A method for forming a single-diameter technical casing in a well using resin

Abstract

This invention relates to the field of petroleum drilling technology, and in particular to a method for forming a single-diameter technical casing downhole using resin. The method includes the following steps: (1) drilling an open-hole section in complex formations; (2) enlarging all or part of the open-hole section; (3) placing the lower part of a central tube into the open-hole section using a drill string, and applying a drillable centralizer on the central tube to ensure the resin tube is centered, forming a central framework in the open-hole section; (4) using a high-temperature resistant, slow-setting resin as raw material, ensuring that the resin solidifies between the outer wall of the central tube framework and the inner wall of the open-hole section, forming a ring-shaped resin solid material; (5) allowing it to solidify for 12-24 hours, and then drilling open the central tube and the resin solid material using a lead drill bit, forming a single-diameter resin casing in the open-hole section. This invention utilizes resin material, in conjunction with a drillable central tube, to form a single-diameter resin casing downhole, solving the problem of temporary sealing in complex formations.

Description

Technical Field

[0001] This invention relates to the field of petroleum drilling technology, and in particular to a method for forming a single-diameter casing downhole using resin. Background Technology

[0002] For complex formations such as rock layers encountered during drilling, casing is often required for open-hole sealing. However, the casing sequence of a well is always affected by factors such as casing size, wellbore size, casing strength, length, and pressure-bearing capacity. Often, in many sections requiring casing sealing, the original wellbore design cannot accommodate additional multiple layers of casing. In such cases, auxiliary materials and technologies such as mud, plugging materials, and liquid additives are needed for temporary formation sealing. These auxiliary technologies often have low pressure-bearing capacity and are difficult to meet drilling requirements. Therefore, a new process needs to be developed that can provide casing performance while offering the same wellbore size as the original wellbore, providing temporary sealing for complex formations. Summary of the Invention

[0003] The purpose of this invention is to provide a method for forming a single-diameter casing in the well using resin, overcoming the shortcomings of the aforementioned prior art. By using resin material in conjunction with a drillable center tube, a resin casing with a certain wall thickness is formed in the well and bonded to the formation, thus solving the problem of temporary sealing in complex formations.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A method for forming a single-diameter casing downhole using resin includes the following steps:

[0006] (1) Start drilling from the upper casing shoe, drill in complex formations, and drill out the open hole section;

[0007] (2) Perform enlargement operations on all or part of the open hole section, and the diameter of the enlarged open hole section is 2 ± 0.2 inches larger than the casing diameter in conventional formations;

[0008] (3) Select a center tube of appropriate size, use the drilling tool to place the center tube into the open hole section after reaming, and use a drillable stabilizer on the tube body of the center tube to ensure that the center tube is centered, forming a central skeleton in the open hole section after reaming.

[0009] (4) Using high-temperature resistant retarded resin as raw material, ensure that the high-temperature retarded resin is cured between the outer wall of the central tube skeleton downhole and the annulus of the open hole section to form a ring-shaped resin solid material.

[0010] (5) After waiting for 12-24 hours, use a drill bit of the same size as the one used to drill the open hole section to drill the center tube and resin solid material to form a new borehole of the same size as the original well hole, that is, a single-diameter resin casing is formed in the open hole section.

[0011] The above method ensures that a new wellbore is drilled at the center of the downhole resin solid material, preventing drilling deviation and avoiding the absence of resin layer protection in open-hole sections where resin-sealed sections are not used, thus ensuring the sealing effect on complex formations.

[0012] Furthermore, in step (3), the length of the central tube is 200±100m longer than the length of the section of the open hole that needs to be sealed.

[0013] Furthermore, in step (3), the central tube is a resin tube, a nylon tube, or a drillable aluminum alloy tube. The central tube is released by pressure or by inverting. The central tube needs to be released before being sealed with resin.

[0014] Furthermore, in step (3), the method of selecting the center tube is as follows: for 12-1 / 4 inch wellbores, a 7-inch to (9-5 / 8) inch center tube is selected, with a coupling outer diameter of 8-12 inches and a thread tensile strength of not less than 200kN; for 8-1 / 2 inch wellbores, a 5-1 / 2 inch to 7-inch center tube is selected, with a coupling outer diameter of 6-inch to (8-1 / 2) inches and a thread tensile strength of not less than 150kN.

[0015] Furthermore, in step (3), the straightening tool is a resin straightening tool that can be drilled, and the maximum outer diameter of the straightening tool does not exceed the outer diameter of the drill bit that drills the open hole section.

[0016] Furthermore, in step (4), the high-temperature resistant retarding resin is resistant to high temperatures of 80-160°C.

[0017] Furthermore, in step (4), the high-temperature retarding resin is selected from high-temperature retarding unsaturated polyester resin, epoxy resin, vinyl unsaturated resin or cyanate ester resin with a temperature resistance of up to 120-160℃.

[0018] Furthermore, in step (4), the initial thickening time of the high-temperature retarding resin is 4-6 hours, and the compressive strength of the high-temperature retarding resin after curing can reach 70-130MPa. The high-temperature retarding resin has stable performance and does not react with common acids, alkalis, and salts. In order to improve the characteristics of the high-temperature retarding resin, commonly used additives can also be added to enhance its performance.

[0019] Furthermore, in step (4), the density of the high-temperature resistant retarded resin can be adjusted between 1.10 and 2.50, and is required to be no less than the density of the drilling mud used to drill through the open hole section of the formation; the viscosity of the high-temperature resistant retarded resin can be adjusted between 40 and 200 mPa·s, and is required to match the fluidity of the high-temperature resistant retarded resin liquid with the viscosity of the drilling mud used to drill through the open hole section of the formation.

[0020] Furthermore, in step (4), the designed volume of the resin solid material is the annulus volume of the open hole section to be sealed plus the annulus volume of 50 meters of casing-center tube.

[0021] The beneficial effects of this invention are as follows: Compared with the prior art, the method of forming a single-diameter casing in the well using resin has the following advantages: low cost and controllable risk. By using resin material in conjunction with a drillable center tube, a resin casing with a certain wall thickness and bonded to the formation is formed in the well. The cooperation of the center tube, the resin material centralizer, and the lead drill bit can ensure that the drilling does not deviate, avoid the situation where some sections of the open hole are not protected by a resin layer, and ensure that a single-diameter resin casing is formed in the open hole section, thus solving the problem of temporary sealing in complex formations. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process principle of the present invention;

[0023] Among them, 1 is the upper casing shoe, 2 is the complex formation, 3 is the open hole section, 4 is the open hole section after enlargement, 5 is the casing, 6 is the center pipe, 7 is the drillable centralizer, 8 is the resin solid material, and 9 is the lead drill bit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0025] like Figure 1 In the illustrated embodiment, a method for forming a single-diameter casing using resin downhole is described. The operation is carried out downhole at depths of 2000-3000 meters, with temperatures ranging from 60-100°C and pressures from 20-60 MPa; at depths of 3000-4000 meters, with temperatures ranging from 80-120°C and pressures from 30-80 MPa; and at depths greater than 4000 meters, with temperatures greater than 100°C and pressures greater than 40 MPa.

[0026] A method for forming a single-diameter casing downhole using resin includes the following steps:

[0027] (1) Drill from the upper casing shoe 1 to the complex formation 2 and drill out the open hole section 3;

[0028] (2) Perform enlargement operation on all or part of the open hole section. The diameter of the enlarged open hole section 4 is 2 ± 0.2 inches larger than the diameter of the casing 5 in the conventional formation.

[0029] (3) Select a center tube 6 of appropriate size, use the drilling tool to put the center tube into the open hole section after reaming, and use a drillable stabilizer 7 on the tube body of the center tube to ensure that the center tube is centered, forming a central skeleton in the open hole section after reaming.

[0030] (4) Using high-temperature resistant retarded resin as raw material, ensure that the high-temperature resistant retarded resin is cured between the outer wall of the central skeleton downhole and the annulus of the open hole section to form a solid ring-shaped resin material 8.

[0031] (5) After waiting for 12-24 hours, use a drill bit 9 of the same size as the drill bit used to drill the open hole section to drill the center tube and resin solid material, forming a new borehole of the same size as the original well hole, that is, forming a single-diameter resin casing in the open hole section.

[0032] The above method ensures that a new wellbore is drilled at the center of the downhole resin solid material, preventing drilling deviation and avoiding the open hole section from being connected to the original formation without resin layer protection, thus ensuring the sealing effect on complex formations.

[0033] In this embodiment, in step (3), the length of the central tube is 200±100m longer than the length of the open hole section. In step (3), the central tube is a resin tube, a nylon tube, or a drillable aluminum alloy tube. The central tube is released by pressure release and reverse release. The central tube is released before resin sealing. In step (3), the central tube is selected as follows: for 12-1 / 4 wells, a 7-inch to (9-5 / 8)-inch central tube is selected, with a coupling outer diameter of 8-12 inches and a thread tensile strength of not less than 200kN; for 8-1 / 2 wells, a 5-1 / 2-inch to 7-inch central tube is selected, with a coupling outer diameter of 6-(8-1 / 2) inches and a thread tensile strength of not less than 150kN. In step (3), the maximum outer diameter of the resin material centralizer does not exceed the outer diameter of the drill bit that drills the open hole section.

[0034] In this embodiment, in step (4), the high-temperature retarding resin is resistant to temperatures of 80-160°C. In step (4), the high-temperature retarding resin is selected from unsaturated vinyl resins with a temperature resistance of 120-160°C, or cyanate ester resins with a temperature resistance of 80-120°C, or epoxy resins. In step (4), the initial thickening time of the high-temperature retarding resin is 4-6 hours, and the cured strength of the high-temperature retarding resin can reach 70-130 MPa. The high-temperature retarding resin has stable performance and does not react with common acids, alkalis, or salts. To improve the properties of the high-temperature retarding resin, commonly used additives can be added to enhance its performance. In step (4), the density of the high-temperature resistant retarded resin can be adjusted between 1.10 and 1.50, and must not be less than the density of the drilling mud used to drill through the open hole section; the viscosity of the high-temperature resistant retarded resin can be adjusted between 40 and 100 mPa·s, and the fluidity of the high-temperature resistant retarded resin liquid must match the viscosity of the drilling mud used to drill through the open hole section. In step (4), the designed volume of the resin solid material is the annulus volume of the open hole section to be sealed plus the annulus volume of 50 meters of casing-center tube.

[0035] In this embodiment, the remaining on-site construction follows common casing cementing operation procedures.

[0036] The above-described specific embodiments are merely specific examples of the present invention. The patent protection scope of the present invention includes, but is not limited to, the product form and style of the above-described specific embodiments. Any appropriate changes or modifications made by a person skilled in the art that conform to the claims of the present invention should fall within the patent protection scope of the present invention.

Claims

1. A method for forming a single-diameter casing downhole using resin, characterized in that: Includes the following steps: (1) Start drilling from the upper casing shoe, drill in complex formations, and drill out the open hole section; (2) Perform enlargement operations on all or part of the open hole section, and the diameter of the open hole section after enlargement is 2±0.2 inches larger than the casing diameter in conventional formations; (3) Select a center tube of appropriate size. The length of the center tube is greater than the length of the well section that needs to be sealed or reinforced in the open hole section. Use the drill string to place the center tube into the open hole section after reaming. Use a drillable resin material stabilizer on the body of the center tube to ensure that the center tube is centered and form a central skeleton in the open hole section after reaming. (4) Using high-temperature resistant retarded resin as raw material, ensure that the high-temperature resistant retarded resin is cured between the outer wall of the central skeleton downhole and the annulus of the open hole section to form a ring-shaped resin solid material. (5) After waiting for 12-24 hours, use a drill bit of the same size as the drill bit used to drill the open hole section to drill the center tube and resin solid material, forming a new borehole of the same size as the original well hole, that is, forming a single-diameter resin casing in the open hole section.

2. The method for forming a single-diameter casing downhole using resin according to claim 1, characterized in that: In step (3), the length of the central tube is 200±100m longer than the length of the section of the open hole that needs to be sealed or reinforced.

3. The method for forming a single-diameter casing downhole using resin according to claim 1, characterized in that: In step (3), the central tube is a resin tube, a nylon tube, or a drillable aluminum alloy tube.

4. The method for forming a single-diameter casing downhole using resin according to claim 1, characterized in that: In step (3), the method of selecting the center tube is as follows: for 12-1 / 4 inch wellbores, a 7-inch to (9-5 / 8) inch center tube is selected, with a coupling outer diameter of 8-12 inches and a thread tensile strength of not less than 200kN; for 8-1 / 2 inch wellbores, a 5-1 / 2 inch to 7-inch center tube is selected, with a coupling outer diameter of 6-inch to (8-1 / 2) inches and a thread tensile strength of not less than 150kN.

5. The method for forming a single-diameter casing downhole using resin according to claim 1, characterized in that: In step (3), the maximum outer diameter of the drillable resin material centralizer does not exceed the outer diameter of the drill bit used to drill the open hole section.

6. The method for forming a single-diameter casing downhole using resin according to claim 1, characterized in that: In step (4), the high-temperature resistant retarding resin is resistant to high temperatures of 80-160°C.

7. A method for forming a single-diameter casing downhole using resin according to claim 1 or 6, characterized in that: In step (4), the high-temperature retarding resin is selected from one or more of the following: high-temperature retarding unsaturated polyester resin, epoxy resin, vinyl unsaturated resin or cyanate ester resin.

8. A method for forming a single-diameter casing downhole using resin according to claim 1 or 6, characterized in that: In step (4), the initial thickening time of the high-temperature retarding resin is 4-6 hours, and the compressive strength of the high-temperature retarding resin after curing can reach 70-130MPa.

9. A method for forming a single-diameter casing downhole using resin according to claim 1 or 6, characterized in that: In step (4), the density of the high-temperature retarded resin can be adjusted between 1.10 and 2.50, and it is required to be no less than the density of the drilling mud used to drill the open hole section of the formation; the viscosity of the high-temperature retarded resin can be adjusted between 40 and 200 mPa.s, and the fluidity of the high-temperature retarded resin liquid is required to match the viscosity of the drilling mud used to drill the open hole section of the formation.

10. A method for forming a single-diameter casing downhole using resin according to claim 1 or 6, characterized in that: In step (4), the designed volume of the resin solid material is the annulus volume of the open hole section to be sealed plus the annulus volume of 50 meters of casing-center tube.

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