A side-drilling window-opening millable composite casing short section, its preparation method, and its application.

Abstract

This invention discloses a millable composite casing sub for side-drilling window opening, its preparation method, and its application. The millable composite casing sub comprises the following components: a matrix, a lubricating phase, and brittle phase reinforcing particles; the matrix is ​​an aluminum alloy matrix; the lubricating phase is graphite particles; and the brittle phase reinforcing particles are brittle mineral particles. During side-drilling window opening operations, an integrated hydraulic directional device is seated inside the lower steel casing below the casing sub. A gyroscope is used for precise orientation, and then a milling cone is lowered to perform side-drilling window opening. The sub body is milled using the milling cone to form the initial window. This invention, while ensuring the overall connection strength and sealing of the wellbore, locally alters the millability of the casing material at the planned window opening point. Through material and structural innovation, it replaces traditional steel casing, shortens the operation cycle, reduces the difficulty of milling operations, and extends the service life of the milling cone, thereby achieving high efficiency, low cost, and safety and reliability in window opening operations.

Description

Technical Field

[0001] This invention relates to the field of casing windowing and sidetracking technology in oil and gas and surface directional grouting drilling engineering, specifically to a sidetracking windowed millable composite casing short section, its preparation method, and the sidetracking windowed casing and its application. Background Technology

[0002] Casing-based side-drilling is a key technology in industries such as oil and gas, and directional drilling grouting, enabling the combined use of a main borehole and multiple branch boreholes for regional surface extraction and remediation. However, existing side-drilling technologies face challenges such as low efficiency in the combination of milling tapers and casing milling.

[0003] Currently, most well casings use high-strength steel casing of grade J55, which has excellent mechanical properties and wear resistance. While this greatly ensures the integrity of the well casing, it also presents problems such as severe wear of the milling tool during milling operations, slow mechanical drilling speed, and long operation cycles.

[0004] Currently, existing research generally improves window opening speed by optimizing milling tools and drilling parameters. For example, using cemented carbide to arrange two rows of shaping teeth to form an integral cutter blade improves the milling efficiency of the cutter blade; or changing the material of the cutting teeth, such as using high-strength diamond alloy, can accelerate the milling efficiency. These methods can effectively improve window opening efficiency, but they do not change the fundamental issues of the high hardness and high wear resistance of the milled object (casing), so there is a certain bottleneck in improving window opening speed. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide a side-drilling window-opening millable composite casing short section, its preparation method, and side-drilling window-opening casing and its application. Without sacrificing the overall connection strength and sealing performance of the wellbore, the millability of the casing material is locally changed at the planned window-opening point, thereby fundamentally breaking through the bottleneck of window-opening efficiency, shortening the operation cycle, and reducing the operation cost.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A side-drilling, window-opening, millable composite casing sub has a density of 2.8 g / cm³. 3 The tensile strength is 350-450 MPa, the yield strength is 300-380 MPa, and the Brinell hardness is 80-120 HB; the side-drilling window-opening millable composite casing short section is composed of the following components: matrix, lubricating phase and brittle phase reinforcing particles.

[0008] The matrix is ​​an aluminum alloy matrix; the lubricating phase is graphite particles; and the brittle phase reinforcing particles are brittle mineral particles.

[0009] The side-drilling, window-opening, millable composite casing sub of this invention uses 7000 series aluminum alloy with excellent millability as the matrix, and adds graphite particles as a lubricating phase and mica particles as brittle reinforcing phase particles. The resulting side-drilling, window-opening, millable composite casing sub has a density of 2.8 g / cm³. 3 The tensile strength is 350-450 MPa, the yield strength is 300-380 MPa, and the Brinell hardness is 80-120 HB. Under the premise of ensuring the overall connection strength and sealing of the wellbore, the machinability of the side-drilling window-opening millable composite casing short section material is locally changed at the planned window-opening point.

[0010] A side-drilling window-opening millable composite casing short section is manufactured using a specific method. The short section body can be connected to the upper and lower steel casings via connecting threads at both ends, forming a side-drilling window-opening casing. This invention replaces traditional steel casing through material and structural innovation. It transforms side-drilling window opening operations from "grinding iron" to "milling aluminum," shortening the operation cycle, reducing the difficulty of grinding and milling operations, and extending the service life of the milling cone. This achieves high efficiency, low cost, and safety in window opening operations. It fundamentally breaks through the bottleneck of window opening efficiency, solving the problems of low efficiency and high tool wear in branch hole side-drilling construction. It is suitable for efficient, low-cost, and safe multi-branch well projects.

[0011] The aforementioned side-drilling, millable composite casing sub has the following component proportions: 82-90 parts matrix, 5-10 parts lubricating phase, and 5-8 parts brittle reinforcing particles. This proportion satisfies the requirements of lubrication, embrittlement, and improved millability without compromising the overall strength and toughness of the material.

[0012] The aforementioned side-drilling, millable composite casing sub uses mica particles as the brittle mineral particles, with both the mica and graphite particles having a particle size of 10-50 μm. The mica particles are brittle and easily broken, and their bonding with the matrix is ​​moderate (too strong a bond makes them difficult to peel off, while too weak a bond results in porosity defects). The graphite particles, with a particle size of 10-50 μm, are effectively dispersed and can be dragged out during milling to form a continuous and effective solid lubricating film on the friction surface, with controllable negative impact on the matrix's mechanical properties. The aluminum alloy matrix is ​​a 7000 series aluminum alloy, ensuring the sub has sufficient strength to withstand downhole pressure and tubing loads.

[0013] The aforementioned side-drilling, window-opening, millable composite casing sub includes a sub body with connecting threads at both ends. One end of the sub body has an internal thread, and the other end has an external thread. Both connecting threads are trapezoidal threads, ensuring a direct and reliable threaded connection between the sub body and conventional steel casing, guaranteeing connection strength and sealing integrity.

[0014] The aforementioned side-drilling, millable composite casing sub has magnetic or groove markings on its outer or inner wall corresponding to the designed window depth. This allows for precise positioning of the sub downhole during casing installation and when using cable-operated tools.

[0015] A method for preparing a side-drilling, millable composite casing sub includes the following steps:

[0016] Step 1: Weigh 82-90 parts by weight of aluminum alloy matrix powder, 5-10 parts by weight of graphite particles and 5-8 parts by weight of mica particles and place them in a ball mill. Mix them evenly to obtain a mixture.

[0017] Step 2: The mixture is formed into a tube blank by cold isostatic pressing and hot pressing sintering, respectively;

[0018] Step 3: After solution treatment and aging treatment of the formed tube blank, the tube blank is machined into inner and outer circles by turning, and connecting threads are machined at both ends of the tube blank to obtain the above-mentioned side-drilled, open-window, millable composite sleeve short section.

[0019] In the above-mentioned method for preparing a side-drilling, millable composite casing short section, in step one, the aluminum alloy matrix powder is 7000 series aluminum alloy powder.

[0020] The above-mentioned method for preparing a side-drilled, millable composite sleeve short section includes step two, cold isostatic pressing, which involves loading the mixture into a flexible mold and applying a pressure of 200-400 MPa at room temperature to form a tubular green blank.

[0021] Hot pressing sintering is a process in which a tubular green blank is placed in a hot pressing mold and shaped under axial pressure of 50-100 MPa at a temperature of 500-580°C.

[0022] In the above-mentioned method for preparing a side-drilling, millable composite casing short section, the solution treatment temperature in step three is 470-480°C; the aging treatment is a single-stage aging process with a temperature of 120°C and a time of 24 hours.

[0023] In the above-mentioned method for preparing a side-drilled, millable composite sleeve short section, after machining connecting threads at both ends of the tube blank in step three, the connecting thread area is also subjected to local heat treatment to ensure that the tensile and torsional strength of the connecting thread area is not lower than that of other parts of the tube body, and to avoid excessive strength differences with the steel.

[0024] The localized heat treatment involves heating the threaded area of ​​the connection using high-frequency induction heating, followed by cooling and then aging. The high-frequency induction heating temperature is 465-480°C; the time is 2 minutes; the frequency is 80 Hz; the cooling treatment is water spray cooling with a cooling rate > 100°C / s; the aging treatment is a single-stage aging process at 120°C for 24 hours.

[0025] A side-drilling window-opening casing includes an upper steel casing, a lower steel casing, and a side-drilling window-opening millable composite casing short section located between the upper steel casing and the lower steel casing, as described above. The bottom of the upper steel casing and the top of the lower steel casing are respectively connected to the connecting threads at both ends of the side-drilling window-opening millable composite casing short section.

[0026] In the aforementioned side-drilling window-opening casing, the inner and outer diameters of the upper and lower steel casings are the same as those of the short section body, ensuring consistent wellbore inner diameter.

[0027] The application of a side-drilling window casing in surface directional drilling pre-grouting, using the aforementioned side-drilling window casing.

[0028] The above-mentioned application of a side-drilling window-opening casing in surface directional drilling pre-grouting involves performing window-opening side-drilling operations on a side-drilling window-opening casing. During this operation, an integrated hydraulic directional tool is seated inside the lower steel casing below the side-drilling window-opening millable composite casing short section. A gyroscope is used for precise orientation. Subsequently, a milling cone is lowered to perform side-drilling window opening. The short section body is milled by the milling cone to form the initial window.

[0029] The specific construction process steps for the application of the above-mentioned side-drilling window-opening casing in surface directional drilling pre-grouting are as follows:

[0030] Step (1), First drilling operation: After the first drilling is completed, the oil casing is lowered and the casing is fixed.

[0031] Step (2), Second-stage drilling operation: After completing the second-stage drilling, the side-drilling window casing is lowered, and the side-drilling window millable composite casing short section is connected at the pre-designed side-drilling window position. The thread inspection and unraveling test are carried out between the side-drilling window and the upper and lower steel casings. Finally, the pipe fixing operation is carried out.

[0032] Step (3), three-stage drilling operation: After completing the three-stage drilling, the casing pipe is lowered and high-pressure grouting is carried out on the target treatment area to achieve the purpose of advanced area treatment such as stratum reinforcement and water channel sealing;

[0033] Step (4), side drilling operation: lower the integrated hydraulic directional tool and set it in the lower steel casing below the side drilling window milling composite casing short section. Use a gyroscope for precise orientation, then lower the milling cone to perform side drilling window opening. The milling cone mills the short section body to form the initial window.

[0034] Repeat steps (3) and (4) to complete the drilling, grouting and side drilling window opening operations of all designed branch holes, and then the construction of the main hole can be completed.

[0035] The technical solution of the present invention achieves the following beneficial technical effects:

[0036] (1) The side-drilling window-opening millable composite casing sub of the present invention uses 7000 series aluminum alloy material with excellent millability as the matrix (ensuring that the sub has sufficient strength to withstand downhole pressure and tubing load), and adds graphite particles as a lubricating phase and mica particles as brittle reinforcing particles. By adding graphite particles, a lubricating film can be formed during the milling process, effectively reducing the friction coefficient and reducing milling tape wear; by adding mica particles, the continuity of the material is disrupted, and stress concentration and breakage are easily generated under the action of milling force, making the material more susceptible to failure; the density of the obtained side-drilling window-opening millable composite casing sub is 2.8 g / cm³. 3 The tensile strength is 350-450 MPa, the yield strength is 300-380 MPa, and the Brinell hardness is 80-120 HB. Under the premise of ensuring the overall connection strength and sealing of the wellbore, the machinability of the side-drilling window-opening millable composite casing short section material is locally changed at the planned window-opening point.

[0037] (2) This invention combines a specific method to produce a side-drilling window-opening millable composite casing short section. The short section body of the side-drilling window-opening millable composite casing short section can be connected to the upper steel casing and the lower steel casing through the connecting threads at both ends to form a side-drilling window-opening casing. Through material and structural innovation, it replaces the traditional steel casing. It transforms the side-drilling window-opening operation from "grinding iron" to "milling aluminum", shortens the operation cycle, reduces the difficulty of grinding and milling operations and extends the service life of the milling cone, thereby achieving high efficiency, low cost and safety and reliability of window-opening operation; it fundamentally breaks through the bottleneck of window-opening efficiency and solves the problems of low efficiency and high tool wear in branch hole side-drilling construction, and is suitable for efficient, low-cost and safe and reliable multi-branch well projects.

[0038] (3) When performing window opening side drilling operations on a two-way casing, the present invention uses an integrated hydraulic directional device for positioning and a gyroscope for orientation to guide the milling cone to prioritize and efficiently mill the short section of the composite casing that can be milled for the side drilling window, quickly forming the initial window, significantly improving the window opening efficiency and effectively protecting the milling cone tool. Attached Figure Description

[0039] Figure 1This is a schematic diagram showing the position of the side-drilling windowable millable composite casing short section of the present invention in the wellbore;

[0040] Figure 2 This is a schematic diagram of the side-drilling, window-opening, millable composite sleeve short section of the present invention;

[0041] Figure 3 This is a schematic diagram of the side-drilling window opening sleeve of the present invention.

[0042] The reference numerals in the figure are as follows: 1-Upper steel casing; 2-Connecting thread; 3-Side-drilled, millable composite casing short section; 4-Lower steel casing; 5-Two-stage cemented pipe; 6-Integrated hydraulic slant; 7-Milling cone; 8-Initial window; 9-One-stage cemented pipe; 10-Short section body. Detailed Implementation

[0043] Example 1

[0044] (i) Side-drilling window millable composite casing short section used for pre-grouting in surface directional drilling

[0045] A side-drilling, millable composite casing sub is manufactured from 82 kg of aluminum alloy matrix powder, 5 kg of graphite particles, and 6 kg of mica particles. The aluminum alloy matrix powder is 7000 series aluminum alloy powder, ensuring that the sub has sufficient strength to withstand downhole pressure and tubing load. The graphite particles have a particle size of 10-50 μm, which can form a lubricating film during milling, effectively reducing the friction coefficient and reducing milling taper wear. The mica particles have a particle size of 10-50 μm, which, by adding brittle phase reinforcing particles, disrupt the material continuity and easily generate stress concentration and breakage under milling force, making the material easier to remove as a whole.

[0046] The density of the traditionally used J55 steel grade casing is 7.85 g / cm³. 3 The tensile strength is ≥517 MPa, the yield strength is 379-552 MPa, and the Brinell hardness is 200 HB. The side-drilling, millingable composite casing sub with a density of 2.8 g / cm³ is also present in this application. 3 The tensile strength is 350-450 MPa, the yield strength is 300-380 MPa, and the Brinell hardness is 80-120 HB. While ensuring the overall connection strength and sealing of the wellbore, the millability of the casing material is locally altered at the planned window opening point, thereby fundamentally breaking through the bottleneck of window opening efficiency, shortening the operation cycle, and reducing operating costs.

[0047] like Figure 2As shown, the side-drilled, millable composite casing stub 3 includes a hollow stub body 10. Both ends of the stub body 10 are provided with connecting threads 2. The length of the stub body 10 is determined according to the opening requirements (usually 20-30 meters). The connecting threads 2 are trapezoidal threads, which are processed strictly in accordance with API 5B standards to ensure that they can achieve a direct and reliable threaded connection with conventional steel casings, guaranteeing connection strength and sealing integrity.

[0048] Magnetic or groove marks are set at specific locations on the outer or inner wall of the short section body 10 (corresponding to the designed window depth) to accurately locate its downhole position during casing installation and when using cable tools.

[0049] This side-drilling window-opening millable composite casing short section 3 is made of aluminum-based composite material with excellent millability. Through material and structural innovation, it transforms side-drilling window-opening operations from "grinding iron" to "milling aluminum," fundamentally solving the problems of low efficiency and high tool wear in side-drilling of branch holes. It is suitable for efficient, low-cost, safe and reliable multi-branch well projects.

[0050] (II) Preparation method of millable composite casing short section for side-drilling window opening

[0051] A method for preparing a side-drilling, millable composite casing sub includes the following steps:

[0052] Step 1: Place 82kg of aluminum alloy matrix powder, 5kg of graphite particles and 6kg of mica particles in a ball mill and mix them evenly to obtain a mixture.

[0053] Step 2: The mixture is formed into a tube blank by cold isostatic pressing and hot pressing sintering, respectively;

[0054] Cold isostatic pressing involves loading the mixture into a flexible mold and applying a pressure of 200-400 MPa at room temperature to form a tubular green body.

[0055] Hot pressing sintering is a process in which a tubular green blank is placed in a hot pressing mold and shaped under axial pressure of 50-100 MPa at a temperature of 500-580°C.

[0056] Step 3: After solution treatment and aging treatment of the formed tube blank, the tube blank is machined into inner and outer circles by turning, and connecting threads are machined at both ends of the tube blank to obtain the above-mentioned side-drilled, open-window, millable composite sleeve short section.

[0057] The solution treatment temperature is 470-480°C; the aging treatment is a single-stage aging process, with a temperature of 120°C and a time of 24 hours.

[0058] (III) A type of side-drilling window opening sleeve

[0059] like Figure 3As shown, the side-drilling window-opening millable composite casing short section 3, as part of the side-drilling window-opening casing, is directly connected to the bottom of the hollow upper steel casing 1 and the top of the lower steel casing 4 via connecting threads 2. It is threaded according to API specifications to form a complete casing string, as shown. Figure 1 As shown, it is also fixed in the wellbore by the second-stage cemented casing 5. The outer and inner diameters of the short section body 10 are exactly the same as the upper steel casing 1 and lower steel casing 4 of the 177.8mm J55 connected above and below, ensuring that the inner diameter of the wellbore is consistent.

[0060] (iv) Application of side-drilling window-opening millable composite casing short section 3 or side-drilling window-opening casing

[0061] This side-drilling window-opening composite casing short section 3 is used to improve the construction efficiency of side-drilling window opening in branch holes under the "one main branch and multiple branches" hole layout design in "surface directional drilling and advanced grouting technology". The construction process of this technology is as follows:

[0062] (1) First drilling operation: After the first drilling is completed using a 311mm drill bit, a 244.5mm standard oil casing (steel casing) is run in, and then single-liquid cement slurry is used for cementing to form the first cement casing 9; the water-cement ratio of the single-liquid cement slurry is 0.6:1.

[0063] (2) Second-stage drilling operation: After the second-stage drilling is completed using a 215.9mm drill bit, a 177.8mm standard oil casing (side-drilling window casing) is run in. The side-drilling window casing is connected to the side-drilling window millable composite casing short section 3 at the pre-designed side-drilling window position. The side-drilling window millable composite casing short section 3 and the upper and lower steel casings are subjected to strict thread inspection and unraveling tests according to API specifications to form a complete side-drilling window casing. Then, single-liquid cement slurry is used for cementing to form the second-stage cemented casing 5.

[0064] (3) Three-section drilling operation: After the three-section drilling is completed using a 152.4mm drill bit, a 133mm sleeve valve pipe is lowered for high-pressure grouting to reinforce the strata in the target treatment area and seal the water diversion channels near the underground structures, so as to provide favorable guarantee for the construction of underground projects in the future.

[0065] (4) Window opening side drilling operation: When performing window opening side drilling operation on the second-stage casing, after setting the orientation using a gyroscope, the integrated hydraulic directional tool 6 is lowered and seated inside the lower steel casing 4 below the side-drilling window-opening millable casing short section. Then, the milling cone 7 is lowered. Through the positioning of the integrated hydraulic directional tool 6 and the orientation of the gyroscope, the milling cone 7 is guided to perform side drilling window opening. The milling cone 7 prioritizes and efficiently mills the short section body 10 to form the initial window. Since the hardness of the side-drilling window-opening millable composite casing short section 3 is much lower than that of steel, the milling cone 7 can quickly grind through it to form the initial window 8, thereby significantly improving the overall efficiency of subsequent milling of the lower steel casing 4.

[0066] Repeat steps (3) and (4) to complete the drilling, grouting and side drilling window opening operations of all designed branch holes, and then the construction of the main hole can be completed.

[0067] This invention, through material innovation and structural design, transforms side-drilling window opening from "grinding iron" to "milling aluminum," fundamentally solving the problem of low operational efficiency and demonstrating significant economic benefits and application prospects.

[0068] Example 2

[0069] The difference between this embodiment and Embodiment 1 is that the threaded area is subjected to localized heat treatment. This localized heat treatment involves heating the threaded area using high-frequency induction heating, followed by cooling and then aging. This ensures that the tensile and torsional strengths of the threaded area are not lower than those of other parts of the pipe body, avoiding excessive strength differences with the steel.

[0070] The high-frequency induction heating temperature was 465°C; the time was 2 minutes; the frequency was 80 Hz; the cooling treatment was water spray cooling with a cooling rate of 150°C / s; and the aging treatment was single-stage aging with a temperature of 120°C and a time of 24 hours.

[0071] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A side-drilling, millable composite casing short section, characterized in that, The density of the side-drilled, millable composite casing sub-section is 2.8 g / cm³. 3 The tensile strength is 350-450MPa, the yield strength is 300-380MPa, and the Brinell hardness is 80-120HB; the side-drilling window-opening millable composite casing short section is composed of the following components: matrix, lubricating phase and brittle phase reinforcing particles. The matrix is ​​an aluminum alloy matrix; the lubricating phase is graphite particles; and the brittle phase reinforcing particles are brittle mineral particles.

2. The side-drilling, millable composite casing short section according to claim 1, characterized in that, The mass fraction ratios of each component are as follows: 82-90 parts of matrix, 5-10 parts of lubricating phase, and 5-8 parts of brittle phase reinforcing particles.

3. The side-drilling, millable composite casing short section according to claim 1, characterized in that, The brittle mineral particles are mica particles, and the particle size of both the mica particles and the graphite particles is 10~50 μm. The aluminum alloy matrix is ​​a 7000 series aluminum alloy.

4. The side-drilling, millable composite casing short section according to claim 1, characterized in that, The side-drilled, millable composite casing short section (3) includes a short section body (10), and the two ends of the short section body (10) are provided with connecting threads (2).

5. The side-drilling, millable composite casing short section according to claim 4, characterized in that, Magnetic marks or groove marks are set on the outer or inner wall of the short section body (10) at the position corresponding to the designed window opening depth.

6. A method for preparing a side-drilling, millable composite casing sub, characterized in that, Includes the following steps: Step 1: Weigh 82-90 parts by weight of aluminum alloy matrix powder, 5-10 parts by weight of graphite particles and 5-8 parts by weight of mica particles and place them in a ball mill. Mix them evenly to obtain a mixture. Step 2: The mixture is formed into a tube blank by cold isostatic pressing and hot pressing sintering, respectively; Step 3: After performing solution treatment and aging treatment on the formed tube blank, the tube blank is machined into inner and outer circles by turning, and connecting threads are machined at both ends of the tube blank to obtain the side-drilled, millable composite sleeve short section as described in any one of claims 1 to 5.

7. A side-drilling window opening sleeve, characterized in that, It includes an upper steel casing (1), a lower steel casing (4), and a side-drilling window-opening millable composite casing short section as described in any one of claims 1 to 5 located between the upper steel casing (1) and the lower steel casing (4). The bottom of the upper steel casing (1) and the top of the lower steel casing (4) are respectively connected to the connecting threads (2) at both ends of the side-drilling window-opening millable composite casing short section.

8. A side-drilling window opening sleeve according to claim 7, characterized in that, The inner and outer diameters of the upper steel sleeve (1) and the lower steel sleeve (4) are the same as those of the short section body (10).

9. The application of a side-drilling window-opening casing in surface directional drilling pre-grouting, characterized in that, Use the side-drilling window opening sleeve as described in any one of claims 7 to 8.

10. The application of a side-drilling window-opening casing according to claim 9 in surface directional drilling pre-grouting, characterized in that, When performing side-drilling operation on the side-drilling window-opening casing, the integrated hydraulic directional tool (6) is seated in the lower steel casing below the side-drilling window-opening millable composite casing short section. A gyroscope is used for precise orientation. Then, the milling cone (7) is lowered to perform side-drilling window opening. The short section body is milled by the milling cone to form the initial window (8).

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