Electrically powered system for use in fracturing underground formations

BACKGROUND

one. Reference to related application [0001] This application claims the benefit and priority benefit of U.S. Provisional Patent Application No. 61 / 472,861 filed on April 7, 2011 called "ELECTRICALLY MODULAR AND MOBILE SYSTEM FOR USE IN UNDERGROUND FORMATIONS (MOBILE, MODULAR, ELECTRICALLY POWERED SYSTEM FOR USE IN FRACTURING UNDERGROUND FORMATIONS) ”whose content is incorporated herein in its entirety.

two. Field of the Invention [0002] This invention relates in general to the hydraulic stimulation of underground formations with hydrocarbons and more particularly to the generation and use of electrical energy to supply fracturing fluid to a drilling well.

3. Description of the related art [0003] During the life cycle of a typical drilling well that produces hydrocarbons, various fluids (together with additives, support agents, gels, cement, etc.) can be supplied to the drilling well under pressure and injected in the drilling well. Surface pumping systems must have the ability to accommodate these various fluids. Such pumping systems are typically mobilized on skates or tractors with trailers and are powered by diesel engines.

[0004] Technological advances have greatly improved the ability to identify and recover unconventional oil and gas resources. In particular, horizontal drilling and multi-stage fracturing has led to the emergence of new opportunities for the production of natural gas from shale formations. For example, more than twenty fractured intervals have been reported in a single horizontal drilling well in a compact natural gas formation. However, important fracturing operations are required to recover these resources.

[0005] Currently, the natural gas recovery opportunities considered require a considerable operational infrastructure that includes large investments in fracturing equipment and related personnel. In particular, standard fluid pumps require large amounts of diesel fuel and frequent equipment maintenance programs. Typically, each fluid pump is housed in a dedicated truck and trailer configuration. The average fracturing operations require as much as fifty fluid pumps, therefore, the area or occupied space that is required in situ to accommodate these fracturing operations is enormous. As a result, the operational infrastructure required to sustain these fracturing operations is extensive. Greater operational efficiency in natural gas recovery would be desirable.

[0006] When large fracturing operations are planned, an important logistics issue is the availability of diesel fuel. Excessive volumes of diesel fuel required require constant transportation of diesel fuel in tankers to the site and result in significant carbon dioxide emissions. Others have tried to reduce fuel consumption and emissions by running the engines of large pumps with Bi-fuel, a mixture of natural gas and diesel fuel but with limited success. In addition, attempts to reduce the number of personnel on site by implementing remote monitoring and operational control have not been successful because personnel are still required at the site to transport equipment and fuel to and from the site.

SUMMARY [0007] Several illustrative embodiments of a system and method for hydraulic stimulation of underground formations with hydrocarbons are provided herein. According to one aspect of the described content, a method of supplying fracturing fluid to a drilling well is provided. The method can comprise the steps of: provide a dedicated source of electrical energy at a site that contains a drillhole to be fractured, provide one or more electrical fracturing modules at the site where each electrical fracturing module comprises an electric motor and a coupled fluid pump and each motor electric is operatively associated with the dedicated source of electric power, provide a drilling well treatment fluid for pressurized supply to a drilling well where the drilling well treatment fluid can be continuous with the fluid pump and with the drilling well and operate the fracturing unit by means of the use of electric power from the dedicated source to pump the treatment fluid into the drilling well.

[0008] In some illustrative embodiments, the dedicated source of electric power is a turbine generator. A source of natural gas can be provided therefore the natural gas drives the turbine generator for the production of electrical energy. For example, natural gas can be provided by pipe or natural gas produced in situ. Liquid fuels such as condensates can also be provided to drive the turbine generator.

[0009] In some illustrative embodiments, the electric motor may be a permanent AC magnet motor and / or a variable speed motor. The electric motor may have the ability to operate in the range of up to 1500 rpm and up to 20,000 feet / pounds of torque. The pump can be a triple or fivefold plunger fluid pump.

[0010] In some illustrative embodiments, the method may further comprise the steps of: providing a continuous mixing electric module and / or operatively associated with the fluid pump, wherein the mixing module comprises: a source of fluid, a source of fluid additive and a centrifugal mixing tank and supplying the electrical energy from the source dedicated to the mixing module to effect the mixing of the fluid with the fluid additives to generate the treatment fluid.

[0011] According to another aspect of the described content, a system is provided for use in the supply of pressurized fluid to a drilling well. The system may include: a well site comprising a drilling well and a dedicated source of electricity, an electrically driven fracturing module that is operatively associated with the dedicated source of electricity, where the electrically driven fracturing module comprises an electric motor and a fluid pump coupled to the electric motor, a fluid treatment source where the treatment fluid can be continuous with the fluid pump and with the drilling well and a control system to regulate the fracturing module in the supply of treatment fluid from the fluid source of drilling well treatment.

[0012] In some illustrative embodiments, the source of treatment fluid may comprise an electrically driven mixing module that is operatively associated with the dedicated source of electricity. The system may further comprise a fracturing trailer at the well site to accommodate one or more fracturing modules. Each fracturing module can be adapted to be installed detachably on the trailer. The system may further comprise a replacement pump module comprising a pump and an electric motor, where the replacement pump module is adapted to be removably installed in the trailer. In some illustrative embodiments, the replacement pump module may be a nitrogen pump module or a carbon dioxide pump module. The replacement pump module can be, for example, a high torque and low speed motor or a low torque and high speed motor.

[0013] According to another aspect of the described content, a fracturing module is provided for use in the supply of pressurized fluid to a drilling well. The fracturing module may comprise: a permanent AC magnet motor capable of operating in the range of up to 1500 rpm and up to 20,000 feet / pounds of torque and a piston-type fluid pump coupled to the motor.

[0014] According to another aspect of the described content, a method of mixing a fracturing fluid is provided to supply a drillhole to be fractured. A dedicated source of electrical energy can be provided at a site that contains a drillhole to be fractured. At least one electrical mixing module can be provided on site. The electric mixing module may include a fluid source, a fluid additive source and a mixing bowl. Electric power can be supplied from the source dedicated to the electric mixing module to effect mixing a fluid from the fluid source with a fluid additive from the fluid additive source to generate the fracturing fluid. The dedicated source of electrical energy can be a turbine generator. A source of natural gas can be provided where natural gas is used to drive the turbine generator for the production of electrical energy. The fluid from the fluid source can be mixed with the fluid additive from the fluid additive source in the mixing bowl. The electric mixing module may also include at least one electric motor that is operatively associated with the dedicated source of electrical energy and that mixes the fluid from the fluid source with the fluid additive from the fluid additive source.

[0015] In some illustrative embodiments, the electric mixing module may include a first electric motor and a second electric motor, each of which is operatively associated with the dedicated source of electric power. The first electric motor can effect the fluid supply from the fluid source to the mixing bowl. The second electric motor can effect the mixing of the fluid from the fluid source with the fluid additive from the source of fluid additive to the mixing bowl. In some illustrative embodiments, an optional third electric motor may also be present and may also be operatively associated with the dedicated source of electrical energy. The third electric motor can effect the supply of fluid additive from the source of fluid additive to the mixing bowl.

[0016] In some illustrative embodiments, the electric mixing module may include a first mixing unit and a second mixing unit, each arranged adjacent to the other in the mixing module and each, as desired, with independent operation capacity or collective cooperative operation capacity. Each of the first mixing unit and the second mixing unit may include a source of fluid, a source of fluid additive and a mixing vessel. The first mixing unit and the second mixing unit can each have at least one electric motor that is operatively associated with the dedicated source of electrical energy and that mixes the fluid from the fluid source with the fluid additive from the source of fluid additive Alternatively, the first mixing unit and the second mixing unit can each have a first electric motor and a second electric motor, both operatively associated with the dedicated source of electric power, wherein the first electric motor makes the supply of the fluid from the fluid source to the mixing bowl and the second electric motor effects the mixing of the fluid from the fluid source with the fluid additive from the source of fluid additive in the tank mixer. In some illustrative embodiments, each of the first mixing unit and the second mixing unit may also have a third electric motor operatively associated with the dedicated source of electric power, wherein the third electric motor effects the supply of the fluid additive from the source of fluid additive to the mixing bowl.

[0017] According to another aspect of the described content, an electric mixing module is provided for use in the supply of a mixed fracturing fluid to a drilling well. The electric mixing module may include a first electrically operated mixing unit and a first input manifold coupled to the first electrically operated mixing unit and with the ability to deliver a fracturing fluid without mixing therein. A first outlet manifold may be coupled to the first electrically operated mixing unit and may have the ability to deliver the mixed fracturing fluid out of it. A second electrically operated mixing unit can be provided. A second inlet manifold may be coupled to the second electrically operated mixing unit and with the ability to deliver the fracturing fluid without mixing therein. A second outlet manifold may be coupled to the second electrically operated mixing unit and may have the ability to deliver the mixed fracturing fluid out of it. A crossed inlet line can be coupled to both the first inlet manifold and the second inlet manifold and can have the ability to deliver the fracturing fluid without mixing between them. A crossed outlet line can be coupled to both the first outlet manifold and the second outlet manifold and can have the ability to deliver the fracturing fluid mixed therebetween. A skate can be provided to house the first electrically operated mixing unit, the first input manifold, the second electrically operated mixing unit and the second input manifold.

[0018] Other aspects and features of the present invention will be apparent to those skilled in the art after analyzing the following detailed description in conjunction with the attached figures.

BRIEF DESCRIPTION OF THE FIGURES [0019] A better understanding of the content currently described can be obtained when the following detailed description is considered in conjunction with the following figures in which:

[0020] Figure 1 is a schematic plan view of a traditional fracturing site, [0021] Figure 2 is a schematic plan view of a fracturing site in accordance with some illustrative embodiments described herein, [ 0022] Figure 3 is a schematic perspective view of a fracturing trailer in accordance with some illustrative embodiments described herein, [0023] Figure 4A is a schematic perspective view of a fracturing module according to some illustrative embodiments described herein, [0024] Figure 4B is a schematic perspective view of a fracturing module with personnel of maintenance in accordance with some illustrative embodiments described herein, [0025] Figure 5A is a schematic side view of a mixing module according to some illustrative embodiments described herein, [0026] Figure 5B is an end view of the mixing module shown in Figure 4A, [0027] Figure 5C is a schematic top view of a mixing module according to some illustrative embodiments described herein, [0028] Figure 5D is a schematic side view of the mixing module shown in Figure 5C, [0029] Figure 5E is a schematic perspective view of the mixing module shown in Figure 5C, [0030] Figure 6 is a schematic top view of an input manifold for a mixing module according to some illustrative embodiments described herein, and [0031] Figure 7 is a schematic top view of an outlet manifold for a mixing module in accordance with some illustrative embodiments described herein.

DETAILED DESCRIPTION [0032] The content currently described refers substantially to an electrically driven fracturing system and a system and method for the provision of electrical energy in situ and the supply of fracturing fluid to a drilling well in a fracturing operation.

[0033] In a conventional fracturing operation, a suspension of fluids and additives is injected into a rock formation with hydrocarbons in a drilling well to propagate the fracturing. The low pressure fluids are mixed with chemicals, sand and if necessary acid and then transferred at medium pressure and high speed to vertical and / or deflected portions of the drilling well by means of multiple high-pressure plunger pumps driven by diesel powered machines. Most of the injected fluids will flow again through the drilling well and will be recovered while the sand will remain in the newly created fracture, so it is propped up to open it and a permeable membrane is provided for the hydrocarbon and gas fluids so that flow through so that they can recover.

[0034] In accordance with the illustrative embodiments described herein, natural gas (either supplied to the site or produced in situ) can be used to drive a dedicated source of electrical energy, such as a generator turbine, for the completion of drilling wells that produce hydrocarbons. A sizable fleet of electrically driven fracturing is provided to supply pressurized treatment fluid, such as fracturing fluid, to a drillhole in a fracturing operation where a constant supply of diesel fuel for the site is not needed and the location is reduced. occupied site area and the infrastructure required for the fracturing operation when compared to conventional operations. In some illustrative embodiments, the treatment fluid that is provided for a pressurized supply to the drillhole may be continuous with the drillhole and with one or more components of the fracturing fleet. In these embodiments, continuous substantially means that bottomhole hydrodynamics depends on the constant flow (velocity and pressure) of the fluids supplied and that there must be no interruption in the fluid flow during delivery to the drilling well if The fracture must be propagated as desired. However, this should not be construed as meaning that the operations of the fracturing fleet cannot be substantially stopped and initiated, as one skilled in the art will understand.

[0035] With reference to Figure 1, a site plan is shown for a traditional fracturing operation at a land site. Multiple trailers 5 are provided where each has at least one diesel tank installed or otherwise disposed therein. Each trailer 5 is connected to a truck 6 to allow refueling of diesel tanks as required. Trucks 6 and trailers 5 are located within region A at the fracturing site. Each truck 6 requires a dedicated operator. One or more driving machines are supplied with diesel and are used to energize the fracturing operation. One or more separate chemical handling skates 7 are provided for housing mixing tanks and related equipment.

[0036] With reference to Figure 2, an illustrative embodiment of a location plan for an electrically driven fracturing operation in a solid ground location is shown. The fracturing operation includes one or more trailers 10, where each houses one or more fracturing modules 20 (see Figure 3). Trailers 10 are located in region B at the fracturing site. One or more natural gas-powered turbine generators 30 are located in region C at the location that is located at a remote distance D from region B where trailers 10 and fracturing modules 20 are located for safety reasons. The turbine generators 30 replace the diesel powered machines used in the site plan of Figure 1. The turbine generators 30 provide a dedicated source of on-site electrical power. Preferably there is a physical separation between the generation of natural gas energy in region C and the fracturing operation and drilling well located in region B. The generation of natural gas energy may require greater safety precautions than the fracturing operation. and the wellhead. Therefore, security measures can be taken in region C to limit access to this most dangerous location while maintaining separate safety standards in region B where most site personnel are typically located. In addition, the natural gas supply of electricity can be monitored and regulated remotely so that if desired, it is not required that personnel be within region C during operation.

[0037] In particular, the configuration of Figure 2 requires significantly less infrastructure than the configuration shown in Figure 1 and at the same time provides comparable pumping capacity. Fewer trailers 10 are present in region B of Figure 2 than trucks 6 and trailers 5 in region A of Figure 1 as a consequence of the lack of need for a constant supply of diesel fuel. In addition, each trailer 10 in Figure 2 does not need a truck 6 and a dedicated operator as in Figure 1. Fewer chemical handling skates 7 are required in region B of Figure 2 than in region A of Figure 1 because the skates 7 in Figure 2 can be electrically operated. In addition, by eliminating diesel engines, all associated machinery necessary for energy transfer, such as transmission, torque converter, clutch, drive shaft, hydraulic system, etc. can be eliminated and the need is significantly reduced of cooling systems that include pumps and circulation fluids. In an illustrative embodiment, the physical space occupied by the in situ area in region B of Figure 2 is approximately 80% smaller than the area occupied by the conventional system in region A of Figure 1.

[0038] With reference to the illustrative embodiments of Figure 3, the trailer 10 is shown to accommodate one or more fracturing modules 20. The trailer 10 can also be a skate in some illustrative embodiments. Each fracturing module 20 may include an electric motor 21 and a fluid pump 22 coupled thereto. During fracturing, the fracturing module 20 is operatively associated with a turbine generator 30 to receive electrical energy from it. In some illustrative embodiments, a plurality of electric motors 21 and pumps 22 may be transported in a single trailer 10. In the illustrative embodiments of Figure 3, four electric motors 21 and pumps 22 are transported in a single trailer 10 . Each electric motor 21 is paired with a pump 22, such as a single fracturing module 20. Each fracturing module 20 can be detachably installed in the trailer 10 to facilitate replacement as necessary. The fracturing modules 20 use electric power from the turbine generator 30 to pump the fracturing fluid directly to the drill hole.

[0039] Electric power generation [0040] The use of a turbine to directly drive a pump has been previously investigated. In such systems, a transmission is used to regulate the power of the turbine to the pump so as to allow speed and torque control. In the present operation, natural gas is used instead to drive a dedicated energy source for the production of electricity. In illustrative embodiments, the dedicated energy source is an on-site turbine generator. This eliminates the need for a transmission and the electricity generated can be used to power the fracturing modules, mixers and other on-site operations as necessary.

[0041] On the site the electrical power of the electricity network may be accessible in some fracturing operations but the use of a dedicated energy source is preferred. During the start of a fracturing operation, huge amounts of energy are required so that the use of electric power from the power grid would not be practical. Natural gas powered generators are more appropriate for this application based on the possible availability of natural gas in situ and the ability of natural gas generators to produce large amounts of energy. In particular, the possibility of very large instantaneous adjustments of the energy extracted from the power grid during a fracturing operation can jeopardize the stability and reliability of the power grid. Therefore, a dedicated and generated on-site source of electricity provides a more feasible solution to supply an electrical fracturing system. In addition, a dedicated on-site operation can also be used to provide energy for the operation of other local equipment , including rolled pipe systems, service platforms, and so on.

[0042] In an illustrative embodiment, a single natural gas-powered turbine generator 30 that is housed in a restricted area C of Figure 2 can generate enough power (for example 31 MW at 13,800 volts AC power) to supply several electric motors 21 and pumps 22 and thus avoid the current need to supply and operate each fluid pump separately from a separate diesel engine truck. An appropriate turbine for this purpose is a TM2500 + turbine generator sold by General Electric. Other generation systems can be supplied, for example, by Pratt & Whitney or Kawasaki. There are many options available for turbine power generation that depend on the amount of electricity required. In an illustrative embodiment, liquid fuels such as condensates can also be provided to drive a turbine generator 30 instead or in addition to natural gas. Condensate is cheaper than diesel fuel and thus reduces operating costs.

[0043] Fracturing module [0044] With reference to Figures 4A and 4B, an illustrative embodiment of the fracturing module 20 is provided. In some illustrative embodiments, the fracturing module 20 may include a coupled electric motor 21 to one or more electric pumps 22. A suitable pump is a five-fold or triple plunger pump, for example, the Well Service

Pump SWGS-2500 sold by Gardner Denver, Inc.

[0045] In some embodiments the electric motor 21 is operatively associated with the turbine generator 30. Typically, each fracturing module 20 will be associated with a drive housing for controlling the electric motor 21 and the pumps 22 and also a transformer. electric and drive unit 50 (see Figure 3) to reduce the power voltage of the turbine generator 30 to an appropriate voltage for the electric motor 21. In various embodiments, the electric transformer and drive unit 50 can be provided as a separate unit to be associated with the fracturing module 20 or can be permanently attached to the trailer 10. If they are permanently fixed, then the transformer and unit of drive 50 can be sized to allow the addition or subtraction of pumps 22 or other components to accommodate operational requirements.

[0046] Each pump 22 and electric motor 21 are modular in order to simplify the removal and replacement of the fracturing module 20 for maintenance purposes. The removal of a single fracturing module 20 from the trailer 10 is also simplified. For example, any fracturing module 20 can be disconnected and separated from the trailer 10 and removed and another fracturing module 20 can be installed in place within minutes.

[0047] In the illustrative embodiment of Figure 3, the trailer 10 can accommodate four fracturing modules 20 together with a transformer and drive unit 50. In this particular configuration, each of the trailers 10 provides more pumping capacity than four of the traditional diesel-fueled fracturing trailers 5 of Figure 1 because the parasitic losses are minimal in the electrical fracturing system compared to the parasitic losses typical of diesel fueled systems. For example, a fluid pump fed with conventional diesel has a nominal 2250 hp. However, as a consequence of the parasitic losses in the transmission, the torque converter and the cooling systems, diesel fueled systems typically only provide 1800 hp to the pumps. In contrast, the current system can deliver real 2500 hp directly to each pump 22 because the pump 22 is directly coupled to the electric motor 21. In addition, the nominal weight of a conventional fluid pump is up to 120,000 pounds. In the current operation, each fracturing module 20 weighs approximately 28,000 pounds and thus allows the placement of four pumps 22 in the same physical dimension (size and weight) as the space required for a single pump in conventional diesel systems, as well It also allows up to 10,000 hp total for the pumps. In other embodiments, more or less fracturing modules 20 may be located in the trailer 10, as desired or required for operational purposes.

[0048] In some illustrative embodiments, the fracturing module 20 may include an electric motor 21 which is a permanent AC magnet motor with operating capacity in the range of up to 1500 rpm and up to 20,000 feet / pounds of torque. The fracturing module 20 may also include a pump 22 which is a piston-type fluid pump coupled to an electric motor 21. In some illustrative embodiments, the fracturing module 20 may have dimensions of approximately 136 wide x 108 long x 100 high. These dimensions allow the fracturing module 20 to be easily portable and enter an intermodal container according to ISO standard for transport purposes without the need to disassemble it. Standard container lengths according to ISO standard are typically 20 ', 40' or 53 '. In some illustrative embodiments, the fracturing module 20 may have dimensions not greater than 136 in width x 108 in length x 100 in height. These dimensions of the fracturing module 20 also allow gang members to easily enter within the limits of the fracturing module 20 for repairs, as illustrated in Figure 4b. In some illustrative embodiments, the fracturing module 20 may have a width not greater than 102 so as to be within the transport arrangements and route restrictions. In a specific embodiment, the fracturing module 20 has the capacity to operate 2500 hp while still having the dimensions specified above, and meets the aforementioned specifications for rpm and feet / pounds of torque.

[0049] Electric motor [0050] With reference to the illustrative embodiments of Figures 2 and 3, a medium low voltage AC permanent magnet electric motor 21 receives electric power from the turbine generator 30 and is directly coupled to the pump 22. In some illustrative embodiments, in order to ensure convenience of use the electric fracturing motor 21 has to have an operating capacity of up to 1500 rpm with a torque of up to 20,000 feet / pounds. An appropriate engine for this purpose is sold under the TeraTorq® trademark that is available from Comprehensive Power, Inc. of Marlborough, Massachusetts. A compact motor with sufficient torque will allow the amount of fracture modules 20 placed on each trailer 10 to be maximized.

Γ00511 Mixer [0052] For greater efficiency, conventional diesel-powered mixers and chemical aggregate units can be replaced with electrically driven mixing units. In some illustrative embodiments, as described herein, the electrically driven mixing units can be modular in nature and are housed in the trailer 10 instead of the fracturing module 20 or are housed independently and are associated with each trailer 10. An electric mixing operation allows greater precision and control of the fracturing fluid additives. In addition, centrifugal mixing vats typically used in mixing trailers to mix fluids with support agents, sand, chemicals, acid, etc. before supplying them to the drill hole are a common source of maintenance costs in traditional fracturing operations. .

[0053] With reference to Figures 5A-5E and Figures 6-7, illustrative embodiments of a mixer module 40 and its components are provided. The mixer module 40 may be operatively associated with the turbine generator 30 and has the ability to provide fracturing fluid to the pump 22 for delivery to the drilling well. In some embodiments, the mixer module 40 may include at least one source of fluid additive 44, at least one source of fluid 48 and at least one centrifugal mixing bowl 46. Electric power may be supplied from the turbine generator 30 to the Mixer module 40 for mixing a fluid from the fluid source 48 with a fluid additive from the fluid additive source 44 to generate the fracturing fluid. In some embodiments, the fluid from the fluid source 48 may be, for example, water, oils or mixtures of methanol and the fluid additive from the fluid additive source 44 may be, for example, friction reducer, gelling, gelling or biocide cutting.

[0054] In some illustrative embodiments, the mixer module 40 may have a dual configuration with a first mixing unit 47a and a second mixing unit 47b that are adjacent to each other. This dual configuration is designed to provide redundancy and facilitate access for maintenance and replacement of components as needed. In some embodiments, each mixing unit 47a and 47b may have its own electrically driven bowl and suction motors disposed therein and optionally other electrically driven motors may be used for additional operational functions of chemicals and / or other functions. auxiliary operations, as described in more detail herein.

[0055] For example, in some illustrative embodiments, the first mixing unit 47a may have a plurality of electric motors that includes a first electric motor 43a and a second electric motor 41a that are used to drive various components of the mixer module 40 The electric motors 41a and 43a can be driven by the turbine generator 30. The fluid can be pumped into the mixer module 40 through an inlet manifold 48a by the first electric motor 43a and added to the tank 46a. Thus, the first electric motor 43a acts as a suction motor. The second electric motor 41a can drive the centrifugal mixing process in the tank 46a. The second electric motor 41a can also drive the mixed fluid supply out of the mixer module 40 and into the drill hole through an outlet manifold 49a. Thus, the second electric motor 41a acts as a tank motor and a discharge motor. In some illustrative embodiments, a third electric motor 42a can also be provided. The third electric motor 42a can also be driven by the turbine generator 30 and can supply fluid additives to the mixer 46a. For example, a support agent of a hopper 44a can be supplied to a mixing bowl 46a, for example, a centrifugal mixing tank by an auger screw conveyor 45a which is driven by the third electric motor 42a.

[0056] Similarly, in some illustrative embodiments, the second mixing unit 47a may have a plurality of electric motors that includes a first electric motor 43b and a second electric motor 41b that are used to drive various components of the mixer module 40. Electric motors 41b and 43b can be driven by turbine generator 30. The fluid can be pumped into the mixer module 40 through an inlet manifold 48b by the first electric motor 43b and added to the bowl 46b. Thus, the second electric motor 43a acts as a suction motor. The second electric motor 41b can drive the centrifugal mixing process in the tank 46b. The second electric motor 41b can also drive the mixed fluid supply out of the mixer module 40 and into the drill hole through an outlet manifold 49b. Thus, the second electric motor 41b acts as a tank motor and a discharge motor. In some illustrative embodiments, a third electric motor 42b can also be provided. The third electric motor 42b can also be driven by the turbine generator 30 and can supply fluid additives to the mixer 46b. For example, a hopper support agent 44b can be supplied to a mixing vessel 46b, for example, a centrifugal mixing vessel by an auger screw conveyor 45b which is driven by the third electric motor 42b.

[0057] The mixer module 40 may also include a control cabinet 53 to house the equipment controls of the first mixing unit 47a and the second mixing unit 47b and may also include, as required, appropriate actuators and chillers.

[0058] Conventional mixers driven by a diesel oil system are typically housed in a forty-five-foot tractor trailer and can accommodate approximately 100 barrels / minute. In contrast, the dual configuration of mixer module 40 having a first mixing unit 47a and a second mixing unit 47b can provide a total production capacity of 240 barrels / minute in the same physical area occupied as a conventional mixer, without the need for a separate emergency unit in case of failure.

[0059] In the past, redundant system mixers have been tried with limited success, mainly as a result of problems with trailer weights while still supplying the appropriate amount of energy. Typically, two separate engines each of approximately 650 hp are installed side by side on the nose of the trailer. In order to drive all the necessary systems, each engine must drive a mixing vessel by means of a transmission, lower discharge box and extended transmission shaft. A large hydraulic system is also placed for each motor to drive all auxiliary systems, such as chemical additives and suction pumps. The parasitic energy losses are very large and the hose and wiring system is complex.

[0060] In contrast, the electrically driven mixer module 40 described in some exemplary embodiments herein may decrease the parasitic power losses of conventional systems by directly driving each piece of critical equipment with a dedicated electric motor. In addition, the electrically driven mixer module 40 described in some exemplary embodiments herein allows pipe paths that are not available in conventional applications. For example, in some illustrative embodiments, the fluid source may be an inlet manifold 48 that may have one or more crossed inlet lines 50 (see Figure 7) that connect the dedicated inlet manifold section 48 to supply fluid to the first mixing unit 47a with the inlet manifold section 48 dedicated to supply fluid to the second mixing unit 47b. Similarly, in some illustrative embodiments, the outlet manifold 49 may have one or more crossed outlet lines 51 (see Figure 6) that connect the dedicated outlet manifold section 49 to supply fluid from the first unit of mixing 47a with the dedicated outlet manifold section 49 dedicated to supply fluid from the second mixing unit 47b. The crossed lines 50 and 51 allow the flow between the first mixing unit 47a and the second mixing unit 47b to be directed or diverted. Therefore, the mixer module 40 can mix from either side or from both sides and / or discharge on either side or on both sides, if necessary. As a result, the speeds attainable by the electrically driven mixer module 40 are much larger than that of a conventional mixer. In some illustrative embodiments, each side (ie, first mixing unit 47a and second mixing unit 47b) of the mixer module 40 has a capacity of approximately 120 barrels / minute. In addition, each side (i.e. first mixing unit 47a and second mixing unit 47b) can displace approximately 15 t / min of sand, at least in part because the length of the screw conveyor 45 is shorter (approximately 6 ' ) if compared with conventional units (approximately 12 ').

[0061] In some illustrative embodiments, the mixer module 40 may be reduced or reduced to a single compact module comparable in size and dimensions to the fracturing module 20 described herein. For smaller fracturing or treatment jobs that require less than four fracturing modules 20, a reduced mixer module 40 can replace one of the fracturing modules 20 in the trailer 10 and thus reduces operating costs and improves the ease of transport of the system . [0062] Control system [0063] A control system can be provided to regulate various equipment and systems within the electrically driven fracturing operation. For example, in some illustrative embodiments, the control system may regulate the fracturing module 20 in the supply of the treatment fluid of the mixer module 30 to the pumps 22 to be supplied to the drilling well. The controls for the electrically driven operation described herein are a significant improvement over those of conventional diesel engine systems. As a consequence of the fact that electric motors are controlled by frequency inverters, the absolute control of all the equipment in the site can be maintained from a central point. When the system operator sets a maximum pressure for the treatment, the control software and the frequency inverters calculate a maximum current available for the motors. Frequency inverters essentially inform the motors what is allowed.

[0064] Electric motors controlled by means of frequency inverters are much safer and easier to control than conventional diesel engine equipment. For example, conventional fleets with pumps powered by diesel engines use electronically controlled transmission and engine in the unit. There may be up to fourteen different parameters that need to be monitored and controlled for proper operation. These signals are typically sent through cables permanently connected to an operator console controlled by the pump actuator. The signals are converted from digital to analog so that the inputs can be made through switches and control commands. The inputs are then converted from analog to digital again and sent back to the unit. The unit control module then informs the engine or transmission to perform the required task and the signal becomes a mechanical operation. This process takes time.

[0065] Accidental overpressures are quite common in these conventional operations because the signal must travel to the console, back to the unit and then perform a mechanical function. Overpressures can occur in milliseconds as a result of the nature of the operations. These in general are due to human errors and can be as simple as a single operator that does not react to a command. They are also often due to a closing valve that accidentally creates a neutral situation.

[0066] For example, in January 2011, a large-scale fracturing operation was carried out in the Horn River basin in northeastern British Columbia, Canada. A leak occurred in one of the lines and a closing order was given. The main valve in the wellhead was then closed remotely. Unfortunately, multiple pumps continued to operate and an overpressure system ensued. Iron treatment with 10,000 psi nominal was taken to more than 15,000 psi. A line connected to the well was also released and began to strike around it. The incident caused the entire operation to stop for more than a week while an investigation was being conducted and damage was assessed.

[0067] The control system provided, in accordance with the present illustrative embodiments, being electrically actuated virtually eliminates the possibility of these types of scenarios occurring. A maximum pressure value set at the beginning of the operation is the maximum amount of energy that can be sent to the electric motor 21 for the pump 22. When extrapolating a maximum current value from this input, the electric motor 21 does not have the energy available to exceed its operating pressure. In addition, since there are virtually no mechanical systems between the pump 22 and the electric motor 21, a smaller moment of inertia of the gears and clutches must be dealt with. An almost instantaneous stop of the electric motor 21 results in an almost instantaneous stop of the pump 22.

[0068] An electrically driven and controlled system as described herein greatly increases the ease with which all equipment can be synchronized or subordinated to each other. This means that a change at a single point will be carried out by all pieces of equipment, unlike diesel equipment. For example, in conventional diesel engine operations, the mixer typically supplies all the fluids necessary for the entire system. In order to make a change of operation speed, the mixer must change the speed before the pumps change their speeds. This can often result in accidental overflow of mixer vats and / or pump cavitation due to the temporary phase shift of each piece of equipment that is given manual commands.

[0069] In contrast, in some illustrative embodiments, the present operation uses a single point control that is not linked solely to the mixing operations. All operating parameters can be entered before starting fracturing. If a speed change is required, the system will increase the speed of the entire system with a single command. This means that if the pumps 22 are informed to increase the speed, then the mixer module 40 together with the chemical units and even the auxiliary equipment, such as the abrasive belts, will increase the speeds to compensate automatically.

[0070] Appropriate controls and computational monitoring of the entire fracturing operation can be performed in a single central location, which facilitates compliance with the pre-established safety parameters. For example, a control center 40 is indicated in Figure 2 from which operations can be managed through the communications link 41. Examples of operations that can be remotely controlled and monitored from the control center 40 via the communications link 41 may be the function of generating energy in Area B or the supply of treatment fluid from the mixer module 40 to the pumps 22 for Supply it to the drilling well.

[0071] Comparison example [0072] Table 1 below compares and contrasts the operating costs and labor requirements for a conventional diesel engine operation (as shown in Figure 1) with the of the electrically operated operation (as shown in Figure 2).

Γ0073Ί Table 1 [0074] Comparison of conventional qasoil motor operation versus electrically operated operation

Diesel engine operation

Electrically operated operation

Total cost of fuel (diesel) Total cost of fuel (natural gas) about $ 80,000 per day about $ 2,300 per day

Maintenance interval

Maintenance interval of diesel engine electric motor approximately every 200-300 approximately every 50,000 hours hours

Dedicated crew size - Dedicated crew size approximately 40 people approximately 10 people [0075] In Table 1, the diesel engine operation uses at least 24 pumps and 2 mixers and requires at least 54,000 hp to run the fracturing program in that location. Each pump burns approximately 300-400 liters per hour of operation and the mixing units burn a similar amount of diesel fuel. Due to the fuel consumption and fuel capacity of this conventional unit, it requires refueling during operation which is extremely dangerous and represents a fire hazard. In addition, each piece of conventional equipment needs a dedicated tractor to move it and a driver / operator to drive it. The size of the crew required to operate and maintain a conventional operation, such as that of Figure 1, represents a direct cost to the site operator.

[0076] In contrast, the electrically driven operation, as described herein, uses a turbine that only consumes about 6 MMSCF of natural gas every 24 hours. At current market values ​​(approximately $ 2.50 per MMBtu), this amounts to a reduction in the direct cost to the site operator of more than $ 77,000 per day compared to the diesel engine operation. In addition, the maintenance interval of electric motors is approximately 50,000 hours, which allows most of the reliability and maintenance costs to disappear. Moreover, the need for multiple actuators / operators is significantly reduced and electrically driven operation means that a single operator can run the entire system from a central location. The size of the crew can be reduced by approximately 75%, since only approximately 10 people are needed in the same location to carry out the same tasks as in conventional operations where the 10 people include off-site maintenance personnel. In addition, the size of the crew does not change with the amount of equipment used. Thus, the electrically driven operation is significantly more economical.

[0077] Modular design and alternative embodiments [0078] As noted above, the modular nature of the electrically driven fracturing operation described herein provides significant operational advantages and efficiencies over traditional fracturing systems. Each fracturing module 20 is located in the trailer 10 that houses the necessary supports and the collecting systems for low pressure suctions and high pressure discharges. Each fracturing module 20 can be removed from service and replaced without closing or compromising the extent of fracturing. For example, the pump 22 can be isolated from the trailer 10, removed and replaced by a new pump 22 in a few minutes. If the fracturing module 20 requires maintenance, it can be isolated from the fluid lines, disconnected, separated and removed with a forklift. Another fracturing module 20 can then be reinserted in the same way and thus a drastic saving of time is realized. In addition, the removed fracturing module 20 can be repaired or its maintenance is performed on site. On the other hand, if one of the pumps in a conventional diesel engine system goes out of service or requires maintenance, the tractor / trailer combination must be disconnected from the collecting system and moved from the site. Next, a replacement unit must be backed up on the line and reconnected. The handling of these units within these narrow limits is difficult and dangerous.

[0079] The electrically driven fracturing operation that is currently described can easily be adapted to accommodate additional types of pumping capabilities as necessary. For example, a replacement pump module can be provided that is adapted to be removably installed on the trailer 10. The replacement pump module can be used to pump liquid nitrogen, carbon dioxide or other chemicals or fluids as necessary to increase the versatility of the system and expand the range and operating capacity. In a conventional system, if a nitrogen pump is required, a separate truck / trailer unit must be taken to the site and joined at the fracturing extent. In contrast, the operation currently described allows a replacement nitrogen module with substantially the same dimensions as the fracturing module 20, so that the replacement module can enter the same groove in the trailer as the fracturing module 20. The Trailer 10 can contain all the necessary distributions of electrical energy as required by a nitrogen pump module so that modifications are not required. The same concept applies to the carbon dioxide pump modules or any other piece of equipment that might be required. Instead of another truck / trailer, a specialized replacement module can be used instead.

[0080] Natural gas is considered to be the most efficient and cleanest source of available fuel. Through the design and construction of equipment suitable for the purpose that is fed to natural gas, it is expected that each of the occupied fracturing space, labor and maintenance requirements can be reduced by more than 60% compared to operations fed with Traditional diesel.

[0081] In addition, the electrically driven fracturing operation currently described resolves or mitigates the environmental impacts of traditional diesel-fueled operations. For example, the natural gas-powered operation currently described can provide a significant reduction in carbon dioxide emissions compared to diesel-fueled operations. In an illustrative embodiment, a fracturing site using the natural gas-fed operation currently described would have a level of carbon dioxide emissions of approximately 2200 kg / h depending on the quality of the combustible gas which represents a reduction of approximately 200% of carbon dioxide emissions from diesel fueled operations. Also, in an illustrative embodiment, the natural gas-powered operation currently described can produce no more than approximately 80 decibels of sound with a silencer package used in turbine 30 that meets the requirements of the Occupational Health and Safety Administration (OSHA) for noise emissions. In comparison, a conventional diesel-powered fracturing pump that operates at maximum rpm emits about 105 decibels of sound. When multiple diesel fueled fracturing pumps operate simultaneously, noise is a significant risk associated with conventional operations.

[0082] In some illustrative embodiments, the electrically driven fracturing operation described herein can also be used for offshore oil and gas applications, for example, fracturing a drilling well at an offshore location. . Conventional offshore operations already have the capacity to generate electricity at the site. These vessels are typically diesel rather than electric, which means that the diesel power plant on the ship generates electricity to meet all the power requirements that include propulsion. The conversion of offshore pumping services to work with an electric power supply will allow transported diesel fuel to be used in power generation rather than to drive the fracturing operation and thereby reduce the fuel consumption of gasoil. The electrical energy generated from the offshore ship's power plant (which is not necessary during station maintenance) can be used to power one or more fracturing modules 10. This is much cleaner, safer and more more efficient than the use of equipment with diesel engines. Fracturing modules 10 are also smaller and lighter than the equipment typically used on the deck of offshore vessels, therefore some of the current ballast problems are suppressed and allows offshore vessels to transport more equipment or raw materials.

[0083] In a deck distribution of a conventional offshore stimulation vessel, skid-based diesel-powered pumping equipment and storage facilities on the ship's deck create ballast problems. On the deck of the ship too much heavy equipment makes the vessel have a higher center of gravity. In addition, the fuel lines must be directed to each piece of equipment which greatly increases the risk of fuel spills. In the illustrative embodiments of a deck distribution of an offshore vessel that uses electrically driven fracturing operations as described herein, the physical space occupied by the distribution of the equipment is significantly reduced when compared to the distribution conventional. More free space is available on the deck and the weight of the equipment is drastically reduced, therefore most ballast problems are eliminated. A ship already designed as diesel-electric can be used. When the ship is in position on a platform and in the position conservation mode, most of the power that the ship's engines generate can be carried to the deck to drive the modules. The storage facilities on the boat can be located below the deck, and this lowers the center of gravity further, while additional equipment, for example, a three-phase separator or rolled pipe unit, can be provided in the cover what_xwhich is difficult on ships with diesel engines. These benefits together with the electronic control system offers much greater advantages over conventional vessels.

[0084] While the present description specifically contemplates a fracturing system, the system can be used to feed pumps for other purposes or to power other oilfield equipment. For example, high speed and pressure pumping equipment, hydraulic fracturing equipment, well stimulation pumping equipment and / or well maintenance equipment can also be fed with the present system. In addition, the system can be adapted for use in other art fields that require high-torque or high-speed pumping operations, such as pipe cleaning or mine drainage.

[0085] It should be understood that the content herein is not limited to the exact details of construction, operation, exact materials or illustrative embodiments shown and described as modifications and equivalents will be apparent to one skilled in the art. Accordingly, the content is limited only by the scope of the appended claims.