Underground dynamic cyclone separation system for screw pump

A kind of screw pump downhole dynamic cyclone separation system technical field

[0001] The present invention relates to a two-phase separation treatment device applied in the fields of petroleum, chemical industry and environmental protection.

Background technique

[0002] At present, most of the technology used in the treatment of produced fluids in oil production well sites is to pump the produced fluids to the ground and then subject the produced fluids to sedimentation, swirling and other separation treatments. However, in oilfields, a wide range of The cost of adopting such a treatment method is too high. At present, the technology of oil-water separation and reinjection under the same well injection and production well is becoming more and more mature. This technology can directly process high water-cut produced fluid through the downhole, avoiding a large amount of invalid water from being transported to the surface, and instead realize the reinjection and recycling in the wellbore, which can greatly reduce Lifting energy consumption and operating costs, reduce the lower limit of economic and effective exploitation of high water-cut oil fields, extend the life of oil wells, and provide new technologies for the economic exploitation of high water-cut oil fields.

[0003] The downhole cyclone separation system is a system in the same well injection and production process, and is usually designed as a downhole static cyclone used in the downhole to separate the produced fluid in the wellbore. The problem in the prior art is that due to the structural characteristics and working methods of the static hydrocyclone itself, the static hydrocyclone is subject to various restrictions in further improving the separation efficiency, especially when dealing with high viscosity media (such as heavy oil) During the separation operation, the viscosity of the working medium is large, the internal friction resistance is large, and the pressure loss increases, which is difficult to meet the special production needs of the oilfield site. In practice, some dynamic cyclones are also used, and most of these dynamic cyclones are driven by an external motor to rotate a part of the static cyclone. However, this additional power equipment also brings problems such as high energy consumption, easy damage to rotating parts, unreliable sealing, and easy wear.

Summary of the invention

[0004] In order to solve the technical problems mentioned in the background art, the present invention provides a screw pump downhole dynamic cyclone separation system, which can be used to drive the outer cylinder of the cyclone to rotate through the screw pump shaft in the downhole. The cyclone is dynamically rotated to generate a strong centrifugal force field, and the immiscible two-phase mixture such as oil and water of different densities is separated by cyclone centrifugation. The separated low-density oil phase is lifted to the ground, and the water phase can be reinjected to the underground reinjection layer. Recycle and reuse. This separation system has the advantages of high separation strength, high separation efficiency, low separation cost, small radial size, compact structure and convenient operation.

[0005] The technical solution of the present invention is: this kind of screw pump downhole dynamic cyclone separation system includes an outer sleeve 4, a stator 2, a cyclone overflow pipe 9, a cyclone cavity 14, a cyclone bottom pipe 19 and The unique feature of the cyclone inner cone 13 is that the cyclone separation system further includes a screw shaft rotor 3, an overflow oil pipe 7, a first bearing 8, a second bearing 17, and a second bearing filling ring 18.

[0006] Wherein, the inner wall of the outer sleeve 4 is provided with wall array openings 10; the inner wall of the outer sleeve 4, the first bearing 8, the second bearing 17, the second bearing filling ring 18, the swirler overflow The outer wall of the flow tube 9, the outer wall of the swirling cavity 14, the outer cone section 16 of the swirler and the underflow tube 19 of the swirler together constitute an inlet cavity;

[0007] The cyclone cavity 14 is formed by the cyclone cylindrical section 12, the cyclone inner cone 13 and the cyclone outer cone section 16 connected in sequence, and is arranged on the side wall of the top of the cyclone cylindrical section 12 The cyclone rectangular tangential inlet 11; the cyclone inner cone 13 is fixed at the top axis of the cyclone cylindrical section 12.

[0008] The screw shaft rotor 3, the overflow branch pipe 7, the cyclone overflow pipe 9, the cyclone inner cone 13, the swirl cavity 14, the outer cone section 16, and the underflow tube 19 are in sequence on the same central axis Fixed connection to form an integral rotating structure, on the belt of the screw shaft rotor 3

It rotates together under movement; the rectangular tangential entrance 11 of the cyclone is opposite to the spiral rotation direction, which is used to ensure that the rotation direction of the fluid entering the swirl cavity 14 is consistent with the rotation direction of the screw shaft rotor 3, forming a swirl centrifugal separation flow field.

[0009] The stator 2 cooperates with the overflow oil pipe 7 and the screw shaft rotor 3 at the upper part of the cyclone overflow pipe 9 to form an oil collection cavity 6 and a spiral oil gap 5 for centrifugal separation and flow into the center The oil phase at the inlet 15 of the overflow pipe flows out, and the water phase separated by centrifugation enters the underflow pipe 19 of the cyclone, and flows into the water collection chamber 21 through the underflow circular hole outlet 20.

[0010] The outer sleeve 4 and the swirler overflow tube 9 are transitionally connected by the first bearing 8, the first bearing 8 is next to the stator 2 above and is sealed to the inner side of the outer sleeve 4; the outer sleeve 4 and the rotary The underflow pipe 19 of the cyclone is connected by a second bearing 17 and a second bearing filling ring 18 at the junction of the outer cone section 16 of the cyclone and the underflow pipe 19 of the cyclone.

[0011] The present invention has the following beneficial effects: First, the screw shaft rotor, the overflow oil pipe, the cyclone overflow pipe, the inner cone, the swirl cavity, the outer cone section, and the underflow tube are in the same center through structural design. The axis is fixedly connected in sequence to form an integral rotating structure. Under the drive of the screw, the integral rotation can realize the dynamic separation of downhole oil and water. Secondly, the dynamic rotation of the cyclone comes from the rotation of the screw pump shaft, so it can be ground Directly control and adjust the rotational speed of the downhole dynamic cyclone; again, a structure where the rectangular tangential entrance of the cyclone is opposite to the spiral rotation direction is designed, which can effectively ensure that the rotation direction of the fluid entering the swirl cavity is consistent with the screw rotation direction, thus forming a swirl Flow field of centrifugal separation; in addition, the overall structure is novel, the size of the equipment is small, and there is no external moving equipment compared with the conventional wellbore, and the reliability is high. Compared with the separation effect of the existing cyclone separation equipment, it has a stronger centrifugal separation strength, so the separation is more pure , Has outstanding advantages, and has considerable prospects for promotion and application for applications in oilfield production and other fields.

[0012] Description of the drawings: Figure 1 is a schematic structural diagram of a screw pump downhole dynamic cyclone separation system of the present invention.

[0013] Figure 2 is a schematic diagram of the internal fluid flow and phase separation of the screw pump downhole dynamic cyclone separation system. The arrows in the figure indicate the flow direction of the fluid entering the system.

[0014] FIG. 3 is a schematic diagram of the cross-sectional structure of AA in FIG. 1.

[0015] FIG. 4 is a schematic diagram of the cross-sectional structure of BB in FIG. 1.

[0016] FIG. 5 is a schematic diagram of the cross-sectional structure of FIG. 1 CC.

[0017] FIG. 6 is a schematic diagram of the cross-sectional structure of the DD section of FIG.

[0018] FIG. 7 is a schematic diagram of the cross-sectional structure of the EE section of FIG. 1.

[0019] FIG. 8 is a schematic diagram of the screw pump downhole dynamic cyclone of the present invention and the screw shaft rotor connected integrally, the dotted arrow in the figure represents the screw pump rotation direction, and the solid arrow represents the fluid entering the tangential inlet direction.

[0020] Figure 1-oil phase spiral outlet; 2-stator; 3-screw shaft rotor; 4-outer sleeve; 5- spiral oil gap formed by the stator and the screw shaft rotor; 6-oil collection chamber; 7 -Overflow oil conveying branch pipe; 8-first bearing; 9-cyclone overflow pipe; 10-tubing and casing array opening; 11-rectangular tangential inlet of cyclone; 12-cylindrical section of cyclone; 13 -Cyclone inner cone; 14-Swirl chamber; 15 Center overflow pipe inlet; 16- Cyclone outer cone section; 17-Second bearing; 18-Second bearing filling ring; 19-Screw underflow pipe ; 20- underflow round hole outlet; 21- catchment cavity.

[0021] Specific implementation mode: The present invention will be further explained below with reference to the accompanying drawings: First, the purpose of the present invention is introduced as follows: make full use of the screw pump downhole rotation working conditions, innovative design to achieve downhole oil-water two-phase dynamic cyclone separation (with oil and water two For example, it is not limited to two phases of oil and water), which solves the problems of low oil-water density difference, small dispersed phase oil droplets, high continuous phase viscosity and low separation efficiency in the existing downhole separation technology, and realizes high-efficiency separation of two phases.

[0022] This kind of screw pump downhole dynamic cyclone separation system has a slender cylindrical shape as a whole structure, which can be matched with an oil production wellbore. As shown in Figure 1, its structure mainly includes: stator 2, screw shaft rotor 3, outer sleeve 4, overflow oil pipe 7, first bearing 8, cyclone overflow pipe 9, oil casing array opening Hole 10, cyclone rectangular tangential inlet 11, cyclone cylindrical section 12, cyclone inner cone 13, cyclone outer cone section 16, second bearing 17, second bearing filling ring 18, cyclone underflow The pipe 19 and the underflow round hole outlet 20.

[0023] As shown in Figure 2 is a schematic diagram of fluid flow and two-phase separation, the arrow in the figure indicates the flow direction of the fluid entering the system, the oil-water mixture to be separated in the wellbore flows in through the tubing and casing array openings 10, and first enters the liquid inlet cavity , The liquid inlet cavity is formed by the inner wall of the outer sleeve 4 of the wall array opening 10, the first bearing 8, the second bearing 17, the second bearing filling ring 18, the outer wall of the swirler overflow pipe 9, the outer wall of the swirling cavity 14, The outer cone section 16 of the cyclone and the underflow pipe 19 of the cyclone are jointly enclosed. The pressure of the oil-water mixture in the inlet cavity is higher than the pressure in the cyclone. At this time, the designed rectangular tangential inlet 11 cooperates with the rotation of the cyclone to generate suction at the rectangular tangential inlet 11 and inside the cyclone (centrifugal movement center) The area is a low-pressure area), so under the dual action of pressure drive and centrifugal suction, the oil-water mixture in the liquid inlet cavity enters the swirling cavity 14 in the cyclone along the rectangular tangential inlet 11. In order to ensure that the streamline movement of the fluid entering the cyclone is consistent with the rotation direction of the cyclone, the designed rectangular tangential inlet 11 opening direction is opposite to the rotation direction of the cyclone, as shown in Figure 8, the dotted arrow in the figure indicates the screw The direction of rotation of the pump, the solid arrow indicates the direction of the fluid entering the tangential inlet. The cyclone chamber 14 is respectively surrounded by the cylindrical section 12 of the cyclone, the inner cone 13 of the cyclone, and the outer cone section 16 of the cyclone. The cyclone chamber 14 is the area where the two-phase centrifugal separation occurs. Diversion of rectangular tangential inlet 11 When used, the oil-water mixture entering the swirling cavity 14 will make a rotating circular motion in the swirling cavity in the form of a high-speed jet. Due to the different densities of the oil and water phases, the light phase oil phase receives less centrifugal force and will rotate with it. Moving to the center area of the cyclone, the heavy phase water phase is subjected to greater centrifugal force and gradually migrates to the side wall of the cyclone. The conical structure design of the wall surface of the inner cone 13 of the swirler, which is a component of the swirl cavity, can stabilize the flow field of the incoming fluid and the coalescence and collection of the light phase migration to the side wall.

[0024] After the cyclone centrifugal separation process in the cyclone chamber 14, the light phase oil phase collected to the center after separation enters the overflow pipe 9, the oil collection chamber 6, the overflow oil branch pipe 7, and the stator and screw in turn. The spiral oil delivery gap 5 formed by the shaft rotor finally flows out from the oil phase spiral outlet 1; the separated water phase enters the cyclone underflow pipe 19 along the side wall of the outer cone section 16 of the cyclone, and passes through the underflow circular hole outlet 20 Inflow into the sump 21.

[0025] In order to divert the collected oil phase flowing into the overflow pipe 9 to the oil collection chamber 6, a transitional connection part-an overflow oil delivery branch pipe 7 is designed, which is inserted into the oil accumulation from the center of the bottom by four inclined pipe holes. In the cavity 6, the oil phase of the central overflow pipe 9 can be easily drained into the oil accumulation cavity 6; the oil phase that enters the oil collection cavity 6 enters the spiral oil delivery gap 5 under the rotation of the screw shaft rotor. The pressure is thus transported to other manifolds or the ground.

[0026] In addition, the overall rotational movement of the outer wall of the cyclone will also cause the oil and water two phases in the liquid inlet chamber 14 to follow circular motions. At this time, the light phase oil phase will migrate to the outer wall of the central cyclone, so that there will be a certain amount of The coalescence effect is better than static cyclone or sedimentation separation device.

[0027] This system relies on the way that the rotary shaft core of the screw pump well drives the outer cylinder of the cyclone to rotate, so that the cyclone dynamically rotates to generate a strong centrifugal force field, and performs cyclonic centrifugal separation of immiscible two-phase mixtures such as oil and water with different densities. . The system simplifies the power structure by driving the screw to rotate, and at the same time uses the spiral cavity of the screw sleeve to transmit the oil phase to reduce the equipment volume, realize the downhole oil-water two-phase dynamic cyclone separation, and improve the overall two-phase separation efficiency. It is suitable for working conditions such as small density difference, small oil droplets in the dispersed phase, and high viscosity of the continuous phase.

[0028] The present invention provides a new idea for the design of two-phase separation equipment and promotes the development of separation technology. At the same time, the present invention will enable downhole cyclone separation and same-well reinjection technology to a new level. The equipment can also be used for centrifugal separation of immiscible two-phase media in petroleum, chemical, municipal environmental protection and other industries, such as sewage deoiling, sewage degassing, and downhole washing.

Coal sewage liquid-solid separation, etc.