Wellbore reconstruction method

Abstract

The present invention belongs to the technical field of wellbore repair, and discloses a wellbore reconstruction method. The wellbore reconstruction method includes: lowering and setting a removable hanging plug at a first preset position in the damaged casing, and the first preset position is below the damaged section; the cementing accessory includes a float shoe, a bumping seat, a repair liner and an expandable liner hanger which are hermetically connected in sequence from bottom to top. Lower the cementing accessory into the damaged casing, the bottom end of the repair liner is lower than the damaged section and is spaced from the hanging plug, and the expandable liner hanger is higher than the top end of the damaged section; inject cement slurry into the annulus space outside the bottom end of the cementing accessory and above the hanging plug, and after a preset setting time, seal the annulus space between the lower end of the repair liner and the damaged casing; the expandable liner hanger expands to seal the annulus space between the expandable liner hanger and the damaged casing; in step S5, remove the hanging plug, and drill down to remove the float shoe, the bumping seat and the cement block between the float shoe and the hanging plug.

Description

Technical Field

[0001] The present invention relates to the technical field of wellbore repair, and particularly to a wellbore reconstruction method. Background Art

[0002] The damage of oil well casing will cause the injection-production system to be damaged, the reserve control degree to become worse, and the production decline to accelerate.

[0003] Currently, the expansion pipe patch technology is used to repair the damaged wellbore casing. The basic principle of this method is: first, mill and drill a channel to repair the inner diameter of the casing, and then lower the expansion pipe to patch the original casing to reconstruct the integrity of the wellbore.

[0004] However, the expansion pipe patch technology requires the inner diameter of the casing to be repaired to be close to the original inner diameter. For example, when patching and repairing a 7-inch casing (wall thickness 9.19 mm, inner diameter 159.42 mm), the inner diameter of the wellbore casing needs to be repaired to more than 156 mm first. However, this only applies to wellbores with slightly damaged casings. For wells with relatively serious casing damage, for example, in the case of casing reduction and deformation damage, the casing repair tool is prone to sticking accidents, making it difficult to achieve this inner diameter target. Another example is that in the case of casing break and deformation damage, due to the casing being disconnected and axially misaligned, large-sized casing repair tools cannot pass through, and it is also difficult to achieve this inner diameter target. Moreover, the casing often deforms and rebounds again after casing repair, and it is also difficult to achieve the inner diameter target.

[0005] Currently, there is also a method of injecting cement to treat casing damage, directly injecting cement at the casing damage point. However, for wells with relatively serious well leakage, the injected cement is prone to leakage, and it is difficult to ensure the pressure-bearing capacity of the wellbore. Summary of the Invention

[0006] The purpose of the present invention is to provide a wellbore reconstruction method with simple construction technology, high pressure-bearing capacity of the reconstructed wellbore, and can also be used when the size after repairing the casing diameter cannot meet the requirements of the casing patch diameter.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] A wellbore reconstruction method for repairing a damaged section of a damaged casing, comprising:

[0009] Step S1, lower and set a removable hanging plug at a first preset position in the damaged casing, and the first preset position is below the damaged section;

[0010] Step S2: The cementing accessories include a float shoe, a bumping seat, a repair liner, and an expandable liner hanger that are hermetically connected in sequence from bottom to top. Lower the cementing accessories to the second preset position inside the damaged casing. At the second preset position, the bottom end of the repair liner is lower than the damaged section and is spaced from the suspended plug, and the expandable liner hanger is higher than the top end of the damaged section.

[0011] Step S3: Inject cement slurry into the annulus space outside the bottom end of the cementing accessories and above the suspended plug. After a preset setting time, an annular cement body is formed to seal the annulus space between the lower end of the repair liner and the damaged casing.

[0012] Step S4: Expand the expandable liner hanger to seal the annulus space between the expandable liner hanger and the damaged casing.

[0013] Step S5: Remove the suspended plug, and run in hole to remove the float shoe, the bumping seat, and the cement blocks between the float shoe and the suspended plug.

[0014] As an optional embodiment of the wellbore reconstruction method, in step S2, the specific operation of lowering the cementing accessories to the second preset position inside the damaged casing includes: connecting the cementing accessories to the head end of the central pipe, and using the central pipe to lower the cementing accessories to the second preset position.

[0015] As an optional embodiment of the wellbore reconstruction method, the cementing accessories further include a first rubber plug, and a second rubber plug is provided inside the repair liner. Step S3 specifically includes the following steps:

[0016] S301: Inject cement slurry into the cementing accessories using the central pipe. The cement slurry flows out through the bumping seat and the float shoe, and returns upward to the annulus space between the cementing accessories and the damaged casing.

[0017] S302: The first rubber plug descends along the central pipe to displace the cement slurry inside the central pipe.

[0018] S303: The first rubber plug descends along the cementing accessories to be combined with the second rubber plug to form a composite rubber plug.

[0019] S304: The composite rubber plug descends to displace the cement slurry inside the cementing accessories until it bumps against the bumping seat, closes the flow guiding holes of the bumping seat, and completes the operation.

[0020] As an optional embodiment of the wellbore reconstruction method, before step S1, it further includes: milling the damaged casing to repair the internal diameter of the damaged casing to meet the smooth lowering of the cementing accessories.

[0021] As an alternative embodiment of the wellbore reconstruction method, the suspended plugging plug is a soluble bridge plug, and the suspended plugging plug is dissolved in the step S5.

[0022] As an alternative embodiment of the wellbore reconstruction method, before the step S2, it further includes: surveying the length of the damaged section, determining the length of the repair liner according to the length of the damaged section, and the length of the repair liner is greater than that of the damaged section.

[0023] As an alternative embodiment of the wellbore reconstruction method, the expandable liner hanger includes an expandable tube, a sealing ring sleeved and fixed on the outer periphery of the expandable tube, and an expansion cone movably arranged in the expandable tube. The step S4 includes: forming a pressure buildup in the cementing accessory through the central tube, and after the pressure reaches the preset pressure value, the expansion cone moves upward to expand the expandable tube, so that the sealing ring seals and abuts against the damaged casing above the damaged section.

[0024] As an alternative embodiment of the wellbore reconstruction method, at the second preset position, the upper end of the repair liner is more than 5 m higher than the upper end of the damaged section, and the lower end of the repair liner is more than 5 m lower than the lower end of the damaged section.

[0025] As an alternative embodiment of the wellbore reconstruction method, the distance between the suspended plugging plug and the lower end of the damaged section is not greater than 10 m.

[0026] Advantageous effects:

[0027] The wellbore reconstruction method provided by the present invention uses the suspended plugging plug as the bottom, and injects cement slurry into the annular space between it and the damaged casing through the cementing accessory to return upward, so as to realize the sealed connection between the repair liner and the lower part of the damaged section. The cement slurry returns and fills, with good sealing effect, high stability and high pressure-bearing capacity. The use of the suspended plugging plug is convenient for controlling the amount of cement slurry used, and the cement slurry is mainly used to return to the annular space of the damaged section, greatly saving the construction cost of sealing the lower part of the damaged section. The expandable liner hanger is used to realize the sealed fixation with the upper part of the damaged section, with mature technology and simple implementation. The repair liner and the expandable liner hanger are hermetically connected as a whole, and the whole replaces the original damaged section, thus ensuring a high pressure-bearing capacity. Description of the drawings

[0028] Figure 1 is a flowchart of the wellbore reconstruction method provided by the embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the cementing accessory in the damaged casing provided by the embodiment of the present invention;

[0030] Figure 3 is a wellbore structure diagram after the operation of the wellbore reconstruction method provided by the embodiment of the present invention is completed.

[0031] In the figure:

[0032] 1. First rubber plug; 2. Central tube; 3. Expansion tube; 4. Sealing ring; 5. Expansion cone; 6. Second rubber plug; 7. Repair liner; 8. Collapse seat; 9. Float shoe; 10. Damaged casing; 11. Annular cement body; 12. Damaged section. Specific embodiments

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention rather than all structures are shown in the drawings.

[0034] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over", and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under", and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0036] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "right", and "left" are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and do not have special meanings.

[0037] As Figure 1 shown, this embodiment provides a wellbore reconstruction method for repairing the damaged section 12 of the damaged casing 10. As Figure 3As shown, there are multiple damage notches distributed on the damaged section 12. Specifically, the wellbore reconstruction method includes:

[0038] Step S1: Lower and set a removable hanging plug at a first preset position inside the damaged casing 10. The first preset position is below the damaged section 12. The setting of the hanging plug in the wellbore is a prior art and will not be elaborated here.

[0039] Step S2: As Figure 2 shown, the cementing accessory includes a float shoe 9, a bumping seat 8, a repair liner 7, and an expandable liner hanger that are hermetically connected in sequence from bottom to top. Lower the cementing accessory into the second preset position inside the damaged casing 10. At the second preset position, the bottom end of the repair liner 7 is lower than the damaged section 12 and is spaced from the hanging plug. The expandable liner hanger is higher than the top end of the damaged section 12. The repair liner 7 can be selected as a common oil well casing, so that its pressure-bearing capacity can reach the same pressure-bearing capacity as the original wellbore.

[0040] Step S3: Inject cement slurry into the annulus outside the bottom end of the cementing accessory and above the hanging plug. After a preset setting time, an annular cement body 11 is formed to seal the annulus between the lower end of the repair liner 7 and the damaged casing 10. It should be noted that the annular cement body 11 only needs to fill the annulus at the lower end of the repair liner 7 to ensure the seal between the lower end of the repair liner 7 and the damaged casing 10, and it is not necessary to fill the entire annulus in the axial direction of the repair liner 7. The above preset setting time is determined according to the construction process and is not limited here.

[0041] Step S4: Expand the expandable liner hanger to seal the annulus between the expandable liner hanger and the damaged casing 10. On the contrary, if directly attempting to return the cement slurry to the top of the repair liner 7 in Step S3 to seal the annulus between the top of the cementing accessory and the damaged casing 10 with cement, due to the damage in the damaged section, a large amount of cement slurry will flow out from the damage notches, resulting in failure. Using the expandable liner hanger for sealing can effectively avoid this situation.

[0042] Step S5: Remove the hanging plug, lower the drill to remove the float shoe 9, the bumping seat 8, and the cement blocks between the float shoe 9 and the hanging plug, and form a wellbore as Figure 3 shown.

[0043] Through step S1, a suspended plug is set and sealed below the damaged section 12, temporarily isolating the damaged section 12 from the lower part of the casing, providing a stable environment for the operation in step S3. Through step S2, the cementing accessory for repairing the damaged section 12 is sent to the second preset position. Through steps S3 and S4, the annular space between the repair liner 7 and the damaged casing 10 is sealed, and the annular space between the expandable liner hanger and the damaged casing 10 is sealed. Thus, the expandable liner hanger and the repair liner 7 together replace the damaged section 12 as a whole and become part of the wellbore, making the wellbore complete and realizing the repair of the damaged section 12. Through step S5, the wellbore is penetrated to complete the operation.

[0044] For the wellbore reconstruction method provided in this embodiment, with the suspended plug as the base, cement slurry is injected into the annular gap between it and the damaged casing 10 and returns upward, realizing the sealed connection of the repair liner 7 to the lower part of the damaged section 12. The upward return and filling of the cement slurry have good sealing effect and high stability. The use of the suspended plug facilitates the control of the amount of cement slurry used, mainly using the cement slurry to return to the annular space of the damaged section 12, greatly saving the construction cost and being beneficial to the construction when the damaged section 12 is far from the bottom of the well. On the contrary, without the suspended plug, the cement slurry flowing out from the cementing accessory first needs to fill the space between the bottom of the well and the cementing accessory before it can start to return upward. However, the wellbore is several kilometers long. When the damaged section 12 is close to the upper end of the wellbore and far from the bottom of the well, this will significantly increase the material cost and construction period. The expandable liner hanger is used to achieve the sealed fixation above the damaged section 12, with mature technology and simple implementation. The repair liner 7 and the expandable liner hanger are sealed and connected as a whole, replacing the original damaged section 12 as a whole, thus ensuring a relatively high pressure-bearing capacity.

[0045] The first preset position is determined according to the position of the damaged section 12. Optionally, the distance between the suspended plug and the lower end of the damaged section 12 is not greater than 10 m. That is to say, in step S3, after the cement slurry flowing out from the bottom end of the cementing accessory through the central pipe 2 fills the above 10 m space, it returns upward to the annular space between the cementing accessory and the damaged casing 10. If the distance between the suspended plug and the damaged section 12 is too large, it will cause a large waste of cement slurry, increase the construction workload, slow down the operation efficiency, and increase the workload of removing cement blocks in step S5. In this embodiment, the suspended plug is located 10 m below the lower end of the damaged section 12.

[0046] Specifically, in step S2, lowering the cementing accessory into the damaged casing 10 to the second preset position specifically includes: connecting the cementing accessory to the head end of the central pipe 2 and using the central pipe 2 to lower the cementing accessory to the second preset position.

[0047] The cementing accessory further includes a first rubber plug 1. A second rubber plug 6 is disposed inside the repair liner 7. Step S3 specifically includes the following steps: S301: Inject cement slurry into the cementing accessory through the central pipe 2. The cement slurry flows out through the bumping seat 8 and the float shoe 9, and returns upward to the annular space between the cementing accessory and the damaged casing 10; S302: The first rubber plug 1 descends along the central pipe 2 to displace the cement slurry inside the central pipe 2; S303: The first rubber plug 1 descends along the cementing accessory until it combines with the second rubber plug 6 to form a composite rubber plug; S304: The composite rubber plug descends to displace the cement slurry inside the cementing accessory until it bumps against the bumping seat 8, closes the diversion hole of the bumping seat 8, and completes the operation. After bumping, shut down the cement pump outside the well, and relieve the pressure inside the central pipe 2. This operation process is similar to the wellbore cementing operation process, with mature technology and convenient implementation.

[0048] After expansion, the expandable liner hanger is firmly suspended and has good sealing performance. Specifically, the expandable liner hanger includes an expansion pipe 3, a sealing ring 4 sleeved and fixed on the outer periphery of the expansion pipe 3, and an expansion cone 5 movably disposed inside the expansion pipe 3. Step S4 includes: creating a pressure buildup in the cementing accessory through the central pipe 2. After the pressure reaches the preset pressure value, the expansion cone 5 moves upward to expand the expansion pipe 3, so that the sealing ring 4 seals and abuts against the damaged casing 10 above the damaged section 12. Specifically, use a cement pump to build up pressure inside the cementing accessory to 20 - 25 MPa to drive the expansion cone 5 to move upward. The sealing ring 4 is a rubber ring. The expandable liner hanger is a prior art, and its specific structure and working principle can be referred to the Chinese patent document with the publication number CN101906946A.

[0049] Before step S2, it further includes: surveying the length of the damaged section 12, determining the length of the repair liner 7 based on the length of the damaged section 12. The length of the repair liner 7 is greater than that of the damaged section 12, so as to effectively replace the damaged section 12. Specifically, at the second preset position, the upper end of the repair liner 7 is more than 5 m higher than the upper end of the damaged section 12, and the lower end of the repair liner 7 is more than 5 m lower than the lower end of the damaged section 12.

[0050] Optionally, before step S1, it further includes: using a milling cone to mill the damaged casing 10 to repair the internal diameter of the damaged casing 10 to meet the smooth lowering of the cementing accessory. It should be noted that for the repair of the internal diameter of the damaged casing 10, it is not necessary to repair the internal diameter of the damaged casing 10 to the original internal diameter as in the expandable liner patch technology, and it only needs to meet the lowering of the cementing accessory.

[0051] The suspended plugging plug can be a cement plug, a rubber plug, etc. Optionally, the suspended plugging plug is a soluble bridge plug, and the soluble bridge plug is dissolved in step S5. The soluble bridge plug does not need to be removed by drilling, saving the process.

[0052] In another embodiment, for sealing the annular space between the bottom of the repair liner 7 and the damaged casing 10, an oil / water self-expanding packer can also be used to replace the float shoe 9 and the bumping seat 8 and be directly installed at the bottom of the repair liner 7. The oil / water self-expanding packer expands in volume after absorbing oil or water, thereby sealing the annular space between the bottom of the repair liner 7 and the damaged casing 10 downhole. This process no longer requires the installation of the float shoe 9 and the bumping seat 8, and there is no need to inject cement slurry, making the process more simple and saving the construction period and cost. However, the chemical reaction process effect of the oil / water self-expanding packer is unstable, resulting in poor sealing stability; in addition, the rubber on the oil / water self-expanding packer has limited expansion in the case of small sizes, resulting in the inability to completely seal the wellbore, and the rubber on the oil / water self-expanding packer will wear against the wellbore during the process of lowering a large-size packer into the well, still resulting in poor sealing stability. For the wellbore reconstruction method using cementing accessories, an annular cement body 11 is formed at the bottom end of the damaged section 12, with good sealing stability, high strength, and long service life.

[0053] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments, and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A wellbore reconstruction method for repairing a damaged section (12) of a casing damage pipe (10), characterized in that: include: Step S1, inserting and setting a removable suspended seal into a first preset position in the damaged casing pipe (10), wherein the first preset position is below the damaged section (12); Step S2, the cementing accessories include a floating shoe (9), a bumping seat (8), a repair liner (7) and an expandable liner hanger which are sealed and connected in sequence from bottom to top, and the cementing accessories are lowered into the second preset position in the damaged casing (10). At the second preset position, the bottom end of the repair liner (7) is lower than the damaged section (12) and is spaced from the suspended sealing plug, and the expandable liner hanger is higher than the top end of the damaged section (12); Step S3, injecting cement slurry into the annular space at the outer periphery of the bottom end and above the suspended sealing plug through the cementing accessory, and after a preset waiting time, forming an annular cement body (11) that seals the annular space between the lower end of the repair liner (7) and the damaged casing pipe (10); Step S4, the expandable liner hanger expands to seal the annular space between the expandable liner hanger and the damaged casing tube (10); the expandable liner hanger and the repair liner (7) replace the damaged section (12) as a whole and become a part of the wellbore; Step S5, clearing the suspended sealing plug, drilling down to clear the float shoe (9), the impact pressure seat (8) and the cement block between the float shoe (9) and the suspended sealing plug.

2. The wellbore reconstruction method according to claim 1, characterized in that: In the step S2, lowering the cementing accessory into the second preset position in the casing damage pipe (10) specifically comprises: connecting the cementing accessory to the head end of the central pipe (2), and using the central pipe (2) to lower the cementing accessory to the second preset position.

3. The wellbore reconstruction method according to claim 2, characterized in that: The cementing accessory further comprises a first rubber plug (1), the repair liner (7) has a second rubber plug (6), and the step S3 specifically comprises the following steps: S301, using the central pipe (2) to inject cement slurry into the cementing accessory, the cement slurry flows out through the impact seat (8) and the floating shoe (9), and returns to the annular space between the cementing accessory and the casing damage pipe (10); S302, the first rubber plug (1) moves downward along the central tube (2) to replace the cement slurry in the central tube (2); S303, the first rubber plug (1) moves downward along the cementing attachment until it is combined with the second rubber plug (6) to form a composite rubber plug; S304, the composite rubber plug moves downward to displace the cement slurry in the cementing accessory until it hits the impact seat (8), closes the diversion hole of the impact seat (8), and completes the operation.

4. The wellbore reconstruction method according to claim 1, characterized in that: Before the step S1, the method further includes: milling the damaged casing pipe (10) to repair the diameter of the damaged casing pipe (10) so as to ensure smooth lowering of the cementing accessories.

5. The wellbore reconstruction method according to claim 1, characterized in that: The suspended sealing plug is a soluble bridge plug, and the suspended sealing plug is dissolved in the step S5.

6. The wellbore reconstruction method according to claim 1, characterized in that: Before step S2, the method further includes: surveying the length of the damaged section (12), determining the length of the repair liner (7) according to the length of the damaged section (12), and the length of the repair liner (7) is greater than the damaged section (12).

7. The wellbore reconstruction method according to claim 1, characterized in that: The expandable liner hanger comprises an expansion tube (3), a sealing ring (4) sleeved and fixed on the outer periphery of the expansion tube (3), and an expansion cone (5) movably arranged in the expansion tube (3), and the step S4 comprises: forming a pressure build-up in the cementing accessory through a central tube (2), and after the pressure reaches a preset pressure value, the expansion cone (5) moves upward to expand the expansion tube (3), so that the sealing ring (4) seals against the damaged casing tube (10) above the damaged section (12).

8. The wellbore reconstruction method according to claim 1, characterized in that: At the second preset position, the upper end of the repair liner (7) is more than 5 m higher than the upper end of the damaged section (12), and the lower end of the repair liner (7) is more than 5 m lower than the lower end of the damaged section (12).

9. The wellbore reconstruction method according to claim 1, characterized in that: The distance between the suspended sealing plug and the lower end of the damaged section (12) is no more than 10 m.

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