Downhole screw pump rotor limiting device

Abstract

The application relates to a downhole screw pump rotor limiting device, which belongs to the technical field of oil pumping devices and comprises an extension pipe, positioning joints arranged side by side from top to bottom at the position close to the lower end of the extension pipe and a connecting head, wherein the positioning joints and the connecting head are rotatably installed in the interior of the extension pipe through axial limiting structures, the positioning joints and the connecting head are detachably arranged, and the positioning joints and the connecting head are provided with oil liquid channels which are communicated with the inner cavities of the extension pipe. The application solves the problem that relative rotation between the rotor and the interior of the connecting head produces abrasion when the anti-sinking distance of the traditional technology is unreasonable, and the pump will be stuck after the abrasion reaches a certain degree.

Description

Technical Field

[0001] This utility model relates to the technical field of oil pump equipment, specifically to a rotor limiting device for downhole screw pumps. Background Technology

[0002] A downhole screw pump consists of a stator and a rotor. The rotor rotates inside the stator to pump well fluid. During the installation of the screw pump into the well, the stator is first lowered to a depth of over 1000 meters along with the tubing, and then the rotor is lowered into the stator along with the drive sucker rod. Therefore, a limiting device needs to be installed at the bottom of the stator to ensure accurate positioning and normal operation of the screw pump.

[0003] The existing technology disclosed in patent CN206554815U mainly solves the problem that existing screw pump limiters easily cause rotor bending and deformation, resulting in pump jamming. The stator tube reducing coupling and the lower connector are connected by a limiting short-circuit. The lower connector has an internal threaded limit plate with an axial liquid passage hole. An anti-backlash screw is connected to the left end of the lower connector corresponding to the limit plate. An anti-rotation screw is radially connected to the side wall of the lower connector, and a spring is connected to the end of the anti-rotation screw. The other end of the spring has a steel ball, which presses against the outer wall of the limit plate. This adjustable rotary limit device for screw pumps eliminates wear-induced limiting, prevents rotor bending and deformation in the stator, reduces the probability of damage to the stator rubber and pump jamming, and extends the overall service life of the pump.

[0004] The shortcomings of existing technology have gradually become apparent with use, mainly in the following aspects:

[0005] Firstly, one method involves inserting a cylindrical pin with a diameter of approximately 25mm into an extended tube installed at the bottom of the stator. The inserted steel cylindrical pin is positioned in the middle of the extended tube, serving to block the rotor. However, this method has two problems: firstly, it is not secure; secondly, if the anti-sinking distance is not properly increased, the rotor and the pin may rotate relative to each other, causing wear and breakage, which could lead to a pump jamming accident.

[0006] The second method involves installing a connector with a female thread on the upper end and a male thread on the lower end of an extended pipe installed at the bottom of the stator. The connector has an internal plane with multiple connecting holes facing downwards, allowing well fluid to flow from the bottom to the top and enter the pump. The problems with this method are: first, if the anti-sinking distance is not properly increased, relative rotation between the rotor and the inside of the connector can cause wear, which can lead to pump jamming after the wear reaches a certain level; second, the structure requires more materials, involves more processing, and is more expensive.

[0007] In conclusion, the existing technology obviously has inconveniences and defects in practical use, so it is necessary to improve it. Utility Model Content

[0008] In view of the defects in the existing technology, the downhole screw pump rotor limiting device provided by this utility model is used to solve the problem of wear caused by relative rotation between the rotor and the inside of the joint when the anti-sinking distance is not properly increased in the traditional technology. After the wear reaches a certain degree, the pump jamming accident will occur.

[0009] To achieve the above objectives, this utility model provides the following technical solution:

[0010] The downhole screw pump rotor limiting device includes an extension tube. Near the lower end of the extension tube, a positioning joint and a connecting head are arranged side by side from top to bottom. The positioning joint and the connecting head are rotatably installed inside the extension tube through an axial limiting structure. The positioning joint and the connecting head are detachably connected. The positioning joint and the connecting head are provided with an oil passage communicating with the inner cavity of the extension tube.

[0011] As an optimized solution, the axial limiting structure includes a concave annular groove formed circumferentially on the inner wall of the extended tube, in which a left half retaining ring and a right half retaining ring are fitted together. The lower surfaces of the left half retaining ring and the right half retaining ring abut against the connector, and the upper surfaces of the left half retaining ring and the right half retaining ring abut against the positioning joint.

[0012] As an optimized solution, a bearing ring is fitted on the connector head above the left and right half retaining rings. The upper surface of the bearing ring abuts against the lower end of the positioning joint, and the lower surface of the bearing ring abuts against the upper surfaces of the left and right half retaining rings.

[0013] As an optimized solution, the outer wall of the connector is provided with a shoulder section that abuts against the lower surfaces of the left and right half-rings.

[0014] As an optimized solution, the positioning joint is provided with a protruding section whose diameter is smaller than the inner diameter of the extended tube, and a groove is provided at the upper end of the protruding section.

[0015] As an optimized solution, the oil passage includes an inlet hole formed in the protruding section, and a channel connected to the inlet hole and extending vertically through the connector.

[0016] As an optimized solution, the outer wall of the protruding section is surrounded by several connecting grooves that communicate with the liquid inlet hole.

[0017] As an optimized solution, the connector has an external thread on the outer wall near the upper end, and the lower end of the positioning connector has a threaded groove that connects to the liquid inlet hole, and the external thread is threadedly connected to the threaded groove.

[0018] Compared with the prior art, the beneficial effects of this utility model are:

[0019] The positioning joint can rotate inside the extended pipe. When the anti-sinking distance is not properly increased, the positioning joint and the rotor do not need to rotate relative to each other, so there will be no pump jamming accident. The connecting groove on the positioning joint is located on the side and will not be blocked by the rotor. Only a few small parts are installed on the extended pipe, which is cheaper than the processing cost of existing positioning joints. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0021] Figure 1 This is a schematic diagram of the structure of this utility model.

[0022] In the diagram: 1-Extended tube; 2-Positioning connector; 3-Connector; 4-Bearing ring; 5-Left half retaining ring; 6-Right half retaining ring; 7-Protruding section; 8-Inlet hole; 9-Connecting groove; 10-Slot; 11-Channel; 12-Threaded groove; 13-Shoulder section. Detailed Implementation

[0023] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0024] like Figure 1 As shown, the downhole screw pump rotor limiting device includes an extension tube 1. Near the lower end of the extension tube 1, a positioning joint 2 and a connecting head 3 are arranged side by side from top to bottom. The positioning joint 2 and the connecting head 3 are rotatably installed inside the extension tube 1 through an axial limiting structure. The positioning joint 2 and the connecting head 3 are detachably connected. The positioning joint 2 and the connecting head 3 are provided with an oil passage 11 that connects to the inner cavity of the extension tube 1.

[0025] The axial limiting structure includes a concave annular groove formed circumferentially on the inner wall of the extended tube 1. A left half retaining ring 5 and a right half retaining ring 6 are fitted into the concave annular groove and are mated together. The lower surfaces of the left half retaining ring 5 and the right half retaining ring 6 abut against the connector 3, and the upper surfaces of the left half retaining ring 5 and the right half retaining ring 6 abut against the positioning connector 2.

[0026] A bearing ring 4 is fitted on the connector 3 above the left half retaining ring 5 and the right half retaining ring 6. The upper surface of the bearing ring 4 abuts against the lower end of the positioning connector 2, and the lower surface of the bearing ring 4 abuts against the upper surface of the left half retaining ring 5 and the right half retaining ring 6.

[0027] The outer wall of the connector 3 is provided with a shoulder section 13 that abuts against the lower surfaces of the left half retaining ring 5 and the right half retaining ring 6.

[0028] The positioning connector 2 has a protruding section 7 with a diameter smaller than the inner diameter of the extension tube 1, and a groove 10 is provided at the upper end of the protruding section 7.

[0029] The oil passage 11 includes an inlet hole 8 opened in the protruding section 7, and a channel 11 that is connected to the inlet hole 8 and passes through the connector 3 vertically.

[0030] The outer wall of the raised section 7 is surrounded by several connecting grooves 9 that are connected to the liquid inlet hole 8.

[0031] The connector 3 has an external thread on its outer wall near the upper end, and the lower end of the positioning connector 2 has a threaded groove 12 that connects to the liquid inlet hole 8. The external thread is threadedly connected to the threaded groove 12.

[0032] The working principle of this device is as follows:

[0033] A recessed annular groove is provided inside the lower part of the extended tube 1. The right half retaining ring 6 and the left half retaining ring 5 are engaged in the recessed annular groove. The bearing ring 4 is placed on the right half retaining ring 6 and the left half retaining ring 5. The positioning connector 2 is inserted downward from the upper part of the extended tube 1, and the connecting head 3 is inserted upward from the lower part of the extended tube 1. The positioning connector 2 and the connecting head 3 are connected as one unit by external threads and threaded groove 12. The inner diameter of the right half retaining ring 6 and the left half retaining ring 5 is equal to the upper outer diameter of the connecting head 3, so that the right half retaining ring 6... The left half retaining ring 5 will not come out of the concave ring groove. The outer diameter of the lower part of the positioning joint 2 is larger than the inner diameter of the bearing ring 4. The outer diameter of the outer shoulder of the connector 3 is larger than the inner diameter of the combined inner circle of the right half retaining ring 6 and the left half retaining ring 5, so that the positioning joint 2 cannot move inside the extension tube 1. The upper outer wall of the positioning joint 2 is provided with a groove 10 for installing and placing tools. The lower part of the positioning joint 2 has a liquid inlet hole 8. The side wall of the positioning joint 2 has a connecting groove 9, which is connected to the liquid inlet hole 8.

[0034] The positioning joint 2 can rotate inside the extension pipe 1. When the anti-sinking distance is not properly increased, the positioning joint 2 and the rotor do not need to rotate relative to each other, so there will be no pump jamming accident. The connecting groove 9 on the positioning joint 2 is located on the side and will not be blocked by the rotor. Only a few small parts are installed on the extension pipe 1, which is cheaper than the existing positioning joint 2.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A rotor limiting device for a downhole screw pump, characterized in that: The device includes an extension tube (1), and a positioning connector (2) and a connector (3) are arranged side by side from top to bottom near the lower end of the extension tube (1). The positioning connector (2) and the connector (3) are rotatably installed inside the extension tube (1) through an axial limiting structure. The positioning connector (2) and the connector (3) are detachably arranged. The positioning connector (2) and the connector (3) are provided with an oil passage (11) that communicates with the inner cavity of the extension tube (1).

2. The downhole screw pump rotor limiting device according to claim 1, characterized in that: The axial limiting structure includes a concave annular groove opened circumferentially on the inner wall of the extended tube (1). A left half retaining ring (5) and a right half retaining ring (6) are fitted in the concave annular groove. The lower surfaces of the left half retaining ring (5) and the right half retaining ring (6) abut against the connector (3), and the upper surfaces of the left half retaining ring (5) and the right half retaining ring (6) abut against the positioning connector (2).

3. The downhole screw pump rotor limiting device according to claim 2, characterized in that: The connector (3) is fitted with a bearing ring (4) located above the left half retaining ring (5) and the right half retaining ring (6). The upper surface of the bearing ring (4) abuts against the lower end of the positioning connector (2), and the lower surface of the bearing ring (4) abuts against the upper surfaces of the left half retaining ring (5) and the right half retaining ring (6).

4. The downhole screw pump rotor limiting device according to claim 3, characterized in that: The outer wall of the connector (3) is provided with a shoulder section (13) that abuts against the lower surfaces of the left half retaining ring (5) and the right half retaining ring (6).

5. The downhole screw pump rotor limiting device according to claim 1, characterized in that: The positioning connector (2) has a protruding section (7) with a diameter smaller than the inner diameter of the extension tube (1), and a groove (10) is provided at the upper end of the protruding section (7).

6. The downhole screw pump rotor limiting device according to claim 5, characterized in that: The oil passage (11) includes an inlet hole (8) opened in the protruding section (7) and a channel (11) connected to the inlet hole (8) and passing through the connector (3) vertically.

7. The downhole screw pump rotor limiting device according to claim 6, characterized in that: The outer wall of the protruding section (7) is surrounded by several connecting grooves (9) that are connected to the liquid inlet hole (8).

8. The downhole screw pump rotor limiting device according to claim 6, characterized in that: The connector (3) has an external thread on its outer wall near the upper end, and the lower end of the positioning connector (2) has a threaded groove (12) that connects to the liquid inlet hole (8). The external thread is threadedly connected to the threaded groove (12).

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