Well completion pipe string

Abstract

The utility model provides a well completion pipe column which comprises a pipe column body, a mechanical packer is arranged on the outer wall of the upper pipe column, an anchoring sealing back-inserting connector is arranged at the bottom end of the upper pipe column, an anchoring sealing releasing tool is arranged at the top end of the lower pipe column, and the mechanical packer is arranged on the outer wall of the lower pipe column. A plurality of through holes are formed in the tail end of the lower pipe column body, and the anchoring sealing back-inserting connector is inserted back into the anchoring sealing releasing tool so that the upper pipe column body and the lower pipe column body can be connected into a whole. According to the utility model, the fixed-point acid fracturing oil-gas well exploitation can be realized while the setting success rate is ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of oil and gas well exploitation, and specifically relates to a completion string. Background Art

[0002] In some oilfields, the Ordovician carbonate reservoir has extremely strong heterogeneity. For some wells, the completion string is directly run after drilling into the karst reservoir body and put into production directly. However, most oil and gas wells cannot be directly put into production after completion and need acid fracturing treatment. For high-density and high-pressure gas wells, it is necessary to ensure both the setting success rate and the fixed-point acid fracturing of oil and gas wells during exploitation, which is difficult to achieve with the existing completion strings. Summary of the Utility Model

[0003] An object of the utility model is to provide a completion string to achieve the fixed-point acid fracturing of oil and gas wells while ensuring the setting success rate.

[0004] According to the utility model, a completion string is provided, including a string body, which comprises an upper string and a lower string arranged below the upper string. A mechanical packer is arranged on the outer wall of the upper string. An anchor seal back-off joint is arranged at the bottom end of the upper string. An anchor seal release is arranged at the top end of the lower string. A plurality of through holes are formed at the end of the lower string. The anchor seal back-off joint is inserted back into the anchor seal release to connect the upper string and the lower string into one body.

[0005] In a preferred embodiment, a mechanical packer is further arranged on the outer wall of the upper string. The upper string has a first telescopic joint above the mechanical packer and a second telescopic joint below the mechanical packer. The anchor seal back-off joint is arranged below the second telescopic joint.

[0006] In a preferred embodiment, the anchor seal back-off joint is threadedly connected to the bottom end of the upper string.

[0007] In a preferred embodiment, the completion string further comprises a kill sleeve arranged on the upper string. The kill sleeve is located above the mechanical packer, and the first telescopic joint is arranged above the kill sleeve.

[0008] In a preferred embodiment, the lower string further comprises a liner arranged below the anchor seal release.

[0009] In a preferred embodiment, a round nose guide shoe is arranged at the end of the horizontal pipe section of the liner.

[0010] In a preferred embodiment, a plurality of the through holes are formed in the liner near the round nose guide shoe.

[0011] In a preferred embodiment, the side of the round - head guide shoe away from the liner is configured as an arc surface.

[0012] In a preferred embodiment, a downhole safety valve is provided at the top end of the upper pipe string.

[0013] In a preferred embodiment, the kill sleeve is integrated with the upper pipe string.

[0014] The utility model has at least the following technical effects:

[0015] According to the utility model, a pipe string body is provided, which includes an upper pipe string and a lower pipe string arranged below the upper pipe string. Since a mechanical packer is arranged on the outer wall of the upper pipe string, by using the mechanical packer to block the annulus and displace the fluid, it can ensure well control safety and subsequent fluid displacement during the wellhead replacement period in a high - density mud environment, thereby ensuring the reliability of fluid displacement and the setting reliability in high - density mud. In a high - density and high - pressure gas well, the setting success rate can be guaranteed. Also, since an anchor - seal back - insert joint is provided at the bottom end of the upper pipe string, an anchor - seal release is provided at the top end of the lower pipe string, and a plurality of through - holes are opened at the end of the lower pipe string, the anchor - seal back - insert joint is back - inserted into the anchor - seal release so that the upper pipe string and the lower pipe string are connected into one body. Thus, during the completion process, acid fluid can flow from the upper pipe string to the lower pipe string and enter the formation through the multiple holes of the lower pipe string, avoiding the situation where acid fluid cannot enter the formation from the pipe string body, and thus ensuring the realization of targeted acid fracturing.

[0016] According to the utility model, since the upper pipe string has a first expansion joint above the mechanical packer, the contraction amount of the pipe string body generated by the temperature effect during acid fracturing can be compensated when the first expansion joint is pulled open during lowering. Also, since a second expansion joint is provided below the mechanical packer and the anchor - seal back - insert joint is arranged below the second expansion joint, when the second expansion joint is pulled open during lowering, it can be used to compensate the pipe string contraction amount generated by the temperature effect during acid fracturing, facilitating the back - insertion of the anchor - seal back - insert joint into the anchor - seal release. Thus, the contraction amount generated by the temperature effect during acid fracturing can be compensated, facilitating the targeted acid fracturing transformation of high - quality reservoirs in the target layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematically shows the overall structural schematic diagram of a completion pipe string according to an embodiment of the utility model.

[0018] In this application, all the drawings are schematic drawings, only used to illustrate the principle of the utility model and not drawn to actual scale. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The technical solution of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0020] In the present utility model, unless otherwise clearly defined and limited, the term "connection" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meaning of the above terms in the present utility model can be understood according to specific circumstances.

[0021] As Figure 1 shown, the completion string 100 of the present utility model includes: a string body a, which includes an upper string b and a lower string c provided below the upper string b. A mechanical packer 4 is provided on the outer wall of the upper string b, and an anchor seal back-in joint 6 is provided at the bottom end of the upper string b. An anchor seal release 7 is provided at the top end of the lower string c. The anchor seal back-in joint 6 is back-in inserted into the anchor seal release 7 so that the upper string b and the lower string c are connected into one body. A plurality of through holes 9 are provided at the end of the lower string b. The lower string b includes a vertical section and a horizontal section. Among them, the top end of the vertical section is connected to the anchor seal release 7, and a plurality of holes 9 are provided at the end of the horizontal section. After the upper string b and the lower string c are connected into one body, acid fluid can flow from the upper string b to the lower string c and enter the formation through the plurality of holes 9 in the lower string c to achieve acid fracturing. Optionally, the anchor seal back-in joint 6 is threadedly connected to the bottom end of the upper string. The anchor seal release 7 is inserted from the top end of the lower string and threadedly connected to the top end of the lower string.

[0022] According to the present utility model, a tubular string body a is provided, which includes an upper tubular string b and a lower tubular string c disposed below the upper tubular string b. Since a mechanical packer 4 is provided on the outer wall of the upper tubular string b, the annulus and displacement fluid can be blocked by the mechanical packer 4, ensuring well control safety and subsequent displacement fluid during the replacement of the wellhead in a high-density mud environment. Thus, the reliability of displacement slurry and the setting reliability in high-density mud can be guaranteed, and the setting success rate can be ensured in a high-pressure gas well with high density. Also, since an anchor sealing back-in joint 6 is provided at the bottom end of the upper tubular string b, an anchor sealing releasing joint 7 is provided at the top end of the lower tubular string c, and a plurality of through holes 9 are formed at the end of the lower tubular string b, the anchor sealing back-in joint 6 is back-inserted into the anchor sealing releasing joint 7, so that the upper tubular string b and the lower tubular string c are connected into one body. Therefore, during the completion process, acid fluid can flow from the upper tubular string b to the lower tubular string c and enter the formation through the plurality of holes 9 of the lower tubular string c, preventing the acid fluid from being unable to enter the formation from the tubular string body a, and thus ensuring the realization of targeted acid fracturing.

[0023] In one or more embodiments, the upper tubular string b has a first expansion joint 2 above the mechanical packer 4, and a second expansion joint 5 is provided below the mechanical packer 4. The anchor sealing back-in joint 6 is disposed below the second expansion joint 5. It should be noted that the expansion joint is a common tool used to compensate for the elongation or contraction of the tubular string in the well due to factors such as pressure and temperature, and is used to reduce or eliminate the force exerted by the tubular string on the mechanical packer or the wellhead, ensuring the sealing state of the mechanical packer and the wellhead during production. The specific structure is not described herein.

[0024] According to the present utility model, since the upper tubular string b has a first expansion joint 2 above the mechanical packer 4, the contraction amount of the tubular string body a generated by the temperature effect during acid fracturing can be compensated when the first expansion joint 2 is pulled open during lowering. Also, since a second expansion joint 5 is provided below the mechanical packer 4 and the anchor sealing back-in joint 6 is disposed below the second expansion joint 5, when the second expansion joint 5 is pulled open during lowering, it can be used to compensate for the contraction amount of the tubular string generated by the temperature effect during acid fracturing, facilitating the back-insertion of the anchor sealing back-in joint 6 into the anchor sealing releasing joint 7. Thus, the contraction amount generated by the temperature effect during acid fracturing can be compensated, facilitating the targeted acid fracturing transformation of high-quality reservoirs in the target layer.

[0025] In one or more embodiments, the completion tubular string 100 of the present utility model further includes a kill sleeve 3 provided on the upper tubular string b. The kill sleeve 3 is located above the mechanical packer 4, and the first expansion joint 2 is provided above the kill sleeve 3.

[0026] According to the present utility model, a kill sleeve 3 is provided on the upper pipe string b. The kill sleeve 3 is located above the mechanical packer 4 and the first telescopic joint 2 is provided above the kill sleeve 3. The kill sleeve 3 plays a role in balancing the casing-tubing pressure before the mechanical packer 4 is released, facilitating the release of the mechanical packer 4 and reducing the swabbing effect during the lifting of the pipe string.

[0027] In one or more embodiments, the lower pipe string c further includes a liner 8 provided below the anchor seal release 7. The liner 8 can effectively support the wellbore wall, thereby ensuring the smoothness of the production wellbore.

[0028] In one or more embodiments, the liner 8 is provided with a round head guide shoe 10 at the end of the horizontal well section.

[0029] In one or more embodiments, the liner 8 is provided with a plurality of through holes 9 near the round head guide shoe 10.

[0030] According to the present utility model, the liner 8 is provided with a plurality of through holes 9 near the round head guide shoe 10, and the wellbore wall can be effectively supported through the through holes in the liner 8 near the round head guide shoe 10, thereby ensuring the smoothness of the production wellbore.

[0031] In one or more embodiments, a downhole safety valve 1 is provided at the top of the upper pipe string b.

[0032] In one or more embodiments, the side of the round head guide shoe 10 away from the liner 8 is configured as an arc surface.

[0033] Before use, the anchor seal release 7, the liner 8, and the round head guide shoe 10 on the lower pipe string c are sent into the well through a drill pipe. A double drill collar and a single milling column are used to simulate wellbore cleaning to ensure the smooth lowering of the liner 8 and the round head guide shoe 10. After the liner 8 is lowered in place, the anchor seal release 7 is rotated, and after circulating and washing the well until the liquid properties at the inlet and outlet are the same, the upper pipe string b is run in, and the anchor seal backinsertion joint 6 is backinserted into the anchor seal release 7, and the entire pipe string body a is adjusted to ensure that the mechanical packer 4 is in the setting position. The pipe string body a is rotated forward and lowered with pressure to set the packer. After the entire wellbore is displaced with a solid-free completion fluid, a ball is dropped and positive pressure is applied to close the displacement valve on the mechanical packer 4, and a seal check is performed. During acid fracturing construction, the acid fluid enters the high-quality reservoir through the plurality of through holes 9 provided in the liner 8 near the round head guide shoe 10 for acid fracturing treatment, and then the well is opened for testing to obtain industrial oil and gas flow.

[0034] Although the present utility model has been described with reference to the preferred embodiments, various improvements can be made thereto and components thereof can be replaced with equivalents without departing from the scope of the present utility model. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any manner. The present utility model is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A completion string, characterized in that, Comprising: A tubing string body, which includes an upper tubing string and a lower tubing string disposed below the upper tubing string. A mechanical packer is provided on the outer wall of the upper tubing string. An anchor seal back-in joint is provided at the bottom end of the upper tubing string. An anchor seal release is provided at the top end of the lower tubing string. A plurality of through holes are formed at the end of the lower tubing string. The anchor seal back-in joint is back-in inserted into the anchor seal release so that the upper tubing string and the lower tubing string are connected into one body.

2. The completion string according to claim 1, characterized in that, The upper tubing string has a first expansion joint above the mechanical packer and a second expansion joint is provided below the mechanical packer. The anchor seal back-in joint is disposed below the second expansion joint.

3. The completion string according to claim 1 or 2, characterized in that, The anchor seal back-in joint is threadedly connected to the bottom end of the upper tubing string.

4. The completion string according to claim 2, wherein, It further includes a kill sleeve provided on the upper tubing string. The kill sleeve is located above the mechanical packer, and the first expansion joint is provided above the kill sleeve.

5. The completion string according to claim 1, characterized in that, The lower tubing string further includes a liner disposed below the anchor seal release.

6. The completion string according to claim 5, characterized in that, The liner is provided with a round nose guide shoe at the end of the horizontal pipe section.

7. The completion string according to claim 6, characterized in that, A plurality of the through holes are formed in the liner near the round nose guide shoe.

8. The completion string according to claim 7, wherein One side of the round nose guide shoe away from the liner is configured as an arc surface.

9. The completion string according to claim 1, wherein, A downhole safety valve is provided at the top end of the upper tubing string.

10. The completion string according to claim 4, characterized in that, The kill sleeve is integrated with the upper tubing string.

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