Accurate grinding and milling control tool and using method

Abstract

The invention discloses a precise grinding and milling control tool and a using method. An upper connector is in threaded connection with a circulating outer cylinder, the circulating outer cylinder is in threaded connection with a stroke control cavity outer cylinder, a pressure control mandrel is installed in the circulating outer cylinder, a circulating hole is formed in the pressure control mandrel, and a telescopic pipe is installed in the stroke control cavity outer cylinder; the pressure control mandrel is in threaded connection with the telescopic pipe, a milling stroke control cavity is formed between the telescopic pipe and the stroke control cavity outer cylinder, and the telescopic pipe is in threaded connection with the lower connector. The problem of accurate footage of milling is effectively solved by changing the structure of a well entering pipe column; a tubular column does not need to be lowered in the milling construction process; the torque transmission mandrel transmits rotating torque, the pressure control mandrel provides stable drilling pressure through vertical sliding of hanging weight of a drill collar on the lower portion, the milling efficiency is effectively improved, and the service life of a drill bit is prolonged. The milling footage condition can be judged by circulating pressure change; the drilling tool is static in the milling process, so that the driller labor intensity is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of oilfield downhole operation technology, and in particular to a precision milling control tool and its usage method. Background Technology

[0002] With the continuous development of well workover operations, various technologies are gradually moving towards digitalization, intelligence, and precision. However, the casing and milling processes, crucial in well workover operations, have not seen significant improvements in their construction techniques. Construction has traditionally relied on downhole drilling and milling followed by surface measurements to determine the cut length. This approach fails to adequately account for factors such as tubing bending under pressure and tubing shortening due to milling, leading to inaccurate cut length measurements from the surface. This is particularly problematic for processes like permanent packers used in gas storage facilities, where precise milling length determination is essential. Surface measurements alone are inaccurate, impacting the success rate of the first-time operation and even complicating downhole conditions. In conventional casing and milling operations, drill pressure (DPI) relies on the driller's experience for control, resulting in instability. Excessive DPI causes rapid torque changes, leading to drill string jamming and skipping, and is susceptible to tooth breakage and loss due to axial impact, affecting drill bit lifespan and reducing milling efficiency due to repeated tripping. Conversely, insufficient DPI results in low milling efficiency. Therefore, there is an urgent need to develop a precision milling control tool to effectively address these issues. Summary of the Invention

[0003] This invention addresses the problem that determining the milling length during casing and milling operations by measuring the pipe string advance from the ground is inaccurate due to the inability to accurately measure the pipe string stress and the shortening caused by thread tightening, thus preventing precise milling. In actual construction, insufficient milling length may lead to misjudgment of downhole conditions, resulting in construction complications or even well abandonment. This invention provides a precise milling control tool and its usage method.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a precision milling control tool, including an upper connector, which is threadedly connected to a circulating outer cylinder, and the circulating outer cylinder is threadedly connected to the outer cylinder of the stroke control cavity. A pressure control mandrel is installed inside the circulating outer cylinder, and a circulation hole is opened on the pressure control mandrel. A telescopic tube is installed inside the outer cylinder of the stroke control cavity, and the pressure control mandrel is threadedly connected to the telescopic tube. The telescopic tube and the outer cylinder of the stroke control cavity form a milling stroke control cavity, and the telescopic tube is threadedly connected to a lower connector.

[0005] Furthermore, the upper connector is connected to the lower drilling tool via threads.

[0006] Furthermore, the lower connector is connected to the drill collar, and the drill collar is connected to the milling tool.

[0007] Furthermore, four circulation holes are evenly distributed on the pressure control spindle.

[0008] Furthermore, the length C of the milling stroke control cavity is greater than the distance D from the circulation hole of the pressure control mandrel to the small inner diameter at the bottom of the outer cylinder of the pressure control mandrel.

[0009] Furthermore, the inner cavity of the circulating outer cylinder has a stepped structure, with the inner diameter of the outer cylinder at point E being larger than that at point F.

[0010] Furthermore, the end of the outer circulating cylinder is opposite to the end of the telescopic tube.

[0011] A method for using a precision milling control tool includes the following steps:

[0012] Step 1: Before going down into the well, adjust the length of the milling stroke control cavity inside the precision milling control tool;

[0013] Step 2: Design the grinding, milling, drilling, and pressing techniques;

[0014] Step 3: Connect the upper connector to the lower drilling tool, the lower connector to the drill collar, and the drill collar to the milling tool;

[0015] Step 4: During the drilling process, the drill collar is under the influence of gravity tension, and the pressure control mandrel is in a tensioned state. The tension length is consistent with the milling length. Before lowering to the design depth, control the lowering speed and observe the change of suspended weight until the drill bit touches the top of the fish and record the depth.

[0016] Step 5: Continue to slowly lower the drill string, and use the weight of the drill string to judge the pressure control mandrel and the milling stroke control cavity to fully compress them, and then apply the brakes.

[0017] Step Six: Begin rotating the drill bit for milling, keeping the drill bit stationary during the milling process;

[0018] Step 7: Constant drilling pressure milling operation is achieved by using pressure control mandrel to slide up and down. The drilling pressure is provided by the drill collar below the precision milling control tool; the rotational torque is transmitted by the torque transmission mandrel.

[0019] Step 8: The kill fluid is circulated from the upper connector through the circulation hole on the pressure control mandrel and the lower connector;

[0020] Step 9: When the pressure control spindle is fully retracted, the circulating pump pressure increases and the turntable torque decreases due to the reduced circulating flow area, indicating that the expected milling depth has been completed.

[0021] Step 10: After milling to the desired depth, lower the drill bit and control the mandrel to descend under pressure until it encounters resistance. Then, lower the suspended weight, record the depth, calculate the milling length, and verify whether the milling length is consistent with the design.

[0022] Furthermore, in step one, before going down into the well, adjust the length of the milling stroke control cavity inside the precision milling control tool according to the milling length. The length of the milling stroke control cavity determines the milling distance, thus precisely controlling the advance.

[0023] Further, in step two, design the milling and drilling pressure, select a reasonable combination of drill tools and counterweight drill collars, and the weight of the drill collars determines the amount of drilling pressure.

[0024] The beneficial effects of this invention are as follows: The ingenious structural design changes traditional thinking. By modifying the wellbore string structure, it effectively solves the problem of precise milling footage; the milling process eliminates the need to lower the wellbore string; the torque transmission mandrel transmits rotational torque, and the pressure control mandrel utilizes the lower drill collar's suspended weight to provide stable drilling pressure, effectively improving milling efficiency and extending drill bit life; changes in circulating pressure can indicate the milling footage; and the drill string remains stationary during milling, significantly reducing the driller's workload. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in this invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the present invention;

[0027] Figure 2 yes Figure 1 AA section view;

[0028] Figure 3 This is a schematic diagram of the pressure control mandrel structure;

[0029] Figure 4 yes Figure 3 BB cross-sectional view.

[0030] Among them: 1-upper connector, 2-circulation outer cylinder, 3-circulation hole, 4-pressure control spindle, 5-milling stroke control cavity, 6-stroke control cavity outer cylinder, 7-telescopic tube, 8-lower connector. Detailed Implementation

[0031] The following will be combined with the appendix Figure 1-4 The technical solutions of the present invention have been clearly and completely described. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0033] In the description of this invention, it should be noted that the terms "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used only for distinction and should not be construed as indicating or implying relative importance.

[0034] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0035] A precision milling control tool includes an upper connector 1, which is threadedly connected to a lower drilling tool, a circulating outer cylinder 2, and a stroke control chamber outer cylinder 6. A pressure control mandrel 4 is installed inside the circulating outer cylinder 2, and four circulation holes 3 are evenly distributed on the pressure control mandrel 4. A telescopic tube 7 is installed inside the stroke control chamber outer cylinder 6, and the pressure control mandrel 4 is threadedly connected to the telescopic tube 7. The telescopic tube 7 and the stroke control chamber outer cylinder 6 form a milling stroke control chamber 5. The telescopic tube 7 is threadedly connected to a lower connector 8, which is connected to a drill collar. The drill collar is connected to the milling tool, and the end of the circulating outer cylinder 2 is opposite to the end of the telescopic tube 7.

[0036] The length C of the milling stroke control cavity 5 is greater than the distance D from the circulation hole 3 of the pressure control mandrel 4 to the small inner diameter at the bottom of the outer cylinder of the pressure control mandrel 4. The length C determines the milling feed length. The size of the counterweight drill collar determines the drilling pressure. The inner cavity of the circulation outer cylinder 2 has a stepped structure, with the inner diameter at point E being larger than that at point F. Four circulation holes 3 are opened on the upper part of the pressure control mandrel 4. When the pressure control mandrel 4 moves to the bottom, the circulation holes 3 enter the small diameter F from the inner diameter E. Due to the reduced flow area, the circulation pump pressure increases, indicating that the milling has been completed.

[0037] A method for using a precision milling control tool includes the following steps:

[0038] Step 1: Before going down into the well, adjust the length of the milling stroke control cavity 5 inside the precision milling control tool according to the milling length. The length of the milling stroke control cavity 5 determines the milling distance and precisely controls the advance.

[0039] Step 2: Design the drilling pressure for milling and grinding, select a reasonable combination of drill tools and counterweight drill collars, the weight of which determines the drilling pressure;

[0040] Step 3: Connect the upper connector 1 to the lower drilling tool, connect the lower connector 8 to the drill collar, and connect the drill collar to the milling tool;

[0041] Step 4: During the drilling process, the drill collar is under the influence of gravity tension, and the pressure control mandrel 4 is in a tensioned state. The tension length is consistent with the milling length. Before lowering to the design depth, control the lowering speed and observe the change of suspended weight until the drill bit contacts the top of the fish and record the depth.

[0042] Step 5: Continue to slowly lower the drill bit, and use the weight of the drill bit to judge the pressure control mandrel 4 and the milling stroke control cavity 5 to fully compress them, and then apply the brakes.

[0043] Step Six: Begin rotating the drill bit for milling, keeping the drill bit stationary during the milling process;

[0044] Step 7: Constant drilling pressure milling operation is achieved by using the pressure control mandrel 4 to slide up and down. The drilling pressure is provided by the drill collar below the precision milling control tool; the rotational torque is transmitted by the torque transmission mandrel.

[0045] Step 8: The kill fluid is circulated from the upper connector 1 through the circulation hole 3 on the pressure control mandrel 4 and the lower connector 8;

[0046] Step 9: When the pressure control spindle 4 is fully retracted, the circulating flow area decreases, the circulating pump pressure increases, and the turntable torque decreases, indicating that the expected milling depth has been completed.

[0047] Step 10: After milling to the desired depth, lower the drill bit and control the mandrel 4 to descend under pressure until it encounters resistance. Then, lower the suspended weight, record the depth, calculate the milling length, and verify whether the milling length is consistent with the design.

[0048] The upper connector 1 connects to the drill string; the circulating outer cylinder 2 works with the pressure control mandrel 4 to change the circulation channel of the kill fluid; the pressure control mandrel 4 matches the drill collar to provide reasonable drilling pressure for milling; by analyzing the length of the falling object, the milling stroke control chamber 5 pre-sets the milling length, which, together with the pressure control mandrel 4, achieves precise quantitative milling; the torque transmission mandrel transmits rotational torque through the key-to-key connection. This tool determines the contact point with the top of the drill string by the change in the weight of the drill string, brakes, rotates the drill string, and keeps the drill string stationary during the milling process. The pressure control mandrel 4 slides up and down to achieve constant drilling pressure milling operation. When the circulating pump pressure increases and the rotary table torque decreases, it indicates that the predetermined milling footage has been completed. Compared with conventional milling, the drilling pressure is more stable, the footage is more accurate, and the labor intensity is lower.

[0049] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. For those skilled in the art, any obvious modifications made without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims. Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no technical conflict, the features in the embodiments disclosed in the present invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A precision milling control tool, characterized by, It includes an upper connector (1), which is threadedly connected to the circulating outer cylinder (2), and the circulating outer cylinder (2) is threadedly connected to the stroke control cavity outer cylinder (6). A pressure control spindle (4) is installed inside the circulating outer cylinder (2), and a circulation hole (3) is opened on the pressure control spindle (4). A telescopic tube (7) is installed inside the stroke control cavity outer cylinder (6), and the pressure control spindle (4) is threadedly connected to the telescopic tube (7). The telescopic tube (7) and the stroke control cavity outer cylinder (6) form a milling stroke control cavity (5). The telescopic tube (7) is threadedly connected to the lower connector (8).

2. The precision milling control tool of claim 1, wherein, The upper connector (1) is connected to the lower well drilling tool by a thread.

3. The precision milling control tool according to claim 1, characterized in that, The lower connector (8) is connected to the drill collar, and the drill collar is connected to the milling tool.

4. The precision milling control tool according to claim 1, characterized in that, The pressure control spindle (4) is provided with four circulation holes (3) evenly distributed on it.

5. The precision milling control tool according to claim 1, characterized in that, The length C of the milling stroke control cavity (5) is greater than the distance D from the circulation hole (3) of the pressure control spindle (4) to the small inner diameter of the bottom of the outer cylinder of the pressure control spindle (4).

6. The precision milling control tool according to claim 1, characterized in that, The inner cavity of the circulating outer cylinder (2) has a stepped structure, and the inner diameter of the outer cylinder at point E is larger than that at point F.

7. The precision milling control tool according to claim 1, characterized in that, The end of the circulating outer cylinder (2) is opposite to the end of the telescopic tube (7).

8. A method for using a precision milling control tool, characterized in that, A precision milling control tool according to any one of claims 1-7 comprises the following steps: Step 1: Before going down into the well, adjust the length of the milling stroke control cavity (5) inside the precision milling control tool; Step 2: Design the grinding, milling, drilling, and pressing techniques; Step 3: Connect the upper connector (1) to the lower well drill string, connect the lower connector (8) to the drill collar, and connect the drill collar to the milling tool; Step 4: During the drilling process, the drill collar is under the influence of gravity tension, and the pressure control mandrel (4) is in a tension state. The tension length is consistent with the milling length. Before lowering to the design depth, control the lowering speed and observe the change of suspended weight until the drill bit touches the top of the fish and record the depth. Step 5: Continue to slowly lower the drill bit, and judge the pressure control mandrel (4) and milling stroke control cavity (5) by the weight of the drill bit to fully compress them, and then brake them. Step Six: Begin rotating the drill bit for milling, keeping the drill bit stationary during the milling process; Step 7: Use the pressure control mandrel (4) to slide up and down to achieve constant drilling pressure milling operation. The drilling pressure is provided by the drill collar below the precision milling control tool; use the torque transmission mandrel to transmit rotational torque; Step 8: The kill fluid is circulated from the upper connector (1) through the circulation hole (3) on the pressure control mandrel (4) and the lower connector (8); Step 9: When the pressure control spindle (4) is fully retracted, the circulating flow area becomes smaller, the circulating pump pressure increases, and the turntable torque decreases, indicating that the expected milling depth has been completed. Step 10: After milling to the desired position, lower the drill bit and control the mandrel (4) to descend until it encounters resistance. The suspended weight then descends, the depth is recorded, the milling length is calculated, and the milling length is verified to be consistent with the design.

9. The method of using the precision milling control tool according to claim 8, characterized in that, In step one, before going down into the well, the length of the milling stroke control cavity (5) inside the precision milling control tool is adjusted according to the milling length. The length of the milling stroke control cavity (5) determines the milling distance and precisely controls the advance.

10. The method of using the precision milling control tool according to claim 8, characterized in that, In step two, the drilling pressure is designed, and a reasonable combination of drill tools and counterweight drill collars are selected. The weight of the drill collars determines the drilling pressure.

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