Valve and seat assembly for a high pressure pump

An apparatus can include a housing, a plunger configured to reciprocate along an axis within the housing, and an internal fluid chamber disposed in the housing. A valve, having a valve base and a deformable seal, can also be included in the apparatus. The apparatus can further include a seat having an aperture therein. The valve is configured to move into and out of contact with the seat when the plunger reciprocates within the housing, based upon a fluid pressure in the internal flow chamber. In addition, an outer diameter of the deformable seal of the valve is less than an outer diameter of the seat.

BACKGROUND

Field

The present invention relates to a high pressure pump valve assembly, for use in high pressure applications such as hydraulic fracturing. In particular, the invention relates to the design and composition of intake and discharge valve assemblies.

Description of the Related Art

The use of high pressure pumps for a variety of different applications is well known in the industry. Some of the most common applications include industrial cleaning, water jet cutting, hydroforming, as well as a wide range of hydraulic applications. Because the components of these pumps are subject to high levels of pressure, they require continuous upkeep, which is both expensive and time consuming. One of the most popular applications of high pressure pumps is in hydraulic fracturing.

Given the ever increasing demand for affordable oil and natural gas, many alternatives to traditional oil drilling have developed over the years. One alternative, which has seen tremendous growth over the past decade, is hydraulic fracturing. Hydraulic fracturing is the process of drilling vertically into a targeted shell area, and then proceeding to drill horizontally across that shell. The shell formation is then fractured, generally with the use of explosives, and fracturing fluid, which is generally a mixture of water, sand or proppant, as well as other additives, is pumped into these fractures. The fracturing fluid helps to expand the initial fractures created in the shell. Once the fracturing fluid is pumped out of the wellbore, natural gas or oil begins to flow through the created cracks into the wellbore, at which point the gas or oil is extracted.

During drilling, a pressurized drilling solution, known as mud, composed of water and sand, is fed to the drill head in order to prevent the drill head from overheating and to provide proper lubrication. Another function of the mud is that it is used to help remove cuttings from the drilling wellbore. Throughout the drilling process, mud, cuttings, and the previously mentioned fracturing fluid are moved up and out of the wellbore. A high pressure hydraulic fracturing pump is used to control the discharge of these substances from the wellbore.

High pressure pumps utilize both intake and discharge valves. These valves are subjected to high pressures from both the pump itself and in certain applications fluid from a wellbore. This pressure causes the valves to have a very short life span, typically between 10 to 30 hours. As such, these valves have to frequently be replaced. Replacing these valves, however, is a cumbersome undertaking. One must first take apart the pump, in order to gain access to the valves, and then the entire valve assembly has to be removed and replaced with specialty tooling.

A typical valve assembly contains a seat and a valve. The function of the valve assembly is to allow the fluid to flow through it in one direction, and prevent the fluid from flowing through it in the opposite direction. The seat is traditionally a metal body that is pressed firmly into the fluid end housing to create a seal. Fluid enters through the first end of the seat, and then reaches the valve. Once a certain pressure differential is reached, the valve opens, a spring disposed above the valve compresses, and fluid moves past the valve. When the pressure on one side of the valve is equal to the pressure on the second side, the spring will start to close the valve. When the pressure on the top of the valve is greater than that on the bottom, the valve is pushed against the seat in order prevent the fluid from flowing in that direction. Due to the high pressures involved in this application, the valve generates high impact forces on the seat which causes both the seat and the valve to become warped and damaged within a short period of time.

The valve and the seat are deformed in such a way that they can no longer efficiently effectuate the desired flow of the fluid into and out of the pump. The high pressure causes the valve to be pushed against the seat, and in turn creates a high impact force which deforms the metal of the valve and of the seat. This causes the deformable seal of the valve to compress in such a way that is beyond its capabilities. This also has the effect of allowing the edge of the deformable seal to extend beyond the outer edge of the seat, which causes the deformable seal to crack. As the metal of the valve and seat wear down, the deformable seal is required to compress even further, which quickly escalates the rate of failure of the valve assembly. These effects are exacerbated by the fact that a grainy fluid is flowing through the intake and discharge valves and can become crushed and lodged between the surfaces.

As such, the valve and the seat need to be replaced at a high frequency. This replacement is a cumbersome, time-consuming, expensive process. The seat is pressed into the fluid end housing with sufficient force to prevent any fluid from leaking out of the pump, and to withstand high levels of pressure. Removing the seat, therefore, is a difficult undertaking. Although removing the valve is less difficult than removing the seat, many other components still need to be removed in order to get to the valve. Additionally, the seat is generally replaced every time the valve is replaced because of excessive wear on both components.

For the foregoing reasons, there is a need for a more durable valve assembly with an increased life span. Such a valve assembly needs to be better able to withstand the pressures and harshness of various applications, including hydraulic fracturing pumping.

SUMMARY

An apparatus, according to certain embodiments, comprises a housing and a plunger configured to reciprocate along an axis within the housing. An internal fluid chamber is disposed in the housing. The apparatus also comprises a valve having a valve base and a deformable seal, the valve having a first side and a second side. The apparatus further comprises a seat having a first end, a second end, and an aperture therein. The first side of the valve is configured to move into and out of contact with the second end of the seat when the plunger reciprocates within the housing, based upon a fluid pressure in the internal flow chamber. An outer diameter of the deformable seal is less than an outer diameter of the seat.

According to certain embodiments, a valve assembly for a high pressure pump may include a valve comprising a valve base and a deformable seal, the valve having a first side and a second side. The valve assembly further comprises a seat having a first end, a second end, and an aperture therein. When the valve is closed, the first side of the valve is disposed on the second end of the seat. An outer diameter of the deformable seal is smaller than an outer diameter of the second end of the seat.

According to certain embodiments, a seat for a high pressure pump comprising a seat body having a first end and a second end, the second end having an inner seat edge and an outer seat edge. The seat further comprises a sleeve disposed in the seat body, and having an aperture therein. At least one of the inner seat edge and the outer seat edge of the seat is rounded.

According to certain embodiments, a valve for a high pressure pump comprising a valve base, and a deformable seal disposed on the valve base. The deformable seal includes a first side, a second side, and a seal contact surface. The deformable seal is in contact with the valve base. A diameter of the first side of the deformable seal is less than a diameter of the second side of the deformable seal. An outside rim of the deformable seal is inwardly curved.

DETAILED DESCRIPTION

Embodiments of the present invention relate to a high pressure pump including a fluid end housing15. In the example shown inFIG. 1, fluid end housing15has a discharge end A and an intake/suction end B. A plunger2reciprocates axially pressurizing an internal fluid chamber3and enabling the positive displacement of fluid. An intake valve assembly4can be disposed at intake/suction end B of internal fluid chamber3, while a discharge valve assembly5can be disposed at discharge end A of internal fluid chamber3. Intake valve assembly4and discharge valve assembly5operate between an open and closed position in response to shifting differential pressures caused by the reciprocation of plunger2.

Although certain embodiments of the fluid end of the pump, as shown inFIG. 1, have the plunger2reciprocating horizontally, and intake valve assembly4and discharge valve assembly5disposed vertically to one other, the present invention is not limited to such an embodiment.FIG. 1is merely an embodiment of the invention, and as such should not be interpreted as limiting the scope of the invention.

Both normally closed intake valve assembly4and normally closed discharge valve assembly5include a seat6and a valve7. When valve assemblies4,5are closed, valve7is in contact with seat6. In one embodiment, when plunger2reciprocates in a first direction, the pressure differential between internal fluid chamber3and the suction/intake end B is such that valve7opens to allow fluid to enter internal fluid chamber3through intake valve assembly4. Once the pressure differential changes, valve7closes, and engages seat6. When plunger2reciprocates in a second direction, the pressure differential between internal fluid chamber3and discharge end A is such that valve7opens to allow fluid to exit internal fluid chamber3through discharge valve assembly5.

Intake valve assembly4can include a seat6and a valve7. A spring can be used to maintain the normally closed position the valve assembly. In a normally closed intake valve assembly4, valve7is in contact with seat6so as to seal intake valve assembly4, and prevent any fluid from entering internal fluid chamber3. In one embodiment, intake seat6includes a tapered body19pressed into a taper in fluid end housing15so as to create a seal which prevents leakage of fluid. The tapered body19is pressed in with sufficient force to prevent the seat from being displaced from the fluid end housing15as a result of high pressures. In certain embodiment, the length of the taper in the fluid end housing15is shorter than the length of the tapered seat body19so that only part of the seat is in contact with fluid end housing15. In this embodiment, the part of the seat that is not in contact with fluid end housing15is disposed in internal fluid chamber3.

In some embodiments, seat6includes a cylindrical body with an axial bore therein. The axial bore can extend all the way through seat6, from a first end to a second end of seat6. The first end of the seat can be, for example, a planar annular surface. The second end12, hereinafter referred to as seat contact surface, of seat6is a frusto-conical, frusto-spherical, or tapered surface. Seat contact surface12is the part of seat6that comes into contact with valve7when valve7is closed. Further, seat6can have an inner diameter D1and an outer diameter D2. In one embodiment, inner diameter D1can be 3.0 inches, and outer diameter D2can be 4.57 inches. To increase the surface area of seat contact surface12, one can make inner diameter D1much smaller than outer diameter D2. To further increase the surface area one can also increase a surface area of a valve contact area10, located on a first side of valve7. This enables the contact force, caused by the closing of valve7, to be distributed throughout a greater surface area of seat contact surface12and valve contact surface10, thus decreasing the likelihood of deformity of seat6and valve7after repeated impact loads. One example of the surface area of seat contact surface12and valve contact surface10is 5.45 and 1.92 square inches, respectively.

In certain embodiments of seat6, the edges of seat contact surface12are rounded. As shown inFIG. 1, and further illustrated inFIG. 4, the seat contact surface12has an inner seat edge13and an outer seat edge14. Both inner seat edge13and outer seat edge14can be rounded. In one example, inner seat edge13can have a radius of 0.118 inches, while outer seat edge14can have a radius of 0.063 inches. Rounding inner seat edge13and outer seat edge14helps prevent potential damage to valve7caused by repeated impact loads. When intake valve assembly4is closed, valve7is pushed against seat6. If inner seat edge13and outer seat edge14are not rounded, they can deform, and even cut through, valve7.

Seat6can be composed of hardened steel, such as a forged 8620H or similar material. In one example the forged 8620H is carburized and hardened to between 57 to 63 Rockwell C (HRC) to a depth of 0.047 to 0.059 inches. The seat can also be composed of other materials that provide the necessary characteristics.

Additionally, embodiments of the invention include valve7, which can have a first side and a second side, and can include a valve base18, a deformable seal9, a valve contact surface10, and a valve guide11. In one example, valve7has a circular body fit to create a seal when the first side of valve7engages seat6, and comes into contact with seat contact surface12. This action seals the bore of seat6. Once the bore is sealed, the intake valve assembly4is deemed closed. In the embodiment shown inFIG. 1, valve guide11protrudes from the first side of the intake valve, and is fully disposed inside the bore of seat6. Once the intake valve assembly4opens, spring8compresses, and valve7is no longer in contact with seat contact surface12. When the intake valve assembly4is closed, spring8decompressed, and valve7is pushed into seat6, at which point valve7seals the bore of seat6.

Deformable seal9and valve base18can be in direct contact with each other. In one example, deformable seal9is molded and bonded onto valve base18. In some embodiments, valve guide11and valve base18are cast as one piece. Valve base18can be made of metal, such as cast 8630. In one example, cast 8630 is carburized and hardened to between 45-50 HRC. In one example, deformable seal9is composed of urethane having a hardness of Shore D 40-45. Certain other embodiments of the deformable seal9are composed of other materials that provide the necessary characteristics.

In one embodiment, the diameter of deformable seal9is smaller than outer diameter D2of seat6. The deformable seal9, therefore, does not extend beyond outer seat edge14of seat contract surface12. By keeping deformable seal9within outer seat edge14, the risk of deformable seal9being damaged or cut by seat6is minimized. In addition, this feature helps orient the flow of the fluid passing through the intake valve assembly4, into the internal fluid chamber3, towards discharge end A. In the embodiment shown inFIG. 1, wear and wash out on fluid end housing15is minimized since the flow can be directed vertically, towards discharge end A, rather than being pushed out horizontally. In some embodiments, deformable seal9engages seat contract surface12, but does not make contact with outer seat edge14. In other embodiments, valve contact surface10engages seat contact surface12.

When intake valve assembly4is closed, both valve contact surface10and deformable seal9can engage seat contract surface12. In the embodiment shown inFIG. 1, valve contact surface10is an annular upwardly inclined surface inclined at an angle θ2. In one example, valve contact surface angle θ2is inclined at an angle of 30°. In one example, the contact area between valve contact surface10and seat6can be 1.92 square inches. Where valve contact surface10and seat6are composed of metal, and outer diameter D2of seat6is 4.57 inches, the metal-to-metal contact area between valve contact surface10and seat6is 1.92 square inches, which is 80% more metal-to-metal contact than is known in the prior art. In another example, the contact area between valve contact surface10and seat6can be 3.12 square inches. Where valve contact surface10and seat6are composed of metal, and outer diameter D2of seat6is 5.07 inches, the metal-to-metal contact area between valve contact surface10and seat6is 3.12 square inches, which is 99% more metal-to-metal contact than is known in the prior art.

Deformable seal9has a first side with a first diameter D3, a second side with a second diameter D4, and a seal contact surface17. Seal contact surface17engages seat contact surface12when the intake valve assembly4is closed. In the embodiment shown inFIG. 1, seal contact surface17is an annular upwardly inclined surface that is inclined at a seal contact surface angle θ1. Seal contact surface angle θ1can range between 23° to 28°. In one example, seal contact surface angle θ1is inclined at an angle of 26.1°. In another example, seal contact surface angle θ1is inclined at an angle of 25.1°. Such an incline is created in order to increase the contact area of deformable seal9that is in contact with seat contact surface12. In an alternative embodiment, seal contact surface17can be downwardly declined at a certain angle. In certain other embodiments, seal contact surface17can be curved.

As shown inFIG. 1, and further illustrated inFIG. 2, first diameter D3is the outer diameter of deformable seal9, while second diameter D4is an inner diameter of deformable seal9. In certain embodiment first diameter D3is larger than second diameter D4. In one example, first diameter D3is 4.842 inches and second diameter D4is 4.724 inches. In another example, first diameter D3is 4.409 inches and second diameter D4is 4.291 inches. The outside geometry of the rim21of seal9is such that the seal is inwardly curved from the first side of the seal to the second side of the seal. This outside geometry allows deformable seal9to flex, which enables more cycles to pass before deformable seal9takes a permanent set. In addition, the outside geometry, along with diameter D3being smaller than diameter D2on seat6, helps orient the flow of the fluid passing through intake valve assembly4, into the internal fluid chamber3, towards discharge end A. In the embodiment shown inFIG. 1, wear and wash out on fluid end housing15is minimized since the flow can be directed vertically, towards discharge end A, rather than being pushed out horizontally.

Furthermore, in some embodiments, the incline of seal contact surface17has a mismatched angle to seat contact surface12. This allows for a better seal and enables deformable seal9to clear fluid, or in some applications proppant, out of the way while valve7closes. While valve7is closing, deformable seal9can compress to further secure the sealing of the seat aperture. In one example, deformable seal9is compressed by one millimeter.

In one example, valve base18has a lower hardness value than seat6which allows for valve7to become more easily deformed than valve6due to the repeated impact loads. Therefore, seat6can remain installed in fluid end housing15while only valve7is replaced. This will greatly decrease the amount of time needed to service the pump. Deformable seal9can also have a lower hardness value than seat6, while still maintaining the necessary hardness to withstand abrasion and pitting from the fluid flowing through seat6.

Spring8may be a coil spring, and can engage the second side of valve7. In certain embodiments spring8engages valve boss20. Boss20can be designed to a specific height in order to increase or decrease the lift of valve7, which can affect the flow area of the valve assembly. An increase to the lift of the valve directly results in an increase to the flow area between valve7and seat6. The valve assembly flow area is restricted by either the flow area between valve7and seat6, or the flow area through seat6. In one example, the restricted flow area can be 5.07 square inches, which can be as much as 5.3% to 14.5% more than other standard valves having similar diameters. In addition, increasing the flow area allows the pump to experience less of a pressure drop across intake valve assembly4, and reduces the risk of cavitation caused by starvation of fluid flowing into the pump.

As seen in the embodiment illustrated inFIG. 1, valve7is normally closed. The intake valve assembly4can be opened as a result of the pressure differential caused by the reciprocation of plunger2. In one example, plunger2moves axially, with a typical stroke being between 8 to 12 inches. When plunger2moves away from internal fluid chamber3, it causes the pressure in the internal fluid chamber3to decrease below the pressure of the intake/suction end B. The intake/suction end B, located below the intake valve assembly4in the embodiment shown inFIG. 1, generally exhibits pressure levels between 40 to 80 psi. Therefore, when the plunger is moved away from internal fluid chamber3, the pressure in internal fluid chamber3is lower than the pressure below intake valve assembly4plus the spring force, causing valve7to open, and allowing fluid to flow into internal fluid chamber3. Once the pressure in internal fluid chamber3equalizes with that of the suction/intake end B, the spring8will start to close valve7and seal the bore of seat6.

In certain embodiments of the invention, intake valve assembly4and discharge valve assembly5are identical to each other. Discharge valve assembly5can include a seat6′ and a valve7′. Valve7′ can include a deformable seal9′, a seal contact surface10′, a valve base18′, and a valve guide11′. In addition, seat6′ includes a seat contact surface12′.

The difference between intake valve assembly4and discharge valve assembly5, however, is the location in which they are placed in fluid end housing15, and the effect of the pressure differential caused by plunger2on opening their respective valve. Discharge valve assembly5is placed towards discharge end A. Fluid flows from suction/intake end B into internal fluid chamber3, and is then discharged through discharge valve assembly5. Discharge end A, located above discharge valve assembly5in the embodiment shown inFIG. 1, exhibits constant high pressure. When plunger2axially moves towards internal fluid chamber3, the pressure in the internal fluid chamber3becomes more than or equal to the pressure above discharge valve assembly5plus the spring force, and valve7′ will open. Once valve7′ is open, the fluid flows out of internal fluid chamber3, through discharge valve assembly5, and is subsequently discharged from the pump. When the pressure inside the chamber becomes less than the pressure above discharge valve assembly5, valve7′ closes and seals the bore of seat6′.

FIG. 2illustrates a side view of one embodiment of valve7. Valve guide11is shown as a four legged protrusion emanating from valve base18. In certain embodiments, valve guide11, valve base18, and valve contact surface10are cast as one piece, with valve guide11protruding from one end of the valve base18. When valve7is closed, valve guide11can be fully disposed within the bore of seat6. Seal contact surface17and valve contact surface10are also shown in the embodiment ofFIG. 2. Spring8, not shown in the figure, fits over boss20located on second side of valve7. In some embodiments, the valve contact surface10can be made larger in order to increase the contact area between seat6and valve7.

Further, first diameter D3and second diameter D4are shown. First diameter D3is larger than second diameter D4. The geometry of rim21is also clearly shown. The seal curves inwardly from the first side of the seal to the second side of the seal. Both seal contact surface angle θ1and valve contact surface angle θ2are also shown. In the embodiment illustrated inFIG. 1seal contact surface angle θ1is smaller than valve contact surface angle θ2.

FIG. 3illustrates a side view of one embodiment of seat6. Outer seat edge14is shown as a rounded edge. In addition, a slot16, which secures an o-ring, is shown on tapered body19. The outer diameter D2of seat6is also illustrated.

FIG. 4illustrates a perspective view of seat6. Seat contact surface12is shown along with inner seat edge13and outer seat edge14. In this embodiment, both inner seat edge13and outer seat edge14are rounded. In addition, inner diameter D1and outer diameter D2are illustrated. Inner diameter D1does not include inner seat edge13. Outer diameter D2, on the other hand, includes both inner seat edge13and outer seat edge14. In some embodiments, inner diameter D1can be made much smaller than outer diameter D2. Doing so increases the surface area of seat contact surface12, and increases the available contact area between seat6and valve7.

In certain embodiments, the hardness of seat6can be greater than the hardness of valve7. Because of this difference in hardness, when valve7and seat6engage each other, the harder seat will be able to withstand more impact loads from the softer valve before it deforms.

The embodiments described above help increase the longevity of both seat6and valve7. By making the hardness of seat6greater than the hardness of seat valve7, seat6will not be easily deformed. As such, seat6will last longer and will need to be replaced less often. Since removing seat6is a cumbersome undertaking, improving its longevity is advantageous. In addition, by increasing the surface area of seat contact area12and/or by increasing valve contact surface10, the amount of contact area between seat6and valve7is increased. Therefore, when seat6and valve7are in contact, the resulting force is distributed across a greater surface area, thus decreasing the likelihood of deformity of seat6and valve7after repeated impact loads.

The embodiments described above also help increase the longevity of valve7. Deformable seal diameter D4being smaller than seat outer diameter D2will help prevent deformable seal9from being deformed and/or cut by outer seat edge14. Additionally, this difference in diameter allows the flow of the fluid passing through the intake valve assembly4, into the internal fluid chamber3, to be oriented towards discharge end A. In the embodiment shown inFIG. 1, the difference in diameter will orient the fluid in a more vertical direction instead of a horizontal direction, which decreases wear and wash out on fluid end housing15.

The design of first end deformable seal9also helps to preserve valve7. The incline angle of seal contact surface17is different than seat contact surface12, which helps form a better seal when valve7is closed. In addition, the inwardly curved outside geometry of the rim21of deformable seal9enables the seal to flex and withstand greater impact loads before being cracked. This ultimately acts to increase the life of the deformable seal. In addition, the outer geometry of seal9allows the deformable seal to deform and rebound for more cycles without permanent damage.

The hardness of deformable seal9is another characteristic that helps improve the longevity of valve7. By being composed of harder material, deformable seal9will be better equipped to withstand abrasion and pitting from the fluid. In addition, deformable seal9, valve contact surface10, and valve base18have a lower hardness than seat6, which helps further preserve seat6. All of the above mentioned benefits apply to both intake valve assembly4and discharge valve assembly5.

The features, structures, or characteristics of certain embodiments described throughout this specification may be combined in any suitable manner in one or more embodiments. For example, the usage of the phrases “certain embodiments,” “some embodiments,” or other similar language, throughout this specification refers to the fact that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present invention. Thus, appearance of the phrases “in certain embodiments,” “in some embodiments,” “in other embodiments,” or other similar language, throughout this specification does not necessarily refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention.