Rotatable telescoping nipple, acid fracturing completion tubing string, and acid fracturing completion method

Abstract

The application discloses a rotatable telescopic short section, which comprises a longitudinally extending core shaft, a body sealedly sleeved outside the core shaft, and a connecting mechanism connecting the core shaft and the body with each other. The connecting mechanism comprises a connecting body fixedly connected with the body, and a torque transmission member fixedly connected with the connecting body. The torque transmission member is configured to be connected with the core shaft through a shear pin and a longitudinally arranged key groove assembly in an initial state, to be movable along the longitudinal direction after the shear pin is sheared by stress borne by the rotatable telescopic short section in a first state, and to be capable of transmitting a rotating torque from the body to the core shaft through the key groove assembly in a second state in which rotation is required. The rotatable telescopic short section can be used to compensate for the contraction of a well completion pipe string, and can realize the function of rotating torque transmission, thereby meeting the requirement of handling abnormal conditions on site. The application further discloses an acid fracturing well completion pipe string and an acid fracturing well completion method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil production, in particular to a rotatable telescopic nipple, an acid fracturing completion pipe string comprising the same, and an acid fracturing completion method using the same. BACKGROUND

[0002] In the process of oil and gas production, acid fracturing is a very effective stimulation method, and the stimulation effect is more obvious for carbonate reservoirs. Generally, a packer needs to be arranged above the reservoir for acid fracturing. In order to achieve the purpose of stimulation, the acid liquid is usually made to enter the production layer smoothly by the packer before fracturing. However, when the normal temperature acid liquid is injected into the wellbore, a temperature difference is formed between the well temperature and the acid liquid temperature, thereby generating an additional tensile force on the packer. The tensile force will cause the contraction of the entire completion pipe string, so that the packer is prematurely unhooked or lost, thereby affecting the stimulation effect under acid fracturing.

[0003] In the prior art, a common way is to install a telescopic nipple at the upper end of the packer. When the additional tensile force is generated in the wellbore due to the temperature difference, the telescopic nipple compensates for the contraction of the entire completion pipe string by means of automatic telescoping. In this case, the packer no longer bears the additional tensile load, thereby ensuring the sealing performance of the packer.

[0004] However, in the actual process of oil and gas production, the telescopic nipple is not suitable for some packers that need to be unhooked and unsealed by rotation. Therefore, at present, there is no telescopic nipple that can both unhook and unseal the packer by telescoping and rotate. SUMMARY

[0005] The present application aims to provide a rotatable telescopic nipple, which can be used to compensate for the contraction of the completion pipe string and can also realize the function of rotating torque transmission, thereby meeting the needs of handling abnormal situations. The present application also aims to provide an acid fracturing completion pipe string and an acid fracturing completion method.

[0006] According to a first aspect of the present application, a rotatable telescopic nipple is provided, comprising a longitudinally extending core shaft, a body telescopically sleeved on the outside of the core shaft, and a connecting mechanism connecting the core shaft and the body to each other, wherein the connecting mechanism comprises a connecting body fixedly connected with the body, and a torque transmission member fixedly connected with the connecting body, wherein the torque transmission member is configured to be connected with the core shaft through a shear pin and a key groove assembly arranged along the longitudinal direction in an initial state, to be movable along the longitudinal direction in a first state after the shear pin is sheared by the stress borne by the rotatable telescopic nipple, and to transmit the rotating torque from the body to the core shaft through the key groove assembly in a second state requiring rotation.

[0007] In one embodiment, the connecting body is configured as a hollow cylinder, an outer surface of which is provided with a protrusion, two sides of the protrusion are respectively provided with a first connecting part and a second connecting part, the first connecting part is fixedly connected with the body, and the second connecting part is fixedly connected with the torque transmitting member.

[0008] In one embodiment, a limiting step is arranged on an outer surface of the mandrel, for abutting against an end surface of the connecting body in the first state, so as to limit the longitudinal movement of the connecting body.

[0009] In one embodiment, the key groove assembly comprises a plurality of key grooves arranged in a circumferential direction, and a key arranged in each key groove, wherein each key groove comprises a first part arranged on an outer surface of the mandrel in a longitudinal direction, and a corresponding second part arranged on an inner surface of the torque transmitting member in a longitudinal direction.

[0010] In one embodiment, the rotatable telescopic sub further comprises an end ring arranged on a side opposite to the connecting mechanism of the mandrel and fixedly connected with the mandrel.

[0011] In one embodiment, the rotatable telescopic sub comprises a combined sealing ring arranged between the mandrel and the end ring.

[0012] In one embodiment, the combined sealing ring comprises at least two of a V-shaped ring, a square-shaped ring and an O-shaped ring.

[0013] In one embodiment, the rotatable telescopic sub further comprises a mud scraping ring mounted on an outer surface of the mandrel and in contact with an inner surface of the body.

[0014] According to a second aspect of the present application, there is provided an acid fracturing completion pipe string, comprising a bidirectional anchoring packer, and a rotatable telescopic sub as described above arranged upstream of the bidirectional anchoring packer.

[0015] According to a third aspect of the present application, there is provided an acid fracturing completion method, comprising: placing an acid fracturing completion pipe string into a well; when a temperature stress acting on the acid fracturing completion pipe string exceeds a predetermined threshold, shearing a shear pin, so that the rotatable telescopic sub can change in length in a longitudinal direction; when it is necessary to rotate the acid fracturing completion pipe string under abnormal conditions, a rotating torque is transmitted to the mandrel through the body, the connecting body and the torque transmitting member of the rotatable telescopic sub, so as to realize overall rotation of the acid fracturing completion pipe string. BRIEF DESCRIPTION OF DRAWINGS

[0016] The present application will be described in detail below with reference to the accompanying drawings, in which:

[0017] Figure 1 This is a longitudinal half-section view of the rotatable telescopic sub before it is inserted into the well, according to the present invention;

[0018] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0019] Figure 3 for Figure 1 Enlarged view of point B in the middle;

[0020] Figure 4 A partial cross-sectional view of the rotatable telescopic sub section according to the present invention shows the keyway assembly connecting the torque transmission element to the spindle;

[0021] Figure 5 This is a schematic diagram of the rotatable telescopic section according to the present invention in its maximum stretched state;

[0022] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale. Detailed Implementation

[0023] The invention will now be further described with reference to the accompanying drawings. For ease of understanding, in this specification, the directional terms "longitudinal" or "axial" refer to the direction along the length of the rotatable telescopic sub-section, i.e. Figure 1 In this context, the vertical direction, referred to as "horizontal" or "radial," means the direction perpendicular to the "longitudinal" or "axial" direction. Figure 1 The horizontal direction in the text, referred to as "upstream," "above," or similar terms, refers to the direction closer to the wellhead, i.e. Figure 1 The term "downstream," "below," or similar terms refer to the direction away from the wellhead. Figure 1 The bottom direction in the middle.

[0024] Figure 1 This is a longitudinal half-sectional view of the rotatable telescopic sub-section 100 according to the present invention before it is inserted into the well. Figure 1 As shown, the rotatable telescopic section 100 according to the present invention mainly includes a longitudinally extending spindle 80, a body 20 sealed and sleeved on the outside of the spindle 80, and a connecting mechanism that connects the spindle 80 and the body 20 to each other.

[0025] The mandrel 80 includes a first end 81 and a second end 82 sequentially from upstream to downstream. The outer surface of the first end 81 of the mandrel 80 is provided with connecting threads for connection with corresponding threads on the external end ring 72, protecting the mandrel 80 from damage during longitudinal movement. The outer surface of the second end 82 of the mandrel 80 is also provided with connecting threads for connection with corresponding threads on the lower connector 11.

[0026] Figure 2 An enlarged view of the upstream side portion of the rotatable expansion joint 100 according to the present application is shown. As shown, the body 20 is sleeved on the outside of the mandrel 80, and a bidirectional sealing effect between the mandrel 80 and the body 20 is achieved by the combined sealing ring 70 installed on the mandrel 80 and in contact with the body 20. Meanwhile, the outer surface of the upstream side of the body 20 is provided with connecting threads for connecting with the corresponding threads on the upper joint 10. Figure 2

[0027] In a preferred embodiment according to the present application, the combined sealing ring 70 includes, but is not limited to, a V-shaped ring, a square ring, and an O-shaped ring, which are combined by two or more numbers of the above-mentioned sealing rings.

[0028] Figure 3 An enlarged view of the downstream side portion of the rotatable expansion joint 100 according to the present application is shown. As shown, the connecting mechanism includes the connecting body 40 fixedly connected with the body 20, and the torque transmission member 30 fixedly connected with the connecting body 40. Therefore, the connecting body 40 serves as a bridge to indirectly fixedly connect the body 20 and the torque transmission member 30 together. Figure 3

[0029] In the embodiment shown, the connecting body 40 is configured as a hollow cylinder, and the outer surface thereof is provided with a protruding portion 41, and the stepped surfaces 44 on both sides of the protruding portion 41 are respectively in contact with the end surfaces of the body 20 and the torque transmission member 30. The first connecting portion 42 and the second connecting portion 43 are respectively arranged on the outer surface of the connecting body 40 on both sides of the protruding portion 41. Figure 3

[0030] Among them, the outer surface of the first connecting portion 42 is fixedly connected with the inner surface of the body 20 through threads. In this way, the two ends of the body 20 are respectively fixedly connected with the upper joint 10 and the first connecting portion 42 through threads, so as to avoid the phenomenon of the body 20 being bounced outwards during the elongation of the rotatable expansion joint 100.

[0031] In addition, the outer surface of the second connecting portion 43 is fixedly connected with the inner surface of the torque transmission member 30 through threads. As mentioned above, the torque transmission member 30 is indirectly fixedly connected with the body 20 through the connecting body 40.

[0032] In the embodiment shown, the connecting body 40 is configured as a hollow cylinder, and the outer surface thereof is provided with a protruding portion 41, and the stepped surfaces 44 on both sides of the protruding portion 41 are respectively in contact with the end surfaces of the body 20 and the torque transmission member 30. The first connecting portion 42 and the second connecting portion 43 are respectively arranged on the outer surface of the connecting body 40 on both sides of the protruding portion 41. Figure 3 ​​​In the illustrated embodiment, the torque transmission element 30 includes an inner stepped surface 31, dividing the torque transmission element 30 into an upper section 33 and a lower section 34. As described above, the upper section 33 of the torque transmission element 30 is threadedly connected to the second connecting portion 43 of the connecting body 40, and the inner stepped surface 31 of the torque transmission element 30 abuts against the end face of the second connecting portion 43 of the connecting body 40, thereby forming an integral unit capable of longitudinal movement of the upper connector 10, the body 20, the torque transmission element 30, and the connecting body 40. The lower section 34 of the torque transmission element 30 is connected to the spindle 80 via the keyway assembly 50 and the shear pin 60 as described below.

[0033] Figure 4 A partial cross-sectional view of the rotatable telescopic sub section according to the present invention shows the keyway assembly connecting the torque transmission member 30 to the spindle 80, such as... Figure 4 As shown, the keyway assembly 50 includes a plurality of keyways arranged circumferentially, and keys 51 disposed in each keyway. Each keyway includes a first portion 83 arranged longitudinally on the outer surface of the spindle 80, and a corresponding second portion 32 arranged longitudinally on the inner surface of the torque transmission member 30.

[0034] During the installation of the rotatable telescopic section 100, the key 51 is first placed into the first part 83 of the keyway arranged on the outer surface of the spindle 80. Next, the second part 32 of the keyway arranged on the inner surface of the torque transmission member 30 is aligned with the position of the key 51 and inserted, thereby fixing the spindle 80 and the torque transmission member 30 together.

[0035] like Figure 4 As shown, a shear pin groove 61 is arranged between every two adjacent keyways. As described above, after the first portion 83 on the outer surface of the mandrel 80 and the second portion 32 on the inner surface of the torque transmission member 30 are combined, a complete shear pin groove 61 is formed. At this time, the shear pin 60 is inserted into the shear pin groove 61 to fix the mandrel 80 and the torque transmission member 30. The shear pin 60 passes entirely through the torque transmission member 30, and the head 62 of the shear pin 60 is embedded in the mandrel 80.

[0036] In a preferred embodiment of the invention, the rotatable telescopic sub 100 is part of the acid fracturing completion string, with tubing connected upstream and a bidirectional anchor packer installed downstream. This ensures that acid can smoothly enter the producing formation before fracturing, effectively increasing production capacity.

[0037] In a rotatable telescopic sub 100 according to the present invention, the rotatable telescopic sub 100 exhibits different forms at different stages of acid fracturing operations, and from the beginning to the end of the acid fracturing process, it sequentially includes an initial state, a first state, and a second state.

[0038] In the initial state, the rotatable telescopic nipple 100 is in a stable state due to the fixed effect of the shear pin 60 and the keyway assembly 50. At this time, the acid fracturing completion pipe string is sent to the preset position in the well according to the design requirements of the rotatable telescopic nipple 100. Then, the wellbore liquid is replaced by the completion fluid, the sealing capacity of the bidirectional anchoring packer is tested by the annulus test, and various preparations for the acid fracturing operation are carried out, such as replacing the wellhead, preparing acid, etc.

[0039] During the acid fracturing operation, due to the difference between the temperature of the acid and the temperature in the well, additional tension is caused to the completion pipe string. When the tension exceeds the preset shear value of the shear pin 60 in the telescopic nipple, the shear pin 60 is sheared. In this way, the whole consisting of the upper joint 10, the body 20, the torque transmission member 30 and the connecting body 40 moves in the upstream direction relative to the mandrel 80 under the action of the tension, and the whole telescopic nipple 100 is elongated, so as to realize the compensation of the completion pipe string. At this time, the key 51 slides in the keyway in the longitudinal direction. Figure 5 A schematic view of the rotatable telescopic nipple 100 according to the present application in the maximum tension state is shown in Figure 5 As shown, the process of elongating the telescopic nipple due to the additional tension caused by the temperature difference is called the first state.

[0040] As shown in Figure 5 , the state of the rotatable telescopic nipple 100 according to the present application after elongation, which is the most extreme position allowed for the rotatable telescopic nipple 100 to be stretched. At this time, the mandrel 6 is in contact with the connecting body 7 to realize the transmission of the axial load.

[0041] Specifically, a limiting step 84 is arranged on the outer surface of the mandrel 80. As described above, in the first state, the whole consisting of the upper joint 10, the body 20, the torque transmission member 30 and the connecting body 40 moves in the upstream direction relative to the mandrel 80 until the end face of the first connecting portion 41 of the connecting body 40 abuts against the limiting step 84. At this time, the whole telescopic nipple 100 cannot continue to be elongated. In this way, the longitudinal movement of the connecting body 40 is limited, and thus the maximum compensation length of the whole telescopic nipple 100 is limited.

[0042] When the acid fracturing rotating completion pipe string is required due to special circumstances, since the keyway assembly 50 is arranged, the rotating torque from the body 20 can be transmitted to the mandrel 80 to realize the rotation of the whole rotatable telescopic nipple 100. This process of transmitting the rotating torque through the keyway assembly 50 in the rotating state is called the second state.

[0043] Specifically, first, the rotating torque is transmitted to the connecting body 40 and the torque transmission member 30 through the upper joint 10 and the body 20. Second, as shown in Figure 4The torque transmission member 30 transmits the rotating torque to the mandrel 12 through the key 51, and the rotating torque is further transmitted to the lower joint 11 by the mandrel 12, so that the rotation of the whole rotatable telescopic sub 100 is completed.

[0044] In a preferred embodiment according to the present application, a mud scraping ring 71 is arranged on the rotatable telescopic sub 100, which is installed on the outer surface of the mandrel 80 and is in contact with the inner surface of the body 20 to keep the body 20 and the mandrel 80 clean during the longitudinal movement and prevent mud from entering.

[0045] According to the second aspect of the present application, an acid fracturing completion pipe string is also provided. The acid fracturing completion pipe string comprises, from upstream to downstream, a tubing, a telescopic sub, a hydraulic anchor and a bidirectional anchor in sequence. The telescopic sub is the rotatable telescopic sub 100 as described above.

[0046] According to the third aspect of the present application, an acid fracturing completion method is also provided. The assembled acid fracturing completion pipe string according to the present application is put into a well, and the telescopic effect of the acid fracturing completion pipe string is used to compensate for the additional tension in the well due to the temperature difference between the acid temperature and the well temperature.

[0047] Specifically, when the additional tension of the acid fracturing completion pipe string exceeds a predetermined threshold, the shear pin 60 is sheared off, so that the rotatable telescopic sub 100 can change in length along the longitudinal direction, thereby achieving compensation of the acid fracturing completion pipe string.

[0048] In addition, when the acid fracturing completion pipe string needs to be rotated under abnormal conditions, the rotating torque is transmitted to the mandrel 80 through the upper joint 10, the body 20, the connecting body 40 and the torque transmission member 30 of the rotatable telescopic sub 100, so that the whole acid fracturing completion pipe string is rotated.

[0049] The above is only a preferred embodiment of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art can easily make changes or modifications within the scope of the present application, and such changes or modifications should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A rotatable telescopic sub (100), characterized in that, It includes a longitudinally extending mandrel (80), a body (20) that is sealed and sleeved on the outside of the mandrel (80), and a connecting mechanism that connects the mandrel (80) and the body (20) to each other. The connecting mechanism includes a connecting body (40) fixedly connected to the main body (20), and a torque transmission component (30) fixedly connected to the connecting body (40). The torque transmission member (30) is configured such that, in an initial state, it is connected to the spindle (80) via a shear pin (60) and a keyway assembly (50) arranged along the longitudinal direction; in a first state after the shear pin (60) is sheared by the stress borne by the rotatable telescopic section (100), it is capable of moving along the longitudinal direction; and in a second state requiring rotation, it is capable of transmitting rotational torque from the body (20) to the spindle (80) via the keyway assembly (50), the keyway assembly (50) including a plurality of keyways arranged circumferentially spaced, and a key (51) disposed in each keyway, wherein each keyway includes a first portion (83) arranged longitudinally on the outer surface of the spindle (80), and a corresponding second portion (32) arranged longitudinally on the inner surface of the torque transmission member (30), and a shear pin groove (61) is arranged between each two adjacent keyways. When acid pressure is required to rotate the well completion tubing string, the rotational torque is first transmitted to the connector (40) and torque transmission component (30) through the upper connector (10) and the body (20). Then, the torque transmission component (30) transmits the rotational torque to the mandrel (80) through the key (51), and the mandrel (80) transmits the rotational torque to the lower connector (11), thereby completing the rotation of the entire rotatable telescopic sub (100).

2. The rotatable telescopic subsection according to claim 1, characterized in that, The connecting body (40) is constructed as a hollow cylinder, and a protrusion (41) is provided on its outer surface. A first connecting part (42) and a second connecting part (43) are respectively provided on both sides of the protrusion. The first connecting part (42) is fixedly connected to the body (20), and the second connecting part (43) is fixedly connected to the torque transmission component (30).

3. The rotatable telescopic subsection according to claim 1, characterized in that, A limiting step (84) is provided on the outer surface of the mandrel (80) for abutting against the end face of the connector (40) in the first state to restrict the longitudinal movement of the connector (40).

4. The rotatable telescopic subsection according to any one of claims 1-3, characterized in that, The rotatable telescopic section (100) also includes an end ring (72), which is disposed on the side of the mandrel (80) opposite to the connecting mechanism and is fixedly connected to the mandrel (80).

5. The rotatable telescopic subsection according to claim 4, characterized in that, The rotatable telescopic section (100) includes a combined sealing ring (70) disposed between the mandrel (80) and the end ring (72).

6. The rotatable telescopic subsection according to claim 5, characterized in that, The combined sealing ring (70) includes at least two of the following: a V-ring, a rectangular ring, and an O-ring.

7. The rotatable telescopic sub-section according to any one of claims 1-3, characterized in that, The rotatable telescopic section (100) also includes a mud scraper (71), which is mounted on the outer surface of the mandrel (80) and contacts the inner surface of the body (20).

8. An acid-firing completion string, comprising a bidirectional anchor packer and a rotatable telescopic sub (100) disposed upstream of the bidirectional anchor packer according to any one of claims 1 to 7.

9. An acid fracturing completion method, comprising: The acid-fracturing completion tubing string according to claim 8 is placed into the well; When the temperature stress on the acid-fusing completion tubing exceeds a predetermined threshold, the shear pin (60) is cut, allowing the rotatable telescopic sub (100) to change length along the longitudinal direction. When the acid-filled completion string needs to be rotated under abnormal circumstances, the rotational torque is transmitted to the mandrel (80) through the body (20), connector (40) and torque transmission component (30) of the rotatable telescopic section (100), thereby realizing the overall rotation of the acid-filled completion string.

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