Screw pump capable of throwing and fishing and throwing and fishing method thereof

Abstract

The invention relates to a screw pump capable of being thrown and fished and a throwing and fished method thereof. The screw pump capable of being thrown and fished comprises an oil pipe fitting, an overhead limiter and a stator which are connected in sequence, and further comprises a sucker rod, an adjusting shaft and a rotor which are connected in sequence; the throwing and fishing assembly is arranged in the oil pipe fitting, so that the rotor and the sucker rod can be thrown and bailed separately, the size of the rotor is not limited by the oil pumping pipe and an overhead limiter any more, a stator and a rotor with the large pump diameter can still be used in a thin shaft with the small diameter or a high-yield well, and therefore the displacement is increased, and the oil exploitation efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of screw pump technology, and in particular to a retrieval-capable screw pump and its retrieval method. Background Technology

[0002] As oil fields continue to be developed, well conditions are becoming increasingly complex, with a growing number of directional wells, horizontal wells, and highly deviated wells. Under different environments, the diameter of the well casing also varies. In some narrow-diameter wells, traditional screw pumps are limited by the structural dimensions of internal components, resulting in smaller stator and rotor diameters.

[0003] For example, patent CN118128749A discloses a bottom-mounted submersible screw pump unit. During well installation, the external structures such as tubing, positioner, and stator are first deployed downhole. Then, the internal structures, including the sucker rod and rotor, are fixed in place and sequentially lowered downhole through the external structures, allowing the rotor to engage with the stator. Because the rotor needs to pass through the tubing and positioner, its maximum radial dimension must be smaller than the inner diameter of the tubing and positioner, limiting crude oil discharge and resulting in poor oil production.

[0004] Therefore, we propose a retrieving screw pump and its retrieving method. Summary of the Invention

[0005] In response to the shortcomings of the prior art mentioned above, the applicant provides a retrieval-capable screw pump and its retrieval method, which can effectively increase crude oil discharge and improve pump efficiency.

[0006] The technical solution adopted in this invention is as follows:

[0007] In a first aspect, the present invention discloses a retrievable screw pump, comprising an oil pipe fitting 1, an upper limiter 2, and a stator 3 connected in sequence; the oil pipe fitting 1 is provided with a sucker rod 4 and a retrievable assembly 5, the sucker rod 4 is connected to an adjusting shaft 6 through the retrievable assembly 5; the adjusting shaft 6 is fixedly connected to a rotor 7; the upper limiter 2 is used for load-bearing and limiting, so that the rotor 7 rotates within the stator 3 at a set position to achieve oil extraction.

[0008] Further technical solutions include that the fishing and retrieval assembly 5 includes a docking screw 501 and a docking nut 502, and the docking screw 501 and the docking nut 502 are connected by a transmission thread.

[0009] Further technical solutions include n annularly arranged protrusions 5021 on the outer wall of the mating nut 502.

[0010] Further technical solutions include that the launching and retrieval assembly 5 also includes a positioning ring 503 fixed to the inner wall of the oil pipe fitting 1. The positioning ring 503 has n annularly arranged slots 5031. The slots 5031 cooperate with the protrusions 5021 to fix the position of the rotor 7 after lifting the rotor 7.

[0011] Further technical solutions include: the head end of the connecting screw 501 is provided with a stepped hole, and the stepped hole is provided with an internal thread 5011 for connecting the sucker rod 4; the screw end of the connecting screw 501 is provided with an external transmission thread 5012 for connecting the connecting nut 502.

[0012] The further technical solution includes that the docking nut 502 has a through hole, and one end of the through hole has an internal transmission thread 5022 for connecting the docking screw 501; the other end of the through hole has an internal thread 5023 for connecting the adjusting shaft 6.

[0013] A further technical solution includes that the docking nut 502 has at least one radial hole 5024, which is connected to a through hole to balance the pressure difference between the inside and outside of the docking nut 502.

[0014] Secondly, this invention discloses a screw pump deployment and retrieval method, comprising deploying a deployable screw pump:

[0015] S110, sequentially lower stator 3, rotor 7, adjusting shaft 6, upper limiter 2, and tubing fitting 1 to the set well depth;

[0016] S120, lower the sucker rod 4 until the connecting screw 501 at the lower end of the sucker rod 4 is connected to the connecting nut 502 at the upper end of the adjusting shaft 6.

[0017] Thirdly, this invention discloses a screw pump retrieval method, including retrieving a retrievalable screw pump:

[0018] A110, rotate the sucker rod 4 to separate the connecting screw 501 from the connecting nut 502;

[0019] A120, sequentially lift the sucker rod 4, oil pipe fitting 1, upper limit switch 2, adjusting shaft 6, rotor 7, and stator 3.

[0020] Fourthly, this invention discloses a screw pump deployment and retrieval method, comprising retrieving a deployable screw pump:

[0021] A210, lift the sucker rod 4 until the protrusion 5021 on the docking nut 502 engages with the groove 5031 on the positioning ring 503, so that the docking nut 502 and the positioning ring 503 are relatively fixed.

[0022] A220, rotate the sucker rod 4 to separate the connecting screw 501 from the connecting nut 502;

[0023] A230, sequentially lift the sucker rod 4, oil pipe fitting 1, upper limit switch 2, adjusting shaft 6, rotor 7, and stator 3.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention connects the tubing, the upper limiter, and the stator in sequence, and designs a casting and retrieval assembly inside the tubing, allowing the rotor to be cast and retrieved separately from the sucker rod. The rotor size is no longer limited by the sucker pipe and the upper limiter. In small wellbores with smaller diameters or in high-yield wells, stators and rotors with larger pump diameters can still be used, thereby increasing the discharge capacity and improving oil extraction efficiency.

[0026] The deployment and retrieval assembly designed in this invention includes a connecting screw and a connecting nut, with the connecting screw and the connecting nut connected by a transmission thread. When deploying the screw pump, the connecting screw can engage with the connecting nut downhole under the weight of the sucker rod and the pulling force of the lifting device; when retrieving the screw pump, due to the characteristics of the transmission thread structure, it can be easily disengaged by simply reversing the rotation, which is highly efficient and convenient, greatly reducing the difficulty of downhole assembly.

[0027] The retrieval assembly of the present invention also includes a positioning ring, which is fixed inside the tubing. During well dismantling, the connecting nut is fixed inside the positioning ring by lifting the sucker rod, and at the same time the rotor is disengaged from the stator, the channel is enlarged, and the crude oil mixture that was originally stuck in the tubing can fall down, which facilitates the subsequent retrieval of the screw pump.

[0028] The positioning ring in the launch and retrieval assembly of the present invention can also be used for steam injection. Before steam injection, the positioning ring is used to fix the position of the sucker rod after it is lifted, so that the injected high-temperature gas can pass smoothly through the screw pump, realizing the integration of injection and production, greatly simplifying the steam injection process and improving the steam injection efficiency. Attached Figure Description

[0029] Figure 1 This is the front view of the present invention.

[0030] Figure 2 yes Figure 1 A sectional view of section AA in the middle.

[0031] Figure 3 This is a schematic diagram of the connecting screw in this invention.

[0032] Figure 4 This is the front view of the connecting screw in this invention.

[0033] Figure 5 yes Figure 4 A sectional view of section BB in the middle.

[0034] Figure 6This is a schematic diagram of the structure of the docking nut in this invention.

[0035] Figure 7 This is the front view of the mating nut in this invention.

[0036] Figure 8 yes Figure 7 A sectional view of section CC.

[0037] Figure 9 This is a schematic diagram of the positioning ring in this invention.

[0038] Figure 10 This is an assembly diagram of the casting and retrieval components in this invention.

[0039] The components include: 1. Oil pipe fittings; 101. Oil pipe one; 102. Oil pipe two; 2. Upper-mounted limit switch; 3. Stator; 4. Sucker rod; 5. Fishing assembly; 501. Connecting screw; 5011. Internal thread one; 5012. External drive thread; 502. Connecting nut; 5021. Protrusion; 5022. Internal drive thread; 5023. Internal thread two; 5024. Radial hole; 503. Positioning ring; 5031. Slot; 6. Adjusting shaft; 7. Rotor; 8. Eccentric tube; 9. Eccentric rod. Detailed Implementation

[0040] The specific embodiments of this application are described below with reference to the accompanying drawings.

[0041] Example 1

[0042] like Figure 1 As shown, this embodiment discloses a deployable screw pump for oilfield development. Its structure includes a tubing component 1, an upper-mounted limiter 2, and a stator 3 connected in sequence. The oil well has a pre-installed casing. The deployable screw pump of this invention is located inside the casing; therefore, the design must ensure that the outer diameter of each component is smaller than the inner diameter of the casing.

[0043] like Figure 2 As shown, the oil pipe fitting 1 of the present invention is provided with a sucker rod 4 and a casting and retrieval assembly 5. The sucker rod 4 is connected to the adjustment shaft 6 through the casting and retrieval assembly 5. The adjustment shaft 6 is fixedly connected to the rotor 7. The upper limiter 2 is used for load-bearing limit, so that the rotor 7 rotates in the stator 3 at a set position to realize oil extraction.

[0044] Optionally, the upper limiter also engages with the adjusting shaft 6 via a thread to adjust the relative position of the rotor 7 and the stator 3, thereby adjusting the stator-rotor gap.

[0045] In practical use, the present invention also includes a lifting device and a motor for driving the rotor 7 to rotate. The lifting device is used to control the raising and lowering of the sucker rod 4 and adjust the stator-rotor gap; the motor is used to provide rotational driving force for the rotor 7.

[0046] Optionally, the dredging screw pump of the present invention further includes an eccentric tube 8 and an eccentric rod 9 located inside the eccentric tube 8; one end of the eccentric tube 8 is connected to the upper limiter 2 and the other end is connected to the stator 3; one end of the eccentric rod 9 is connected to the adjusting shaft 6 and the other end is connected to the rotor 7, which is used to eliminate eccentricity while transmitting rotational driving force.

[0047] In this embodiment, the casting and retrieval assembly 5 includes a docking screw 501 and a docking nut 502, and the docking screw 501 and the docking nut 502 are connected by a transmission thread.

[0048] Optionally, the drive thread may be a rectangular thread.

[0049] like Figure 3-5 As shown, the head end of the connecting screw 501 is provided with a stepped hole, and the stepped hole is provided with an internal thread 5011 for connecting the sucker rod 4; the screw end of the connecting screw 501 is provided with an external drive thread 5012 for connecting the connecting nut 502.

[0050] like Figure 6-8 As shown, the outer wall of the docking nut 502 has n annularly arranged protrusions 5021. The docking nut 502 has a through hole, and one end of the through hole has an internal drive thread 5022 for connecting the docking screw 501; the other end of the through hole has an internal thread 5023 for connecting the adjusting shaft 6.

[0051] Optionally, both internal thread 1 (5011) and internal thread 2 (5023) are made of ordinary thread.

[0052] To prevent excessive pressure within the mating nut 502 during the engagement of the screw 501 and nut 502, thus ensuring a proper fit, the nut 502 has at least one radial hole 5024. This radial hole 5024 connects to a through hole to balance the pressure difference between the inside and outside of the nut 502. Optionally, there is also a section of unmachined threaded through hole between the internal drive thread 5022 and the second internal thread 5023, with the radial hole 5024 axially positioned within this section of unmachined threaded through hole.

[0053] Optionally, the contact surfaces of the mating screw 501 and the mating nut 502 are mutually matching annular ramp steps to limit the engagement of the transmission threads.

[0054] In this embodiment, as Figure 9 , 10 As shown, the launching and retrieval assembly 5 also includes a positioning ring 503 fixed to the inner wall of the oil pipe fitting 1. The positioning ring 503 has n annularly arranged slots 5031. The slots 5031 cooperate with the protrusions 5021 to fix the position of the rotor 7 after lifting the rotor 7.

[0055] Depend on Figure 9 As can be seen, during the process of entering the slot 5031, the protrusion 5021 first slides into the cavity with a smaller inlet diameter along one side of the downward sloping line segment distributed in a figure-eight shape, and then slides to the highest point in the slot 5031 along the upward sloping line segment; after the sucker rod 4 falls, the protrusion 5021 will sit on the horizontal line segment of the slot 5031 cavity, thereby limiting the sucker rod 4 and the rotor 7.

[0056] The larger the value of n, the smaller the axial force borne by each protrusion 5021. For example, n=3, meaning there are 3 pairs of protrusions 5021 that engage with the slots 5031. In addition, to ensure that the protrusions 5021 can smoothly enter the cavity of the slots 5031 when rotated to any angle, the downward sloping line segments of two adjacent slots 5031 are designed to connect.

[0057] Optionally, the tubing fitting 1 includes tubing one 101 and tubing two 102. Tubing one 102 is the tubing that comes with the oil well in the oil field, and it is usually hundreds to thousands of meters long; tubing two 102 is several meters long, and the positioning ring 503 of the present invention is fixed to the inner wall of tubing two 102.

[0058] Example 2

[0059] This embodiment discloses a screw pump deployment and retrieval method, which includes deploying the deployable screw pump disclosed in Embodiment 1, and the specific steps include:

[0060] S110, the stator 3, rotor 7, adjusting shaft 6, upper limiter 2, and tubing fitting 1 are lowered sequentially to the set well depth.

[0061] S120, lower the sucker rod 4 until the connecting screw 501 at the lower end of the sucker rod 4 is connected to the connecting nut 502 at the upper end of the adjusting shaft 6.

[0062] In actual well loading operations, clamping assemblies are provided at the wellhead to hold the various components of the screw pump tightly, facilitating assembly. For example, the stator 3 is clamped using the clamping assembly, then the rotor 7 is placed inside the stator 3, and the adjusting shaft 6 is fixedly connected to the rotor 7; the upper limiter 2 is placed over the adjusting shaft 6 and lowered down, and after the upper limiter 2 contacts the stator 3, the two are fixedly connected, and the whole assembly is lowered down, with the clamping assembly holding the upper limiter 2 tightly. This process is repeated until all components of the screw pump are lowered down.

[0063] In one embodiment, when the retrieval screw pump of the present invention includes an eccentric tube 8 and an eccentric rod 9, after the stator 3 is lowered and before the upper limiter 2 is lowered, the eccentric tube 8 needs to be lowered, and after the rotor 7 is lowered and before the adjusting shaft 6 is lowered, the eccentric rod 9 needs to be lowered.

[0064] Example 3

[0065] This embodiment discloses a screw pump retrieval method, which includes retrieving the retrievalable screw pump disclosed in Embodiment 1, and the specific steps include:

[0066] A110, rotate the sucker rod 4 to separate the connecting screw 501 from the connecting nut 502.

[0067] Because the connecting screw 501 and the connecting nut 502 are connected by a transmission thread, and transmission threads are easier to loosen when rotating in the opposite direction compared to ordinary threads, the fit is more flexible. Therefore, when rotating the sucker rod 4, although the connecting screw 501 and the sucker rod 4, and the connecting nut 502 and the adjusting shaft 6 are also threaded connections, the function of these two pairs of threaded connections is to tighten them and they will not easily come apart.

[0068] A120, sequentially lift the sucker rod 4, oil pipe fitting 1, upper limit switch 2, adjusting shaft 6, rotor 7, and stator 3.

[0069] In one embodiment, when the retrieval screw pump of the present invention includes an eccentric tube 8 and an eccentric rod 9, after lifting the upper limiter 2 and before lifting the stator 3, the eccentric tube 8 needs to be lifted, and after lifting the adjusting shaft 6 and before lifting the rotor 7, the eccentric rod 9 needs to be lifted.

[0070] Example 4

[0071] This embodiment discloses a screw pump retrieval method, which includes retrieving the retrievalable screw pump disclosed in Embodiment 1, and the specific steps include:

[0072] A210, lift the sucker rod 4 until the protrusion 5021 on the docking nut 502 engages with the groove 5031 on the positioning ring 503, so that the docking nut 502 and the positioning ring 503 are relatively fixed.

[0073] A220, rotate the sucker rod 4 to separate the connecting screw 501 from the connecting nut 502.

[0074] A230, sequentially lift the sucker rod 4, oil pipe fitting 1, upper limit switch 2, adjusting shaft 6, rotor 7, and stator 3.

[0075] This embodiment adds step A210 to embodiment three. This step is mainly to lift the rotor 7 to separate it from the stator 3. In actual well dismantling, the motor must first be stopped. After stopping, a large amount of crude oil mixture remains in the tubing. Due to the small gap between the stator and rotor, this crude oil mixture usually has difficulty falling. By separating the stator and rotor through step A210 in this embodiment, the oil passage is enlarged, which can discharge the crude oil mixture in the screw pump, making subsequent well dismantling easier.

[0076] Furthermore, step A210 of this embodiment can also be used before steam injection. During steam injection in an oil well, the maximum temperature can reach 350°C. When the stator and rotor are tightly fitted, high-temperature gas has difficulty passing through the narrow gap between them, thus preventing steam injection. Raising the rotor 7 before steam injection increases the passageway, facilitating the passage of high-temperature gas and enabling steam injection.

[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A dredging screw pump, characterized in that, It includes an oil pipe fitting (1), an upper limiter (2) and a stator (3) connected in sequence; the oil pipe fitting (1) is provided with a sucker rod (4) and a casting and retrieval assembly (5), and the sucker rod (4) is connected to an adjusting shaft (6) through the casting and retrieval assembly (5); the adjusting shaft (6) is fixedly connected to the rotor (7); the upper limiter (2) is used for load-bearing and limiting, so that the rotor (7) rotates in the stator (3) at a set position to realize oil extraction.

2. The dredging screw pump according to claim 1, characterized in that, The launching and retrieval assembly (5) includes a docking screw (501) and a docking nut (502), and the docking screw (501) and the docking nut (502) are connected by a transmission thread.

3. The dredging screw pump according to claim 2, characterized in that, The outer wall of the docking nut (502) is provided with n annularly arranged protrusions (5021).

4. The dredging screw pump according to claim 3, characterized in that, The launching and retrieval assembly (5) also includes a positioning ring (503) fixed to the inner wall of the oil pipe fitting (1). The positioning ring (503) has n annularly arranged slots (5031). The slots (5031) cooperate with the protrusions (5021) to fix the position of the rotor (7) after lifting the rotor (7).

5. The dredging screw pump according to claim 2, characterized in that, The head end of the docking screw (501) is provided with a stepped hole, and the stepped hole is provided with an internal thread (5011) for connecting the sucker rod (4); the screw end of the docking screw (501) is provided with an external transmission thread (5012) for connecting the docking nut (502).

6. The dredging screw pump according to claim 2, characterized in that, The docking nut (502) has a through hole, and one end of the through hole has an internal drive thread (5022) for connecting the docking screw (501); the other end of the through hole has an internal thread (5023) for connecting the adjusting shaft (6).

7. The dredging screw pump according to claim 5, characterized in that, The docking nut (502) has at least one radial hole (5024), which is connected to the through hole and is used to balance the pressure difference between the inside and outside of the docking nut (502).

8. A screw pump method for launching and retrieving fish, characterized in that, The method for retrieving the deployable screw pump of claim 2 includes deploying the deployable screw pump: S110, the stator (3), rotor (7), adjusting shaft (6), upper limiter (2), and tubing (1) are lowered sequentially to the set well depth; S120, lower the sucker rod (4) until the connecting screw (501) at the lower end of the sucker rod (4) is connected to the connecting nut (502) at the upper end of the adjusting shaft (6).

9. A screw pump method for launching and retrieving fish, characterized in that, For retrieving the retrievalable screw pump of claim 2, the retrieval method includes retrieving the retrievalable screw pump: A110, rotate the sucker rod (4) to separate the connecting screw (501) from the connecting nut (502); A120, sequentially lift the sucker rod (4), oil pipe fitting (1), upper limiter (2), adjusting shaft (6), rotor (7), and stator (3).

10. A screw pump method for launching and retrieving fish, characterized in that, For retrieving the retrievalable screw pump of claim 4, the retrieval method includes retrieving the retrievalable screw pump: A210, lift the sucker rod (4) until the protrusion (5021) on the docking nut (502) engages with the groove (5031) on the positioning ring (503), so that the docking nut (502) and the positioning ring (503) are fixed relative to each other; A220, rotate the sucker rod (4) to separate the connecting screw (501) from the connecting nut (502); A230, sequentially lift the sucker rod (4), oil pipe fitting (1), upper limiter (2), adjusting shaft (6), rotor (7), and stator (3).

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