A method for drilling and completing ultra-short radius multi-branch horizontal wells

Abstract

The present invention relates to the technical field of oil and gas field development, and specifically to a method for drilling and completing ultra-short radius multi-branch horizontal wells, comprising the following steps: step 1, selecting a well in which a horizontal section is to be drilled; step 2, starting to drill a first branch in the main wellbore of the horizontal section, and determining the connection point between the first branch and the main wellbore as the first branch connection point; step 3, side-drilling the main wellbore in mid-air to the second branch connection point, and continuing to drill to complete the second branch; step 4, repeating the process of step 3 to complete N branches; step 5, drilling down to 3 meters above the Nth branch connection point, side-drilling the main wellbore in mid-air until the well is completed; step 6, completing the completion operation of the side-drilled multi-branch well; the present invention can realize drilling operations of various well types such as multi-branch in the same layer, multi-branch in different layers, and multi-branch in a single wellbore, greatly improving the well control area of the oil reservoir, ensuring continuous, long-term and efficient production of the wellbore, and greatly improving the transformation and production increase of the oil reservoir.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development, and in particular to an ultra-short radius multi-branch horizontal well drilling and completion method. Background Art

[0002] At present, most domestic oil and gas field exploitation adopts single-side drilling ultra-short radius horizontal well technology. After the completion of a single-side drilling ultra-short radius horizontal well, only one target layer can be exploited. The well control area of the oil reservoir is small, making it impossible to fully exploit the oil reservoir and the wellbore unable to continuously and efficiently produce for a long time, resulting in a low oil reservoir recovery rate. Summary of the Invention

[0003] The purpose of the present invention is to address the above-mentioned deficiencies and provide an ultra-short radius multi-branch horizontal well drilling and completion method, which can realize drilling and completion operations of various well types such as multi-branch in the same layer, multi-branch in different layers, and multi-branch in a single wellbore, greatly improving the well control area of the oil reservoir, ensuring continuous long-term and efficient production of the wellbore, and greatly improving the transformation and production increase of the oil reservoir.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for drilling and completing an ultra-short radius multi-branch horizontal well comprises the following steps:

[0006] Step 1: Select a well where the horizontal section will be drilled:

[0007] The target layer of the well can be a single layer or multiple layers;

[0008] Step 2: Drill the first branch in the main wellbore of the horizontal section, and determine the connection point between the first branch and the main wellbore as the first branch connection point;

[0009] Run a screen into the first branch and connect an expansion casing to the top of the screen. Release the screen tool so that the top of the releaser is below the first branch connection point. Ensure that the distance between the top of the releaser and the first branch connection point is 10 to 30 cm.

[0010] Step 3: Sidetrack the main wellbore to the second branch connection point and continue drilling to complete the second branch;

[0011] When the horizontal drilling tool is used at a height of 1 meter above the first branch connection point in the horizontal section main wellbore, start the suspended sidetracking of the main wellbore to the second branch connection point, continue drilling until the second branch is completed, and after drilling is completed, lower the connected screen, packer and releaser into the second branch, release the releaser so that the tail end of the releaser is below the second branch connection point, and ensure that the distance between the top end of the releaser and the second branch connection point is within 10 to 30 centimeters;

[0012] Step 4: Repeat step 3 to complete N branches;

[0013] Step 5: Drill down to 3 meters above the Nth branch connection point, and sidetrack the main wellbore until the well is completed;

[0014] The connected main wellbore screen, ball seat and multi-branch re-entrant body are lowered into the horizontal main wellbore. A gyroscope is used to measure the tool face of the multi-branch re-entrant body to ensure that the multi-branch re-entrant body is aligned with the direction of each branch releaser.

[0015] The multi-branch re-entrant body includes a plurality of multi-branch re-entrants connected by sleeves, and the multi-branch re-entrants correspond to the branch connection points one by one;

[0016] Step 6: Complete the sidetracked multi-branch well completion operation;

[0017] Place the multi-branch re-entrant above the branch connection point. When the distance between the multi-branch re-entrant and the branch connection point is 15 to 25 cm, put in a soluble ball and pump it into the multi-branch re-entrant body to pressurize it. After the pressure causes the multi-branch re-entrant to stretch out, it is connected to the releaser in the adjacent branch well. The multi-branch re-entrant is connected to the screen pipe through the releaser and the expansion casing to complete the well completion operation. After the soluble ball dissolves, a complete oil and gas channel is established.

[0018] Furthermore, the dogleg angle of each meter of the branch is 30 to 90°.

[0019] Furthermore, the distance between adjacent branches is 50 to 100 meters.

[0020] Further, in step six, the multi-branch re-entrant includes a tube body, a rubber sealing tube coaxially arranged in the middle of the tube body, an adjusting thread arranged on the tube body, and an insertion tube directional locking ring sleeved on the adjusting thread. An elastic recess is provided on the outer wall of the rubber sealing tube, and an insertion tube is movably provided in the elastic recess. After one end of the insertion tube penetrates into the interior of the rubber sealing tube, a soluble one-way valve plate is obliquely provided. When the multi-branch re-entrant is in an extended state, the insertion tube is plugged into the releaser in the adjacent branch, and the soluble ball and the soluble one-way valve plate are both made of soluble material.

[0021] Furthermore, the outer diameter of the insertion tube is in the range of 45 to 51 mm, and the inner diameter of the releaser is in the range of 60 to 76 mm.

[0022] Furthermore, the minimum inner diameter of the tube body is greater than the maximum diameter of the soluble ball.

[0023] The beneficial effects of the present invention are:

[0024] It can be seen from the above technical solution that the beneficial effects of the present invention are:

[0025] The present invention can realize drilling operations of various well types such as multiple branches in the same layer, multiple branches in different layers, and multiple branches in a single wellbore, greatly improving the well control area of the oil reservoir, ensuring continuous long-term and efficient production of the wellbore, and greatly improving the transformation and production increase of the oil reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0027] Figure 1 A diagram showing the steps of the method of the present invention;

[0028] Figure 2 This is a schematic diagram of the structure after well completion of the present invention;

[0029] Figure 3 Schematic diagram of the structure of the multi-branch re-entrant device when the insertion tube is in a retracted state;

[0030] Figure 4 Schematic diagram of the structure of the multi-branch re-entrant device of the present invention when the insertion tube is in an extended state;

[0031] Figure markings: main wellbore 1; first branch 2; second branch 3; branch re-entrant body 4; multi-branch re-entrant 40; pipe body 401; rubber sealing cylinder 402; elastic recess 4021; sealing thread 403; insertion tube directional locking ring 404; insertion tube 405; one-way valve plate 406; main wellbore screen 5; ball seat 6. DETAILED DESCRIPTION

[0032] See Figure 1 、 Figure 2 and Figure 3 As shown, this embodiment provides a method for drilling and completing an ultra-short radius multi-branch horizontal well, comprising the following steps:

[0033] Step 1: Select a well where the horizontal section will be drilled:

[0034] The target layer of the well can be a single layer or multiple layers;

[0035] Step 2: Drill the first branch 2 in the main wellbore 1 of the horizontal section, and determine the connection point between the first branch 2 and the main wellbore 1 as the first branch connection point;

[0036] Run a screen into the first branch 2 and connect an expansion casing to the top of the screen. Release the screen tool so that the top of the releaser is below the first branch connection point, and ensure that the distance between the top of the releaser and the first branch connection point is 10 to 30 cm.

[0037] Step 3: Sidetrack the main wellbore to the second branch connection point and continue drilling to complete the second branch 3;

[0038] When the horizontal drilling tool is 3 meters above the first branch connection point in the horizontal section main wellbore 1, start the suspended sidetracking of the main wellbore 1 to the second branch connection point, continue drilling until the second branch 3 is completed, and after drilling is completed, lower the connected screen, packer and releaser into the second branch 3. Release the releaser so that the tail end of the releaser is below the second branch connection point, and ensure that the distance between the top end of the releaser and the second branch connection point is within the range of 10 to 30 centimeters.

[0039] Step 4: Repeat step 3 to complete N branches;

[0040] Step 5: Drill down to 3 meters above the Nth branch connection point, and sidetrack the main wellbore 1 until the well is completed;

[0041] The connected main wellbore screen 5, ball seat 6 and multi-branch re-entrant body 4 are lowered into the horizontal main wellbore 1. The gyroscope is used to measure the tool face of the multi-branch re-entrant body 4 to confirm that the multi-branch re-entrant body 4 is aligned with the direction of each branch releaser;

[0042] The multi-branch re-entrant body 4 includes a plurality of multi-branch re-entrants 40 connected by sleeves, and the multi-branch re-entrants 40 correspond to the branch connection points one by one;

[0043] Step 6: Complete the sidetracked multi-branch well completion operation;

[0044] Place the multi-branch re-entrant 40 above the branch connection point. When the distance between the multi-branch re-entrant 40 and the branch connection point is 15 to 25 cm, put in a soluble ball and pump it into the multi-branch re-entrant body 4 to pressurize it. After the pressure causes the multi-branch re-entrant 40 to stretch out, it is connected to the releaser in the adjacent branch well, so that the multi-branch re-entrant 40 is connected to the screen pipe through the releaser and the expansion casing, completing the well completion operation. After the soluble ball dissolves, a complete oil and gas channel is established.

[0045] The dogleg angle of each branch is 30 to 90 degrees every 30 meters.

[0046] See Figure 1 、 Figure 2 and Figure 3As shown, the dogleg angle of each branch is 30-90 degrees every 30 meters. In this embodiment, when the dogleg angle of each branch is 30-90 degrees every 30 meters, the screen pipe inserted into the branch can be self-locked in the branch and is not easy to slide out or rotate.

[0047] See Figure 1 、 Figure 2 and Figure 3 As shown, the distance between adjacent branches is 50 to 100 meters. In this embodiment, when the distance between branches is 50 to 100 meters, the well control area of the oil reservoir is greatly improved, the continuous long-term efficient production of the wellbore is ensured, and the transformation and production increase of the oil reservoir are greatly improved.

[0048] See Figure 1 、 Figure 2 and Figure 3 As shown, in step six, the multi-branch re-entrant 40 includes a tube body 401, a rubber sealing tube 402 coaxially arranged in the middle of the tube body 401, a sealing thread 403 arranged on the tube body 401, and an insertion tube directional locking ring 404 sleeved on the sealing thread 403, an elastic recess 4021 is provided on the outer wall of the rubber sealing tube 402, an insertion tube 405 is movably provided in the elastic recess 4021, and one end of the insertion tube 405 is inserted into the interior of the rubber sealing tube 402 and is obliquely provided with a soluble one-way Valve plate 406, when the multi-branch re-entrant 40 is in the extended state, the insertion tube 405 is plugged into the releaser connector in the adjacent branch, and the soluble ball and the soluble one-way valve plate 406 are both made of soluble material; in this embodiment, the soluble ball is cyclically put into the multi-branch re-entrant body 4, and in the process of the soluble ball pressing the soluble one-way valve plate 406, the insertion tube 405 is gradually inserted into the connector of the releaser until the one-way valve plate 406 presses the soluble one-way valve plate 406 to no longer tilt, and the insertion tube 405 can be completely plugged into the releaser in the adjacent branch.

[0049] See Figure 1 、 Figure 2 and Figure 3 As shown, the outer diameter range of the insertion tube 405 is 50 to 70 mm, and the inner diameter range of the pipe joint of the releaser is 80 to 90 mm. In this embodiment, when the outer diameter range of the insertion tube 405 is 50 to 70 mm and the inner diameter range of the pipe joint of the releaser is 80 to 90 mm, it is convenient to insert the insertion tube 405 into the pipe joint of the releaser.

[0050] See Figure 1 、 Figure 2 and Figure 3As shown, the minimum inner diameter of the tube body 401 is larger than the maximum diameter of the soluble ball; in this embodiment, the soluble ball can enter the tube body 401 and press the soluble one-way valve plate 406 only when the minimum inner diameter of the tube body 401 is larger than the maximum diameter of the soluble ball.

[0051] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them with similar methods without departing from the scope defined by the spirit of the present invention.

Claims

1. A method for drilling and completing an ultra-short radius multi-branch horizontal well, characterized by: The steps include: Step 1: Select a well where the horizontal section will be drilled: The target layer of the well can be a single layer or multiple layers; Step 2: Drilling the first branch (2) in the main wellbore (1) of the horizontal section, and determining the connection point between the first branch (2) and the main wellbore (1) as the first branch connection point; A screen is lowered into the first branch (2), and an expansion casing is connected to the top of the screen, and the screen tool is released so that the top of the releaser is below the first branch connection point, and the distance between the top of the releaser and the first branch connection point is ensured to be within a range of 10 to 30 cm; Step 3: Sidetrack the main wellbore to the second branch connection point, and continue drilling to complete the second branch (3); Using a horizontal drilling tool, when the horizontal section main wellbore (1) is 3 meters above the first branch connection point, the main wellbore (1) is started to be suspended side drilling to the second branch connection point, and the drilling is continued until the second branch (3) is completed. After the drilling is completed, the connected screen pipe, packer and releaser are lowered into the second branch (3), and the releaser is released so that the tail end of the releaser is below the second branch connection point, and the distance between the top end of the releaser and the second branch connection point is ensured to be in the range of 10 to 30 centimeters; Step 4: Repeat step 3 to complete N branches; Step 5: Drill down to 3 meters above the Nth branch connection point, and side-drill the main wellbore (1) in mid-air until the well is fully drilled; The connected main wellbore screen (5), ball seat (6) and multi-branch re-entrant body (4) are lowered into the horizontal section main wellbore (1), and a gyroscope is used to measure the tool face of the multi-branch re-entrant body (4) to determine whether the multi-branch re-entrant body (4) is aligned with the direction of each branch releaser; The multi-branch re-entrant body (4) comprises a plurality of multi-branch re-entrants (40) connected by sleeves, and the multi-branch re-entrants (40) correspond one to one to the branch connection points; Step 6: Complete the sidetracked multi-branch well completion operation; The multi-branch re-entrant (40) is placed above the branch connection point. When the distance between the multi-branch re-entrant (40) and the branch connection point is 15 to 25 cm, a soluble ball is put in and pumped into the multi-branch re-entrant body (4) to pressurize. After the multi-branch re-entrant (40) is stretched out by the pressure, it is connected to the releaser in the adjacent branch well, and the multi-branch re-entrant (40) is connected to the screen pipe through the releaser and the expansion casing to complete the well completion operation. After the soluble ball is dissolved, a complete oil and gas channel is established.

2. The method for drilling and completing an ultra-short radius multi-branch horizontal well according to claim 1, characterized in that: The dogleg angle of every 30 meters of the branch is 30 to 90 degrees.

3. The ultra-short radius multi-branch horizontal well drilling and completion method according to claim 1, characterized in that: The distance between adjacent branches is 50 to 100 meters.

4. The ultra-short radius multi-branch horizontal well drilling and completion method according to claim 1, characterized in that: In step six, the multi-branch re-entrant (40) includes a tube body (401), a rubber sealing tube (402) coaxially arranged in the middle of the tube body (401), an adjusting thread (403) arranged on the tube body (401), and an insertion tube directional locking ring (404) sleeved on the adjusting thread (403), an elastic recess (4021) is provided on the outer wall of the rubber sealing tube (402), an insertion tube (405) is movably provided in the elastic recess (4021), one end of the insertion tube (405) is inserted into the interior of the rubber sealing tube (402), and a soluble one-way valve plate (406) is obliquely provided thereon, when the multi-branch re-entrant (40) is in an extended state, the insertion tube (405) is plugged into a releaser in an adjacent branch, and the soluble ball and the soluble one-way valve plate (406) are both made of soluble material.

5. The method for drilling and completing an ultra-short radius multi-branch horizontal well according to claim 4, characterized in that: The outer diameter of the insertion tube (405) ranges from 45 to 51 mm, and the inner diameter of the releaser ranges from 60 to 76 mm.

6. The method for drilling and completing an ultra-short radius multi-branch horizontal well according to claim 4, characterized in that: The minimum inner diameter of the tube (401) is greater than the maximum diameter of the soluble ball.

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