Abstract:
A method of operations in a subterranean formation, including driving a pump with an electrically powered motor to pressurize fluid, inserting a tool into a wellbore that intersects the formation, and directing the pressurized fluid into the wellbore above the tool to push the tool into the wellbore.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 15/291,842, filed on Oct. 12, 2016, which issued as U.S. patent Ser. No. ______ on ______, and claims priority to and the benefit of U.S. Provisional Application Ser. No. 62/242,173, filed Oct. 15, 2015, and is a continuation-in-part of, and claims priority to and the benefit of co-pending U.S. patent application Ser. No. 15/202,085, filed Jul. 5, 2016, and which claims priority to and the benefit of U.S. patent application Ser. No. 13/679,689, filed Nov. 16, 2012, which issued as U.S. Pat. No. 9,410,410 on Aug. 9, 2016; the full disclosures of which are hereby incorporated by reference herein for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
       [0002]    The present disclosure relates to operations in a subterranean formations. In particular, the present disclosure relates to a system that uses fluid pressurized by electrically powered pumps for fracturing and for pump down operations. 
       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 (nitrogen and water), diesel, or other fluids is sometimes used as the primary component instead of water. Typically hydraulic fracturing fleets include a data van unit, blender unit, hydration unit, chemical additive unit, hydraulic fracturing pump unit, sand equipment, 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 is usually composed of a power end and a fluid end. The hydraulic fracturing pump also generally contains seats, valves, a spring, and keepers internally. These parts allow the hydraulic fracturing pump to draw in low pressure fluid slurry (approximately 100 psi) and discharge the same fluid slurry at high pressures (over 10,000 psi). Recently electrical motors controlled by variable frequency drives have been introduced to replace the diesel engines and transmission, which greatly reduces the noise, emissions, and vibrations generated by the equipment during operation, as well as its size footprint. 
         [0005]    On each separate unit, a closed circuit hydraulic fluid system is often used for operating auxiliary portions of each type of equipment. These auxiliary components may include dry or liquid chemical pumps, augers, cooling fans, fluid pumps, valves, actuators, greasers, mechanical lubrication, mechanical cooling, mixing paddles, landing gear, and other needed or desired components. This hydraulic fluid system is typically separate and independent of the main hydraulic fracturing fluid slurry that is being pumped into the wellbore. 
       SUMMARY OF THE INVENTION 
       [0006]    Certain embodiments of the present technology provide a method of operations in a subterranean formation. The method includes driving a pump with an electrically powered motor to pressurize fluid, inserting a tool into a wellbore that intersects the formation, and directing the pressurized fluid into the wellbore above the tool to push the tool into the wellbore. In some embodiments, the method can further include urging the tool into the wellbore with the pressurized fluid until the tool reaches a predetermined location in the formation. In addition, the tool can be a perforating gun. 
         [0007]    According to some embodiments, the wellbore can include a first wellbore, wherein the pressurized fluid is simultaneously directed to a second wellbore that also intersects the subterranean formation. Hydraulic fracturing can be performed in the second wellbore. Furthermore, the pump can include a first pump and a second pump, wherein fluid pressurized by the first pump is directed into the first wellbore to push the tool into the first wellbore, and fluid pressurized by the second pump is directed into the second wellbore to use in hydraulic fracturing. 
         [0008]    Additional embodiments can include pressurizing fluid with an electric blender to form a boost fluid, directing the boost fluid to the pump. In addition, the electricity that powers the motor can be generated with a generator that is proximate the electric motor, and a wireline system can be powered by the electricity. 
         [0009]    Alternate embodiments of the present technology can include a method of operations in a subterranean formation, including generating electricity, energizing electric motors with the electricity, driving a fracturing pump with at least one of the electric motors, and driving a pump down pump with at least one of the electric motors. In certain embodiments, the electricity can be generated by a turbine generator, and the method can include powering a sand conveyer and hydration unit with the electricity. 
         [0010]    In some embodiments, the method can further include using a first fluid pressurized by the fracturing pump to fracture the formation, and using a second fluid that is pressurized by the pump down pump in a pump down operation. In addition, the first fluid can be directed to a first wellbore that intersects the formation, and the second fluid can be directed to a second wellbore that intersects the formation. 
         [0011]    Yet another embodiment of the present technology includes system for use in a subterranean formation operation. The system includes a pump down pump in communication with a first wellbore that intersects the formation, and that pressurizes fluid in the first wellbore, an electric motor that drives the pump down pump, and a tool positioned in the wellbore below at least a portion of the fluid pressurized by the pump down pump, and that is pushed toward the bottom of the wellbore by the fluid. Certain embodiments of the system can also include a hydraulic fracturing pump in communication with a second wellbore that intersects the formation, and that pressurizes fluid in the second wellbore, and the electric motor that drives the hydraulic fracturing pump. 
         [0012]    According to some embodiments, the electric motor can be a first electric motor and a second electric motor, the first electric motor driving the pump down pump, and the second electric motor driving the hydraulic fracturing pump. In addition, the system can further include gas powered turbine generators, and a wireline system that is in electrical communication with the turbine generators. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]    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: 
           [0014]      FIGS. 1A and 1B  are schematic examples of a system for use in fracturing and pump down operations. 
           [0015]      FIG. 2  is a plan schematic view of an alternate example of the system of  FIG. 1 . 
           [0016]      FIG. 3  is a plan schematic view of an example of an electrically powered pump down system. 
           [0017]      FIG. 4  is a perspective view of an example of a pump system for use with the hydraulic fracturing system of  FIGS. 1A and 1B . 
           [0018]      FIG. 5  is a perspective view of an example of a blender unit for use with the system of  FIGS. 1A and 1B . 
           [0019]      FIGS. 6 and 7  are plan schematic views of alternate examples of an electrically powered pump down system. 
           [0020]      FIG. 8  is a perspective view of an example of an auxiliary unit for use with the system of  FIGS. 1A, 1B, and 5 . 
       
    
    
       [0021]    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. 
       DETAILED DESCRIPTION OF INVENTION 
       [0022]    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. 
         [0023]    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. 
         [0024]      FIG. 1A  is a schematic example of a system  10  that is used for providing pressurized fluid to wellbores  12   1 ,  12   2  shown intersecting a subterranean formation  16 . As will be described in more detail below, the pressurized fluid can be used in fracturing and/or pump down operations in the wellbores  12   1 ,  12   2 . 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  FIG. 1A , 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 slurry, which is then transferred to a pump assembly  36  via line  38 ; thus fluid in line  38  includes the discharge of blender unit  28 , which is the suction (or boost) for the pump assembly  36 . Blender unit  28  can have an onboard chemical additive system, such 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 assembly  36 . A motor  39 , which connects to pump assembly  36  via connection  40 , drives pump assembly  36  so that it can pressurize the slurry. 
         [0025]    After being discharged from pump assembly  36 , slurry is injected into a wellhead assembly  41   1 ,  41   2 ; discharge piping  42   1 ,  42   2  connects discharge of pump assembly  36  with wellhead assembly  41   1 ,  41   2  and provides a conduit for the slurry between the pump assembly  36  and the wellhead assembly  41   k ,  41   2 . In an alternative, hoses or other connections can be used to provide a conduit for the slurry between the pump assembly  36  and the wellhead assembly  41   1 ,  41   2 . Optionally, any type of fluid can be pressurized by the pump assembly  36  to form injection fluid that is then pumped into the wellbores  12   1 ,  12   2 , and is not limited to fluids having chemicals or proppant. As detailed below, fluid from pump assembly  36  can be used for fracturing the formation  16 , for pump down operations in wellbores  12   1 ,  12   2 . Examples exist wherein the system  10  includes multiple pump assemblies  36 , and multiple motors  39  for driving the multiple fracturing pump assemblies  36 . Valves  43   1 ,  43   2 , are shown provided respectively on lines  42   1 ,  42   2  for selectively allowing flow into the wellhead assemblies  41   1 ,  41   2 . 
         [0026]    An example of a turbine  44  is provided in the example of  FIG. 1A  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, a pipeline, 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 . 
         [0027]    An example of a micro-grid  54  is further illustrated in  FIG. 1A , 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 system  10 . In another example, the power generated by the turbine generator and the power utilized by the electrical powered devices in the 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, transformer  56  steps the voltage down from 13.8 kV to around 600 V. Other stepped 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  71  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  71  connects bus  60  to a variable frequency drive (“VFD”)  72 . Line  73  connects VFD  72  to motor  39 . In one example, VFD  72  selectively provides electrical power to motor  39  via line  73 , and can be used to control operation of motor  39 , and thus also operation of pump  36 . 
         [0028]    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. 
         [0029]    Still referring to  FIG. 1A , a pump down operation is shown being performed in wellbore  12   1  and wherein a perforating string  80   1  is being pumped down within wellbore  12   1  by pressurized fluid from the pump system  36 . Thus in this example, fluid being discharged from pump system  36  is handled within discharge piping  42   1  and into wellhead assembly  41   1  where it is used to urge the perforating string  80   1  deeper into wellbore  12   1 . The example of the perforating string  80   1  includes perforating guns  82   1  stacked in series and coaxial with one another. Each of the perforating guns  82   1  include a number of shaped charges  84   1  that when detonated create perforations (not shown) within formation  16 . In addition, the perforating guns typically may include plugs, to isolate the guns from certain portions of the well, such as portions down hole from the guns. As will be described below, the perforations provide a starting point for fractures to be formed within formation  16  by introduction of high pressure fluid within wellbore  12   1 . Each of wellbores  12   1 ,  12   2  are shown having vertical, deviated and horizontal sections; however, wellbores  12   1 ,  12   2  can each be substantially vertical, or one can be vertical and the other have deviated and horizontal portions. Further illustrated in  FIG. 1A  is a wireline  86   1  which depends downward from the wellhead assembly  41   1  and to perforating string  80   1 . Wireline  86   1  can be used to deploy and retrieve perforating string  80   1  from within wellbore  12   1 . Moreover, signals for initiating detonation of the shaped charges  84   1  can come via wireline  86   1  and from surface. 
         [0030]      FIG. 1B  illustrates an example where pressurized fluid from pump system  36  has been introduced into wellbore  12   1  and so that perforations  90  are formed in formation  16  and that project radially outward from wellbore  12   1 . As indicated above, the perforations  90  created by shaped charges  84   1  ( FIG. 1A ) provide initiation points within formation  16  from which fluid can propagate into formation  16  to form fractures. 
         [0031]    An advantage of the system  10  is that in situations when wellbores  12   1 ,  12   2  are proximate one another, the pump system  36  can provide pressurized fluid to each of these wellbores  12   1 ,  12   2 , and for different purposes. As illustrated in  FIG. 1B , the step of hydraulic fracturing is taking place in wellbore  12   1 , while substantially simultaneously a pump down operation is occurring in wellbore  12   2 . More specifically, a perforating string  80   2 , similar in construction to the perforating string  80   1  of  FIG. 1A , is being deployed within wellbore  12   2 . Also, perforating string  80   2  includes coaxially coupled perforating guns  82   2  and which each include a number of shaped charges  84   2  for creating perforations (not shown) within formation  16 . Deployment, retrieval, and signal communication between surface and perforating string  80   2  can be accomplished via wireline  86   2  shown inserted within wellbore  12   2 . 
         [0032]    In one example of operation, the system  10  can be used to selectively provide the pressurized fluid to the adjacent wellbores  12   1 ,  12   2  so that what is referred to in the industry as a zipper operation can take place. A zipper operation is where adjacent wellbores are perforated and fractured along an alternating sequence. Moreover, the zipper operation is done sequentially so that the different operations can be performed on different wells on the same well site, which speeds up completion activities. As illustrated in the figures described below, separate pumping systems can provide the fluid for the fracturing and the pump down operations. 
         [0033]    Shown in  FIG. 2  is a schematic plan view of one example of system  10 A where turbine generators  53 A 1,2  and  53 A 3,4  respectively generate electricity that is delivered to switch gear  92 A 1  and  92 A 2 , that in turn deliver the output electricity to transformers  56 A 1-n  and auxiliary units  94 A 1,2 . Auxiliary unit  94 A 1  transmits electricity to sand equipment  32 A, hydration unit  18 A, frac blender  28 A, and a frac data van  95 A. In one example, frac data van  95 A is an enclosed vehicle that provides controls and monitoring equipment for use in controlling and monitoring the fracturing system. Electricity from transformers  56 A 1-n , which is received from switch gear  92 A 1,2  is delivered at a designated voltage to fracturing pumps  36 A 1-n , wherein fracturing pumps  36 A 1-n  are dedicated to pressurizing fluid for use in fracturing operations. Also from transformers  56 A 1-n  electricity is transmitted to pump down units  96 A 1-n  that are used for pressurizing fluid used in pump down operations as described above. It should be pointed out, that the pump down operations are not limited to disposing perforating strings within wellbores, but can include any other type of equipment that is to be positioned at a designated depth within a wellbore. 
         [0034]    Further illustrated in  FIG. 2  is that auxiliary  94 A 2  has an output that delivers electricity to a blender  98 A for use in pump down and a data van  100 A that is also used for pump down. The separate data van  100 A and blender  98 A can be used, for example, during zipper fracturing operations, but are not required for stack fracturing operations. This is because during stack fracturing operations, only one operation is occurring at a time, so the frac datavan  95 A and frac blender  28 A can be used for all operations. Further illustrated in  FIG. 2  is that the power from auxiliary  94 A 2  transmits to an optional transformer  102 A, which can be used to step down electricity for use by a crane  104 A and wireline system  106 A if the crane  104 A and wireline system  106 A require a lower voltage than the fracturing equipment. Examples exist where crane  104 A and wireline system  106 A provide the hoisting and signal capabilities for the wireline  86   1,2  of  FIGS. 1A and 1B . Moreover, wireline system  106 A can include a wireline truck having a spool of wireline as well as controllers and initiation hardware for sending communication and initiation signals down the wireline  86   1,2 . 
         [0035]      FIG. 3  shows, in a schematic plan view, one example of a pump down system  108 B that pressurizes fluid for use in a pump down operation. In this example, a turbine set  53 B is used for generating electricity, and that like the other turbine sets described herein is powered by combustion of natural gas that then drives a generator to produce electricity. The electricity is delivered to switch gear  92 B and which has an output shown in communication with transformers  56 B 1-N  and auxiliary  94 B. One of transformers  56 B 1-N  delivers electricity to other equipment  110 B which can include, for example, glycol heaters, light plants, a company man trailer, water transfer pumps, a crane, wellsite tools, etc. Others of the transformers  56 B 1-n  have outputs at designated voltages (e.g., 600V, 480V, or step up transformers) that communicate with pump down pumps  96 B 1-n  that are schematically illustrated provided on trailers and within the pump down system  108 B. Further included with the pump down system  108 B is a blender  98 B for blending the fluid that is then to be pressurized by the pump down pumps, and a data van  100 B which provides a location for personnel to control and monitor equipment within the pump down system  108 B. In this example, electricity is generated specifically for the pump down pumps and is not diverted from that being used to drive pumps used for fracturing. Additionally, the fluid being pressurized is from the pump down pumps and not from a fracturing pump. 
         [0036]    Provided in a perspective view in  FIG. 4  is one example of a pump system  36 C, which can be used either for pump down operations or for fracturing operations. In the illustrated example, pumps  112 C 1,2  are shown mounted on a trailer  114 C so that the pumps  112 C 1,2  can be readily transported to different locations for onsite operation. Additionally, a VFD housing  116 C is also mounted on trailer  114 C and in which equipment such as VFDs for pumps, isolation breakers, and a motor control center can be situated during operation of pumps  112 C 1,2 . The motor control cabinet can be a breaker cabinet that contains breakers for smaller motors such as blower motors, lube motors, and fan motors. 
         [0037]    Shown in  FIG. 5  is an example of a blender unit  28 D shown in a perspective view. Here, blender unit  28 D is shown including a hopper  118 D and auger assembly  119 D, and wherein the hopper  118 D receives sand or other proppant from a sand source, such as a conveyor (shown in  FIG. 1 ). Auger assembly  119 D, which is an elongated section having barrel and auger screws rotatably disposed within, urge the sand upward. Hopper  118 D and auger assembly  119 D are mounted on a trailer  120 D and adjacent a mixing tub  122 D, which is typically an open top tub where sand, water, and chemicals are mixed together to form a slurry that is then provided to pumps where the fluid is pressurized. The slurry that flows to pumps is directed through a manifold  124 D that mounts on a lower end of trailer  120 D. Also included with the blender unit  28 D is a control room  126 D which communicates with the datavan, houses operations personnel, and provides monitoring and controls devices for operating and monitoring of the blender unit  28 D. 
         [0038]    An alternate embodiment of a pump down system  108 E is shown in a plan schematic view in  FIG. 6 , where turbine set  53 E with a gas powered turbine generator generates electricity that is then delivered to a switch gear  92 E. Output from switch gear  92 E is delivered to transformers  56 E 1,2  that in turn provide electrical power to pump down pumps  96 E 1-2  shown mounted on trailers. Electricity from switch gear  92 E is also directed to an auxiliary unit  94 E that supplies electricity to both a blender  98 E and data van  100 E. Included within blender  98 E is a pump (not shown) that in some embodiments pressurizes fluid to a boost pressure that is then delivered to the pump down pumps  96 E 1-2 . In an example, the blender  98 E pressurizes the fluid in a range from about 70 psi to about 120 psi. Further, within electric blender  98 E chemical additives can be added to the fluid that is then delivered to the pump down pumps. Other examples exist, wherein blender for use with a pump down system is a blender that is part of the fracturing system. 
         [0039]    Another alternate example of the pump down system  108 F is illustrated in plan schematic view in  FIG. 7  and where turbine set  53 F, which uses gas-powered turbines to generate electricity, delivers electricity to switch gear  92 F. In this example, a transformer  56 F receives electricity from switch gear  92 F and delivers it to other equipment  110 F. Also fed by switch gear  92 F is auxiliary  94 F, which in turn provides electrical power to pump down unit  96 F that is independent of electrical power for the hydraulic fracturing pumps. In the embodiment of  FIG. 7 , the pump down unit  96 F can include a small boost pump (capable of, for example, up to about 20 barrels per minute (bpm) at 100 psi instead of about 130 bpm for a blender), and a water pump (capable of about 20 bpm at 10,000 psi) to replace the hydraulic fracturing pumps. Thus, the pump down system  108 F of  FIG. 7  is capable of operating separately from the rest of the fracking system, or from the hydraulic fracturing pumps. This flexibility allows use of the electric powered pump down system with any type of hydraulic fracturing system, whether such system is powered by electricity, diesel, or otherwise. This is also true of the embodiments shown in  FIGS. 3 and 6 . 
         [0040]      FIG. 8  shows in a side perspective view an example of an auxiliary unit  94 G and which includes a trailer  128 G and on which a transformer  130 G and a VFD house  132 G are mounted. The VFD house  132 G and transformer  130 G can be used to power and control the desired equipment, such as, for example, the blender, the hydration unit, the conveyor, and/or the datavan. The VFD house  132 G can also contain soft starters for, large non speed controlled motors, smaller blower motors and radiator fans for cooling. Power can be provided from turbines, to a switchgear, then to the auxiliary unit  94 G. The transformer  130 G can be used, for example, to convert power from 13.8 kV to 600V to provide power to the VFD house. The blender did not have room to contain its own VFD therefore the Auxiliary Trailer was created to serve this purpose. Each hydraulic fracturing site can benefit from the use of a single auxiliary unit  94 G or multiple auxiliary units  94 G depending on the individual needs and circumstances at the site. 
         [0041]    Use of auxiliary units  94 G is advantageous because each separate auxiliary unit  94 G provides a separate power grid, thereby creating multiple power centers, which in turn allows for greater flexibility in the positioning of equipment at a site, and creates redundancy in the operations. The use of auxiliary units  94 G also helps with power cable management, providing multiple different cable routing for the equipment. 
         [0042]    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.