A kind of undercut device for replacing casing in underground well

Abstract

The present invention discloses a casing undercut device, which is used for replacing casing in oil and gas wells, and comprises a rotating input shaft (20), wherein the rotating input shaft (20) is connected to a sun gear inputted by a planetary gear reducer (X); the planetary gear reducer (X) comprises a planetary gear for outputting rotation, wherein the planetary gear for outputting rotation is connected to a coupling locator (Y) and a lower anchor (Z); and the inner gear ring (8) of the planetary gear reducer (X) is connected to an upper anchor (Q). The lower anchor (Z) and the upper anchor (Q) are respectively used for fixing relatively to two adjacent sections of undercut casing, and respectively comprise a detachable anchoring structure for fixing to the two adjacent sections of undercut casing. The present invention loosens and detaches the couplings 1 to 2 below the damaged part of the casing, removes the damaged casing, and re-inserts a new casing to buckle with the lower end casing. The present invention does not reduce the diameter of the casing, and the replaced casing has the advantage of a long service life.

Description

Technical Field

[0001] The invention relates to a casing replacement device for a petroleum oil and gas well, and more specifically to an undercut device for casing (limited to wells where the technical casing is not cement-sealed). Background Art

[0002] The casing of oil and gas wells is damaged due to corrosion or external forces, affecting normal production and other engineering operations. Figure 1 As shown, the downhole casing includes a multi-section pipe body 2 which is composed of a plurality of couplings 1 connected in series. In the prior art, when the casing is damaged, the casing is patched or cement is injected outside the casing to repair it. The diameter of the casing after the casing patching is generally 15 to 20 mm smaller than the original inner diameter, which has a great impact on other operations in the later stage. Although the casing is relatively simple to construct, the success rate of repair is low, and it is easy to be damaged again in a short time after repair.

[0003] To this end, the present invention provides a set of operating methods for removing damaged casing for replacement. The problem is that the coupling 1 of the casing in the prior art is welded and fixed, and it is very difficult to remove it from a deep well. To this end, the present invention also uses the planetary gear principle of the prior art, such as Figure 2 The planetary gear shown includes an inner gear ring located on the outside, a sun gear located in the middle, and planetary gears located between the inner gear ring and the sun gear.

[0004] The present invention also uses the prior art of the principle of a planetary gear reducer with more than three stages. For details, please refer to the description of the internal structure of the prior art planetary gear reducer with more than three stages. The specific content of the existing related article is as follows: "When working, the motor is connected to the reducer input device through a coupling to drive the first-stage sun gear, and the sun gear drives the first-stage planetary gear, driving the first-stage planet carrier to rotate around the sun gear axis, thereby driving the second-stage sun gear, and in turn driving the second and third-stage planetary gear transmission mechanisms, and finally the output device outputs the torque. The number of planetary gears in each stage of the planetary gear transmission mechanism can also be more than four." Summary of the invention

[0005] In view of the problem of replacing downhole casing, the present invention utilizes the principle of planetary gears and the principle of planetary gear reducers above three levels to solve the problems of single-use and difficult repair of existing downhole casing. It has the characteristics of convenient replacement operation, high efficiency and low cost. The new casing is re-inserted and fastened with the lower casing, which has the advantages of no reduction in the diameter of the casing and a long service life after replacement.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a casing undercut device, comprising a rotating input shaft, wherein the rotating input shaft is connected to the sun gear of the planetary gear reducer input rotation; the planetary gear reducer comprises a planetary gear for output rotation, and the planetary gear for the rotating output is connected to the coupling locator and the lower anchor; the inner gear ring of the planetary gear reducer is connected to the upper anchor.

[0007] The lower anchor and the upper anchor include a detachable anchoring structure for fixing with the inverted casing, and the lower anchor and the upper anchor are respectively used to fix relatively with two adjacent sections of the inverted casing. Specifically, the anchoring structure can be a method of inserting anchor bolts, or other anchoring or adsorption fixing forms can be selected as needed, but according to the use of oil and gas wells, the present invention preferably uses the structure of the downhole oil production screw pump fixer of Chinese patent CN200610045411.8.

[0008] In a preferred embodiment, a further improvement of the present invention lies in that the coupling locator comprises a tubular locating joint associated with the rotation output of the reducer; a locating ring fixed by a shear pin is sleeved on the outside of the locating joint; a plurality of locating claws are supported at intervals on the outside of the circumference of the locating ring, so that there is a gap between the lower end of the locating claw and the outer surface of the locating joint; the locating claw comprises a plate-like connecting part, and a claw head with an upper outer surface inclined upward and a lower outer surface inclined downward; the upper parts of the plurality of locating claws are connected as a whole and sleeved on the outside of the locating joint, and are located on the upper part of the locating ring and the pin; an annular protrusion with an outer diameter consistent with that of the locating ring is also provided on one side of the claw head of the locating joint, so that in the locating state, the claw head of the locating claw is supported by the annular protrusion and stuck in the coupling between the upper section of the casing and the lower section of the casing at the damaged part of the downhole casing.

[0009] In a preferred embodiment, the present invention is further improved in that the lower anchor and the upper anchor include an anchor claw and a cam device; the cam device includes a central tube associated with a rotation input; the anchor claw is arranged outside the central tube. A friction block radially supported by a spring is also embedded outside the central tube; the friction blocks are arranged in a plurality of intervals around the central tube, and each of the friction blocks is supported in a friction block seat by a plurality of the springs 25.

[0010] The planetary gear reducer includes three stages of planetary gears; the inner gear rings of each stage of planetary gears are a common reducer inner gear ring; the rotation input shaft is connected to the sun gear of the first stage planetary gear; the wheel carrier of the first stage planetary gear planetary gear is relatively fixed to the sun gear of the second stage planetary gear, and the wheel carrier of the second stage planetary gear planetary gear is relatively fixed to the sun gear of the third stage planetary gear; the third stage planetary gear planetary gear is associated with the lower anchoring central tube to realize rotation input.

[0011] The casing undercut device of the present invention is used for casing replacement. The 1-2 couplings below the damaged part of the casing are loosened and unhooked (only limited to the wells where the technical casing is not cemented), the damaged casing is pulled out, and a new casing is put in again to be buckled and tightened with the lower casing. The present invention does not reduce the diameter of the casing, and the replaced casing has the advantage of long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The present invention is a structural schematic diagram of a downhole casing of a petroleum oil and gas well in the prior art.

[0013] Figure 2 It is a structural schematic diagram of the planetary gear principle in the prior art.

[0014] Figure 3 It is a schematic diagram of the overall structure of the undercut device of the present invention.

[0015] Figure 4 It is a schematic diagram of the state in which the undercut device of the present invention is positioned at the damaged position of the casing.

[0016] Figure 5 yes Figure 3 An enlarged structural schematic diagram of the left part of the overall structure is shown.

[0017] Figure 6 yes Figure 3 An enlarged structural schematic diagram of the middle part of the overall structure is shown.

[0018] Figure 7 yes Figure 3 An enlarged structural schematic diagram of the right side of the overall structure shown.

[0019] Figure 8 yes Figure 3 Cross-sectional view at AA and BB in the middle.

[0020] Fig. 9 yes Figure 4 Schematic diagram of the enlarged structure at point C in the middle.

[0021] Fig.10 yes Figure 3 Schematic diagram of the enlarged structure at D in the middle. DETAILED DESCRIPTION

[0022] like Figure 3-7 As shown, the casing undercut device mainly consists of five parts: power input part P, upper anchor Q, reducer X, coupling locator Y, and lower anchor Z.

[0023] The power input part P is a rotating input shaft 20, and the rotating input shaft 20 drives the sun gear 12 of the first-stage planetary gear of the reducer X to rotate.

[0024] The inner gear rings of the planetary gears of each stage of the reducer X are the common inner gear rings 8 of the reducer. In the inverted state, the inner gear ring 8 is relatively fixed to the upper casing section of the downhole casing at the damaged part. Thus, the planetary gear 11 of the first-stage planetary gear moves under the drive of the sun gear 12. The wheel frame of the planetary gear 11 of the first-stage planetary gear is relatively fixed to the sun gear 17 of the second-stage planetary gear, thereby driving the second-stage sun gear 17; similar to the above structure, the sun gear 17 drives the planetary gear 10 of the second-stage planetary gear; the second-stage planetary gear 10 drives the third-stage sun gear 18; the third-stage sun gear 18 drives the third-stage planetary gear 9. The above process is consistent with the principle of the three-stage or more planetary gear reducer in the prior art. Therefore, the present invention can also select multi-stage or one-stage planetary gears according to the above principle to realize the function of the present invention, which is specifically determined according to the output torque and the specific design.

[0025] The planetary gear 9 of the third stage drives the coupling locator Y and the lower anchor Z to move partially. Specifically, the planetary gear 9 of the third stage is connected to and drives the output shaft 7 to rotate, and the output shaft 7 is connected to the tubular positioning joint 6 of the coupling locator Y. The coupling locator Y also includes a positioning ring 5 that is located around the outside of the positioning joint 6, and the positioning ring 5 is fixed to the outside of the positioning joint 6 by a shear pin 4. The shear pin 4 is a formed product of the prior art and will be disconnected and fixed under shear force. The outer side of the positioning ring 5 supports a plurality of positioning claws 3 at intervals on the circumference, so that there is an elastic gap (such as the right side in the figure) between the lower end of the positioning claw 3 and the outer surface of the positioning joint 6. Fig.10 As shown in the figure, the state of the coupling locator before positioning). The positioning claw 3 includes a plate-shaped connecting portion, and a claw head whose upper outer surface is inclined upward and whose lower outer surface is inclined downward. The lower outer surface of the claw head is inclined downward, so that the positioning claw 3 can enter the downhole casing more easily. Fig. 9 As shown, the claw head, which is formed by the upper outer surface being inclined upward and the lower outer surface being inclined downward, is just stuck at the collar 1 between the upper casing 2 and the lower casing 2 at the damaged part of the downhole casing in the positioning state. In addition, as shown in the figure, the upper parts of the plurality of positioning claws 3 are connected as a whole and sleeved on the outside of the positioning joint, and are located on the upper part of the positioning ring 5 and the pin 4 (on the left side in the figure); Fig. 9 and Fig.10 As shown, an annular protrusion 26 having an outer diameter substantially identical to that of the positioning ring 5 is also provided on one side of the positioning joint 6, so that in the positioning state, the claw head of the positioning claw 3 is supported by the annular protrusion 26 and is stuck at the coupling 1 between the upper section casing 2 and the lower section casing 2 at the damaged part of the downhole casing.

[0026] The positioning process of the positioning claw 3 is as follows: first, when the positioning claw 3 does not enter the downhole casing, Fig.10After entering the downhole casing, the claw head abuts against the positioning joint 6; when the claw head reaches the coupling 1 between the upper casing 2 and the lower casing 2 at the damaged part of the downhole casing, it pops out and gets stuck at the coupling 1 between the upper casing and the lower casing. At this time, it is necessary to lift the undercut device of the present invention, so that under the clamping action of the claw head, the positioning claw 3 is relatively displaced relative to the positioning joint 6 until Fig. 9 and then continue to pull the force of the undercut device claw head will act on the upper end of the undercut device through the positioning ring 5 and the pin 4, so that the positioning can be judged by the force whether it is accurate.

[0027] The positioning ring 5 and the pin 4 have another function, that is, when the undercut is completed, the upper casing of the damaged part of the downhole casing is separated from the lower casing at the coupling. At this time, the undercut assembly is pulled by lifting. Fig. 9 In the state shown, the lifting is continued, and under a greater shear force, the shear pin 4 is cut off; the positioning claw 3 continues to have a relative displacement with the positioning joint 6, so that the claw head of the positioning claw is Fig. 9 The right side position of the annular protrusion 26 can be elastically contracted toward the surface of the positioning joint 6, so that the undercut device can be taken out from the downhole casing under the premise that the anchor Q and the lower anchor Z are reversed and released.

[0028] The upper anchor Q and the lower anchor Z can use the anchor structure of the prior art, such as Figure 8 As shown, it includes an anchor claw 13 and a cam device 22. For specific prior art, reference may be made to the structure of a downhole oil production screw pump fixer in Chinese patent CN200610045411.8. Moreover, the anchoring structure of the patent may also be used in the present invention.

[0029] The cam device 22 of the upper anchor Q includes a central tube 14 sleeved on the outside of the rotating input shaft 20; the outer side of the central tube 14 is provided with an anchor claw 13 in the manner of an anchor structure of the prior art. Moreover, the central tube 14 is also fixedly connected to the reducer inner gear ring 8, as shown in FIG. Figure 6 shown.

[0030] Figure 6 A friction block 15 radially supported by a spring 25 is embedded on the outside of the central tube 14, which is located above the anchor claw 13 (left side in the figure). After entering the downhole casing, the friction block 15 is supported by the outer side of the spring against the inner wall of the casing, so that the central tube 14 fixed with the friction block 15 and the anchor claw 13 of the upper anchor Q rotate relative to each other, thereby realizing the anchoring function. The anchor claw, friction block and central tube of the lower anchor Z are arranged in the same way, but the rotation direction is opposite.

[0031] Among them, Figure 5 , 6 The shaded parts in 7 correspond to the relatively fixed parts during the undercut operation. Figure 5The shaded portion is the rotation input portion of the rotation input shaft 20, which is used to bring the sun gear 12 of the first-stage planetary gear to rotate.

[0032] When working in reverse, Figure 6 The shaded part of is the relatively fixed part with the upper casing section where the downhole casing is damaged; it should be noted that the reducer inner gear ring 8 is relatively fixed with the upper casing section where the downhole casing is damaged, that is, Figure 3 The anchor claw 13 is relatively fixed to the upper casing at AA, and the anchor claw 13 is relatively fixed to the reducer inner gear ring 8 through a certain connection.

[0033] Figure 7 The shaded part of the well casing is relatively fixed to the lower casing section where the casing is damaged during the reverse operation; that is, Figure 3 The anchor claw 13 is relatively fixed to the upper casing at the BB position, and the anchor claw 13 is relatively fixed to the reducer inner gear ring 8 through a certain connection.

[0034] and Figure 5 , 6 The components in the shaded areas in 7 can be fixed relative to each other by the prior art connection methods such as pins, keys, screws, etc., or by snap-fitting, embedding, etc., or by transition connecting rings, connecting columns, etc. The connection and fixing structure can be designed according to specific requirements. In addition, Figure 3-7 The device shown should be in a vertical position with the right side down in actual use.

[0035] Working principle of the present invention:

[0036] The casing reverse buckle device is lowered into the casing to the predetermined position, and the coupling locator Y can be positioned at the position of the casing coupling, so that the upper anchor Q and the reducer X are above the coupling. The lower anchor Z is below the coupling. The drill pipe connected in the forward rotation will transmit the input torque of the rotating input shaft 20 to the reducer, so that the lower anchor Z rotates forward, while the upper anchor Q rotates in the reverse direction. The lower anchor Z rotates forward and the upper anchor Q rotates in reverse, and then they are anchored to the inner wall of the casing one after another. The drill pipe is continuously rotated (input torque). When the torque reaches the loosening torque of the coupling thread and the casing thread, the buckle is started. The torque of the rotating drill pipe (input torque) will gradually decrease with the increase of the reverse opening number until the casing thread is completely loosened.

[0037] The following is a construction example of the device of the present invention.

[0038] 1. Casing damage location and well cleaning:

[0039] Accurately measure the damaged position of the casing, determine the approximate shackle position (to avoid the upper anchor being anchored on the damaged casing, it is generally shattered between the first and second anchors below the damaged casing), lower the well gauge (51 / 2″-φ117*2000, 7″-φ153*2000) and smoothly pass 40 meters below the damaged position of the casing, and pull out the well gauge.

[0040] 2. Inspection before entering the well:

[0041] Verify whether the thread connection between the drill pipe and the casing undercut device matches. If not, use a variable joint to make a transition connection. Measure the drill pipe and record it accurately. The anchor claws of the upper and lower anchors can be smoothly rotated out and retracted. The positioning claws of the coupling locator have no defects such as missing, cracks, and severe wear. The reducer rotates smoothly without jamming, and the connection between the various tools is not loose.

[0042] 3. Tools entering the well:

[0043] When the operating equipment hoists the tool, it should be lifted slowly. Before introducing the wellhead casing, retract the anchor claw and slowly lower it. When the coupling locator enters the casing, straighten the introduced locator claw until it enters the casing smoothly. Connect the drill pipe and lower the tool 30 meters below the casing damage position. The lowering speed should be controlled within 20 meters / min, and the suspended weight of the drill string should be recorded. Note: When connecting each drill pipe thread, ensure that the hydraulic tongs backing tongs do not slip and rotate, because when the anchor rotates in the pipe string, the anchor claw will rotate out and get stuck on the inner wall of the casing. If there is a jam or resistance during the lowering process, it can be reversed appropriately, and the drill pipe can be slightly raised and lowered until the jam is eliminated.

[0044] 4. Coupling positioning:

[0045] Slowly lift up the casing inverted device and observe the hanging weight of the pipe string. If it increases, slow down the lifting speed. When the hanging weight increases by 4 to 5 tons, it can be confirmed that the casing locating claws are stuck in the coupling position and the drill string is lowered to the original hanging weight.

[0046] 5. Reverse operation:

[0047] Fix the tail of the hydraulic pliers to the stand of the work vehicle with a wire rope ≥16mm, ensure that the wire rope is clamped tightly, and connect the hydraulic pliers operating handle with a hemp rope of appropriate length for operation. Pay attention to personnel safety during operation. Rotate the drill pipe in the forward direction to observe the torque change. The increase in torque (usually 10 to 20 weeks) indicates that the upper and lower anchors have been anchored. Continue to rotate the drill pipe and observe whether the wellhead casing has signs of reverse rotation. If there is a reverse phenomenon, it means that the casing coupling has begun to loosen. After loosening, continue to reverse the casing for more than 25 weeks and stop rotating the drill pipe. During this process, it can be seen that the torque of the drill pipe gradually decreases. Lift the casing column to confirm that the casing coupling is completely reversed. After confirming that the casing coupling is completely reversed, lower the casing column.

[0048] 6. Extraction tools:

[0049] Lift the drill string to release the locating claws of the coupling locator, and then you can pull out the tool. The speed of lifting the drill bit should be controlled within 20 m / min to avoid damaging the locating claws due to excessive speed, causing the locating claws to fall and jam the tool.

[0050] 7. Tool maintenance and care:

[0051] After the casing undercut device is removed, the tool should be maintained and serviced as soon as possible to prevent the tool from rusting. During maintenance, each component should be inspected and the damaged or severely worn components should be replaced and repaired.

[0052] 8. Replace the casing:

[0053] The inverted casing is lifted out, and it is decided whether to replace all or part of it according to the corrosion and strength damage of the casing. The new casing is then fastened and tightened, and then subjected to internal pressure test. After passing the test, it is accepted and handed over to the well.

[0054] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A down-hole casing replacement device, characterized in that: It comprises a rotating input shaft (20), wherein the rotating input shaft (20) is connected to a sun wheel of a planetary gear reducer (X) for inputting rotation; The planetary gear reducer (X) comprises a planetary wheel for outputting rotation, and the planetary wheel for outputting rotation is connected to a coupling locator (Y) and a lower anchor (Z); The inner gear ring (8) of the planetary gear reducer (X) is connected to the upper anchor (Q); The lower anchor (Z) and the upper anchor (Q) are respectively used to relatively fix with two adjacent sections of the inverted casing, and respectively include a detachable anchoring structure for fixing with the two adjacent sections of the inverted casing; The coupling locator (Y) comprises a tubular locating joint (6) associated with the rotation output of the reducer (X); The positioning joint (6) is externally sleeved with a positioning ring (5) fixed by a shear pin (4); the positioning ring (5) supports a plurality of positioning claws (3) at intervals on the outer side of the circumference, so that a gap exists between the lower end of the positioning claw (3) and the outer surface of the positioning joint (6); The positioning claw (3) comprises a plate-shaped connecting part and a claw head with an upper outer surface inclined upward and a lower outer surface inclined downward; the upper parts of the plurality of positioning claws (3) are connected as a whole and sleeved on the outside of the positioning joint (6), and are located on the upper part of the positioning ring (5) and the pin (4); the positioning joint (6) is also provided with an annular protrusion (26) with an outer diameter consistent with that of the positioning ring (5) on one side of the claw head, so that in the positioning state, the claw head of the positioning claw (3) is supported by the annular protrusion (26) and is stuck in the coupling between the upper casing and the lower casing at the damaged part of the downhole casing; The lower anchor (Z) and the upper anchor (Q) comprise an anchor claw and a cam device; the cam device comprises a central tube associated with a rotation input; the anchor claw (13) is arranged outside the central tube; A friction block (15) radially supported by a spring (25) is also embedded outside the central tube (14); a plurality of friction blocks (15) are arranged at intervals around the central tube (14), and each of the friction blocks (15) is supported in a friction block seat by a plurality of the springs (25).

2. The undercut device for replacing casing in a well according to claim 1 is characterized in that: The planetary gear reducer (X) comprises three stages of planetary gears; the inner gear rings of each stage of the planetary gears are a common reducer inner gear ring (8); the rotating input shaft (20) is connected to the sun gear (12) of the first stage of the planetary gears; The wheel carrier of the first-stage planetary gear (11) is relatively fixed to the sun gear (17) of the second-stage planetary gear, and the wheel carrier of the second-stage planetary gear (10) is relatively fixed to the sun gear (18) of the third-stage planetary gear; the third-stage planetary gear (9) is associated with the central tube (14) for realizing rotation input of the lower anchor (Z).

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