In mixing and pumping cement for the oil drilling and production industry, centrifugal pumps are used for low-pressure pumping of cement slurry. These pumps may be direct driven by using a driveline that runs from a transmission mounted or engine mounted power takeoff to the pump shaft. In other applications, the pumps are driven electrically by mounting an electric motor directly to the pump frame, or the pumps may be driven hydraulically using a hydraulic pump mounted to a power takeoff that transmits power to a hydraulic motor mounted directly to the centrifugal pump.
Each mode of power transmission has advantages and disadvantages. Direct drive systems benefit from high efficiency, simplicity and relatively low weight, although driveline angle restrictions limit where the driven loads may be placed. Electric drive systems provide smooth, quiet operation but such systems are heavy and require a source of substantial electrical power. Hydraulic drive systems are lighter than electric drive systems and provide greater flexibility in load placement and orientation, but they can be vulnerable to oil contamination and other potential problems.
A conventional oilfield cementing unit with fail-safe capability typically employs full redundancy of all components important to operation. For example, if a prime mover, two centrifugal pumps and a triplex pump are required to mix and pump cement in a given cementing unit design, then the conventional redundant, fail-safe system employs two prime movers, four centrifugal pumps, and two triplex pumps. Commonly, each of the centrifugal pumps is direct-driven from a power takeoff and each power takeoff is dedicated to the particular centrifugal pump. The fully redundant system may be overly conservative because it is unlikely that of two operating centrifugal pumps, both would fail within the same job and thereby require both backup pumps to be utilized. Furthermore, the fully redundant system may present new reliability risks that are not present in a non-redundant system due to, for example, damage to or plugging of the additional piping required to plumb the backup pumps into the cementing system.
Driveline systems are known in which a power takeoff drives exactly one output without the ability to exchange pump loads between power sources. The placement and orientation of the pumps are limited by the driveline angle, and the path of the driveline limits the options for placement of major components. Sometimes, right-angle gearbox systems are employed in conjunction with drivelines to increase the number of locations in which the pumps may be placed. However, the additional gearbox adds a failure point, reduces the overall drivetrain reliability and efficiency, and creates an additional need for a gearbox lubrication and cooling system, thus increasing system complexity.
Additionally, closed-loop systems have been employed between a power source and a hydraulic pump. However, existing closed-loop systems do not work well in redundant systems because of the lack of system isolation and because of the additional components and complexity of such systems. In some applications, close-coupled hydraulic systems are employed in which a closed-loop hydraulic pump and a motor are mounted together both mechanically and hydraulically. However, such approaches provide no option for switching between different loads. Open-loop hydraulic systems also have been employed in various applications, however open-loop systems typically require hydraulic reservoirs that are significantly larger than those for closed-loop hydraulic systems.
In general, the present invention provides a system and methodology for powering a variety of oilfield or well-related applications, such as well cementing applications. The system and methodology employ a plurality of prime movers to drive a plurality of loads. The number of loads may be greater than the number of prime movers; however the prime movers may be selectively coupled with different load configurations. The plurality of prime movers and loads are coupled with a hydraulic system that maintains a separate, sealed hydraulic system associated with each prime mover. The hydraulic system also enables the load configuration driven by each prime mover to be changed without losing the benefit of a separate, sealed hydraulic system associated with that specific prime mover.
Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
Embodiments of a system and method for delivering power to a plurality of loads utilized in an oilfield or well-related application are disclosed. In an embodiment, the system is a configurable power delivery system designed to supply power for an oilfield cementing unit. However, the system and methodology enables use of a configurable system to supply power to a variety of loads.
In one example, the power delivery system comprises a plurality, e.g. two, prime movers that each have a separate, sealed hydraulic system. The prime movers supply power to a plurality of loads, e.g. three loads. In the oilfield cementing application, the plurality of loads may comprise a plurality of pumps, such as centrifugal pumps designed to deliver cement slurry downhole. Other than the oilfield cementing application, the present system and methodology may be used in a variety of closed-loop hydraulic systems employing two or more prime movers and two or more loads with the capability of exchanging which loads are driven by each prime mover while maintaining separate, sealed hydraulic systems associated with each prime mover. The prime movers may be powered via a variety of sources for mechanical work, including diesel engines, gasoline engines, electric motors, and other suitable sources. Similarly, the loads may comprise a variety of load types, including fluid pumps, actuators, hydraulically driven components, or other loads requiring power.
Referring generally to
The oilfield cementing unit 34 comprises a configurable power delivery system 38 to deliver the slurry 36 downhole while providing easy, selective reconfiguration of the power delivery system components, as described in greater detail below. The ability to selectively reconfigure the components of system 38 provides an efficient redundancy of components that enables continuation of the cementing operation regardless of the failure of individual components. However, the redundancy is provided without duplicating all of the major system components. It should again be noted that the configurable power delivery system may be used in a variety of well applications and is not limited to the oilfield cementing application described above. The configurable power delivery system may be utilized with other system including wellsite surface equipment such as, but not limited to, fracturing pumps/systems, liquid additive pumps/system, or other oilfield service units. The configurable power delivery system may be utilized in conjunction with the surface equipment to perform at least one well services operation including, but not limited to, a fracturing operation, an acid treatment operation, a cementing operation, a well completion operation, a sand control operation, a coiled tubing operation, and combinations thereof.
Referring generally to
In the example illustrated, the loads 44, 46, 48 may comprise centrifugal pumps 62, 64, 66, respectively, for pumping cement slurry or other substances. However, the loads may comprise a variety of other components for other applications. In the present embodiment, the variable displacement hydraulic pumps are operatively coupled with the respective loads 44, 46, 48 in a variety of configurations for various operational scenarios. In a first normal operating configuration, for example, load 46 operates in combination with either load 44 or load 48 and the other of load 44 and load 48 serves as a backup. For example, initial operation may utilize load 46 in combination with load 44, in which load 46 is sized to require two variable displacement hydraulic pumps, e.g. pumps 52, 54, to operate at full power. The load 48 is then used as a backup load that can replace either load 46 or load 44. The illustrated system maintains fail-safe operation, while minimizing the number of driven loads and reducing the number of potential failure points in the overall system. In an embodiment, the loads, 44, 46, 48 may be coupled to hydraulic motors for receiving hydraulic power from the variable displacement hydraulic pumps 52, 54, 58, or 60 for driving the loads, as will be appreciated by those skilled in the art.
In the first operational scenario illustrated in
Referring generally to
Sometimes the servicing of components or component failure may require selectively changing configurable power delivery system 38 to a backup configuration. In
However, a variety of backup configurations are available and may be utilized. In
The four operational scenarios/configurations discussed above with reference to
The first normal operational configuration also is illustrated in
In embodiments in which pumps 52, 54, 58 and 60 are designed as variable displacement hydraulic pumps, the loads 44, 46, 48 may be of different sizes. However, if the loads are different sizes, variable displacement hydraulic pumps 52 and 58 are designed with sufficiently large capacity to drive load 44. Similarly, pumps 54 and 60 are designed with sufficiently large capacity to drive load 48. The sum of the flows produced by pump 52 and pump 54 also should be large enough to drive load 46. Additionally, the sum of the flows produced by pump 58 and pump 60 should be large enough to drive load 46.
Referring generally to
The binary signal may be a hydraulic signal, pneumatic signal, mechanical signal, electrical signal or other suitable signal. In some applications, the conversion of power delivery system 38 between configurations, such as between the first normal configuration and the second normal configuration discussed above, can be achieved with a single control valve 94 that controls the actuation of valve switches 92 via flow of fluid. The control valve 94 may comprise a solenoid valve and may be controlled mechanically, hydraulically, electrically, or via another suitable medium. The arrangement of valve switches 92 and other components within single valve 90 enables maintenance of separate, hydraulic systems associated with each prime mover 40 and 42 regardless of the configuration of power delivery system 38. This maintenance of separate, hydraulic systems isolates the prime movers from each other such that the working fluids do not mix and cross-contamination does not occur. The conversion of the power delivery system 38 may be achieved by manual or hand operation of valves associated with such a conversion such as valves 90, 92, and/or 94, as will be appreciated by those skilled in the art.
In the embodiment illustrated in
When control valve 94 is energized/opened, the binary signal is provided to the valve switches 92 which transition to a second state, as illustrated in
In both states/configurations illustrated in
Furthermore, the design of configurable hydraulic system 88 also enables easy and automatic transition to the backup configurations of power delivery system 38, as discussed above and illustrated schematically in
Well system 20 may be constructed in a variety of configurations for use in many environments and applications. For example, power delivery system 38 may be designed to drive/supply power to well site surface equipment for performing well services operations, such as oilfield cementing units. However, the power delivery system 38 also may be designed to provide an automatically reconfigurable system able to supply power for operating many other types of loads including but not limited to, fracturing pumps/systems, liquid additive pumps/system, or other oilfield service units. Accordingly, the design of the prime movers and the types of loads driven can be adjusted to accommodate the particular operation to be performed. Regardless, the configurable hydraulic system 88 enables the existing combination of prime mover components and specific loads to be reconfigured while maintaining separate, sealed hydraulic systems for driving the loads. In many applications, the variable displacement hydraulic pumps enable desirable delivery of power to a variety of loads; however other pumps and devices also can be used to direct power to the loads.
Similarly, the configurable hydraulic system 88 may be adjusted to accommodate specific applications. For example, the valve switches may be formed from a variety of components for use in a single valve system or another suitable system. The configurable hydraulic system also may be designed to accommodate different numbers of prime movers and different numbers of loads. In many applications, the number of loads is at least one greater than the number of prime movers, however a variety of prime mover and load combinations may be employed. The configurable hydraulic system also may be designed to respond to a variety of signal inputs, including binary signals, and/or other types of signals that initiate automatic conversion of the configurable hydraulic system from one state/configuration to another. The configurable hydraulic system advantageously provides redundancy at the prime mover level (such as in case of prime mover failure or the like) by decoupling the functioning of one hydraulic system from the other.
Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.
The present document is based on and claims priority to U.S. Provisional Application Ser. No. 61/195,120, filed Oct. 3, 2008.
Number | Date | Country | |
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61195120 | Oct 2008 | US |