Patent Publication Number: US-11391269-B2

Title: Hybrid hydraulic fracturing system

Description:
TECHNICAL FIELD 
     This disclosure relates to a hydraulic fracturing system, and more particularly, to a hybrid hydraulic fracturing system. 
     BACKGROUND 
     Hydraulic fracturing operations may be used during well development in the oil and gas industry. For example, in formations in which oil or gas cannot be readily or economically extracted from the earth, a hydraulic fracturing operation may be performed. Such a hydraulic fracturing operation typically includes pumping large amounts of fracturing fluid at high pressure in the earth to induce cracks, thereby creating pathways via which the oil and gas may flow. Fracturing fluid often contains water, sand, and other additives and is pumped downhole by the hydraulic fracturing pump at a sufficient pressure to cause fractures and fissures to form within the well. 
     The fracturing pump in a fracturing operation is typically driven by a diesel, internal combustion engine. The diesel powered engine is responsive enough to provide the necessary transient power during fracturing operations. Utilizing diesel power for fracturing, however, can be expensive. Although natural gas engines are a cheaper option for performing fracturing operations, the natural gas engines tend to have a slower response time when the hydraulic fracturing rigs have fluctuating load demands. Accordingly, a system is desired that can leverage the lower cost power generation of gas engines, but also have the transient capability to reduce overall ownership costs and operation costs of hydraulic fracturing rigs. 
     WO2015011223 to Sepulveda discloses a drive for providing a high drive dynamic with high drive outputs to a pneumatic, hydraulic, or electrical machine (e.g. pump, fan, compressor) during a gas and/or oil recovery. The drive includes at least one steady-state gas engine with a low load-switching capacity, a first electric motor connected in series or parallel to the gas engine, an energy store is paired with the electric motor, and another electric motor which functions as a generator is coupled to the gas engine. The second electric motor is mechanically coupled to the gas engine and electrically coupled to the first electric motor. 
     SUMMARY 
     In accordance with one aspect of the present disclosure, a hybrid hydraulic fracturing system includes a driveline having an internal combustion engine with a crankshaft, a motor operatively coupled to a forward end of the crankshaft, a transmission operatively coupled to a rearward end of the crankshaft, a driveshaft operatively coupled to the transmission, and a fracturing pump operatively coupled to the driveshaft. The system also includes a power source electrically coupled to the motor for supplying power to the motor and a controller configured to power condition the driveline by operating the driveline in a first mode in response to a load change resulting in an increased power demand on the driveline, where the first mode includes providing torque from the internal combustion engine to drive the fracturing pump and selectively providing torque from the motor to a crankshaft of the internal combustion engine to assist the internal combustion engine in driving the fracturing pump. 
     In accordance with another aspect of the present disclosure, a method of power conditioning in a hydraulic fracturing system having a fracturing pump includes providing a motor operatively connected to a power source and operating a driveline of the hydraulic fracturing system in a first mode in response to a load change resulting in an increased power demand on the driveline. The first mode includes driving the fracturing pump with an internal combustion engine and selectively providing torque from the motor to a crankshaft of the internal combustion engine to assist the internal combustion engine in driving the fracturing pump, wherein the power source provides power to the motor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages will be evident from the following illustrative embodiment which will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawing, in which: 
         FIG. 1  is a schematic representation of an exemplary embodiment of a hybrid hydraulic fracturing system according to the present disclosure; 
         FIG. 2  is a flowchart of an exemplary method of power conditioning in the hybrid hydraulic fracturing system of  FIG. 1  when additional power is needed; and 
         FIG. 3  is a flowchart of an exemplary method of power conditioning in the hybrid hydraulic fracturing system of  FIG. 1  when reduced power is needed. 
     
    
    
     DETAILED DESCRIPTION 
     While the present disclosure describes certain embodiments of a hybrid hydraulic fracturing system, the present disclosure is to be considered exemplary and is not intended to be limited to the disclosed embodiments. Also, certain elements or features of embodiments disclosed herein are not limited to a particular embodiment, but instead apply to all embodiments of the present disclosure. 
       FIG. 1  illustrates an exemplary embodiment of hybrid hydraulic fracturing system  10 . In the illustrated embodiment, the hybrid hydraulic fracturing system  10  is a parallel system having a first driveline  14  and a second driveline  16  arranged in parallel with the first driveline  14 . The second driveline  16  may be identical to the first driveline  14  or may include one or more similar or the same components. In other embodiments, however, the hybrid hydraulic fracturing system  10  may not be a parallel system or may include more or less than two drivelines. 
     In the exemplary embodiment, the first driveline  14  includes a first internal combustion engine  18 , a first power source  20 , a first transmission  24 , and a first fracturing pump  26  arranged in series. In the illustrated embodiment, the second driveline  16  includes the same components as the first driveline  14 . Thus, the second driveline  16  includes a second internal combustion engine  28 , a second power source  30 , a second transmission  34 , and a second fracturing pump  36  arranged in series. The description of the components of the first driveline  14  applies equally to the second driveline  16 . In other embodiments, however, the second driveline  16  may include one or more different components from the first driveline  14 . 
     The first driveline  14  is configured such that the first fracturing pump  26  is driven by a first driveshaft  38  which is driven by the first internal combustion engine  18  and the first motor  20  via the first transmission  24 . The components of the first driveline  14  are arranged in series such that the first motor-generator  20  is operatively connected to the front of the first internal combustion engine  18 , the first transmission  24  is operatively connected to the rear of the first internal combustion engine  18 , and the first driveshaft  38  acts as an output shaft to operatively connect the first fracturing pump  26  to the first transmission  24 . 
     The first internal combustion engine  18  may be configured in a variety of ways. Any suitable internal combustion engine  18  capable of driving the first fracturing pump  26  during a fracturing operation may be used. Suitable internal combustion engines may include diesel, gaseous (e.g., natural gas), gasoline, or dual fuel engines. In one exemplary embodiment, the first internal combustion engine  18  is a natural gas-fueled engine. The size and configuration of the first internal combustion engine  18  may also vary in different embodiments. For example, the displacement of the internal combustion engine  18  may vary and the internal combustion engine  18  may be a V-type, a rotary type, an in-line type, or other types known in the art. The first internal combustion engine  18  includes an engine block  40  and a first crankshaft  42  configured for rotation therein. The first crankshaft  42  includes a forward end  44  and a rearward end  46 . 
     The first fracturing pump  26  may be configured in a variety of ways. In the illustrated embodiment, the first fracturing pump  26  may be a positive displacement reciprocating pump, a centrifugal pump, a rotary pump or other pump types that are capable of flowing water or water with additives such as proppant or chemicals. In some embodiments, first fracturing pump  26  is capable of flowing 1200 gal/minute or more and/or is capable of 15,000 psi output fluid pressure or greater. 
     The first transmission  24  may be configured in a variety of ways. For example, the size and type of the transmission may vary in different applications. Any suitable transmission for the specific embodiment of the first driveline  14  may be used depending on the required speed and torque for driving the first fracturing pump  26 . Suitable transmission types may include, but not be limited to, planetary, countershaft, hydrostatic, or continuously variable transmissions. 
     The first motor  20  may be configured in a variety of ways. Any suitable electric motor capable of driving or assisting the first internal combustion engine  18  in driving the first fracturing pump  26  may be used. The first motor  20  may be a motor, a single integrated motor and generator, or a separate motor and a separate generator collectively referred to herein as a motor. In one exemplary embodiment, the first motor is an induction motor. The first motor  20  may operate over a large speed range. In one exemplary embodiment, the first motor  20  is able to operate in a speed range from 0-2100 rpm. In another exemplary embodiment, a gearbox (not shown) is operatively coupled between the first internal combustion engine  18  and the first motor  20 . The gearbox (not shown) may be operatively coupled between the first internal combustion engine  18  and the first motor  20  in a conventional manner. With the use of the gearbox, the first motor  20  is able to operate in a speed range from 0-700 rpm or greater. 
     The first motor  20  is mechanically coupled to the forward end  44  of the first crankshaft  42 . In particular, the first motor  20  includes a first rotor  54  rotatably mounted within a first stator  56 . The first rotor  54  includes a first rotor shaft  58  having a first end  60 . The first end  60  of the first rotor shaft  58  is mechanically coupled to the forward end  44  of the first crankshaft  42  for rotation therewith. The first end  60  of the first rotor shaft  58  may be mechanically coupled to the forward end  44  of the first crankshaft  42  in any suitable manner. In the illustrated embodiment, the forward end  44  of the first crankshaft  42  include a gear, damper, or the structure to which a hub  62  is mechanically attached, such as by bolting. The first end  60  of the first rotor shaft  58  is mechanically attached to the hub  62  for rotation therewith in any suitable manner, such as for example, by a keyed, interference fit. 
     Similarly, the second driveline  16  is configured such that the second fracturing pump  36  is driven by a second driveshaft  63  which is driven by the second internal combustion engine  28  and the second motor  30  via the second transmission  34 . The second motor  30  is mechanically coupled to a forward end  64  of a second crankshaft  66  of the second internal combustion engine  28  and the second transmission is operatively coupled to a rearward end  67  of the second crankshaft  66 . The second motor  30  includes a second rotor  68  rotatably mounted within a second stator  70 . The second rotor  68  includes a second rotor shaft  72  having a first end  74 . The first end  74  of the second rotor shaft  72  is mechanically coupled to the forward end  64  of the second crankshaft  66  for rotation therewith. The first end  74  of the second rotor shaft  72  may be mechanically coupled to the forward end  64  of the second crankshaft  66  in any suitable manner. In the illustrated embodiment, the forward end  64  of the second crankshaft  66  include a gear, damper, or the structure to which a second hub  76  is mechanically attached, such as by bolting. The first end  74  of the second rotor shaft  72  is mechanically attached to the second hub  76  for rotation therewith in any suitable manner, such as for example, by a keyed, interference fit. 
     The hybrid hydraulic fracturing system  10  also includes a power source  80  that is electrically connected to the first motor  20  by first electrical lines  82  and is electrically connected to the second motor  30  by second electrical lines  84 . The power source  80  may be configured in a variety of ways. Any device capable of providing electrical power to the first motor  20  and the second motor  30  may be used. For example, the power source may be an energy storage device, such as for example, one or more DC batteries. The power source may also be generator, grid power, facility power, or other suitable power source. 
     The hybrid hydraulic fracturing system  10  also includes a first bi-directional rectifier-inverter  90  (e.g., a variable frequency drive) associated with the first motor  20  and a second bi-directional rectifier-inverter  92  associated with the second motor  30 . The first bi-directional rectifier-inverter  90  is electrically connected to the first electrical lines  82  between the energy storage device  80  and the first motor  20  and the second bi-directional rectifier-inverter  92  is electrically connected to the second electrical lines  84  between the energy storage device  80  and the second motor  30 . 
     The first bi-directional rectifier-inverter  90  and the second bi-directional rectifier-inverter  92  are configured to convert the DC current from the energy storage device  80  to AC current for deliver to the first motor  20  and the second motor  30 , respectively, when the first motor  20  and the second motor  30  are acting in a motor mode. The first bi-directional rectifier-inverter  90  and the second bi-directional rectifier-inverter  92  are also configured to convert AC current generated by the first motor  20  and the second motor  30 , respectively, when the first motor  20  and the second motor  30  are in a generator mode, for storage in the energy storage device  80 . 
     The hybrid hydraulic fracturing system  10  may include a control system  94  that is configured to control and monitor the operation of hybrid hydraulic fracturing system  10 . The control system  94  may be communicatively coupled to various components of the hybrid hydraulic fracturing system  10  as showed by dashed lines in  FIG. 1 . The control system  94  may be configured in a variety of ways. In the illustrated embodiment, the control system  94  includes a controller  96  and a memory  98 . The controller  96  may embody a single microprocessor or multiple microprocessors configured to receive signals from the various components of the hybrid hydraulic fracturing system  10 . A person of ordinary skill in the art will appreciate that the control system  94  may additionally include other components and may also perform other functions not described herein. The controller  96  may also be configured to receive inputs from an operator via one or more operator controls  100 . 
     The memory  98  may include information regarding one or more parameters of the hybrid hydraulic fracturing system  10 . Further, the controller  96  may be configured to refer to the information stored in the memory  98 . The memory  98  may also be configured to store various information determined by the controller  96 . In some embodiments, the memory  98  may be integral to the controller  96 . The memory  98  may be a read only memory (ROM) for storing a program or programs, a random access memory (RAM) which serves as a working memory area for use in executing the program(s) stored in the memory  98 , or a combination thereof. Alternatively, the memory  98  may be external to the controller  96  and/or the control system  94 . 
     The control system  94  may be used to operate the hybrid hydraulic fracturing system  10  in different operating modes. The specific programming of the control system  94  and the controller  96  is within the understanding of those skilled in the art, and a detailed discussion of the programming methods is not provided herein. The controller  96  may be communicatively coupled to various portions of the hybrid hydraulic fracturing system  10  to send signals to, and receive signals from, those portions. 
     The controller  96  is configured to operate the hybrid hydraulic fracturing system  10  in a first mode in which, if speed or torque assistance is needed by the first internal combustion engine  18  and/or the second internal combustion engine  28  during operation of the fracturing pumps  26 ,  36 , the control system  94  senses the need and activates the first motor  20  to selectively provide additional torque to the first crankshaft  42  of the first internal combustion engine  18  and/or activates the second motor  30  to selectively provide additional torque to the second crankshaft  66  of the second internal combustion engine  28 . The first mode is considered a motor mode where additional load is provided by the motors  20 ,  30  to operate the fracturing pumps  26 ,  36 . Either or both of the first driveline  14  and the second driveline  16  may operate in the first mode at a given time. 
     The controller  96  is also configured to operate the hybrid hydraulic fracturing system  10  in a second mode in which, if the speed or torque provided by the first internal combustion engine  18  and/or the second internal combustion engine  28  is too high during operation of the fracturing pumps  26 ,  36 , the control system  94  senses it and activates the first motor  20  in a generating mode to selectively provide braking to the first crankshaft  42  of the first internal combustion engine  18  and/or activates the second motor  30  in a generating mode to selectively provide braking to the second crankshaft  66  of the second internal combustion engine  28 . The second mode is considered a brake mode where additional load is removed by the motors  20 ,  30 . During the second mode, the power generated by the motors  20 ,  30  may be sent to the energy storage device  80  for storage. Either or both of the first driveline  14  and the second driveline  16  may operate in the second mode at a given time. 
     The controller  96  is also configured to operate the hybrid hydraulic fracturing system  10  in a third mode in which one or both of the motors  20 ,  30  are not adding torque nor braking load from the corresponding internal combustion engines  18 ,  28 . For example when the first driveline  14  is operated in the third mode, the first rotor  54  of the first motor  20  is rotating with the first crankshaft  42 , but the first motor  20  not being excited or an open circuit is created such that the first motor  20  does not provide torque assist or braking to the first internal combustion engine  18 . Either or both of the first driveline  14  and the second driveline  16  may operate in the third mode at a given time. 
     INDUSTRIAL APPLICABILITY 
     The disclosed hybrid hydraulic fracturing system  10  may be used in a wide variety of fracturing applications. While the exemplary embodiments of the hybrid hydraulic fracturing system  10  are illustrated as a dual driveline, parallel fracturing system, it will be understood that inventive aspects of the disclosed hybrid hydraulic fracturing system  10  may be used in hybrid hydraulic fracturing systems having more than or less than two drivelines and other than parallel arrangements. 
     In the illustrated embodiment, the hybrid hydraulic fracturing system  10  utilizes gaseous fueled engines (e.g. natural gas engines). Natural gas engines, however, tend to be less responsive than, for example, diesel engines. Thus, a natural gas fueled engine may not be able to sufficiently respond to transient load conditions during a fracturing operation. The disclosed hybrid hydraulic fracturing system  10  operatively couples a motor to each internal combustion engine to power condition the hybrid hydraulic fracturing system  10 . Power condition, as used in this disclosure refers to providing load assistance and/or load braking when needed. For example, the system may be configured to power condition the first driveline by operating in the first mode in response to a load change that results in an increased power demand on the first driveline. Thus, the system may provide torque from the first internal combustion engine to drive the first fracturing pump and selectively provide additional torque from the first motor to the first crankshaft of the first internal combustion engine to assist the first internal combustion engine in driving the first fracturing pump. The system may operate the second driveline in the first mode in the same way. 
       FIG. 2  illustrates an exemplary method  200  of power conditioning the hybrid hydraulic fracturing system  10  when additional power is needed. The method  200  includes the step  202  of applying a load to the fracturing pump  26  of the hybrid hydraulic fracturing system  10  (i.e., the power demand to the system). The hybrid hydraulic fracturing system  10 , in step  204 , is then configured to determine if the load step (i.e., the power demand) is greater than the capability of the internal combustion engine  18  to respond by providing the additional power in a required time (i.e., provide a transient response). If the load step is not greater than the capability of the internal combustion engine  18  to respond, then at step  206 , the power output of the internal combustion engine  18  is increased without activating the motor  20 . If, however, the load step is greater than the capability of the internal combustion engine  18  to respond, then, at step  208 , in conjunction with increasing the power output of the internal combustion engine  18 , the motor  20  is activated to provide additional power to the hybrid hydraulic fracturing system  10  by providing torque to the crankshaft  42  of the internal combustion engine  18 . Then, at step  210 , when the engine power has increased to cover the power demand of the hybrid hydraulic fracturing system  10 , the motor  20  is deactivated to remove the additional power the motor  20  is providing via the torque on the crankshaft  42 . 
     The system may be configured to power condition the first driveline by operating in the second mode in response to a load change that results in a decreased power demand on the first driveline. Thus, the system may provide torque from the first internal combustion engine to drive the first fracturing pump and selectively provide braking from the first motor to the first crankshaft of the first internal combustion engine to reduce the speed of the first fracturing pump. The system may operate the second driveline in the second mode in the same way. 
       FIG. 3  illustrates an exemplary method  300  of power conditioning the hybrid hydraulic fracturing system  10  when reducing power is needed. The method  300  includes the step  302  of reducing the load to the fracturing pump  26  of the hybrid hydraulic fracturing system  10  (i.e., the power demand to the system). The hybrid hydraulic fracturing system  10 , in step  304 , is then configured to determine if the load step (i.e., the power demand) is less than the capability of the internal combustion engine  18  to respond by providing reducing power in a required time (i.e., provide a transient response). If the load step is not greater than the capability of the internal combustion engine  18  to respond, then at step  306 , the power output of the internal combustion engine  18  is decreased without activating the motor  20 . If, however, the load step is greater than the capability of the internal combustion engine  18  to respond, then, at step  308 , in conjunction with reducing the power output of the internal combustion engine  18 , the motor  20  is activated to provide braking to the hybrid hydraulic fracturing system  10  by absorbing power from the system via the crankshaft  42 . The motor  20  may act as a generator during braking to generate power that can be send to the power source  80  for storage or use. Then, at step  310 , when the engine power has decreased to match the power demand of the hybrid hydraulic fracturing system  10 , the motor  20  is deactivated to remove the braking the motor  20  is providing. 
     Each driveline of the hybrid hydraulic fracturing system  10  may operate independently of the other drivelines such that a first driveline may be operating in one mode while one or more of the other drivelines is operating in a different mode. In this way, the motors can quickly respond to transient conditions by providing additional torque or braking excess load where the natural gas-fueled engine may not be able to. 
     In the illustrated embodiment, the motors are operatively coupled to the forward end of each engine such that components of each driveline are arranged in series. Having the motors operatively coupled to the front of each engine allows the motors to provide the desired torque assistance and load braking while not requiring modification to the coupling between the engine, the transmission, the driveshaft, and the fracturing pump. 
     Further, the motors are electrically coupled to a power source to both receive power from the power source when required, such as for example, in the first mode, and generate power to be utilized by the power source, such as for example, to store for future use or be used by some other power consumer coupled to the power source. 
     While the present disclosure has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the present disclosure, in its broader aspects, is not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicant&#39;s general disclosure herein. 
     LIST OF ELEMENTS 
     Element Element 
     Number Name 
     
         
           10  hybrid hydraulic fracturing system 
           14  first driveline 
           16  second driveline 
           18  first internal combustion engine 
           20  first motor 
           24  first transmission 
           26  first fracturing pump 
           28  second internal combustion engine 
           30  second motor 
           34  second transmission 
           36  second fracturing pump 
           38  first driveshaft 
           40  engine block 
           42  first crankshaft 
           44  forward end 
           46  rearward end 
           54  first rotor 
           56  first stator 
           58  first rotor shaft 
           60  first end 
           62  hub 
           63  second driveshaft 
           64  forward end 
           66  second crankshaft 
           67  rearward end 
           68  second rotor 
           70  second stator 
           72  second rotor shaft 
           74  first end 
           76  second hub 
           80  power source 
           82  first electrical lines 
           84  second electrical lines 
           90  first bi-directional rectifier-inverter 
           92  second bi-directional rectifier-inverter 
           94  control system 
           96  controller 
           98  memory 
           100  operator controls 
           200  method 
           202  step 
           204  step 
           206  step 
           208  step 
           210  step 
           300  method 
           302  step 
           304  step 
           306  step 
           308  step 
           310  step