A geological drilling casing fishing device

Abstract

This utility model discloses a casing retrieval device for geological drilling, relating to the field of geological drilling accident handling technology. The device includes a connecting pipe with drill pipe joint threads at its upper end, and a casing connector integrally formed at the lower end of the connecting pipe. The inner wall of the casing connector has a spiral inner groove. A casing fixing sleeve is installed inside the casing connector through the spiral outer groove on its outer wall engaging with the spiral inner groove. Several expansion gaps are opened on the side wall of the casing fixing sleeve, and its inner wall has a retrieval internal thread treated with carburizing or nitriding. An anti-disengagement sleeve is fixed near the lower end of the inner wall of the connecting pipe, and the inner wall of the anti-disengagement sleeve has multiple rows of anti-slip pads with right-angled trapezoidal cross-sections. This utility model converts axial force into radial contraction force by rotating the drill string to drive the spiral pair. The device has a reasonable and compact structure, is easy to operate, highly adaptable to fish-top conditions, has a high retrieval success rate and good reliability, and effectively solves the problem of casing retrieval under complex well conditions.

Description

Technical Field

[0001] This utility model relates to the field of geological drilling technology, and in particular to a geological drilling casing retrieval device. Background Technology

[0002] In geological core drilling projects, in-hole accidents are frequent, especially casing breakage and detachment, which seriously affect drilling efficiency and costs. Due to complex geological conditions, phenomena such as borehole collapse and diameter reduction are common, leading to casing jamming, thread damage, or pipe breakage, making it difficult to retrieve using conventional methods. Retrieval operations have become a key technical aspect in handling such in-hole accidents, and their success rate directly affects the drilling cycle and economic benefits.

[0003] Currently, traditional tools such as female cones, male cones, and slip retrieval tubes are commonly used for retrieving fish that have fallen into the casing. These tools have limited functionality, are applicable under demanding conditions, heavily rely on the operator's experience and judgment, and most cannot effectively achieve downhole circulation flushing during the retrieval process, making it difficult to handle annular blockage problems.

[0004] In particular, some integrated fishing devices that have emerged in recent years (such as the type represented by CN223104536U), although attempting to improve fishing adaptability by setting multiple sets of clamping plates and hydraulic drive structures, still have obvious defects: First, their drive structure relies on hydraulic propulsion and electromagnetic locking, which has low reliability in downhole high-pressure, impurity-rich environments and is prone to hydraulic blockage or electrical failure; Second, such devices are highly dependent on the presence of structural features such as screws or steps on the outer wall of the fish, and if the fish body is smooth or severely corroded, it is difficult to achieve effective engagement; Third, they have complex structures, many parts, high manufacturing costs, and insufficient downhole torsional and tensile strength, making it difficult to cope with strong snapping torque and large-tonnage lifting requirements. Therefore, there is an urgent need for a casing fishing device with a reasonable structure, simple operation, reliable fishing, and strong adaptability, which can achieve efficient fishing operations in complex well conditions. Utility Model Content

[0005] The purpose of this invention is to provide a geological drilling casing retrieval device that can overcome the shortcomings of the existing technology.

[0006] To achieve the above objectives, a geological drilling casing retrieval device is provided, including a connecting pipe, the upper end of which is provided with a joint thread for connecting a drill string, and a casing pipe fixedly connected to the lower end of the connecting pipe. A spiral inner groove is fixedly connected to the inner side wall of the casing pipe, and a casing fixing sleeve is movably connected to the casing pipe through the spiral inner groove. The inner side wall of the casing fixing sleeve is provided with a retrieval internal thread. The inner side wall of the sleeve fixing sleeve is provided with several expansion gaps, and the inner side wall of the connecting tube and near the lower side is fixedly connected with an anti-detachment sleeve, and the inner side wall of the anti-detachment sleeve is fixedly connected with several rows of anti-slip pads.

[0007] According to the geological drilling casing retrieval device, a limiting protrusion is fixedly connected to the inner wall of the casing pipe and located directly above the spiral inner groove. The limiting protrusion cooperates with the casing fixing sleeve to effectively limit the vertical movement distance of the casing fixing sleeve.

[0008] According to the geological drilling casing retrieval device, the outer wall of the casing fixing sleeve is provided with a spiral outer groove, which cooperates with the spiral inner groove. The casing pipe installs the casing fixing sleeve on the inner side through the cooperation of the spiral outer groove and the spiral inner groove.

[0009] According to the geological drilling casing retrieval device, the groove cross-section of the spiral inner groove is set as an isosceles triangle, and the vertex angle of the isosceles triangle is set as 10°-20°. When the connecting pipe and the casing pipe are pulled upward, the casing fixing sleeve connected to the casing will undergo relative displacement. The spiral inner groove squeezes the casing fixing sleeve inward, thereby creating a buckle on the outer wall of the casing and improving the connection effect between the casing fixing sleeve and the casing.

[0010] According to the geological drilling casing retrieval device, the cross-section of the anti-slip pad is set as a right-angled trapezoid, with the right-angled waist of the trapezoid facing upwards. When the casing enters the connecting pipe, it contacts the inclined waist surface of the anti-slip pad.

[0011] According to the geological drilling casing retrieval device, the outer side wall of the anti-slip mat is provided with anti-slip texture to improve the anti-slip effect of the anti-slip mat.

[0012] According to the geological drilling casing retrieval device, the retrieval internal thread is configured as a trapezoidal thread groove, and the thread surface of the retrieval internal thread is carburized or nitrided, making it extremely hard and wear-resistant, so as to create a thread on the inner wall of the casing.

[0013] According to the geological drilling casing retrieval device, the connecting pipe and the casing pipe are manufactured using an integral molding technology, which improves the connection strength between the connecting pipe and the casing pipe.

[0014] This utility model has the following beneficial effects: 1. Compared with the prior art, this utility model creatively converts the axial motion of the helical transmission pair into radial contraction motion, so that the sleeve fixing sleeve can actively and controllably contract and bite the fallen fish, with strong and reliable grabbing force, avoiding the excessive dependence of the traditional mother cone on the condition of the fish top.

[0015] 2. Compared with the existing technology, this utility model has set up a dual protection mechanism of "retrieval internal thread grabbing" and "anti-slip pad anti-detachment", which greatly improves the retrieval success rate and safety, and effectively prevents the accident of "retrieval and re-detachment". Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is a schematic diagram of the structure of a geological drilling casing retrieval device according to the present invention; Figure 2 This is a schematic diagram of the casing fixing sleeve structure of a geological drilling casing retrieval device according to the present invention; Figure 3 This is a cross-sectional schematic diagram of a geological drilling casing retrieval device according to the present invention; Figure 4 This is a partial connection diagram of the casing pullback process of a geological drilling casing retrieval device according to the present invention.

[0017] Legend: 1. Connecting pipe; 2. Sleeve pipe; 201. Anti-detachment sleeve; 2011. Anti-slip pad; 202. Spiral inner groove; 3. Sleeve fixing sleeve; 301. Spiral outer groove; 302. Expansion gap; 303. Salvage internal thread. Detailed Implementation

[0018] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0019] Reference Figure 1-4 This utility model discloses a geological drilling casing retrieval device, which includes a connecting pipe 1. The upper end of the connecting pipe 1 is internally machined with standard drill pipe joint threads, such as API standard NC26, NC31, etc., for reliable connection with the drill string. The lower end of the connecting pipe 1 is connected to the casing pipe 2 as a whole through an integral molding technology, ensuring connection strength and being able to withstand huge lifting and torque loads.

[0020] The inner wall of the sleeve 2 is machined with a spiral inner groove 202. The sleeve fixing sleeve 3 is installed inside the sleeve 2 in the form of a threaded pair by engaging the spiral outer groove 301 on its outer wall with the spiral inner groove 202 of the sleeve 2. This engagement allows the sleeve fixing sleeve 3 to move axially and rotationally relative to the sleeve 2 within a certain range.

[0021] The casing fixing sleeve 3 is made of high-strength alloy steel, and its inner sidewall has several evenly spaced expansion gaps 302 along the axial direction, making the casing fixing sleeve 3 an elastic "expansion sleeve". Its inner sidewall is machined with a fishing internal thread 303, which is a trapezoidal thread with higher tensile and shear strength. The thread surface is carburized or nitrided, making it extremely hard and wear-resistant, and can effectively "clip" on the inner wall of the casing.

[0022] A limiting boss is fixedly provided on the inner side wall of the sleeve 2, directly above the spiral inner groove 202. This boss cooperates with the upper end face of the sleeve fixing sleeve 3 to limit the extreme position of the sleeve fixing sleeve 3 to move upward, preventing it from coming out of the sleeve 2.

[0023] In addition, an anti-detachment sleeve 201 is fixedly installed on the inner wall of the connecting pipe 1 near the lower end. Several rows of anti-slip pads 2011 are embedded in the inner wall of the anti-detachment sleeve 201. The cross-section of the anti-slip pad 2011 is a right-angled trapezoid, with its hypotenuse facing downwards to facilitate the introduction of fish, while the right-angled side faces upwards to form an effective anti-slip step. The outer surface of the anti-slip pad 2011 is also processed with anti-slip textures such as a grid or serrated pattern to further increase the friction with the outer wall of the fish-dropping sleeve.

[0024] Working principle: Lowering and introduction: Connect the retrieval device to the lower end of the drill string and lower it to the bottom of the well where it encounters the stuck casing and the top of the fish. Operate the drill string to allow the top of the fish to pass through the anti-dislodgement sleeve 201 and the casing fixing sleeve 3 in sequence. The inclined surface of the anti-slip pad 2011 plays a guiding and correcting role.

[0025] Clamping and Retrieval: Lower the drill string until the top of the fish contacts the retrieval thread 303 inside the casing fixing sleeve 3. Then, assume the right-hand drill string has a conventional right-hand thread. Due to the interaction between the inner spiral groove 202 and the outer spiral groove 301, the right-hand torque causes the casing fixing sleeve 3 to experience a radially inward compressive force generated by the spiral surface as it moves downward. This force forces the casing fixing sleeve 3, with the expansion gap 302, to undergo radial elastic contraction, allowing the retrieval thread 303 on its inner wall to more tightly "bite" and carve into the outer wall of the fish-fallen casing, thus achieving external clamping.

[0026] Lifting and Locking: After the coupling is completed, lift the drill string. Under the lifting force, the casing fixing sleeve 3 tends to move upward relative to the casing tube 2. At this time, the helical pair generates a stronger radial contraction force, making the engagement between the fishing internal thread 303 and the fish more tight, forming a reliable connection. At the same time, the outer wall of the fish-dropping casing will be pulled up to contact the anti-slip pad 2011 inside the anti-slip sleeve 201. The right-angled trapezoidal structure can effectively prevent the fish from slipping off midway, providing double insurance.

[0027] Unless otherwise specified, the constituent units of this utility model are obtained from conventional commercial channels or manufactured by conventional methods. Their specific structure, working principle, and possible control methods and spatial arrangement methods can adopt conventional choices in the field and should not be regarded as the innovation of this utility model. This is understandable to those skilled in the art, and this utility model patent will not be further elaborated in detail.

[0028] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A geological drilling casing fishing device, characterized in that, Includes a connecting pipe (1), the lower end of which is fixedly connected to a sleeve pipe (2), the inner wall of which is fixedly connected to a spiral inner groove (202), the sleeve pipe (2) is movably connected to a sleeve fixing sleeve (3) through the spiral inner groove (202), and the inner wall of the sleeve fixing sleeve (3) is provided with a salvage internal thread (303). The inner side wall of the sleeve fixing sleeve (3) is provided with several expansion gaps (302), and the inner side wall of the connecting pipe (1) and near the lower side is fixedly connected with an anti-detachment sleeve (201), and the inner side wall of the anti-detachment sleeve (201) is fixedly connected with several rows of anti-slip pads (2011).

2. A geological drilling casing fishing device according to claim 1, characterised in that, The inner wall of the sleeve (2) and the upper side of the spiral inner groove (202) are fixedly connected to a limiting protrusion, which cooperates with the sleeve fixing sleeve (3).

3. The geological drilling casing retrieval device according to claim 1, characterized in that, The outer wall of the sleeve fixing sleeve (3) is provided with a spiral outer groove (301), which cooperates with the spiral inner groove (202).

4. A geological drilling casing fishing device according to claim 1, characterised in that, The groove cross-section of the spiral inner groove (202) is set as an isosceles triangle, and the vertex angle of the isosceles triangle is set as 10°-20°.

5. A geological drilling casing fishing device according to claim 1, characterised in that, The cross-section of the anti-slip mat (2011) is set as a right-angled trapezoid, with the right-angled side of the trapezoid facing upwards.

6. A geological drilling casing fishing device according to claim 1, characterised in that, The outer side wall of the anti-slip mat (2011) is provided with anti-slip texture.

7. A geological drilling casing fishing device according to claim 1, characterised in that, The salvage internal thread (303) is configured as a trapezoidal thread groove, and the thread surface of the salvage internal thread (303) is carburized or nitrided.

8. A geological drilling casing fishing device according to claim 1, characterised in that The connecting pipe (1) and the sleeve pipe (2) are made by integral molding technology.

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