FRACTURING SYSTEM LAYOUTS

Abstract

Systems for stimulation a formation include a plurality of variable frequency drives, each in communication with at least two high pressure pumps. A variable frequency drive actuates at least two electric motors associated with the high pressure pumps, such that the pumps pressurize fracturing fluid, proppant, or combinations thereof for flowing the fracturing fluid, proppant, or combinations thereof into the formation.

Description

FIELD

Embodiments usable within the scope of the present disclosure relate, generally, to systems and methods for flowing fluid in association with a wellbore, and more specifically, to systems and methods usable for performing fracturing operations on a formation to stimulate production (e.g., of hydrocarbons) therefrom.

BACKGROUND

To stimulate and/or increase the production of hydrocarbons from a well, a process known as fracturing (colloquially referred to as “fracing”) is performed. In brief summary, a pressurized fluid—often water—is pumped into a producing region of a formation at a pressure sufficient to create fractures in the formation, thereby enabling hydrocarbons to flow from the formation with less impedance. Solid matter, such as sand, ceramic beads, and/or similar particulate-type materials, can be mixed with the fracturing fluid, this material generally remaining within the fractures after the fractures are formed. The solid material, known as proppant, serves to prevent the fractures from closing and/or significantly reducing in size following the fracturing operation, e.g., by “propping” the fractures in an open position. Some types of proppant can also facilitate the formation of fractures when pumped into the formation under pressure.

Non-aqueous fracturing fluids have been used as an alternative to water and other aqueous media, one such successful class including hydrocarbon-based fluids (e.g., crude/refined oils, methanol, diesel, condensate, liquid petroleum glass (LPG) and/or other aliphatic or aromatic compounds). Hydrocarbon-based fracturing fluids are inherently compatible with most reservoir formations, being generally non-damaging to formations while creating acceptable fracture geometry. However, due to the flammability of hydrocarbon-based fluids, enhanced safety preparations and equipment are necessary when using such fluids for wellbore operations. Additionally, many hydrocarbon-based fluids are volatile and/or otherwise unsuitable for use at wellbore temperatures and pressures, while lacking the density sufficient to carry many types of proppant. As such, it is common practice to use chemical additives (e.g., gelling agents, viscosifiers, etc.) to alter the characteristics of the fluids. An example a system describing use of liquid petroleum gas is described in U.S. Pat. No. 8,408,289, which is incorporated by reference herein in its entirety.

Independent of the type of fracturing fluid and proppant used, a fracturing operation typically requires use of one or more high pressure pumps to pressurize the fracturing fluid that is pumped into a wellbore. Conventionally, such equipment is driven/powered using diesel engines, which can be responsible for significant quantities of noise, pollution, and expense at a worksite. Electric drive systems have been contemplated as an alternative to diesel engines; however, such systems require numerous pieces of equipment, extensive cabling and/or similar conduits, and typically utilize on-site power generation, such as a natural gas turbine. Use of turbine prime movers and similar equipment may be unsuitable when utilizing fracturing fluids that include flammable components. An exemplary electrically powered system for use in fracturing underground formations is described in published United States Patent Application 2012/0255734, which is incorporated by reference herein in its entirety.

A need exists for systems and methods for fracturing and/or stimulating a subterranean formation that can overcome issues of formation damage/compatibility, flammability, proppant delivery, and/or power supply.

SUMMARY

Embodiments usable within the scope of the present disclosure include systems and methods usable to perform fracturing operations on a formation using an electrically powered fracturing spread. FIG. 1 enumerates numerous benefits relating to safety, economy, and sustainability of electrically powered fracturing systems.

A power source (e.g., a turbine generator and/or a grid-based power source) can be used to provide electrical power to one or more Variable Frequency Drives (VFDs), which in turn actuate electric motors, used to power associated high pressure pumps (e.g., fracturing pumps). The pumps are usable to pressurize a fracturing fluid (e.g., water, propane, or other suitable media, typically combined with proppant) prior to injection of the pressurized fluid into a wellbore to fracture the underlying formation.

A high pressure pump can be subject to a maximum rate and/or torque at which the pump can be operated without damaging components thereof, and as such, a single VFD or set of VFDs may provide horsepower in excess of what is required by a pump to operate the pump at a maximum rate. As such, embodiments usable within the scope of the present disclosure can include multiple high pressure pumps associated with a single VFD. In an embodiment, pumps can be provided with a “breakaway” usable to disconnect a selected pump from a VFD to enable the full power thereof to be provided to one or more pumps that remain connected therewith. In a further embodiment, a VFD can be associated with different types of pumps (e.g., a qunitiplex and/or a triplex pump), to enable selective use of one or both types of pumps in a manner that minimizes harmonic resonance.

In various embodiments, disclosed systems can be used with medium voltage (e.g., 4160 volts), enabling smaller, lighter power conduits to be used, facilitating transport, installation, and safety, while minimizing line loss and the required amperage to operate the system.

In various embodiments, VFDs and/or similar components can be positioned a selected distance (e.g., 30 meters) from the high pressure pumps, thereby minimizing risks of ignition when pumping a flammable medium, such as propane and/or other hydrocarbon-based fracturing fluids. Separation of potential ignition sources from flammable components can eliminate the need to utilize explosion-proof measures (e.g., explosion-proof housings, pressurized environments, etc.)

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description of various embodiments usable within the scope of the present disclosure, presented below, reference is made to the accompanying drawings, in which:

FIG. 1 depicts a list describing benefits attainable through use of embodiments of systems usable within the scope of the present disclosure.

FIG. 2 depicts a diagrammatic view of an embodiment of a system usable within the scope of the present disclosure.

FIG. 3 depicts a diagrammatic view of an embodiment of a system usable within the scope of the present disclosure.

One or more embodiments are described below with reference to the listed Figures.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before describing selected embodiments of the present invention in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein. The disclosure and description herein is illustrative and explanatory of one or more presently preferred embodiments of the invention and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, order of operation, means of operation, equipment structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit of the invention.

As well, it should be understood the drawings are intended illustrate and plainly disclose presently preferred embodiments of the invention to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views as desired for easier and quicker understanding or explanation of the invention. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention as described throughout the present application.

Moreover, it will be understood that various directions such as “upper”, “lower”, “bottom”, “top”, “left”, “right”, and so forth are made only with respect to explanation in conjunction with the drawings, and that the components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the inventive concept(s) herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting.

FIG. 2 depicts a diagrammatic view of an embodiment of a system usable within the scope of the present disclosure, usable to perform fracturing operations on a formation associated with a wellhead. The diagram depicts a cleared zone (e.g., having a radius of about 30 meters) about the wellhead, outside of which the depicted system can be positioned. At the far left of the diagram a plurality of fracturing fluid storage vessels are shown (e.g., six propane storage tanks; however any number and/or type of storage vessel can be used without departing from the scope of the present disclosure), in association with a proppant storage vessel (which can be representative of any number or type of proppant sources and/or containers).

It should be understood that while the depicted system describes use of propane storage tanks (e.g., containing propane for use as a fracturing fluid), the depicted system can incorporate use of water or any other fracturing fluid without departing from the scope of the present disclosure.

The fracturing fluid and proppant storage vessels are shown proximate to the low pressure manifold of the system, where the fracturing fluid and/or proppant can be injected (e.g., as a slurry). A plurality of high pressure pumps (each powered using an associated electric motor) is shown, the pumps being usable to pressurize the fracturing fluid and/or proppant (e.g., at the high pressure manifold of the system) prior to flowing the fracturing fluid and/or proppant to the wellhead (and subsequently into the wellbore to the formation). While the depicted diagram shows eight high pressure pumps and associated motors, it should be understood that any number of high pressure pumps can be used depending on the nature of the operation. Conceptually, FIG. 2 depicts the eight high pressure pumps divided into three groups—two sets of three pumps and one set of two pumps—each grouping of pumps representative of a single transport load (e.g., the number of pumps that could be transported to an operational site on a single trailer.) It should be understood that this division of pumps is merely conceptual, and that depending on the means of transport and/or the characteristics of the pumps, motors, and/or associated equipment, any number of transport loads could be used without departing from the scope of the present disclosure.

A plurality of Variable Frequency Drives (VFDs) is shown spaced a selected distance (e.g., 30 meters) from the high pressure pumps. Placement of the VFDs a safe distance from the high pressure pumps can allow propane or a similar flammable medium to be used as a fracturing fluid while minimizing the risk of ignition created by the proximity of VFDs or similar potential ignition sources. By placing the VFDs remote from the high pressure pumps, the need for explosion proof housings, pressurized environments, and/or use of similar explosion-proof measures can be eliminated.

While FIG. 2 depicts four VFDs (used in association with the eight depicted high pressure pumps and associated electric motors), it should be understood that any number of VFDs or similar devices can be used depending on the nature and/or requirements of an operation and/or characteristics of equipment being used. Conceptually, FIG. 2 depicts the four VFDs as a single grouping of devices, representative of a single transport load—e.g., it is contemplated that four VFDs could be transported to an operational site on a single trailer. As noted above, depending on the means of transport and/or the characteristics of the equipment utilized, any number of transport loads could be used without departing from the scope of the present disclosure. In the depicted embodiment, four transport loads could be used to position each of the depicted pumps, motors, and VFDs, which is one half the number of loads required to deploy such a quantity of equipment using conventional configurations.

Each VFD is shown in operative association with two high pressure pumps (via the associated electric motors). As described above, the maximum rate at which a high pressure pump can be operated is typically limited to the maximum torque able to be withstood by the components thereof. As such, a single VFD may produce horsepower in excess of that which is required to operate a high pressure pump at its maximum rate, and in an embodiment, the horsepower output of a VFD can be generally sufficient to operate two high pressure pumps at a rate suitable for performing a fracturing operation. For example, four conventional VFDs may output approximately 10,000 horsepower, which would be sufficient to operate eight high pressure pumps at approximately their maximum rate. It should be understood that the type and quantity of VFDs and/or pumps and/or electric motors can be selected such that the output of the VFDs is generally equal to the horsepower requirements to operate the associated pumps.

As described above, in various embodiments, one or both pumps coupled with a VFD can include a breakaway or similar means for decoupling from the VFD, such that the entirety of the output from the VFD can be used to drive a single pump (e.g., at an enhanced rate), and/or to enable a second pump to be used as a backup/redundant pump in the case of a fault or failure of a first pump. Additionally or alternatively, two pumps associated with a single VFD can include different types of pumps, such that a desired type of pump can be selected for use (e.g., depending on operational conditions, wellbore conditions, types of equipment present/available, etc.). For example, selection between a quintiplex and/or a triplex pump can be used to minimize harmonic resonance.

The depicted VFDs are shown in communication with a power source, which can include one or more generators, one or more power storage devices, one or more grid power sources, or combinations thereof. In an embodiment, the incoming power can include a medium voltage source (e.g., 4160 volts), allowing use of smaller and lighter conduits, less line loss, lower amperage, etc. Depending on the characteristics of the VFDs, power source, motors, and/or pumps used, the need for a separate transformer (e.g., to alter the incoming voltage and/or the voltage transmitted between components) can be obviated.

It should be understood that while FIG. 2 depicts eight high pressure pumps and associated electric motors, and four VFDs, independent from trailers or similar transport vehicles (e.g., frame-mounted on the ground or an operational platform or similar surface), in various embodiments, system components could remain in association with trailers or similar transport vehicles to facilitate mobility thereof.

FIG. 3 depicts a diagrammatic view of an embodiment of a system usable within the scope of the present disclosure, usable to perform fracturing operations on a formation associated with a wellhead. The diagram depicts a cleared zone (e.g., having a radius of about 30 meters) about the wellhead, outside of which the depicted system can be positioned. At the bottom of the diagram, a plurality of fracturing fluid storage vessels are shown (e.g., six water storage tanks; however any number and/or type of storage vessel can be used without departing from the scope of the present disclosure), in association with a proppant storage vessel (which can be representative of any number or type of proppant sources and/or containers). It should be understood that while the depicted system describes use of water storage tanks (e.g., containing water for use as a fracturing fluid), the depicted system can incorporate use of any fracturing fluid without departing from the scope of the present disclosure. Due to the close proximity of the depicted VFDs to the depicted high pressure pumps, the depicted configuration is contemplated to be of particular use with non-flammable fracturing fluids.

The fracturing fluid and proppant storage vessels are shown proximate to the low pressure manifold of the system, where the fracturing fluid and/or proppant can be injected (e.g., as a slurry). A plurality of high pressure pumps, each powered using an associated electric motor and each mounted on an associated trailer, is shown, the pumps being usable to pressurize the fracturing fluid and/or proppant (e.g., at the high pressure manifold of the system) prior to flowing the fracturing fluid and/or proppant to the wellhead (and subsequently into the wellbore to the formation). While the depicted diagram shows eight high pressure pumps and associated motors, it should be understood that any number of high pressure pumps can be used depending on the nature of the operation.

A plurality of Variable Frequency Drives (VFDs) is shown in association with the depicted high pressure pumps. Specifically, each trailer is shown having one VFD mounted thereon, adjacent to two high pressure pumps and associated motors. While FIG. 3 depicts four VFDs (each used in association with two high pressure pumps and associated electric motors), mounted on four trailers, it should be understood that any number of VFDs or similar devices, and any number of trailers, can be used depending on the nature and/or requirements of an operation and/or characteristics of equipment being used. In the depicted embodiment, four transport loads could be used to position each of the depicted pumps, motors, and VFDs, which is one half the number of loads required to deploy such a quantity of equipment using conventional configurations.

Due to the horsepower limitations of a typical high pressure pump, described previously, each VFD is shown in operative association with two high pressure pumps. As described above, in various embodiments, one or both pumps coupled with a VFD can include a breakaway or similar means for decoupling from the VFD, such that the entirety of the output from the VFD can be used to drive a single pump (e.g., at an enhanced rate), and/or to enable a second pump to be used as a backup/redundant pump in the case of a fault or failure of a first pump. Additionally or alternatively, two pumps associated with a single VFD can include different types of pumps, such that a desired type of pump can be selected for use (e.g., depending on operational conditions, wellbore conditions, types of equipment present/available, etc.).

The depicted VFDs are shown in communication with one or more power sources, which can include one or more generators, one or more power storage devices, one or more grid power sources, or combinations thereof. In an embodiment, the incoming power can include a medium voltage source (e.g., 4160 volts), allowing use of smaller and lighter conduits, less line loss, lower amperage, etc. Depending on the characteristics of the VFDs, power sources, motors, and/or pumps used, the need for a separate transformer (e.g., to alter the incoming voltage and/or the voltage transmitted between components) can be obviated.

It should be understood that while FIG. 3 depicts four mobile trailers, each trailer having two high pressure pumps and a single VFD mounted thereon, in various embodiments, system components could be removed from trailers (e.g., frame mounted on the ground or a similar operational platform) to reduce the footprint of the system and allow use of the trailers for other purposes while the system is deployed.

In the depicted embodiment, use of two high pressure pumps and a single VFD on a single trailer can enable the two pumps to be operated via the VFD using a single tie line. Using a reduced number of lines for the system in this manner enables the manifold trailer to be reduced in size (e.g., one half of its conventional length), reducing the footprint of the system and facilitating transport thereof.

While various embodiments usable within the scope of the present disclosure have been described with emphasis, it should be understood that within the scope of the appended claims, the present invention can be practiced other than as specifically de scribed herein.

Claims

1. A system for stimulating a formation, the system comprising: a source of fracturing fluid in communication with the formation;a source of proppant in communication with the formation;a power source;a plurality of variable frequency drives in communication with the power source; andat least two high pressure pumps in communication with each of said variable frequency drives,wherein a variable frequency drive receives power from the power source and actuates at least two electric motors associated with said at least two high pressure pumps, and wherein said at least two high pressure pumps pressurize fracturing fluid, proppant, or combinations thereof for flowing said fracturing fluid, proppant, or combinations thereof into the formation.

2. The system of claim 1, wherein the power source comprises a medium voltage power source.

3. The system of claim 1, wherein the plurality of variable frequency drives comprises four variable frequency drives.

4. The system of claim 3, wherein said four variable frequency drives are transportable on a single trailer.

5. The system of claim 3, wherein said four variable frequency drives are in association with at least eight high pressure pumps, and wherein said at least eight high pressure pumps are transportable on three or fewer trailers.

6. The system of claim 1, wherein the plurality of variable frequency drives are spaced a distance from said at least two high pressure pumps sufficient to minimize ignition of fracturing fluid pressurized by said at least two high pressure pumps by said plurality of variable frequency drives.

7. The system of claim 6, wherein the distance comprises at least 30 meters.

8. The system of claim 6, wherein the source of fracturing fluid comprises propane.

9. The system of claim 1, further comprising a wellhead in association with the formation, wherein said at least two high pressure pumps are spaced a distance from the wellhead sufficient to minimize ignition of fracturing fluid pressurized by said at least two high pressure pumps.

10. The system of claim 9, wherein the distance comprise at least 30 meters.

11. A system for stimulating a formation, the system comprising: a source of fracturing fluid in communication with the formation;a source of proppant in communication with the formation;at least one power source;at least one mobile platform comprising a variable frequency drive and at least two high pressure pumps mounted thereon, wherein said at least two high pressure pumps are coupled to the variable frequency drive,wherein the variable frequency drive receives power from said at least one power source and actuates at least two electric motors associated with said at least two high pressure pumps, and wherein said at least two high pressure pumps pressurize fracturing fluid, proppant, or combinations thereof for flowing said fracturing fluid, proppant, or combinations thereof into the formation.

12. The system of claim 11, wherein the power source comprises a medium voltage power source.

13. The system of claim 11, wherein said at least one mobile platform comprises four mobile platforms, each of said mobile platforms having a variable frequency drive and at least two high pressure pumps mounted thereon.

14. The system of claim 11, wherein said at least two high pressure pumps engage the variable frequency drive via a single tie line.

15. The system of claim 11, further comprising a wellhead in association with the formation, wherein said at least two high pressure pumps are spaced a distance from the wellhead sufficient to minimize ignition of fracturing fluid pressurized by said at least two high pressure pumps.

16. The system of claim 15, wherein the distance comprise at least 30 meters.

17. The system of claim 11, wherein at least one of said high pressure pumps comprises a breakway feature adapted to decouple said at least one of said high pressure pumps from the variable frequency drive to enable substantially all output from the variable frequency drive to be provided to at least one other of said high pressure pumps.

18. The system of claim 17, wherein said at least two high pressure pumps comprise a first high pressure pump of a first type and a second high pressure pump of a second type different than the first type.

19. The system of claim 18, wherein the first type comprises a qunitplex pump and the second type comprises a triplex pump.

20. The system of claim 18, wherein the first type, the second type, or combinations thereof is selectable to reduce harmonic resonance, vibration, or combinations thereof generated by said at least two high pressure pumps, the variable frequency drive, or combinations thereof.