Systems and Methods of Generating Electric Power With Compressed Natural Gas

This disclosure generally relates to electrically driven systems, and more specifically to generation of electric power through compressed natural gas.

Field equipment associated with hydrocarbon-producing wellbores has typically been powered by diesel engines or other internal combustion engines. Such engines have certain disadvantages. Diesel is more expensive and is not environmentally friendly. These engines generate large amounts of exhaust and pollutants that may cause environmental hazards, and are extremely loud, among other problems. The amount of diesel fuel needed to power traditional fracturing and production operations requires constant transportation and delivery by diesel tankers onto the well site, resulting in significant carbon dioxide emissions.

There is a need for an improved system that generates power at one or more wellsites.

According to one embodiment, a method for generating electric power at a pad site may include operating a generator to produce electric power from a fuel source. The method may further include actuating at least one electric motor coupled to at least one compression unit based on the produced electric power. The method may further include actuating the at least one compression unit to discharge a flow of gas at an increased pressure. The method may further include directing at least a portion of the flow of gas discharged from the at least one compression unit to a location upstream of the generator. The generator may be configured to receive the at least a portion of the flow of gas discharged from the at least one compression unit and to produce electric power from the at least a portion of the flow of gas discharged from the at least one compression unit.

According to another embodiment, a system for generating electric power at a pad site may include at least one electric motor and at least one compression unit coupled to the at least one electric motor. The at least one electric motor may be configured to receive electric power produced by a generator and to convert the produced electric power into mechanical energy. The at least one compression unit may be configured to receive a flow of gas to be pressurized and to discharge the flow of gas at an increased pressure through a main conduit. The at least one compression unit may be actuated based on the mechanical energy provided by the at least one electric motor. There may be a secondary conduit fluidly coupled to the main conduit and disposed downstream of the at least one compression unit, wherein the secondary conduit may be configured to direct at least a portion of the flow of gas discharged from the at least one compression unit to a location upstream of the generator. The generator may be configured to receive the at least a portion of the flow of gas discharged from the at least one compression unit and to produce electric power from the at least a portion of the flow of gas discharged from the at least one compression unit.

According to another embodiment, a non-transitory computer-readable medium storing instructions that when executed by a processor, may cause the processor to actuate a generator to produce electric power from a fuel source. The processor may be further configured to actuate at least one electric motor coupled to at least one compression unit based on the produced electric power. The processor may be further configured to actuate the at least one compression unit to discharge a flow of gas at an increased pressure. The processor may be further configured to direct at least a portion of the flow of gas discharged from the at least one compression unit to a location upstream of the generator. The processor may be further configured to actuate the generator to produce electric power from the at least a portion of the flow of gas discharged from the at least one compression unit.

Illustrative embodiments of the present invention are described in detail herein. In the interest of clarity, not all features of an actual implementation may be described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation specific decisions may be made to achieve the specific implementation goals, which may vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of the present disclosure.

The terms “couple,” “couples,” and “coupled,” as used herein, are intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection, or through an indirect electrical connection, or a shaft coupling via other devices and connections.

To facilitate a better understanding of the present disclosure, the following examples of certain embodiments are given. The following examples are not to be read to limit or define the scope of the disclosure. Embodiments of the present disclosure and its advantages are best understood by referring to, where like numbers are used to indicate like and corresponding parts. Described herein are various systems and methods that generate electric power through compressed natural gas.

During oilfield services, equipment used to produce hydrocarbons from a well need to be powered by a power source. Typically, a diesel generator has been used that burns diesel fuel to produce electricity used by the equipment. However, the logistics of providing diesel for burning is costly and unclean. Other attempts have been made to connect the equipment to a utility grid for access to electricity, but there are problems with electric transmission. Using natural gas as a fuel may be an improvement over these attempts as it is a result of the servicing operations that is readily available, burns cleaner compared to diesel, and is less expensive. The discloses systems and methods may provide an improved process of generating electricity by compressing natural gas and re-routing the compressed natural gas back to a generator for conversion to electricity.

illustrates an example production system. Production systemmay be disposed at a pad site having one or more wellboresthat intersect with a subterranean formation. In embodiments, surface and/or downhole equipment may be used to extract hydrocarbons from the subterranean formation through the one or more wellbores. When the hydrocarbons reach the surface, they may be processed in a number of ways, including by separating the fluid into different components (i.e., oil, gas, water, mud, etc.), placing the hydrocarbons in storage tanks, or flowing the hydrocarbons through one or more pipelines to a storage/processing center. To produce the hydrocarbons, the surface and/or downhole equipment may require power in order for operations.

In one or more embodiments, production systemand methods of operating said production systemmay use any suitable power source. Without limitations, the production systemmay be powered by combustion engines, an electric power supply, a hydraulic power supply, and any combination thereof. For example, the production systemmay comprise a generatorconfigured to produce electric power from a fuel source (i.e., diesel or natural gas) for the surface and/or downhole equipment. The generatormay be a gas generator operable to receive and burn natural gas in order to produce the electric power. The natural gas received may be in any suitable form, such as cleaned or conditioned after being produced from the one or more wellbores. Without limitations, the generatormay be configured to produce any suitable value of electric power, such as at least about 200W, about 400 kW, about 600 kW, about 800 kW, or about 1 MW. In embodiments, the generatormay be an 800kW natural gas generator.

The production systemmay further comprise one or more compression unitsoperable to increase the pressure of a gas for operations associated with the one or more wellbores, such as for artificial lift. For example, each compression unitmay receive a flow of a gas and may discharge the flow of gas at an increased pressure. The flow of gas may be provided from a gas source, wherein the gas source may be the same as the fuel source for the generator. The one or more compression unitsmay be powered by the generator. In embodiments, each of the one or more compression unitsmay be coupled to an electric motor. The electric motormay be configured to receive the produced electric power from the generatorand convert said electric power into mechanical energy that is usable by the compression unit. Each electric motormay be directly coupled to the corresponding compression unit, and both the electric motorand compression unitmay collectively be disposed in a modular arrangement. Whileillustrates three compression units, the production systemis not limited to such a configuration. For example, there may be more than or less than three compression unitsin the production system. Further, each compression unitmay operate at the same or at different rates. In embodiments, there may be at least one compression unitoperating at about 400 horsepower (hp). In other embodiments, there may be at least one compression unitoperating at about 200 hp.

Depending on the configuration of the production system, the electric motormay receive the produced electric power directly from the generatoror from a variable frequency drive (VFD)electrically coupled to the generator. For example, if the generatorproduces electric power at a voltage level compatible with the electric motor, the electric motormay receive the produced electric power directly from the generator. Otherwise, the generatormay transmit the produced electric power to the VFD, which may be configured to step-up or step-down the voltage level of the produced electric power. There may be a plurality of VFDsconfigured to receive electric power from the generator. In embodiments, the VFDmay convert the received electric power from its initial voltage level to another voltage level that is compatible for the electric motor. In addition, the VFDmay be configured to alter the frequency and current of the electric power for the electric motor. Each VFDand corresponding electric motorwith compression unitmay be collectively disposed on a traileroperable to be transported. In embodiments, each trailermay alternatively be a skid. Whileillustrates three separate VFDscommunicatively coupled to a corresponding electric motor, the production systemis not limited to such a configuration. For example, there may be a singular VFDcommunicatively coupled to each of the electric motorsin the production system.

In one or more embodiments, the production systemmay further comprise a power distribution module. The power distribution modulemay comprise a variety of components for distributing and processing electric power, such as transformers, power distribution components, switchgears, fuses, circuit breakers, and the like. The power distribution modulemay be configured to receive the electric power from the generatorand distribute the electric power to each of a plurality of VFDs. In certain embodiments wherein there is a singular VFDor a singular electric motorand compression unit, the power distribution modulemay not be needed for the production system.

The production systemmay be operable to inject a pressurized flow of gas into the one or more wellboresin order to facilitate production of hydrocarbons. In embodiments, the discharge from the one or more compression unitsmay be received and collected by a manifold for consolidation and distribution to the one or more wellbores. In other embodiments, each of the one or more compression unitsmay be fluidly coupled to each of the one or more wellboresand may selectively direct the discharged flow of gas to the one or more wellbores. As illustrated, there may be a valve 116 disposed downstream of at least one of the compression units. In one or more embodiments, there may be a plurality of valves, wherein each one of the plurality of valvesmay be disposed downstream of a corresponding compression unit. Without limitations, the valvemay be any suitable valve or flow restriction device, such as a gate valve, ball valve, butterfly valve, knife gate valve, or plug valve. The valvemay be disposed on a main conduit, on a secondary conduitcoupled to the main conduit, or at a junction thereof. Both the main conduitand the secondary conduitmay be any suitable tubular configured to transport a fluid. The main conduitmay be configured to receive the pressurized flow of gas discharged from the compression unitand direct the pressurized flow of gas to the one or more wellbores. The secondary conduitmay be fluidly coupled to the main conduitand may be configured to direct at least a portion of the pressurized flow of gas back upstream to the generator. The valvemay be actuated to allow the at least a portion of the pressurized flow of gas to divert from the main conduitand flow through the secondary conduit. In one or more embodiments, the generatormay be further configured to receive the at least the portion of the flow of gas discharged from the compression unitand to produce electric power from that portion of the flow of gas. The electric power produced from that portion of the flow of gas may then be transmitted to the surface and/or downhole equipment (i.e., the VFDs, electric motors, compression units, etc.) for operations.

In embodiments, the production systemmay further comprise a control panelconfigured to monitor and actuate the components within the production system. The control panelmay be communicatively coupled to each of the generator, power distribution module, VFDs, electric motors, and/or the compression units, such as through a wired or wireless connection. The control panelmay transmit and receive signals, such as instructions and/or measurements relative to operation of each of the generator, power distribution module, VFDs, electric motors, and/or the compression units. For example, a sensormay be disposed downstream at least one of the compression unitsfor measuring a pressure of the flow of gas discharged from said compression unit. The sensormay be any suitable sensor operable to measure pressure. In embodiments, the control panelmay receive pressure measurements from the sensorand may actuate the valvebased on the pressure measurements.

As illustrated, the production systemmay include a communication networkfor facilitating communication between the control paneland the surface and/or downhole equipment (i.e., the control panel, sensor, valve, etc.). The communication networkmay include all or a portion of a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), a mobile telephone network (e.g., cellular networks, such as 4G orG), a wireless data network (e.g., WiFi, WiGig, WiMax, etc.), a Long Term Evolution (LTE) network, a Bluetooth network, and/or any other suitable network, operable to facilitate communication between the components of production system.

In one or more embodiments, software running on the control panelmay perform one or more steps of one or more methods described or illustrated herein or provides functionality described or illustrated herein. This disclosure contemplates the control paneltaking any suitable physical form. As example and not by way of limitation, control panelmay be an embedded computer system, a system-on-chip (SOC), a single-board computer system (SBC) (such as, for example, a computer-on-module (COM) or system-on-module (SOM)), a desktop computer system, a laptop or notebook computer system, an interactive kiosk, a mainframe, a mesh of computer systems, a mobile telephone, a personal digital assistant (PDA), a server, a tablet computer system, an augmented/virtual reality device, or a combination of two or more of these. Where appropriate, control panelmay be unitary or distributed; span multiple locations; span multiple machines; span multiple data centers; or reside in a cloud, which may include one or more cloud components in one or more networks. Where appropriate, the control panelmay perform without substantial spatial or temporal limitation one or more steps of one or more methods described or illustrated herein. As an example and not by way of limitation, the control panelmay perform in real-time or in batch mode one or more steps of one or more methods described or illustrated herein.

In particular embodiments, control panelmay include a processor, a memory, an input/output (I/O) interface, a communication interface, and a bus. Although this disclosure describes and illustrates a particular control panel having a particular number of particular components in a particular arrangement, this disclosure contemplates any suitable control panel having any suitable number of any suitable components in any suitable arrangement.

In particular embodiments, processormay include hardware for executing instructions, such as those making up a computer program. As an example and not by way of limitation, to execute instructions, processormay retrieve (or fetch) the instructions from an internal register, an internal cache, memory, or storage; decode and execute them; and then write one or more results to an internal register, an internal cache, memory, or storage. In particular embodiments, processormay include one or more internal caches for data, instructions, or addresses. This disclosure contemplates processorincluding any suitable number of any suitable internal caches, where appropriate. As an example and not by way of limitation, processormay include one or more instruction caches, one or more data caches, and one or more translation lookaside buffers (TLBs). Instructions in the instruction caches may be copies of instructions in memory, and the instruction caches may speed up retrieval of those instructions by processor. Data in the data caches may be copies of data in memoryfor instructions executing at processorto operate on; the results of previous instructions executed at processorfor access by subsequent instructions executing at processoror for writing to memory; or other suitable data. The data caches may speed up read or write operations by processor. The TLBs may speed up virtual-address translation for processor. In particular embodiments, processormay include one or more internal registers for data, instructions, or addresses. This disclosure contemplates processorincluding any suitable number of any suitable internal registers, where appropriate. Where appropriate, processormay include one or more arithmetic logic units (ALUs); be a multi-core processor; or include one or more processors. Although this disclosure describes and illustrates a particular processor, this disclosure contemplates any suitable processor.

In particular embodiments, memorymay include main memory for storing instructions for processorto execute or data for processorto operate on. As an example and not by way of limitation, control panelmay load instructions from storage or another source (such as, for example, another control panel) to memory. Processormay then load the instructions from memoryto an internal register or internal cache. To execute the instructions, processormay retrieve the instructions from the internal register or internal cache and decode them. During or after execution of the instructions, processormay write one or more results (which may be intermediate or final results) to the internal register or internal cache. Processormay then write one or more of those results to memory. In particular embodiments, processorexecutes only instructions in one or more internal registers or internal caches or in memory(as opposed to storage or elsewhere) and operates only on data in one or more internal registers or internal caches or in memory(as opposed to storage or elsewhere). One or more memory buses (which may each include an address bus and a data bus) may couple processorto memory. A bus may include one or more memory buses, as described below. In particular embodiments, one or more memory management units (MMUs) reside between processorand memoryand facilitate access to memoryrequested by processor. In particular embodiments, memoryincludes random access memory (RAM). This RAM may be volatile memory, where appropriate. Where appropriate, this RAM may be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, where appropriate, this RAM may be single-ported or multi-ported RAM. This disclosure contemplates any suitable RAM. Memorymay include one or more memories, where appropriate. Although this disclosure describes and illustrates particular memory, this disclosure contemplates any suitable memory.

In particular embodiments, I/O interfacemay include hardware, software, or both, providing one or more interfaces for communication between control paneland one or more I/O devices. Control panelmay include one or more of these I/O devices, where appropriate. One or more of these I/O devices may enable communication between a person and control panel. As an example and not by way of limitation, an I/O device may include a keyboard, keypad, microphone, monitor, mouse, printer, scanner, speaker, still camera, stylus, tablet, touch screen, trackball, video camera, another suitable I/O device or a combination of two or more of these. An I/O device may include one or more sensors. This disclosure contemplates any suitable I/O devices and any suitable I/O interfacesfor them. Where appropriate, I/O interfacemay include one or more device or software drivers enabling processorto drive one or more of these I/O devices. I/O interfacemay include one or more I/O interfaces, where appropriate. Although this disclosure describes and illustrates a particular I/O interface, this disclosure contemplates any suitable I/O interface.

In particular embodiments, communication interfacemay include hardware, software, or both providing one or more interfaces for communication (such as, for example, packet-based communication) between control paneland one or more networks. As an example and not by way of limitation, communication interfacemay include a network interface controller (NIC) or network adapter for communicating with an Ethernet or other wire-based network or a wireless NIC (WNIC) or wireless adapter for communicating with a wireless network, such as a WI-FI network. This disclosure contemplates any suitable network and any suitable communication interfacefor it. As an example and not by way of limitation, control panelmay communicate with the communication network. Control panelmay include any suitable communication interfacefor said network, where appropriate. Communication interfacemay include one or more communication interfaces, where appropriate. Although this disclosure describes and illustrates a particular communication interface, this disclosure contemplates any suitable communication interface.

In particular embodiments, a bus may include hardware, software, or both coupling components of control panelto each other. As an example and not by way of limitation, a bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a front-side bus (FSB), a HYPERTRANSPORT (HT) interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBAND interconnect, a low-pin-count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCIe) bus, a serial advanced technology attachment (SATA) bus, a Video Electronics Standards Association local (VLB) bus, or another suitable bus or a combination of two or more of these. A bus may include one or more buses, where appropriate. Although this disclosure describes and illustrates a particular bus, this disclosure contemplates any suitable bus or interconnect.

Herein, a computer-readable non-transitory storage medium or media may include one or more semiconductor-based or other integrated circuits (ICs) (such, as for example, field-programmable gate arrays (FPGAs) or application-specific ICs (ASICs)), hard disk drives (HDDs), hybrid hard drives (HHDs), optical discs, optical disc drives (ODDs), magneto-optical discs, magneto-optical drives, floppy diskettes, floppy disk drives (FDDs), magnetic tapes, solid-state drives (SSDs), RAM-drives, SECURE DIGITAL cards or drives, any other suitable computer-readable non-transitory storage media, or any suitable combination of two or more of these, where appropriate. A computer-readable non-transitory storage medium may be volatile, non-volatile, or a combination of volatile and non-volatile, where appropriate.

Although a particular implementation of production systemis illustrated and primarily described, the present disclosure contemplates any suitable implementation of production system, according to particular needs. Moreover, although various components of production systemhave been depicted as being located at particular positions, the present disclosure contemplates those components being positioned at any suitable location, according to particular needs. Further, although certain actions have been described as being performed by certain components of production system, the present disclosure contemplates those actions, and any other actions, as being performed by any suitable component of production system, according to particular needs. In addition, while production systemis depicted as having a certain number of components, the present disclosure contemplates production systemhaving any suitable number of any one of the components, according to particular needs.

is a flowchart of an embodiment of a processfor the production system(referring to). The production systemmay employ processfor diverting at least a portion of pressurized natural gas to the generator(referring to) for producing electric power. At operation, processor(referring to) of the control panel(referring to) may transmit an instruction to actuate the generatorto produce electric power from a fuel source. In embodiments, the produced electric power may be transmitted to any one of the power distribution module(referring to), the VFD(referring to), or the electric motor(referring to). If the produced electric power is not directly transmitted to the electric motor, the produced electric power may be manipulated by either the power distribution moduleor the VFDto a voltage level compatible with the electric motor. During operation, the processormay instruct the VFDto step-up or step-down the received electric power prior to transmission to the electric motor.

At operation, the processormay transmit an instruction to actuate at least one electric motorcoupled to at least one compression unit(referring to) based on the produced electric power. The electric motormay convert the produced electric power into mechanical energy that can be used by the compression unit.

At operation, the processormay transmit an instruction to actuate at least one compression unitto discharge a flow of gas at an increased pressure. In embodiments, the at least one compression unitmay receive the flow of gas to be pressurized. The flow of gas may be sourced from the same source as the fuel provided to the generator. During operation, the sensor(referring to) may be measuring the pressure of the discharged flow of gas and may be communicating pressure measurements to the control panel.

At operation, the processormay transmit an instruction to direct at least a portion of the flow of gas discharged from the at least one compression unitto a location upstream of the generatoror to the generator. In embodiments, the transmission of this instruction may occur in response to the pressure of the discharged flow of gas exceeding a threshold value stored in the memory(referring to) of the control panel. In other embodiments, transmission of the instruction may occur based on a different system parameter or desired output. The instruction may be transmitted to the valve(referring to), wherein the instruction may be to actuate the valveto open at least a portion to allow fluid flow through the secondary conduit(referring to).

At operation, the processormay transmit an instruction to actuate the generatorto produce electric power from the portion of the flow of gas discharged from compression unitand received through the secondary conduit. In embodiments, the control panelmay continuously monitor and control the production systemto provide a portion of the discharged flow back to the generatorfor production of electric power. After an initial start-up process, the generatormay be configured to operate solely on the received portion of discharged flow rather than from the fuel source. In alternate embodiments, the received portion of discharged flow may supplement fuel received from the fuel source. The processmay then proceed to end.

Although a particular implementation of processis illustrated and primarily described, the present disclosure contemplates any suitable implementation of process, according to particular needs. For example, processmay include more or fewer steps, and each step may be performed in any order relative to the other steps. Further, although certain actions have been described as being performed by certain components of production systemthroughout the process, the present disclosure contemplates those actions, and any other actions, as being performed by any suitable component of production system, according to particular needs.

Modifications, additions, or omissions may be made to the systems and apparatuses described herein without departing from the scope of the disclosure. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic.

Modifications, additions, or omissions may be made to the methods described herein without departing from the scope of the disclosure. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. That is, the steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Herein, “or” is inclusive and not exclusive, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A or B” means “A, B, or both,” unless expressly indicated otherwise or indicated otherwise by context. Moreover, “and” is both joint and several, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A and B” means “A and B, jointly or severally,” unless expressly indicated otherwise or indicated otherwise by context.

The scope of this disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments described or illustrated herein that a person having ordinary skill in the art would comprehend. The scope of this disclosure is not limited to the example embodiments described or illustrated herein. Moreover, although this disclosure describes and illustrates respective embodiments herein as including particular components, elements, feature, functions, operations, or steps, any of these embodiments may include any combination or permutation of any of the components, elements, features, functions, operations, or steps described or illustrated anywhere herein that a person having ordinary skill in the art would comprehend. Furthermore, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Additionally, although this disclosure describes or illustrates particular embodiments as providing particular advantages, particular embodiments may provide none, some, or all of these advantages.