Patent Grant
11920452
The present invention generally pertains to downhole oilfield production equipment. It more specifically refers to equipment used for downhole oilfield fluid production and solids control for downhole rod operated pumps.
Rod pumps are the most common form of artificial lift for oil production from subsurface reservoirs. A typical rod pump system consists of a prime mover, a surface rod actuation apparatus (such as a beam pumping unit), a sucker rod string, and a downhole pump. However, a known problem of downhole pumps is that sand and/or other particulate matter can cause the pump to fail. For example, particulates and solids will cause wear in the plunger as it reciprocates with respect to the pump barrel, resulting in a loss of efficiency. Excessive solids can actually cause the plunger to become stuck within the barrel. Solids can accumulate in the dead zone between the traveling valve and standing valve of the pump, resulting in sand accumulation in the barrel which can prevent fluid flow into the barrel. Solids and particulates can interfere with the seal between the balls and seats of the valves, resulting in reduced pump performance or complete pump failure. Solids and particulates generally result in erosion of all pump components and pump degradation over time.
As can be appreciated from the above paragraph, preventing and/or controlling the entry of sand and/or other particulate matter into the mechanisms of the downhole pump is desirable. A variety of solutions to this problem have been proposed over the years, including varieties of downhole sand separators through which downhole fluids are directed prior to flow into the pump barrel. However, the prior art downhole sand separators have designs which differ from the presently proposed solution. First, the prior art separators utilize designs which reduce the overall velocity of the fluid through the separator which can adversely impact the separation efficiency. Second, the known downhole separators are fabricated from metallic materials which are subject to erosion of the material and which also results in required tolerances between the exterior surfaces of the internal components and the interior surfaces of the external components resulting in a loss of efficiency.
A downhole sand separator is disclosed herein which meets the above-identified need. An embodiment of the sand separator receives an inflow of a downhole fluid and separates particulate matter from the inflow, resulting in a cleansed fluid which is directed to the intake of a subsurface pump while a particulate matter comprising sand and other solids is discharged from the separator. For purposes of this disclosure, the term “cleansed fluid” refers to a fluid from which at least some solids and/or particulate matter have been removed prior to being directed to the intake of the downhole pump.
The downhole sand separator may be configured as a separation unit comprising a sleeve member and a liner member disposed inside the sleeve member. The sleeve member has an upper end and a lower end with an outer opening adjacent the upper end. The outer opening penetrates through a wall of the sleeve member. The liner member has an exterior surface which is engaging contact with an interior of the sleeve member. The liner member further has an interior surface. The liner member has an inner opening which penetrates through the exterior to the interior surface. The inner opening in the liner member is positioned to be aligned with the outer opening of the sleeve member, such that the aligned outer opening and inner opening comprise an inlet to the interior of the liner member. The liner member may be fabricated from thermoplastic materials, including nylon for low temperature applications and polyether ether keytone (PEEK) for high temperature applications. Both materials are resistant to both sand abrasion and corrosion.
The separation unit further comprises a vortex guide which is positioned inside the interior surface of the liner member. The vortex guide has a first end and a second end. An axial opening extends from the first end to the second end. The vortex guide further comprises a helical exterior structure. The helical exterior structure is configured to be in engaging contact with the interior surface of the liner member. When so positioned, a single helical passage is formed by the engagement of the helical exterior structure with the interior surface of the liner member. The inlet formed by the alignment of the outer opening with the inner opening may form the beginning of the single helical passage. An outlet of the single helical passage is formed adjacent the second end of the vortex guide where the helical exterior structure terminates. The outer opening may be a tangentially oriented rectangular opening through the wall of the sleeve member, while the inner opening may likewise be a tangentially oriented rectangular opening through the liner member.
The vortex guide may also be fabricated from thermoplastic materials, including nylon for low temperature applications and polyether ether keytone (PEEK) for high temperature applications. Sand separators having components fabricated from steel have, by necessity, a gap between the inner diameter of the sleeve and outside diameter of the vortex guide, resulting in a loss of efficiency. However, because the thermoplastics expand in heat, the embodiments of the present invention which utilize thermoplastic for the components had a 100 percent seal between the surfaces of the components, thereby maximizing efficiency.
The separation unit may be assembled with other components to form a separator assembly. For example, a mandrel may be attached to the lower end of the sleeve member, the mandrel having a top end, a bottom end, and an axial opening extending through the mandrel from the top end to the bottom end, where the axial opening is configured for a flow of the cleaned fluid. A dump valve, which may comprise a ball and seat disposed within a valve cage, may be attached to the bottom end of the mandrel or a sand collection extension may be disposed between the bottom end of the mandrel and the dump valve to provide a dead zone away from the vortex guide to facilitate the gravitation of the solids to the dump valve. The dump valve is configured to release the particulate discharge from the separator assembly upon an opening of the dump valve, which occurs on the downstroke of the subsurface pump, when the ball in the dump valve falloff the seat. On the upstroke of the subsurface pump the ball is lifted and seals against the seat. The dump valve may be set within an optional protective sleeve.
In operation, an inflow of downhole fluid with entrained solids enters the inlet and travels through the single helical passage, creating centrifugal forces which drives the solids to the outside of the helical passage, separating the solids from the downhole fluid, resulting in the cleansed fluid. The cleansed fluid flows up through the axial opening of the thermoplastic vortex guide where it flows out of the top of the separation module and drawn into the pump intake upon the upstroke of the downhole pump. The solids flow out through the bottom of the separation module and are discharged from the separator through a dump valve at the bottom of the separator assembly upon the downstroke of the downhole pump.
Referring now to the figures,
The separator unit 10 also has a liner member 22 disposed inside the sleeve member 12. The liner member 22 has an exterior surface 24 immediately adjacent an inner surface 26 of the sleeve member 12. Liner member 22 has an interior surface 28. The liner member 22 has an opening 30 which penetrates through the exterior surface 24 to the interior surface 28. When the separator unit has been assembled, the opening 30 in liner member 22 aligns with the opening 18 of the sleeve member, to form a single inlet in the separator unit 10.
The separator unit 10 also has a vortex guide 32 which is disposed inside the interior surface 28 of the liner member 22. The vortex guide 32 has a first end 34 and a second end 36, and an axial opening 38 which extends from the first end 34 to the second end 36. The vortex guide 32 has a helical exterior 38 which is configured to be in engaging contact with the interior surface 28 of the liner member 22. When the vortex guide 32 has been installed inside the liner member 22, the engaging contact of the helical exterior 38 with the interior surface 28 of the liner member 22, a single helical passage 40 is formed between the interior surface 28 and the helical exterior 38. The helical passage 40 extends from the single inlet 42 formed by the alignment of the opening 30 in the liner member 22 with the opening 18 of the sleeve member 12 to the second end 36 of the vortex guide 32.
As shown in the figures opening 18 may be configured as a tangentially oriented rectangular opening which penetrates through the wall 20 of the sleeve member 12 which is aligned with opening 30 of the liner member 22, which may also be configured as a tangentially oriented rectangular opening penetrating through the liner member 40.
The liner member 22 and the vortex guide 32 may be fabricated from thermoplastic materials. The use of thermoplastic materials which eliminates any gap between the inner surface 28 of the liner member 22 and the helical exterior 38 because the thermoplastic materials expand when heated. This feature increases the efficiency of the separator because the opposing thermoplastic surfaces provide a 100% seal when heated. In low temperature applications, the thermoplastic material may be nylon. In higher temperature applications, the thermoplastic material may be fabricated from PEEK.
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| 20190106973 | Ayub | Apr 2019 | A1 |
