguards, to address potential safety, noise,
`and environmental problems. Moreover, the number of trac-
`tor trailers required for the conventional fracturing system
`represents a relatively large and undesirable “footprint” at the
`drilling/fracturing site. (Since the use of diesel engines man-
`dates the use of diesel fuel, additional space is required for
`diesel fuel tankers). This potentially large truck fleet also has
`significant “community impact”, in terms of traffic conges-
`tion and road-surface wear and tear.
`[0008] In view of some of these concerns and challenges,
`new hydraulic fracturing systems would be welcome in the
`industry. The new systems should reduce the number of diesel
`engines required for the pumping sub-system in a fracturing
`operation. The new systems should also simplify the power-
`delivery mechanism for energizing all of the pumps required
`for the fracturing process. In some preferred embodiments,
`the new systems should also reduce the amount of large
`equipment required at a hydraulic fracturing site, thereby
`reducing the ecological footprint at the site.
`
`BRIEF DESCRIPTION
`[0009] One embodiment of the invention is directed to a
`fracturing system, comprising:
`[0010] a) an electric motor-driven pumping sub-system,
`configured to pump a pressurized fracturing fluid into at
`least one wellbore, under high pressure conditions suf-
`ficient to increase the downhole pressure of the well-
`bore, to exceed that of the fracture gradient of the solid
`matter surrounding the wellbore; and
`[0011] b) an electric power generation sub-system that
`provides eneigy to the pumping sub-system, comprising
`a multitude of electric motors that are powered by a
`single electrical feed source.
`[0012] Another embodiment of the invention is directed to
`a process for extracting hydrocarbons from a reservoir rock
`formation by a hydraulic fracturing operation, comprising the
`step of introducing a hydraulic fracturing treatment fluid into
`a subterranean formation at a pressure sufficient to form or to
`enhance at least one fracture within the subterranean forma-
`tion. In this method, the fracturing treatment fluid is pumped
`into at least one wellbore in the subterranean formation by an
`electric motor-driven pumping sub-system, configured to
`pump the fluid into the wellbore under high pressure condi-
`tions sufficient to increase the downhole pressure of the well-
`bore, to exceed that of the fracture gradient of the solid matter
`surrounding the wellbore. The pumping sub-system is ener-
`gized by an electric power generation sub-system that pro-
`vides energy to the pumping sub-system, and the power gen-
`eration sub-system comprises a multitude of electric motors
`that are powered by a single electrical feed source.
`
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`DRAWINGS
`[0013] FIG. 1 is a schematic representation of a hydraulic
`fracturing system according to some embodiments of this
`invention.
`[0014] FIG. 2 is a schematic representation of a hydraulic
`fracturing system according to other embodiments of the
`invention.
`
`DESCRIPTION OF THE INVENTION
`[0015] Approximating language, as used herein throughout
`the specification and claims, may be applied to modify any
`quantitative representation that could permissibly vary, with-
`out resulting in a change in the basic function to which it is
`related. Accordingly, a value modified by a term or terms,
`such as “about”, is not limited to the precise value specified.
`In some instances, the approximating language may corre-
`spond to the precision of an instrument for measuring the
`value. The terms “first,” “second,” and the like, herein do not
`denote any order, quantity, or importance, but rather are used
`to distinguish one element from another.
`[0016] As used herein, the terms “may” and “may be”
`indicate a possibility of an occurrence within a set of circum-
`stances; a possession of a specified property, characteristic or
`function; and/or qualify another verb by expressing one or
`more of an ability, capability, or possibility associated with
`the qualified verb. Accordingly, usage of “may” and “may be”
`indicates that a modified term is apparently appropriate,
`capable, or suitable for an indicated capacity, function, or
`usage, while taking into account that in some circumstances,
`the modified term may sometimes not be appropriate,
`capable, or suitable. For example, in some circumstances, an
`event or capacity can be expected, while in other circum-
`stances, the event or capacity cannot occur. This distinction is
`captured by the terms “may” and “may be”, or “can” or “can
`be”.
`[0017] A hydraulic fracturing system is described herein.
`The system can be used as a drilling and stimulation tech-
`nique, e.g., as a procedure that can increase the flow of oil or
`gas (e.g., natural gas) from a well within subsurface rock. The
`system comprises an electric motor-driven pumping sub-sys-
`tem. The sub-system is configured to pump a pressurized
`fracturing fluid into at least one wellbore, under high pressure
`conditions sufficient to increase the downhole pressure to
`exceed that of the fracture gradient of the rock surrounding
`the wellbore. The system further comprises an electric power
`generation sub-system that provides energy to the pumping
`sub-system. (For simplicity, the pumping sub-system and
`power sub-system may be referred to herein as the “pumping
`system” and the “power system”, respectively).
`[0018] In some preferred embodiments, the pumping sys-
`tem comprises a multitude of electric motors that are powered
`by a single electrical feed source, e.g., an electrical feeder.
`The source of the electrical feeder (directly or indirectly) may
`be a transmission line, sub-station, power generation facility,
`or a dedicated power generation sub-system, forexample. (As
`exemplified herein, the power generation system or sub-sys-
`tem may be located on-site or off-site).
`[0019] Moreover, in some specific cases, the electrical feed
`source may comprise at least one gas turbine engine. The gas
`turbine engine could be situated in a location remote from the
`pumping system. Alternatively, the gas turbine could be
`located on the same site (sometimes referred to as a “well-
`pad”) as the pumping system. In some embodiments, the gas
`
`turbine can be fueled by natural gas, oil, or other carbon-
`based fuels that are obtained at the site, e.g., after drilling and
`stimulation of some of the well(s). (In other embodiments, the
`fuel can be piped to the site, or transported there via truck, and
`the like).
`[0020] The pumping system may be arranged in many dif-
`ferent ways, depending in part on various factors. They
`include: the size of the hydraulic fracturing operation, and
`any associated drilling operations. The size of the operations
`depends, in turn, on other factors as well, such as the vertical
`depth and horizontal length of the drilling and fracturing
`operations; the type and composition of earth and rock
`through which the drilling/fracturing operations will proceed;
`as well as the general drilling/fracturing system design. As
`briefly described herein, hydraulic fracturing operations
`often require a great deal of power for the pumping operation.
`[0021] In one embodiment, the pumping system comprises
`one or more platforms, which can be mobile. Each platform
`can support one or more pumps, and one or more electrical
`motors, which together are sometimes referred to as pumping
`units or “pumpers”. An electrical motor could power multiple
`pumps. However, in some specific embodiments (though not
`all embodiments), each electrical motor provides power for
`one pump. Techniques for providing the physical and electri-
`cal connections between the pumps and the motors are known
`in the art.
`[0022] Many different types of pumps may be used; and
`they are commercially available from well-fracturing compa-
`nies, or other drilling and drilling-support companies.
`Examples of pump suppliers include Baker Hughes, Halli-
`burton, Weatherford, Weir Oil & Gas, and Bosch Rexroth.
`The size of each pump will depend on various factors, such as
`the overall pumping requirements at the well site (in terms of
`pumping pressure and pumping rate, for example); and the
`size of the platform on which the pump will be located. In
`some embodiments, each pump has a capacity in the range of
`about 2,000 hp to about 3,000 hp, although this range can vary
`considerably.
`[0023] As one non-limiting illustration, each mobile plat-
`form can be the bed of a truck, e.g., the bed of a tractor-trailer
`rig, or a trailer attached to such a rig. Heavy-duty tractor-
`trailers are often quite suitable for carrying pumps, motors,
`and drilling equipment. Their ability to travel on the highway
`and over many other roads is a distinct advantage fortransport
`of the necessary equipment and materials to many drilling and
`fracturing sites.
`[0024] Each tractor-trailer can accommodate at least one
`pump, and a motor to drive the pump. In some embodiments,
`each tractor-trailer supports two pumps and two electric
`motors, each associated with one of the pumps. As described
`briefly below, the ability to energize each motor from a single
`electrical feed source is a distinct advantage over prior art
`systems, e.g., those that rely on dedicated, direct-drive
`engines on each tractor-trailer.
`[0025] Hydraulic fracturing operations include a number of
`different types of equipment and operational units, and sub-
`stantially all of the equipment and materials must be located
`at the site of the fracturing operation. In general, the fractur-
`ing operations can include:
`[0026] 1) supply containers for fracturing fluid compo-
`nents (including large water supplies), sand and/or other
`proppants, and various fracturing chemicals/additives;
`
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`[0027] 2) blending equipment forblending the fracturing
`fluid/solid components according to pre-selected pro-
`portions;
`[0028] 3) at least one high-horsepower fracturing pump
`(“pumper”), as described above;
`[0029] 4) at least one platform (and usually, and usually,
`a number of them), such as a tractor trailer bed; to
`support motors, generators, pumps; and blenders; and
`[0030] 5) an operations and control unit, usually com-
`puter-based, and containing monitoring, data-recording,
`and communication equipment, as well as remote
`pumper controls to monitor and control each stage of the
`fracturing process, and to record data for each phase.
`[0031] A variety of other equipment, tools, and the like,
`may be on site as well, such as transformers, power distribu-
`tion components, switchgear (including fuses or circuit
`breakers), cables, hoses, air conditioning equipment, wire-
`line, cranes, fluid pumps, and the like. Those familiar with
`drilling and fracturing operations understand the purpose of
`this other equipment, as well as the way in which it is
`deployed at the site.
`[0032] In regard to some specific examples, the switchgear
`and power distribution components provide a number of
`important attributes to the fracturing operation. For example,
`they provide distribution and sharing of the total power from
`the generation sub-system, to and among the units of the
`pumping sub-system. They also control multiple lines of
`power flow, such that faults or failures in individual compo-
`nents or units do not cause secondary damage to other com-
`ponents or units. In this manner, the secondary damage within
`a component or unit with a fault or failure is minimized.
`Moreover, selected power flow can be interrupted for the
`purpose of maintenance and other field operations, while
`providing a safe working environment for the personnel
`involved. Moreover, this allows other units in the power gen-
`eration or pumping sub-systems to be employed as appropri-
`ate, while such maintenance and field operations are being
`carried out.
`[0033] As alluded to above, embodiments of the present
`invention eliminate or minimize many of these drawbacks.
`FIG. 1 is a schematic representation of a hydraulic fracturing
`system according to some embodiments of this invention. The
`figure is a non-limiting illustration of various components at
`a wellpad site 10. As a general means of simplifying the
`description, section 11 can be referred to as the power system;
`and section 13 can be referred to as the pumping system.
`[0034] With continued reference to FIG. 1, wellpad site 10
`contains one or more containers 12 for storing fracturing
`fluids. The site also contains one or more containers 14 for
`storing sand or other types of proppants (e.g., ceramic beads
`or other particulates). The fracturing fluids 12 primarily com-
`prise water, e.g., supplied from storage containers 16. How-
`ever, the fluids also contain various chemical additives, com-
`mercially available, that can aid in creating rock fractures; as
`well as protecting the wellbore surfaces.
`[0035] The proppant materials can be ceramic beads, as
`mentioned above, or grains of sand or other particulates. As
`those skilled in the art understand, injection of the proppant
`materials prevents the hydraulic fractures from closing when
`the injection has stopped. In this manner, the process opera-
`tors can maintain the “fracture width”, or slow the reduction
`in width. This can be especially important at deeper fracturing
`depths, where pressure and stresses on fractures are higher.
`
`[0036] Pre-selected proportions of the fracturing fluid com-
`ponents (including chemical additives) and proppants are
`directed into at least one blender/mixing unit 18 (two such
`units are depicted in the figure). Typically, the blender thor-
`oughly mixes the various components. At least one large
`capacity pump in the blending unit is employed to feed the
`mixture to the pumping sub-system. As in the case of the
`motor/pump platforms described below, the blender unit may
`be situated on the bed of a trailer-tractor, e.g., a truck having
`a trailer with an average length of about 35-50 feet; an average
`width of about 7-12 feet; and an average weight capacity of
`about 60,000 to about 100,000 pounds. (These dimensions
`may of course vary as well, in some circumstances).
`[0037] The blended fracturing fluid composition is then
`directed (by pumping) into a piping array 20, that is capable
`of accommodating dense fluids under relatively high pres-
`sures and high capacities, e.g., about 100 psi to about 140 psi,
`at about 60-80 barrels per minute, or higher. The piping array
`20 is then used to distribute the fracturing fluid into a number
`of pumpers 22 (six are illustrated here, as a general example).
`Each pumper accommodates an appropriate fraction of the
`fluid, and contributes to the task of bringing the fracturing
`material up to the high pressures required for entry into one or
`more wellheads.
`[0038] As described above, each pumper 22 typically
`(though not always) includes at least one pump, and an elec-
`tric motor to drive that pump. In some preferred embodiments
`(depending on the relative size of the platform, motors and
`pumps), each pumper comprises two pump-motor sets. The
`electric motors can all be powered by a single electrical feed
`source 24.
`[0039] Electrical feed source 24 can comprise a power dis-
`tribution unit, for example. In some embodiments, the power
`distribution unit is fed by a single electrical transmission
`cable 26, that may originate from any high-voltage transmis-
`sion line (not shown) or other electrical power source. Feed
`source 24 may comprise a conventional distribution circuit, a
`transformer to reduce the voltage coming from electrical
`cable 26, or some combination of a distribution circuit and
`transformer (or multiple transformers).
`[0040] In some embodiments, at least one variable-fre-
`quency drive (VFD) 28 is employed to control the current
`from electrical feed source 24, according to desired param-
`eters. (Three of the VFD drives are depicted in FIG. 1, as part
`of the pumping sub-system. As with other components, they
`can be deployed on tractor trailers or other suitable platforms.
`For the sake of simplicity, the VFD drives are depicted as the
`trailers on which they might be situated). As those skilled in
`the art understand, the VFD’s control the frequency of the
`electrical power supplied to motors, as well as controlling
`current and voltage. This “controllability” allows energy sav-
`ings, and reduced strain on each motor, during variable
`demand in pumping power. The general design and use of
`VFD’s for an application like that described herein can be
`carried out by those familiar with electric motor technology
`and electric power system technology, without undue effort.
`[0041] Variable-frequency drives 28 direct the required
`electrical power to the pumpers 22, through one or more
`suitable electrical conduits (shown in simple form, in the
`figure). In one embodiment, each of the three VFD’s is con-
`nected to two of the pumpers 22. The most appropriate ratio of
`VFD’s (28) to pumpers (22) will depend on some of the other
`factors described herein, including the size and number of
`electrical motors employed.
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`[0042] As noted above, the electrical-based fracturing
`embodiments described herein can provide a number of
`important advantages over prior art, mechanical-based frac-
`turing systems. With the elimination of individual diesel
`engines for pumping, each platform/trailer can accommodate
`much greater pumping-capacity. Thus, the number of trailers
`on the site can be greatly reduced. Moreover, the electric
`motors that deliver power to each pump—supplied by one
`primary power line and the associated distribution and VFD
`equipment—are generally cleaner and more reliable than the
`diesel power systems.
`[0043] As alluded to previously, portions of the fracturing
`fluid are then directed to each pumper 22. The pumpers are
`capable of increasing the pressure of the fluid to the very high
`levels typically needed for fracturing, e.g., usually above
`about 5,000 psi, and often, about 10,000 psi or higher. The
`total fracturing fluid exiting pumpers 22 can then be directed
`through wellhead conduit (e.g., at least one pipe) 30, to at
`least one of the wellheads 32. (The number of wellheads and
`conduits depicted is exemplary, and can vary considerably,
`depending in part on the nature of the site being explored).
`[0044] Those skilled in the art are familiar with the forma-
`tion and use of wellbores drilled into reservoir rock forma-
`tions, or into any type of subterranean formation. Each well-
`head 32 may represent the terminus for a separate wellbore.
`Each wellbore may extend for some distance, vertically, into
`the earth, and then extend laterally (i.e., parallel with the rock
`layer) for thousands of feet, e.g., up to at least about 10,000
`feet. The wellbores may, for example, extend in many differ-
`ent lateral (though underground) directions emanating from
`site 10. In this manner, a very large reservoir of rock-bearing
`fuel (e.g., petroleum and natural gas) can be stimulated for
`release and recovery, more efficiently than with other above-
`ground pumping and power systems.
`[0045] Another embodiment of the hydraulic fracturing
`system is depicted in FIG. 2. Features and units that are
`identical to those of FIG. 1 are noted in the figure, and are
`usually provided with identical numbers. As in the previous
`embodiment, the system includes the power sub-system 11
`and the pumping sub-system 13, along with an electrical feed
`source 24, electrical transmission cable 26; and VFD’s 28.
`Other units of the pumping system 13 are the same as well,
`e.g., storage containers 12, 14; and pumpers 22.
`[0046] In this embodiment of FIG. 2, power is provided
`on-site. As an example, a relatively large generator unit 50 can
`provide the power to electrical feed source 24, through cable
`26. Many different types of generators can be used for this
`purpose, and the size will depend on a number of variables,
`including the size of the overall fracturing operation. As a
`non-limiting example, the generator can be one capable of
`providing about 15 MW to about 30 MW of power (i.e.,
`usually greater than about 15 MW of power). The generator
`can be energized from any available source of mechanical
`energy, e.g., a turbine; hydro-power; compressed air, an inter-
`nal combustion engine, and the like. In some embodiments,
`the turbine or combustion engine used to energize the gen-
`erator can be supplied with fuel that is at least partially
`obtained from the fracturing site itself, as alluded to previ-
`ously.
`[0047] In addition to generator 50, this embodiment can
`include at least one smaller power generation unit 52 (FIG. 2).
`The smaller unit(s) can each provide about 1 MW to about 10
`MW of power, although this range can vary as well. In FIG. 2,
`two of the smaller power generation units (52, 54) are
`
`depicted, and each can supply electricity directly to feed
`source 24. (In other embodiments, greater than two of the
`smaller power generation units may be employed). The
`smaller units can provide much greater flexibility, in terms of
`power requirements, during operation of the fracturing site.
`[0048] In some cases, one or more of the smaller units may
`comprise a gas engine, attached to, or incorporated with, a
`suitable generator. As those skilled in the art understand, gas
`engines are internal combustion engines that can operate on a
`variety of fuels, such as natural gas, landfill gas, coal gas,
`bio-derived fuels, and the like. (Some of the smaller units can
`also use traditional hydrocarbon fuels, e.g., liquid hydrocar-
`bons). The flexibility of both fuel sources and engine size can
`provide considerable advantages, in terms of the gas engines
`functioning as an accessory to generator 50. Non-limiting
`examples of commercial gas engines include various Jen-
`bacher and Waukesha generation units. (In other instances,
`one or more of the smaller units can be a gas turbine, e.g., in
`the form of a gas turbine generator set, capable of providing
`power in the range described for units 52,54 (FIG. 2)).
`[0049] It should be understood from the above teachings
`that a process for extracting oil and gas by hydraulic fractur-
`ing represents another embodiment of this invention. The
`process includes the use of a pumping system based primarily
`on electric motors that power fracturing pumps. In preferred
`embodiments, the electric motors are powered by a power
`generation sub-system that uses far fewer individual electri-
`cal generators and associated components than the conven-
`tional hydraulic fracturing systems, e.g., as compared to the
`conventional, dedicated engine-pump approach. Other, gen-
`eral details regarding hydraulic fracturing can be found in a
`large number of references. Non-limiting examples include
`U.S. Pat. No. 8,309,498 (Funkhouser et al); U.S. Pat. No.
`7,901,314 (Salvaire et al); U.S. Pat. No. 5,551,516 (Norman
`et al); and U.S. Pat. No. 3,888,311 (Cooke), all incorporated
`herein by reference.
`[0050] Coordination between the power generation sub-
`system and the pumping sub-system is carried out by a control
`system. The control system provides sufficient power quan-
`tity and “quality” (i.e., in terms of frequency, voltage, and
`harmonics) to each pump/electric motor set (i.e, pumper 22).
`The control system also prevents the power generation units
`from being operated beyond their safety- and reliabilty-lim-
`its.
`[0051] The control systems should often include a mecha-
`nism that allows for highly-adjustable variable speed drive
`settings. This adjustability is sometimes critical, since the
`load on the pumpers is also highly variable, based on required
`fracturing forces that may be occuring thousands of feet away
`from the pumpers themselves. As an example, the variable
`speed drive mechanisms, sometimes referred to as adjustable
`speed drives (ASD’s), allow for ramping up power and ramp-
`ing down power in starting and stopping stages, respectively.
`Moreover, VSD/ASD mechanisms as applied to the present
`invention are also capable of delivering relatively short bursts
`(e.g., about several seconds to several minutes) of high-torque
`power, e.g., if the fracturing fluid streams encounter challeng-
`ing rock and sand conditions.
`[0052] The present invention has been described in terms of
`some specific embodiments. They are intended for illustra-
`tion only, and should not be construed as being limiting in any
`way. Thus, it should be understood that modifications can be
`made thereto, which are within the scope of the invention and
`the appended claims. Furthermore, all of the patents, patent
`
`LIBERTY EXHIBIT 1047, Page 7
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`US 2013/0306322 Al
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`5
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`Nov. 21,2013
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`applications, articles, and texts which are mentioned above
`are incorporated herein by reference.
`What is claimed:
`1. A hydraulic fracturing system, comprising
`a) an electric motor-driven pumping sub-system, config-
`ured to pump a pressurized fracturing fluid into at least
`one wellbore, under high pressure conditions sufficient
`to increase the downhole pressure of the wellbore, to
`exceed that of the fracture gradient of the solid matter
`surrounding the wellbore; and
`b) an electric power generation sub-system that provides
`energy to the pumping sub-system, comprising a multi-
`tude of electric motors that are powered by a single
`electrical feed source.
`2. The fracturing system of claim 1, wherein the pumping
`sub-system comprises one or more platforms, and each plat-
`form supports one or more pumping units that each comprise
`at least one pump and at least one electric motor.
`3. The fracturing system of claim 2, wherein each electric
`motor is configured to provide power for one pump.
`4. The fracturing system of claim 2, wherein each pumping
`unit comprises two pump-motor sets.
`5. The fracturing system of claim 1, wherein the electrical
`feed source comprises an electrical feeder that is connected,
`directly or indirectly, to an electrical transmission line, a
`power sub-station, a power generation facility, or a dedicated
`power generation sub-system.
`6. The fracturing system of claim 1, wherein the electrical
`feed source comprises at least one gas turbine engine.
`7. The fracturing system of claim 1, wherein the electric
`power generation sub-system is powered by a large generator
`capable of supplying greater than about 15 MW of power.
`8. The fracturing system