A hydraulic ball centralizer and use method

Abstract

The present invention belongs to the field of downhole operation tools in oil and gas fields, and particularly relates to a hydraulic ball straightener and a method of using the same. A hydraulic ball straightener comprises a straightener body and a piston located inside the straightener body; a straightening bar is provided at the middle position outside the straightener body, a through hole is provided on the straightening bar, and a steel ball is installed in the through hole; a spring is provided inside the straightener body, and an annular oblique concave groove is provided in the middle of the upper section of the piston; the middle of the piston contains a central flow channel. The present invention is directly connected to the sand flushing and drilling and grinding pipe column. When liquid is injected from the oil pipe, under the action of the pressure difference, the piston moves downward, the spring is compressed, and the steel ball extends to play a straightening role. The liquid can be injected while the pipe column is lowered. When there is no pressure difference, the spring is extended, the piston is reset, and the steel ball is retracted. The present invention has a simple structure and is easy to use. It can be widely used for straightening the pipe column during sand flushing and drilling and grinding operations.

Description

Technical Field

[0001] The invention belongs to the field of downhole working tools in oil and gas fields, and in particular relates to a hydraulic ball centralizer and a use method thereof. Background Art

[0002] Conventional tubing sand flushing and drilling and grinding operations, especially in highly deviated wells and horizontal wells, are affected by the wellbore curvature and the tool's own gravity, so the downhole tool is not centered, resulting in increased friction resistance of the tubing string, which brings a greater risk of tubing string sticking during sand flushing and drilling and grinding operations, affecting the operation efficiency. For this reason, it is necessary to install a centralizer on the tubing during field operations to ensure that the downhole tool is centered.

[0003] Conventional tubing centralizers are connected between two tubings and can play a role in centralizing them. However, since the outer diameter of conventional centralizers is fixed and cannot be retracted, they have low adaptability to the sidewalls of oil wells. Currently, there are also centralizers with retractable outer diameters, but the outer diameter retraction operation is complicated and it is not convenient to rotate the oil well tubing. Since a large amount of flushing sand and drilling and grinding materials accumulate in the wellbore during the sand flushing and drilling and grinding operations, once the tubing encounters obstruction, the tubing cannot be rotated, which can easily cause downhole accidents. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a hydraulic ball centralizer and a method of using the same, which can quickly extend and retract the outer diameter of the centralizer according to the downhole conditions during sand flushing and drilling operations, and can rotate the pipe string when it encounters obstruction or jamming, thereby improving operating efficiency and ensuring downhole operation safety.

[0005] The technical solution of the present invention is:

[0006] A hydraulic ball centralizer comprises a centralizer body and a piston located in the centralizer body; wherein: a centralizer bar is provided at the middle position outside the centralizer body, the centralizer bar is provided with a through hole, a steel ball is installed in the through hole, and the diameter of the steel ball is larger than the diameter of the through hole; a spring is provided inside the centralizer body, one end of the spring is a free end connected to the lower end of the piston, and the other end is a fixed end fixed to the step on the inner wall of the centralizer body; the piston is divided into upper and lower sections, the outer diameter of the upper section of the piston is the same as the inner diameter of the centralizer body, the outer diameter of the lower section of the piston is smaller than the inner diameter of the centralizer body, and an annular oblique concave groove is provided in the middle of the upper section of the piston; the middle part of the piston contains a central flow channel.

[0007] A sealing packing groove is provided at the top of the piston upper section, and an O-ring groove is provided at the lower part of the piston lower section. The piston forms a sliding seal with the centralizer body through the packing in the sealing packing groove and the O-ring in the O-ring groove.

[0008] The cross section of the inclined concave groove is asymmetric, the curvature of the concave surface of the lower half is greater than that of the concave surface of the upper half, and the concave surface of the lower half is tangent to the connection between the concave surfaces of the upper half.

[0009] Spiral guide grooves are arranged between the straightening bars, and the number of the straightening bars is ≥3.

[0010] A retaining ring is also provided on the upper part of the inner wall of the centralizer body, and a discharge hole is reserved on the step of the inner wall of the centralizer body.

[0011] The upper part of the centralizer body is an upper connection end, which is a conventional tubing female thread buckle type, and the lower part of the centralizer body is a lower connection end, which is a conventional male thread buckle type.

[0012] A method for using a hydraulic ball centralizer, using any of the hydraulic ball centralizers described above, the specific process is as follows:

[0013] Step 1: Connect the hydraulic ball centralizer to the sandblasting and drilling oil pipe string through the upper and lower connecting ends, and lower the oil pipe string into the well;

[0014] Step 2: Liquid is injected into the tubing string. Under the action of the pressure difference, the piston moves downward, compressing the spring, and the steel ball moves toward the concave surface of the upper part of the inclined concave groove on the piston, from the deep concave surface to the shallow concave surface. The steel ball extends out of the through hole to play the role of straightening the tubing string. At this time, liquid can continue to be injected into the tubing string, so that the tubing string can be lowered while the liquid is injected;

[0015] Step 3: When the injection of liquid into the tubing string stops and there is no pressure difference in the string, the spring resets, driving the piston to move upward, and the steel ball moves toward the concave surface of the lower half of the inclined concave groove on the piston, from the shallow concave surface to the deep concave surface, and the steel ball is retracted into the through hole, the maximum outer diameter of the string becomes smaller, and the straightening effect stops.

[0016] In the step 2, once the pipe string is stuck during the sand flushing and drilling operations, the pipe string can be rotated immediately. At this time, the steel ball rolls circumferentially on the shallow concave surface of the inclined concave groove. The part of the steel ball extending out of the through hole can change from sliding to rolling friction, which can reduce the friction resistance of the pipe string and facilitate unblocking.

[0017] The technical effects of the present invention are:

[0018] 1. The present invention utilizes the pressure difference in the oil pipe to drive the piston-spring to move back and forth, thereby realizing the extension and retraction of the steel ball, thereby changing the maximum outer diameter of the pipe string and realizing the straightening of the oil pipe string. The structure is simple, the operation is convenient and fast, and the pipe string can be lowered while injecting liquid. 2. The steel ball of the hydraulic ball straightener of the present invention moves in the inclined concave groove. Once the pipe string is stuck during sand flushing and drilling and grinding operations, the pipe string can be rotated immediately. At this time, the steel ball can roll circumferentially in the inclined concave groove ring, reducing the friction resistance of the pipe string and facilitating unblocking. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following is a further description with reference to the accompanying drawings:

[0020] Figure 1 It is a structural schematic diagram of the hydraulic ball centralizer of the present invention.

[0021] Figure 2 It is a schematic diagram of the structure of the hydraulic ball centralizer piston of the present invention.

[0022] Figure numerals: 1-centralizer body, 2-retaining ring, 3-sealing packing, 4-steel ball, 5-piston, 6-spring, 7-O-ring, 8-discharge hole, 9-sealing packing groove, 10-inclined concave surface, 11-O-ring groove, 12-centralizer strip, 13-through hole, 14-spiral guide groove, 15-upper connecting end, 16-lower connecting end, 17-center flow channel. DETAILED DESCRIPTION

[0023] Example 1

[0024] In order to overcome the problems that the conventional centralizer has a fixed outer diameter, cannot be retracted, has low adaptability to the side wall of the oil well, and the existing retractable centralizer has a complicated outer diameter retraction operation and is inconvenient for rotating the oil well pipe, the present invention provides a Figure 1 A hydraulic ball straightener and a method of use are shown. The present invention utilizes the pressure difference in the oil pipe to drive the piston-spring to move back and forth, thereby extending and retracting the steel ball, thereby changing the maximum outer diameter of the pipe string and straightening the oil pipe string; by moving the steel ball in the inclined concave groove, the rotating pipe string can roll circumferentially in the inclined concave groove ring, thereby reducing the friction resistance of the pipe string.

[0025] A hydraulic ball centralizer, comprising a centralizer body 1 and a piston 5 located inside the centralizer body 1; wherein: a centralizer bar 12 is provided at the middle position outside the centralizer body 1, a through hole 13 is provided on the centralizer bar 12, a steel ball 4 is installed in the through hole 13, and the diameter of the steel ball 4 is larger than the diameter of the through hole 13; a spring 6 is provided inside the centralizer body 1, one end of the spring 6 is a free end and connected to the lower end of the piston 5, and the other end is a fixed end and fixed to the step on the inner wall of the centralizer body 1; the piston 5 is divided into upper and lower sections, the outer diameter of the upper section of the piston 5 is the same as the inner diameter of the centralizer body 1, the outer diameter of the lower section of the piston 5 is smaller than the inner diameter of the centralizer body 1, and an annular oblique concave groove 10 is provided in the middle of the upper section of the piston 5; the middle part of the piston 5 contains a central flow channel 17.

[0026] The present invention reciprocates under the action of the pressure difference in the oil pipe by the cooperation of the piston 5 and the spring 6, thereby pushing the steel ball 4 to move in the inclined concave groove 10, so that the steel ball 4 can be extended and retracted in the through hole 13, and the oil pipe string is straightened. Since the force comes from the pressure difference in the oil pipe, the straightening operation is convenient and fast, and the pipe string can be lowered while injecting liquid.

[0027] Example 2

[0028] On the basis of Example 1, in this embodiment, preferably, a sealing packing groove 9 is provided at the top of the upper section of the piston 5, and an O-ring groove 11 is provided at the lower part of the lower section of the piston 5. The piston 5 forms a sliding seal with the centralizer body 1 through the packing in the sealing packing groove 9 and the O-ring in the O-ring groove 11. The sliding seal effectively prevents the liquid in the central flow channel 17 from flowing from the centralizer to the outside of the pipe, thereby improving the working stability of the hydraulic ball centralizer and extending its service life.

[0029] Preferably, the cross section of the inclined concave groove 10 is asymmetric, the curvature of the concave surface of the lower half is greater than that of the concave surface of the upper half, and the concave surfaces of the lower half are tangent to each other at the connection point.

[0030] like Figure 2 As shown, the oblique concave groove 10 has an asymmetric structure, and the curvature of the concave surface of the lower part is greater than that of the concave surface of the upper part, which is beneficial to reducing the resistance of the steel ball 4 extending out of the through hole 13 and achieving rapid extension. The oblique concave groove 10 is annular. When the pipe column is rotated, the steel ball 4 can roll circumferentially in the oblique concave groove ring, thereby reducing the friction resistance of the pipe column.

[0031] Preferably, spiral guide grooves 14 are provided between the straightening bars 12, and the number of the straightening bars 12 is ≥3.

[0032] like Figure 1As shown, the spiral guide groove 14 is beneficial to improving the liquid flow state around the stabilizer during the rotation of the pipe string, preventing the accumulation of flushing sand and drilling and grinding materials in the wellbore during sand flushing and drilling and grinding operations; the straightening bar 12 can destroy the accumulation of flushing sand and drilling and grinding materials in the wellbore by rotating, keeping the wellbore clean.

[0033] Preferably, a retaining ring 2 is further provided on the upper portion of the inner wall of the centralizer body 1 , and a discharge hole 8 is reserved on the step of the inner wall of the centralizer body 1 .

[0034] like Figure 1 As shown, the retaining ring 2 is the top dead center of the piston 5 during the resetting process. The retaining ring 2 works together with the spring 6 to effectively limit the movement stroke of the piston; the discharge hole 8 can effectively discharge the liquid and solid debris in the cavity where the spring 6 is located to prevent the spring from failing.

[0035] Preferably, the upper part of the centralizer body 1 is an upper connecting end 15, and the upper connecting end 15 is a conventional tubing female thread buckle type, and the lower part of the centralizer body 1 is a lower connecting end 16, and the lower part of the lower connecting end 16 is a conventional male thread buckle type. Due to the use of conventional thread buckles, the centralizer of the present invention can be conveniently connected to the working pipe string without using a special conversion joint.

[0036] Example 3

[0037] Based on Example 2, a method for using a hydraulic ball centralizer is provided, and the specific process is as follows:

[0038] Step 1: Connect the hydraulic ball centralizer to the sandblasting and drilling oil pipe string through the upper connecting end 15 and the lower connecting end 16, and lower the oil pipe string into the well;

[0039] Step 2: Liquid is injected into the oil pipe string. Under the action of pressure difference, the piston 5 moves downward, compressing the spring 6. The steel ball 4 moves toward the upper concave surface of the inclined concave groove 10 on the piston 5, from the deep concave surface to the shallow concave surface. The steel ball extends out of the through hole 13, playing the role of straightening the oil pipe string. At this time, liquid can be continuously injected into the oil pipe string, so that the pipe string can be lowered while the liquid is injected;

[0040] Step 3: When the injection of liquid into the oil pipe string stops and there is no pressure difference in the pipe string, the spring 6 is reset, driving the piston 5 to move upward, and the steel ball 4 moves toward the concave surface of the lower half of the inclined concave groove 10 on the piston 5, from the shallow concave surface to the deep concave surface, and the steel ball 4 is retracted into the through hole 13, the maximum outer diameter of the pipe string becomes smaller, and the straightening effect stops.

[0041] In the step 2, once the pipe string is stuck during the sand flushing and drilling operations, the pipe string can be rotated immediately. At this time, the steel ball 4 rolls circumferentially on the shallow concave surface of the inclined concave groove 10. The part of the steel ball 4 extending out of the through hole 13 can change from sliding to rolling friction, which can reduce the friction resistance of the pipe string and facilitate unblocking.

[0042] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A hydraulic ball centralizer, characterized in that: It comprises a centralizer body (1) and a piston (5) located in the centralizer body (1); wherein: A straightening bar (12) is provided at the middle position of the outside of the centralizer body (1), and a through hole (13) is provided on the straightening bar (12). A steel ball (4) is installed in the through hole (13), and the diameter of the steel ball (4) is larger than the diameter of the through hole (13). A retaining ring (2) is provided on the upper part of the inner wall of the centralizer body (1), and the retaining ring (2) is the upper dead point of the piston (5) during the resetting process. A discharge hole (8) is left on the step of the inner wall of the centralizer body (1); A spring (6) is provided inside the centralizer body (1), one end of the spring (6) being a free end connected to the lower end of the piston (5), and the other end being a fixed end fixed to the inner wall step of the centralizer body (1); The piston (5) is divided into two sections, the upper section of the piston (5) has an outer diameter that is the same as the inner diameter of the centralizer body (1), and the lower section of the piston (5) has an outer diameter that is smaller than the inner diameter of the centralizer body (1). An annular oblique concave groove (10) is provided in the middle of the upper section of the piston (5). The cross section of the oblique concave groove (10) is asymmetrical, the curvature of the concave surface of the lower section is greater than that of the concave surface of the upper section, and the concave surface of the lower section is tangent to the concave surface of the lower section at the connection point. The middle part of the piston (5) contains a central flow channel (17), the top of the upper section of the piston (5) is provided with a sealing packing groove (9), and the lower part of the lower section of the piston (5) is provided with an O-ring groove (11). The piston (5) forms a sliding seal with the centralizer body (1) through the packing in the sealing packing groove (9) and the O-ring in the O-ring groove (11).

2. A hydraulic ball centralizer according to claim 1, characterized in that: Spiral guide grooves (14) are provided between the straightening bars (12), and the number of the straightening bars (12) is ≥3.

3. A hydraulic ball centralizer according to claim 1, characterized in that: The upper part of the centralizer body (1) is an upper connecting end (15), and the upper connecting end (15) is a conventional oil pipe female thread type.

4. The hydraulic ball centralizer according to claim 1, characterized in that: The lower part of the centralizer body (1) is a lower connecting end (16), and the lower part of the lower connecting end (16) is a conventional male thread buckle type.

5. The method for using the hydraulic ball centralizer according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Connect the hydraulic ball centralizer to the sandblasting and drilling oil pipe string through the upper connecting end (15) and the lower connecting end (16), and lower the oil pipe string into the well; Step 2: Liquid is injected into the oil pipe string. Under the action of the pressure difference, the piston (5) moves downward, compressing the spring (6), and the steel ball (4) moves toward the concave surface of the upper half of the inclined concave groove (10) on the piston (5), from the deep concave surface to the shallow concave surface. The steel ball (4) extends out of the through hole (13) to play the role of straightening the oil pipe string. At this time, liquid can continue to be injected into the oil pipe string, so that the oil pipe string can be lowered while the liquid is injected; Step 3: When the injection of liquid into the tubing string stops and there is no pressure difference in the string, the spring (6) is reset, driving the piston (5) to move upward, and the steel ball (4) moves toward the concave surface of the lower half of the inclined concave groove (10) on the piston (5), from the shallow concave surface to the deep concave surface, and the steel ball (4) is retracted into the through hole (13), the maximum outer diameter of the string becomes smaller, and the straightening effect stops.

6. The method for using a hydraulic ball centralizer according to claim 5, characterized in that: In the second step, when the pipe string is stuck during the sandblasting, drilling and grinding operation, the pipe string can be rotated immediately. At this time, the steel ball (4) rolls circumferentially on the shallow concave surface of the inclined concave groove (10), and the part of the steel ball (4) extending out of the through hole (13) can change from sliding to rolling.

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