Method for oil and gas well bore operations with multiple outer diameter coiled tubing

Abstract

The present application relates to oil and gas field development downhole operation method technical field, it is a kind of multi-outer diameter coiled tubing oil and gas well wellbore operation method, comprising (1) coiled tubing optimization criterion: according to the passability of operation wellbore, select coiled tubing combination;(2) blowout preventer group configuration method: blowout preventer group configuration mode is related to coiled tubing outer diameter specification type, N section different outer diameter specification coiled tubing combination is equipped with N kind of matched blowout preventer group;(3) after determining coiled tubing combination and blowout preventer group, the butt joint process of different pipe diameter coiled tubing is carried out.The present application can realize the efficient operation of coiled tubing in super-deep, variable-diameter wellbore (horizontal well or straight well), break the technical bottleneck of single-pipe-diameter coiled tubing operation in the above complex wellbore, such as strength limitation, insufficient end effect, poor passability, realize the purpose of "variable-diameter pipe string efficient operation in variable-diameter wellbore", it is beneficial to efficient and safe operation.

Description

Technical Field

[0001] This invention relates to the technical field of downhole operation methods for oil and gas field development, and is a wellbore operation method for multi-diameter continuous tubing oil and gas wells. Background Technology

[0002] With the continuous advancement of oil and gas resource development in my country, unconventional and deep oil and gas reservoirs have become the main targets for exploration and development. In the field of unconventional oil and gas exploration and development, significant breakthroughs have been achieved in shale oil and tight oil exploration and development technologies. Volumetric fracturing has become an indispensable technical tool for developing unconventional oil and gas reservoirs. Currently, the most effective development method for shale oil and tight oil is horizontal well staged fracturing. Among them, the "open-hole packer + sliding sleeve" staged fracturing technology has been applied in major oilfields. However, after the implementation of this process, the wellbore diameter decreases step by step, which brings certain difficulties to subsequent wellbore operations. Meanwhile, in the development of deep oil and gas reservoirs, high-pressure oil and gas wells generally use permanent packer completion strings for production. The production string contains a series of functional accessories such as downhole safety valves, packers, and plugs. Some oil and gas wells even use a combined production string with a larger top and smaller bottom, resulting in a multi-diameter structure for the production string, which also poses challenges to subsequent tubing operations. Coiled tubing technology has developed rapidly in recent years, evolving from simple unclogging operations to complex downhole cutting, fishing, drilling, and other specialized operations, making significant contributions to increasing unconventional oil and gas reserves and production. However, given the typical issues of multiple diameter variations and even progressively narrowing diameters in coiled tubing operations, using single-diameter coiled tubing faces a series of problems, including limited strength, insufficient end-effector effect, and poor throughput, which significantly impact the normal production of oil and gas wells. Summary of the Invention

[0003] This invention provides a method for operating oil and gas wells with multi-diameter coiled tubing, which overcomes the shortcomings of the prior art and can effectively solve the problems of limited strength, insufficient end effect and poor throughput faced by single-diameter coiled tubing in variable-diameter wells.

[0004] The technical solution of the present invention is achieved through the following measures: a wellbore operation method for oil and gas wells with multi-outer diameter coiled tubing, comprising three parts: (1) coiled tubing selection criteria; (2) blowout preventer assembly configuration method; (3) docking process for coiled tubing of different diameters;

[0005] (1) Coiled tubing selection criteria: Select coiled tubing combination based on the wellbore passability, that is, determine the basic parameters of coiled tubing specifications and length based on the minimum inner diameter of the wellbore diameter change point and the working depth. Evaluate the performance of the coiled tubing with the determined basic parameters, including tubing string insertion analysis, tubing string strength verification and hydrodynamic parameter verification. Determine the final parameters of coiled tubing specifications and length based on the operational requirements to ensure operational safety.

[0006] (2) Blowout preventer assembly configuration method: The configuration method of blowout preventer assembly is related to the type of outer diameter of coiled tubing. N sections of coiled tubing with different outer diameter specifications need to be equipped with N matching blowout preventer assemblies.

[0007] (3) After determining the coiled tubing assembly and blowout preventer assembly, the process of connecting coiled tubing of different diameters is carried out. After the connection of coiled tubing of different diameters is completed, the connected coiled tubing is lowered into the designated working depth to carry out well operations.

[0008] The following are further optimizations and / or improvements to the above-mentioned technical solution:

[0009] The connection process for the above-mentioned coiled tubing of different diameters is as follows:

[0010] N types of blowout preventers (BOPs) are installed at the wellhead as well control devices, consisting of N sections of coiled tubing with different outer diameters. The BOP groups correspond to the outer diameters of the coiled tubing in descending order from top to bottom. An injection head and BOP are fixedly installed on the top BOP from top to bottom. A support structure is erected at the BOP location to facilitate operator access. The first section of coiled tubing is run in the same way as conventional coiled tubing, using a coiled tubing workover rig to run the first section into the well through the injection head. When only the last half-turn of the first section remains, the injection head is used... The crane, in coordination with the towing of the end of the first section of coiled tubing, is suspended at the top plane of the blowout preventer. Then, the drum of the coiled tubing installation machine is replaced and the second section of coiled tubing is lowered in. After the beginning of the second section of coiled tubing is lowered into the injection head, the operator standing on the support opens the blowout preventer and uses a different diameter coiled tubing connection device to connect the end of the first section of coiled tubing with the beginning of the second section of coiled tubing. In this connection method, N sections of coiled tubing with different diameters are connected, and the connected coiled tubing is lowered into the designated working depth to carry out wellbore operations.

[0011] The selection principles for the basic parameters of the specifications and length of the aforementioned coiled tubing are as follows:

[0012] Based on the minimum inner diameter D of the diameter change point 1 of the working well shaft. 1min Depth L B1 With working depth L W The parameter range for the outer diameter and length of the first section of coiled tubing is determined. The basic parameters for the outer diameter and length of the Nth section of coiled tubing are determined by the depth of the diameter change point N, the minimum inner diameter, and the depth of the diameter change point N-1, as shown in the following formula:

[0013]

[0014] Among them, D LNThis represents the diameter of the Nth continuous tubing segment;

[0015] L LN This represents the basic length parameter of the Nth segment of continuous tubing;

[0016] D Nmin This represents the minimum diameter at the Nth diameter change point;

[0017] L BN This represents the depth of the Nth diameter change point;

[0018] L W Indicates the depth of the operation.

[0019] When configuring the above-mentioned blowout preventer (BOP) group, the BOP installed at the top of the wellhead is a four-gate BOP, whose inner diameter corresponds to the outer diameter of the Nth section of coiled tubing. The remaining BOP groups are equipped with at least two-gate BOPs according to the corresponding outer diameter specifications of the coiled tubing. The specifications of each BOP in the BOP group decrease from top to bottom.

[0020] This invention addresses the challenges of ultra-deep, variable-diameter wellbores, particularly those with complex variable-diameter wellbore conditions characterized by "multi-stage diameter changes + gradual diameter reduction." It innovatively proposes a method for operating oil and gas wells with multi-outer-diameter coiled tubing. This method combines and seals coiled tubing of different outer diameters to form a "larger top, smaller bottom" combined operating string. Furthermore, it provides selection criteria for coiled tubing, a method for configuring blowout preventer (BOP) groups, and a process route for connecting coiled tubing of different diameters. This offers a new approach for efficiently and safely conducting variable-diameter wellbore operations. Attached Figure Description

[0021] Appendix Figure 1 This is a schematic diagram of the multi-diameter continuous tubing oil and gas wellbore operation method described in this invention.

[0022] The codes in the attached diagram are as follows: 1 is the first section of coiled tubing, 2 is the second section of coiled tubing, 3 is the Nth section of coiled tubing, 4 is the working tool, 5 is the production / gas tree, 6 is the Nth blowout preventer, 7 is the second blowout preventer, 8 is the first blowout preventer, 9 is the blowout preventer pipe, 10 is the injection head, 11 is the coiled tubing (surface section), 12 is the coiled tubing installation machine, A is the diameter change point 1, B is the diameter change point 2, and C is the diameter change point N. Detailed Implementation

[0023] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0024] In this invention, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1The orientation of the layout is determined by the direction of the map.

[0025] The present invention will be further described below with reference to embodiments:

[0026] Example 1: The wellbore operation method for multi-diameter coiled tubing oil and gas wells includes three parts: (1) coiled tubing selection criteria; (2) blowout preventer assembly configuration method; (3) docking process for coiled tubing of different diameters;

[0027] (1) Coiled tubing selection criteria: Select coiled tubing combination based on the wellbore passability, that is, determine the basic parameters of coiled tubing specifications and length based on the minimum inner diameter of the wellbore diameter change point corresponding to the diameter change string and the working depth. Evaluate the performance of the coiled tubing with the determined basic parameters, including string insertion analysis, string strength verification and hydrodynamic parameter verification. Determine the final parameters of coiled tubing specifications and length based on the operational requirements to ensure operational safety.

[0028] (2) Blowout preventer assembly configuration method: The configuration method of the blowout preventer assembly is related to the outer diameter specifications of the coiled tubing. N sections of coiled tubing with different outer diameter specifications are equipped with N matching blowout preventer assemblies.

[0029] (3) After determining the coiled tubing assembly and blowout preventer assembly, the process of connecting coiled tubing of different diameters is carried out. After the connection of coiled tubing of different diameters is completed, the connected coiled tubing is lowered into the designated working depth to carry out well operations.

[0030] Performance evaluation of the selected coiled tubing combination (tubing run performance analysis, tubing strength verification and hydrodynamic parameter verification), as well as adjustment of the coiled tubing specifications and combination method according to operational requirements, are routine operations before coiled tubing is run into the well. In this operation, the adjustment of the coiled tubing specifications and combination method is common knowledge in the field.

[0031] Different specifications of continuous tubing are connected by sealing joints to achieve a sealed connection.

[0032] Example 2: As shown in the attached document Figure 1 As shown, as an optimization of the above embodiment, the connection process for coiled tubing of different diameters is as follows:

[0033] N types of blowout preventers (BOPs) equipped with N sections of coiled tubing of different outer diameters are installed at the wellhead as well control devices. The BOP assembly consists of N types of BOPs, with the outer diameter of the coiled tubing decreasing sequentially from top to bottom. An injection head 10 and a blowout preventer pipe 9 are fixedly installed on the topmost BOP from top to bottom. A support frame is erected at the blowout preventer pipe 9 to facilitate operation. The first section of coiled tubing 1 is run in the same way as conventional coiled tubing, i.e., the first section of coiled tubing 1 is run into the well through the injection head 10 using a coiled tubing workover machine 12. When the first section of coiled tubing 1 is run down to the last half turn, a crane is used to assist. The end of the first section of coiled tubing 1 is pulled to the upper plane of the top blowout preventer (i.e., the first blowout preventer 8) and suspended. Then, the drum of the coiled tubing installation machine 12 is replaced and the second section of coiled tubing 2 is lowered in. After the starting end of the second section of coiled tubing 2 is lowered into the injection head 10, the operator standing on the support opens the blowout preventer 9 and uses the different diameter coiled tubing connection device to connect the end of the first section of coiled tubing 1 and the starting end of the second section of coiled tubing 2. In this way, N sections of coiled tubing with different diameters are connected and then the connected coiled tubing is lowered into the designated working depth to carry out wellbore operations.

[0034] The support can be a tower-type support disclosed in Chinese patent document CN2013206957741, or other existing and publicly known operating platforms.

[0035] The coupling device for different diameter coiled tubing can adopt the COUPLING APPARATUS FOR COILED TUBINGS OF DIFFERENT DIAMETERS disclosed in US Patent Document No. US11149496B2 (COUPLING APPARATUS FOR COILED TUBINGS OF DIFFERENT DIAMETERS, INSTALLING METHOD FOR COUPLING APPARATUS, AND INSTALLING METHOD FOR TUBINGS OF DIFFERENT DIAMETERSUSING COUPLING APPARATUS).

[0036] Example 3: As an optimization of the above examples, the selection principles for the basic parameters of the coiled tubing specifications and length are as follows:

[0037] Based on the minimum inner diameter D of the diameter change point 1A of the working well shaft. 1min Depth L B1 With working depth L WThe parameter range for the outer diameter and length of the first section of coiled tubing 1 is determined. The basic parameters for the outer diameter and length of the second section of coiled tubing 2 to the Nth section of coiled tubing 3 are determined by the depth of the diameter change point N, the minimum inner diameter, and the depth of the diameter change point N-1, as shown in the following formula:

[0038]

[0039] Among them, D LN This indicates the diameter of the Nth continuous tubing segment 3;

[0040] L LN This represents the basic length parameter of the Nth continuous tubing segment 3;

[0041] D Nmin This represents the minimum diameter at the Nth diameter change point;

[0042] L BN This represents the depth of the Nth diameter change point;

[0043] L W Indicates the depth of the operation.

[0044] Example 4: As an optimization of the above example, when configuring the blowout preventer group, the blowout preventer installed at the top of the wellhead (i.e., the first blowout preventer 8) is a four-gate blowout preventer, and its inner diameter corresponds to the outer diameter of the Nth section of coiled tubing 3 (i.e., the largest outer diameter coiled tubing). The remaining blowout preventer groups are configured with at least two-gate blowout preventers according to the corresponding outer diameter specifications of the coiled tubing. The specifications of each blowout preventer in the blowout preventer group decrease from top to bottom.

[0045] The four-gate blowout preventer (BOP) is a conventional BOP consisting of four gates: a full-sealing gate, a shearing gate, a slip gate, and a semi-sealing gate. The full-sealing gate comprises two symmetrical gate bodies with embedded sealing blocks, its primary function being to completely seal the wellbore. The shearing gate consists of a left and a right shearing gate body, symmetrically equipped with shearing blades, its primary function being to shear the coiled tubing. The slip gate consists of two symmetrical slip gate bodies with clamping jaws and fixed suspension blocks, its primary function being to clamp and suspend the coiled tubing, preventing it from sagging or bulging. The semi-sealing gate consists of two symmetrical semi-sealing gate bodies with embedded semi-sealing blocks, its primary function being to seal the annulus between the wellbore and the tubing string. The two-gate BOP is also a conventional BOP, comprising a slip gate and a semi-sealing gate.

[0046] Equipped with blowout preventers corresponding to coiled tubing of different outer diameters, so that in case of abnormal well conditions during the running or pulling of coiled tubing, the appropriate blowout preventer can be used to carry out blowout prevention operations.

[0047] When running coiled tubing in oil and gas wells using the multi-outer-diameter coiled tubing wellbore operation method described in this invention, unless otherwise specified, other running operations are the same as those for conventional coiled tubing.

[0048] This invention enables efficient operation of coiled tubing in ultra-deep, variable-diameter wellbores (horizontal or vertical wells), breaking through the technical bottlenecks faced by single-diameter coiled tubing in such complex wellbores, such as limited strength, insufficient end effect, and poor throughput. It achieves the goal of "efficient operation of variable-diameter tubing strings in variable-diameter wellbores," which is conducive to efficient and safe operation.

[0049] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for operating the wellbore of a multi-diameter coiled tubing oil and gas well, characterized in that... It includes three parts: (1) selection criteria for coiled tubing; (2) configuration method for blowout preventer assembly; and (3) connection process for coiled tubing of different diameters. (1) Selection criteria for coiled tubing: Select coiled tubing combination based on the wellbore passability, that is, determine the basic parameters of coiled tubing specifications and length based on the minimum inner diameter of the wellbore diameter change point and the working depth. Evaluate the performance of the coiled tubing with the determined basic parameters, including tubing string insertion analysis, tubing string strength verification and hydrodynamic parameter verification. Determine the final parameters of coiled tubing specifications and length based on the operational requirements to ensure operational safety. (2) Blowout preventer assembly configuration method: The configuration method of blowout preventer assembly is related to the type of outer diameter of coiled tubing. N sections of coiled tubing with different outer diameter specifications need to be equipped with N matching blowout preventer assemblies. (3) After determining the coiled tubing assembly and blowout preventer assembly, the process of connecting coiled tubing of different diameters is carried out. After the connection of coiled tubing of different diameters is completed, the connected coiled tubing is run into the designated working depth to carry out well operations. The basic principles for selecting the specifications and length of coiled tubing are as follows: Based on the minimum inner diameter D of the diameter change point 1 of the working well shaft. 1min Depth L B1 With working depth L W The parameter range for the outer diameter and length of the first section of coiled tubing is determined. The basic parameters for the outer diameter and length of the Nth section of coiled tubing are determined by the depth of the diameter change point N, the minimum inner diameter, and the depth of the diameter change point N-1, as shown in the following formula: in, D LN Indicates the first N The diameter of the continuous tubing section; L LN Indicates the first N Basic length parameters of continuous tubing; D Nmin Indicates the first N Minimum diameter at each diameter change point; L BN Indicates the first N The depth of each diameter change point; L W Indicates the depth of the operation.

2. The wellbore operation method for multi-diameter coiled tubing oil and gas wells according to claim 1, characterized in that... The connection process for coiled tubing of different diameters is as follows: N types of blowout preventers (BOPs) are installed at the wellhead as well control devices, consisting of N sections of coiled tubing with different outer diameters. The BOP groups correspond to the outer diameters of the coiled tubing in descending order from top to bottom. An injection head and BOP are fixedly installed on the top BOP from top to bottom. A support structure is erected at the BOP location to facilitate operator access. The first section of coiled tubing is run in the same way as conventional coiled tubing, using a coiled tubing workover rig to run the first section into the well through the injection head. When only the last half-turn of the first section remains, the injection head is used... The crane, in coordination with the towing of the end of the first section of coiled tubing, is suspended at the top plane of the blowout preventer. Then, the drum of the coiled tubing installation machine is replaced and the second section of coiled tubing is lowered in. After the beginning of the second section of coiled tubing is lowered into the injection head, the operator standing on the support opens the blowout preventer and uses a different diameter coiled tubing connection device to connect the end of the first section of coiled tubing with the beginning of the second section of coiled tubing. In this connection method, N sections of coiled tubing with different diameters are connected, and the connected coiled tubing is lowered into the designated working depth to carry out wellbore operations.

3. The wellbore operation method for multi-diameter coiled tubing oil and gas wells according to claim 1 or 2, characterized in that... When configuring a blowout preventer (BOP) assembly, the BOP installed at the top of the wellhead is a four-gate BOP, whose inner diameter corresponds to the outer diameter of the Nth section of coiled tubing. The remaining BOP assemblies are equipped with at least two-gate BOPs according to the corresponding outer diameter specifications of the coiled tubing. The specifications of each BOP in the BOP assembly decrease from top to bottom.

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