LINEAR ELECTRIC MOTOR FOR AN OILFIELD PUMP
An oilfield pump employing a linear electric motor. The linear electric motor replaces a conventional crankshaft or hydraulic techniques for driving a plunger of the pump. This may reduce the number of equipment parts and amount of maintenance expenses associated with the operation of oilfield pumps. Furthermore, the use of a linear electric motor may also increase the precision and control over the fluid delivery provided by the pump assembly.
Embodiments described relate to oilfield pumps for delivering a variety of oilfield fluids to a well at an oilfield. In particular, embodiments of oilfield pumps employing a linear electric motor (LEM) are described. The presence of a LEM in place of crankshaft or hydraulic driving techniques may reduce the number of equipment parts and therefore maintenance expenses dedicated to a pump assembly at an oilfield. The presence of an LEM may also increase the precision and control over the fluid delivery provided by the pump assembly.
BACKGROUND OF THE RELATED ARTDrilling, completing, and operating hydrocarbon wells involves the employment of a variety of large scale equipment. Thus, well operations may be inherently expensive in terms of both capital equipment expenditures and equipment maintenance. Furthermore, in many circumstances, conventional large scale equipment tends to provide output in a fairly imprecise manner, no matter the amount of expenditures incurred.
As an example of large scale oilfield equipment, a host of crankshaft driven positive displacement pumps are often employed at an oilfield. A positive displacement pump may be a fairly massive piece of equipment with a plunger driven by a crankshaft toward and away from a chamber in order to dramatically effect a high or low pressure on the chamber. This makes it a good choice for high pressure applications. Indeed, where fluid pressure exceeding a few thousand pounds per square inch (PSI) is to be generated, a crankshaft driven positive displacement pump is generally employed. Crankshaft driven positive displacement pumps may be employed in large scale operations such as cementing, coiled tubing operations, water jet cutting, or hydraulic fracturing of underground rock to name a few. Hydraulic fracturing of underground rock, for example, often requires an abrasive containing fluid to be pumped at pressures of 10,000 to 15,000 PSI in order to create a “fracture” in the underground rock in order to facilitate the release of oil and gas from rock pores for extraction. Such pressures and large scale applications are readily satisfied by the noted crankshaft driven positive displacement pumps.
As alluded to above, a crankshaft driven positive displacement pump may include a variety of equipment parts that must be maintained to ensure the continued effectiveness of the oilfield operation involved. Such equipment parts may include an associated engine, transmission, crankshaft, driveline and other parts, operating at between about 1,500 Hp and about 4,000 Hp. Unfortunately, with such a large piece of equipment having numerous equipment parts playing a role in the mechanics of the pump, it may be difficult to attain a reliably precise output level from the pump. Techniques of compensating for such imprecision may be employed. For example, crankshaft driven pump operations may take place at higher output levels and for longer durations than necessary in order ensure that the minimum output levels are provided for a given operation. However, compensating for the imprecise output of such pumps in this manner results in wasted pump output and leads to premature wear of pump parts.
In order to address the inherent imprecision of crankshaft driven pump output, hydraulically driven pumps may be substituted for crankshaft driven pumps at the oilfield where the oilfield application allows. The hydraulic nature of such pumps may provide a degree of precision to pump output that is not available from the above noted crankshaft driven pumps. For example, rather than employing a large crankshaft to rotably actuate linear motion of a plunger, a hydraulically driven pump may include a plunger that is driven by more tightly controllable hydraulics that are directed at the plunger. Thus, the output of the hydraulically driven pump may be more precisely controlled.
Unfortunately, the employment of a hydraulically driven pump may dramatically increase the variety of equipment and parts employed in the pumping application. That is, in the case of a crankshaft driven pump a prime mover may be coupled to a transmission that directs the movement of the noted crankshaft. However, in the case of a hydraulically driven pump, the prime mover may be coupled to multiple hydraulic pumps that are employed to drive the hydraulically driven pump or intensifier. The additional pumps may be equipped with their own hydraulic lines therebetween. Furthermore, all of this equipment and parts such as the hydraulic lines and additional valving need to be maintained in order to realize the benefit of improved output precision that may be afforded by use of hydraulically driven pumps. That is, in order to attain the improved output precision, added expense in terms of capital equipment expenditures and equipment maintenance may be incurred.
SUMMARYIn one embodiment, the present invention is an oilfield pump assembly that is provided at an oilfield and includes a plunger for reciprocating relative to a chamber. The reciprocating may be employed for directing an oilfield fluid from the pump assembly and to a well at the oilfield. The plunger may be coupled to a linear electric motor in order to power the reciprocating.
Embodiments are described with reference to certain linear electric motor (LEM) pump assemblies, particularly for cementing operations at an oilfield. However, other operations may be addressed at the oilfield employing LEM pump assembly embodiments described herein. For example, LEM pump assemblies described herein may be employed in fracturing, drilling, dosing, and other fluid delivery operations at an oilfield. Regardless, embodiments described herein include the use of an LEM to drive an oilfield pumping assembly, as opposed to crankshaft or hydraulic driving techniques, thereby potentially reducing equipment parts and maintenance expenses and increasing the precision and control over the fluid delivery as compared to conventional crankshaft or hydraulic driven pump assemblies.
Referring now to
In the embodiment shown, the pump assemblies 100, 200 are to be employed at an oilfield 101 for a cementing operation. While only a single pump assembly 100, 200 is shown in each of
Continuing with reference to
Cementing as described above may be achieved with the pump assembly 100, 200 operating at between about 200 Hp and about 800 Hp, preferably at about 300 Hp. In this manner, between about 1,500 PSI and about 15,000 PSI may be generated for driving the cement slurry 170 under pressure as noted above. As also indicated, cementing of this nature may be achieved through employment of multiple pump assemblies 100, 200 coupled together through a common delivery manifold that is ultimately coupled to the wellhead 160 (e.g. through a transfer line 150). In this manner, the cement slurry 170 may be driven from the pump assembly 100, 200
Continuing now with particular reference to the prior art crankshaft pump assembly 100 of
As shown in
Referring now to
Continuing with reference to
Referring now to
Continuing with reference to
As shown in
Regardless of the particular stator 400 and plunger rear 435 configurations employed, the stator 400 may be effectuated in a poly-phase manner (e.g. from magnet to magnet) in order to drive the linear movement of the plunger rear 435 in one direction and then back again. This reciprocating movement of the plunger 450 is achieved in a manner that includes substantially no friction between the plunger rear 435 and the wall of the cylinder 425. That is, the magnetic nature of the interface between the plunger rear 435 and the stator 400 may be self-centering such that the plunger rear 435 is kept out of contact with the wall of cylinder 425 during its reciprocation.
In addition to the self-centered friction free nature of the reciprocation, the stator 400 is able to drive the movement of the plunger 450 from its rear 435 in a fairly precise manner. That is, as alluded to above, the power supplied to the stator 400 is direct and does not require translation through other equipment parts in order to effect the fluid end 327. Rather, the power is transferred directly through precisely controllable magnets of the stator 400 and to the plunger rear 435 as noted herein. This degree of control also allows for a greater range of achievable plunger reciprocation speeds. For example, the LEM pump assembly 300 may achieve much lower and higher controlled speeds than those available for a conventional crankshaft driven pump 125 with larger less precisely controllable power transfer equipment parts.
Continuing with reference to
As described above, the plunger 450 also effects a low pressure on the chamber 475. That is, as the plunger 450 retreats away from an advanced discharge position near the chamber 475, the pressure therein will decrease. As the pressure within the chamber 475 decreases, the discharge valve 480 will close returning the chamber 475 to a sealed state. As the plunger 450 continues to move away from the chamber 475 the pressure therein will continue to drop, and eventually a low or negative pressure will be achieved within the chamber 475. Similar to the action of the discharge valve 485 described above, the pressure decrease will eventually be enough to effect an opening of an intake valve 480. Thus, this movement of the plunger 450 is often referred to as the intake stroke. The opening of the intake valve 155 allows the uptake of fluid into the chamber 475 from an intake channel 477 adjacent thereto. The amount of pressure required to open the intake valve 480 as described may be determined by an intake mechanism 481, such as spring, which keeps the intake valve 480 in a closed position until the requisite low pressure is achieved in the chamber 475.
The above described mechanics of the LEM pump assembly 300 may be employed for delivery of a variety of fluids under pressure at an oilfield 101 such as that of
In such a configuration an LEM pump assembly according to the present invention includes multiple plungers similar to the plunger 450 of
In addition, the mechanics of an LEM assembly according to the present invention, such as assemblies 200 and 300, avail themselves to stacking or multiple output configurations for increasing the power, pressure, or total output thereof.
Continuing now with reference to
Referring to
Increasing the pressurization capacity, for example, by employment of the LEM pump assembly 500 of
As shown in
An increase in the amount of output per plunger stroke as noted above is an improvement in terms of efficiency. Additionally, increased output in this manner may be of particular benefit to certain applications at an oilfield 101 (see
The above described embodiments provide improved control and precision over a delivery profile of a fluid provided to an oilfield by way of an oilfield pump assembly. This is provided without reliance on a hydraulically driven pump. Therefore an increase in equipment parts such as hydraulic lines and additional valving may be avoided, thereby reducing maintenance expenses.
The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. For example, embodiments described herein are directed primarily at cementing, fracturing, and drilling operations wherein a linear electric motor is driven with between about 150 KW and about 600 KW. However, other operations such as dosing may take advantage of oilfield pump assemblies described herein that are driven with between about 5 KW and about 10 KW. Furthermore, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.
Claims
1. An oilfield pump assembly comprising:
- a plunger for reciprocating relative to a chamber to direct a fluid therefrom; and
- a linear electrical motor coupled to said plunger for the reciprocating.
2. The oilfield pump assembly of claim 1 further comprising a fluid end to house the chamber, the chamber coupled to a cylinder of the linear electric motor to accommodate a rear of said plunger.
3. The oilfield pump assembly of claim 2 wherein said linear electric motor comprises a stator adjacent the cylinder to electromagnetically actuate linear movement of said rear.
4. The oilfield pump assembly of claim 3 wherein said stator comprises an array of magnets and cooling fins.
5. The oilfield pump assembly of claim 3 wherein said rear comprises:
- a ferrous core; and
- an outer layer of bands selected from a group consisting of copper and iron.
6. The oilfield pump assembly of claim 3 wherein said movement is substantially frictionless.
7. The oilfield pump assembly of claim 1 wherein the reciprocating is to direct the fluid to a well at an oilfield for a well services operation thereat.
8. The oilfield pump assembly of claim 7 wherein the well services operation is one of drilling, fracturing, cementing, and dosing.
9. The oilfield pump assembly of claim 7 wherein the oilfield pump assembly is a first oilfield pump assembly coupled to the well, the well coupled to a second oilfield pump assembly for obtaining fluid therefrom.
10. The oilfield pump assembly of claim 2 wherein said fluid end is one of a triplex configuration and a singular configuration.
11. An oilfield pump assembly comprising:
- a plunger for reciprocating relative to a chamber to direct a fluid therefrom;
- a primary linear electric motor coupled to said plunger for the reciprocating; and
- a secondary linear electric motor coupled to said primary linear electric motor for increased power of the reciprocating.
12. The oilfield pump assembly of claim 11 wherein the increased power of the reciprocating is to direct the fluid under a pressure of more than about 15,000 PSI.
13. The oilfield pump assembly of claim 12 wherein the reciprocating is to direct the fluid to a well for a fracturing operation thereat.
14. An oilfield pump assembly comprising:
- a primary pump fluid end;
- a secondary pump fluid end;
- a plunger for reciprocating between a chamber of said primary pump fluid end and a chamber of said secondary pump fluid end to direct fluid from the chambers; and
- a linear electric motor disposed between said primary pump fluid end and said secondary pump fluid end and coupled to said plunger for the reciprocating.
15. The oilfield pump assembly of claim 14 wherein the reciprocating is to direct the fluid to a well for a drilling operation thereat.
16. A method of performing a well services operation in a well at an oilfield, the method comprising:
- powering a linear electric motor with an electric power source at the oilfield, the linear electric motor coupled to a plunger; and
- employing the linear electric motor to reciprocate the plunger relative to a chamber to direct a well services fluid therefrom and to the well.
17. The method of claim 16, wherein the well services operation is one of drilling, fracturing, cementing, and dosing.
18. The method of claim 16, wherein the well services operation comprises cementing a borehole casing, and wherein the well services fluid comprises a cement slurry.
19. The method of claim 18 further comprising:
- driving the cement slurry into the borehole casing through a cementing pipe terminating within the borehole casing; and
- forcing the cement slurry into a space between the borehole casing and a wall of the well for stabilization of the borehole casing.
20. The method of claim 19 wherein said driving and said forcing occur under pressurization of between about 1,500 PSI and about 15,000 PSI.
21. The method of claim 18 wherein said powering delivers between about 150 KW and about 600 KW to the linear electric motor.
22. The method of claim 18 wherein the linear electric motor operates at between about 200 Hp and about 800 Hp.
23. The method of claim 18 wherein the linear electric motor operates in an electromagnetic polyphase manner.
Type: Application
Filed: Apr 26, 2007
Publication Date: Oct 30, 2008
Inventor: Brian Ochoa (Houston, TX)
Application Number: 11/740,750
International Classification: E21B 43/00 (20060101);