Patent Application
20090081034
The present invention relates generally to a method of making oilfield equipment, such as a fluid end for a reciprocating pump out, of a thin layer of a base material and reinforcing the base material with a composite material that supports the stresses incurred by the fluid end during a pump cycle. Preferably, the base material is less subject to abrasion, corrosion, erosion and/or wet fatigue than conventional fluid end materials such as carbon steel.
The fluid end of a reciprocating pump, such as a triplex pump, is the portion of the pump where a fluid is drawn in via a suction valve. A plunger then compresses the fluid and pushes it, with high pressure, through a release valve. These valves open when the pressure on the bottom side thereof is higher than the pressure on the top side thereof.
Fluid ends are often a weak point of reciprocating pumps, as they break after a certain amount of cycle time due to wet fatigue pressure cycles. In addition, it is desirable to limit the weight of fluid ends when they are used, for example, in applications such as oil well fracturing operations. In such situations the load capacity for transporting such oil well fracturing systems is limited. Accordingly, a need exits for an improved oilfield equipment, such as reciprocating pump fluid ends, that are reliable and/or light in weight.
In one embodiment, the present invention includes oilfield equipment composed of a base material which is reinforced with a composite material. In one embodiment, the base material is less subject to abrasion, corrosion, erosion and/or wet fatigue than the material of conventional oilfield equipment, such as carbon steel. In one embodiment, the base material is composed of a thin layer, which is reinforced on its outer surface with a composite material. The use of the composite material increases the stress that can be withstood by the base material, while simultaneously reducing the weight of the oilfield equipment.
In an embodiment where the oilfield equipment is a reciprocating pump fluid end, only the base material is in contact with the fluid pumped by the reciprocating pump. Although such a fluid end may be used in any appropriate application, in one embodiment this fluid end is used on a reciprocating pump in an oil well fracturing operation.
The embodiment of
At some point, the pressure increase will be enough to effect an opening of a discharge valve 118 to allow the release of fluid from the chamber 116, through a discharge channel 128, and out of the pump 102. The amount of pressure required to open the discharge valve 118 as described may be determined by a discharge mechanism 120 such as valve spring which keeps the discharge valve 118 in a closed position until the requisite pressure is achieved in the chamber 116.
The plunger 114 may also effect a low pressure on the chamber 116. That is, as the plunger 114 retreats away from its advanced discharge position near the chamber 116, the pressure therein will decrease. As the pressure within the chamber 116 decreases, the discharge valve 118 will close, returning the chamber 116 to a sealed state. As the plunger 114 continues to move away from the chamber 116, the pressure therein will continue to drop, and eventually a low or negative pressure will be achieved within the chamber 116.
Similar to the action of the discharge valve 118 described above, the pressure decrease will eventually be enough to effect an opening of an intake valve 122. The opening of the intake valve 122 allows the uptake of fluid into the chamber 116 from a fluid intake channel 124 adjacent thereto. The amount of pressure required to open the intake valve 122 may be determined by an intake mechanism 126, such as spring which keeps the intake valve 122 in a closed position until the requisite low pressure is achieved in the chamber 116.
As described above, a reciprocating or cycling motion of the plunger 114 toward and away from the chamber 116 within the pump 102 controls pressure therein. The valves 118,122 respond accordingly in order to dispense fluid from the chamber 116, through the discharge channel 128, and eventually out of the pump 102 at high pressure. The discharged fluid is then replaced with fluid from within the fluid intake channel 124.
Note that although only one plunger 114 is shown in
As mentioned above, the continued cycling of the plungers 114 into and out of the fluid end 104 of the pump 102 and the accompanied fluctuations between positive and negative pressure experienced by the inner surfaces of the fluid end 104 makes the fluid end 104 susceptible to failure.
As such, in one embodiment of the present invention, the inner surface 130 of the fluid end 104 is manufactured from a base material 132 that is less subject to abrasion, corrosion, erosion and/or wet fatigue than typical fluid end materials, such as carbon steel. Exemplary materials for such a base material 132 include inconel, incoloy, titanium and stainless steel, among other appropriate materials.
However, such base materials 132 are often expensive. As such, in one embodiment the inner surface 130 of the fluid end 104 is manufactured from a thin layer of the base material 132, and reinforced by a composite material 134, which forms the outer surface of the fluid end 104. The composite material 134 enables the fluid end 104 to support all the cyclical stresses that it will experience during operation of the pump 102 in which the fluid end 104 is used.
In one embodiment, the composite material 134 is composed of fibers and a matrix. The fibers may include, for example, glass fibers, carbon fibers, Kevlar fibers, metal fibers or any other product that would provide mechanical strength to the base material 132 of the fluid end 104, such as metal wires. The matrix may include epoxy, Peek, or another similar compound, such as any of those from the same family as epoxy or Peek, i.e. a thermoplastic material. Alternatively, the matrix may include a thermoset material.
The matrix, or resin holds the fiber of the composite material 134 in place on the base material 132 of the fluid end 104. In addition, the matrix may add mechanical strength to the base material 132 of the fluid end 104. However, it is the fiber itself that is primarily relied upon for improving the stress resistance of the base material 132 of the fluid end 104. In one embodiment, fibers that are stronger than metal in one direction are positioned adequately to support the load cycle of the fluid end 104.
This configuration not only improves the fluid end's 104 resistance to abrasion, corrosion, erosion and/or wet fatigue, but it also has the added benefit of reducing the overall weight of the fluid end 104, in embodiments where the composite material 134 weighs less than carbon steel material and/or the base material.
In another embodiment, the inner surface 130 of the fluid end 104 may be composed of a carbon steel material which is reinforced by the above described composite material 134 to both increase the overall stress resistance of the fluid end 104 and to decrease the overall weight of the fluid end 104 over typical fluid ends of the prior art which are composed entirely of carbon steel. In an alternative embodiment, the inner surface 130 of the fluid end 104 may be composed of a polymeric material which is reinforced by the composite material 134.
In one embodiment the inner surface 130 of the fluid end 104 is composed of either the base material 132, a polymeric material, or carbon steel, and has a material thickness of approximately ¼″ or ½″. This layer may be thicker with the tradeoff being that the weight and expense of the fluid end 104 increase with increasing thickness to the inner surface 130 of the fluid end 104.
Autofrettage of the fluid end 104, a process often performed on reciprocating pump fluid ends, may be performed. However, even without autofrettage, the implementation of the fibers of the composite material 134 to the fluid end 104 will create compressive strength to the interior section of the fluid end 104.
It is important to note that although fluid ends of reciprocating pump are discussed above, the above described base material 132 with composite material 134 reinforcement may be used for any pressure containing part, or any part that experiences a pressure cycle, and also for parts that need to be light in weight.
For example,
In addition, in another embodiment of the invention, a cementing head may be composed of any of the material combinations described above. Such an cementing head may be used in an oilfield cementing operation.
For example, in the depicted embodiment, as shown in
As shown in
Although,
Also, a fluid end, or any of the other oilfield equipment described above according to any of the embodiments of the present invention, may include integrated measurement means inside the composite material 134,334 to measure temperature distribution, stress distribution, fluid density, fluid flow rate, electrical conductivity, pH and/or acceleration, among other appropriate properties of the oilfield equipment and/or the fluid therein. These measurement means could be part of the fiber itself, or otherwise added inside the composite material 134,334. In exemplary embodiments, the measurement means may include a sensor, a densitometers, a flow meter, such as an electromagnetic high pressure flow meter, or any combination thereof, among other appropriate measurement means.
The preceding description has been presented with reference to presently preferred embodiments of the invention. Persons skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, and scope of this invention. Accordingly, 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.
This application claims priority to and is a Continuation-in-Part of U.S. patent application Ser. No. 11/859,830, filed on Sep. 24, 2007, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11859830 | Sep 2007 | US |
| Child | 11967327 | US |
