A ball protector

Abstract

The present invention discloses a ball protector, which is composed of a coupling, a ball protector assembly, a ball protector blade, a return spring, a retaining ring and a sheath. The upper end of the coupling is connected to the tubing string of the pipe column. The upper end of the ball protector assembly is connected to the coupling, and the lower end is connected to the sand washing bit tip. The ball protector blades are arranged in an annular array, and the lower ends are rotatably inserted into the ball protector assembly. This ball protector can ensure that the blocking ball is always in the perforated interval during the downward movement of the sand washing pipe column and the circulation of the sand washing fluid, accurately and quickly block the perforation holes, avoid the leakage of the sand washing fluid, and realize efficient, fast and pollution-free sand washing measures. Since the ball protector can keep the blocking ball always in the perforated interval, the loss of the blocking ball is avoided, one-time ball throwing is realized, accurate and efficient blocking is completed, the entire sand washing process is quickly completed, the process is simplified, the cost is reduced, and the process success rate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sand washing and well flushing in oil wells, and particularly to a ball protector. Background Art

[0002] With the continuous progress of oilfield development, the reservoir pressure is getting lower and lower. Currently, the pressure coefficient of general heavy oil blocks is less than 0.2, and that of light oil is less than 0.5. It is inevitable that the working fluid leaks into the formation during the sand washing and well flushing operations of most wells, which seriously affects the efficient development of the oilfield. First, during the sand washing operation, mud and fine sand enter the near-wellbore area of the formation along with the sand washing fluid: one is to reduce the permeability of the reservoir, affect the productivity of the oil well, and increase the operation cost of reservoir plugging removal; the second is that the formation sand returns to the reservoir again, causing repeated operations and increasing the production operation cost; the third is the low operation efficiency, which affects the operation progress and thus affects the opening rate of the oil well.

[0003] In the prior art, the technology of temporarily plugging the wellbore perforations with a plugging ball and cooperating with the sand washing and well flushing operations is very suitable for the current mining conditions. Since the high-precision plugging ball moves synchronously with the sand washing fluid, the influence of the axial component force (including gravity or buoyancy) on the movement direction, trajectory, and movement timing of the plugging ball is avoided. Therefore, the plugging ball can still accurately plug the perforation holes under the quite low carrying force of the sand washing working fluid. Therefore, plugging the perforation holes with the plugging ball to avoid the leakage of the sand washing fluid is an efficient sand washing measure.

[0004] However, in the actual use process, to achieve the above technical effects, only when the plugging ball is always in the perforated well section during the advancement of the sand washing string and the continuous circulation of the sand washing fluid, and is ready to perform the plugging task at any time, can the perforation holes be accurately and quickly plugged. However, currently, there are generally two methods for throwing the ball: (1) throwing several times the number of plugging balls of the perforation holes at one time to ensure the plugging effect; (2) when connecting a single joint of the sand washing pipe, throwing the plugging balls in batches that match the number of perforation holes in the well section covered by a single sand washing pipe to ensure. Neither of the above two methods can achieve the technical effect of accurately plugging the perforation holes. The reason is that during the sand washing process, a part of the well section is buried by the sand surface. In this way, before the pen tip passes, the perforation holes are blocked by the sand surface. While the pen tip is continuously advancing, the sand washing working fluid is constantly circulating, and the plugging ball will also leave the perforated well section in advance with the circulation of the sand washing working fluid. No matter how many plugging balls there are, there is no chance to participate in the plugging task. The above methods not only have a poor plugging effect, but also bring complicated operation procedures, such as throwing the ball multiple times, using special devices to retrieve the ball, cleaning the plugging ball, counting the quantity, sorting out the qualified plugging balls for reuse. These procedures waste a large number of plugging balls, prolong the operation time, reduce the operation efficiency, and thus increase the operation cost.

[0005] Therefore, by attaching upper and lower ball protectors to the sand washing string, the blocking ball can be protected to always stay in the perforated interval. At the same time, the ball protectors can deform with the deformation of the casing, without getting stuck or blocked, which can completely solve this problem. However, the ball protectors currently used by people generally consist of N ball protection baffles, upper and lower baffle sheaths, return springs, baffle assemblies, and central pipes. The baffle plates are inserted into the baffle assemblies, and the upper and lower baffle sheaths at both ends are fixed radially and axially. The baffle assemblies are installed on the central pipes. According to its working principle, when encountering casing deformation, the baffle plates will retract radially towards the axis of the central pipe against the spring force, achieving diameter reduction, and then passing through the deformed position of the casing. However, with such a structural design, limited by the structural dimensions of each component, its diameter reduction range is relatively small, so the suitable casing deformation range is small, which limits the application range of this process. Moreover, the flow area of the liquid passage holes on the baffle plates is limited, affecting the circulation of the sand washing fluid during sand washing, and easily forming a sand bridge at small flow positions, causing pipe sticking accidents. At the same time, after the plugging is completed, it is impossible to quickly remove all the adjustment and blocking balls out of the wellbore, and the blocking balls remaining in the wellbore are likely to affect the subsequent work. In view of this, in-depth research on the above problems has led to the generation of this case. Summary of the Invention

[0006] The purpose of the present invention is to solve the above problems, and a ball protector is designed, which solves the problems of the existing ball protector having a relatively small diameter reduction range, a small suitable casing deformation range, limited process application range, easy formation of sand bridges, and causing pipe sticking accidents.

[0007] The technical solution of the present invention to achieve the above purpose is: a ball protector, which consists of a coupling, a ball protector assembly, ball protector flakes, a return spring, a retaining ring, and a sheath. The upper end of the coupling is connected to the tubing string, the upper end of the ball protector assembly is connected to the coupling, and the lower end is connected to the sand washing tip. The ball protector flakes are arranged in a circular array and the lower ends are rotatably inserted into the ball protector assembly. The sheath is axially fixedly connected to the ball protector assembly through threads and the retaining ring. The sheath is sleeved outside the ball protector flakes and the upper end is in contact with the outer wall surface of the ball protector flakes. The return spring is arranged on the inner wall surface of the ball protector flakes and one end is connected to the ball protector assembly. A pressure relief channel is arranged on the side wall of the ball protector flakes.

[0008] The outer wall of the above-mentioned ball protector assembly is successively provided with first, second, third, and fourth step structures from top to bottom.

[0009] Threads are provided on the outside of the first and fourth steps and are respectively connected to the coupling and the sand washing tip. A number of axial flake grooves are arranged in a circular array at the positions of the second and third steps, and a rotating shaft groove is arranged at the third step. The retaining ring is arranged below the third step.

[0010] The above-mentioned ball protection pieces of the ball protector are arranged in an annular array, and after combination, the whole is divided into three sections from top to bottom. The first section is cylindrical, the second section is conical with a larger upper part and a smaller lower part, and the third section is cylindrical.

[0011] The maximum outer diameter of the above-mentioned first cylindrical section is the same as the inner diameter of the wellbore casing, and at the connection between the first cylindrical section and the second conical section, an engagement step is arranged along the width. The width of the engagement step decreases from top to bottom, and the size is the same as the width of the groove for the protection piece. An outer rotating shaft ball is arranged on the outer wall at the connection between the cylindrical part of the third section and the conical part of the second section of the ball protection piece of the ball protector, and an inner rotating shaft ball is arranged on the inner side wall surface.

[0012] The above-mentioned ball protection pieces of the ball protector are installed in the grooves for the protection pieces. The rotating shaft balls and the rotating shaft grooves match each other. The ball protection pieces of the ball protector are fixed radially by being sleeved on the ball protector assembly and the sheath, axially by the grooves for the protection pieces, and circumferentially by the grooves for the protection pieces.

[0013] An axial liquid passage groove is arranged in the large-diameter section of the above-mentioned first conical section.

[0014] The ball protector manufactured by using the technical solution of the present invention can ensure that the ball stopper is always in the perforated well section during the downward movement of the sand washing string and the circulation of the sand washing fluid, accurately and quickly block the perforation holes, avoid the leakage of the sand washing fluid, and realize efficient, rapid and pollution-free sand washing measures.

[0015] The positive effects of the present invention are mainly as follows:

[0016] (1) Since the ball protector can keep the ball stopper always in the perforated well section, the loss of the ball stopper is avoided, one-time ball throwing is realized, accurate and efficient blocking is completed, the whole sand washing process is quickly completed, the process is simplified, the cost is reduced, and the process success rate is improved;

[0017] (2) The ball protection plate of the present invention is reduced in diameter by rotating in a shaft-approaching manner with the inner rotating shaft as the axis. Its minimum reduced diameter can be equal to the diameter of the sheath, and the necking range is large, expanding the application range of this process;

[0018] (3) The present invention can adjust the maximum outer diameter by replacing and adjusting the length of the ball protection plate, so as to be applicable to casings of different specifications;

[0019] (4) Its pressure relief channel is on the ball protection plate, and the equivalent diameter of the flow channel area is large, which has no influence on the sand washing circulation and will not form a sand bridge locally to cause blockage;

[0020] (5) The present invention has a simple structure, is easy to process and maintain, has a low production cost, and due to the rationality of its structure, reliable performance is inevitably produced. Description of the Drawings

[0021] Figure 1Schematic diagram of the main view cross-section structure of a ball protector according to the present invention.

[0022] Figure 2 Schematic diagram of the top view cross-section structure of the A-A position of a ball protector according to the present invention.

[0023] Figure 3 Schematic diagram of the main view structure of the ball protection sheet of the ball protector according to the present invention.

[0024] Figure 4 Schematic diagram of the side view structure of the ball protection sheet of the ball protector according to the present invention.

[0025] In the figure: 1 - coupling, 2 - ball protector assembly, 3 - ball protection sheet, 4 - return spring, 5 - retaining ring, 6 - sheath, 2-1 - groove for the protection sheet, 2-2 - shaft groove, 3-1 - inner shaft ball, 3-2 - outer shaft ball, 3-3 - liquid passage groove. Specific embodiments

[0026] The present invention will be specifically described below with reference to the accompanying drawings. As Figures 1-4 shown, those skilled in the art should connect the components in this case in sequence. For the specific connection and operation sequence, reference should be made to the following working principle. The detailed connection means are well-known techniques in the art. The following mainly introduces the working principle and process.

[0027] Embodiment: As can be seen from the attached Figures 1-4 drawings of the specification, the ball protector of this solution is composed of a coupling 1, a ball protector assembly 2, a ball protection sheet 3, a return spring 4, a retaining ring 5 and a sheath 6. The upper end of the coupling 1 is connected to the pipe string tubing. The upper end of the ball protector assembly 2 is connected to the coupling 1 and the lower end is connected to the sand washing tip. The ball protection sheets 3 are arranged in an annular array and the lower ends are rotatably inserted on the ball protector assembly 2. The sheath 6 and the ball protector assembly 2 are axially fixedly connected through threads and the retaining ring 5. The sheath 6 is sleeved outside the ball protection sheets 3 and the upper end is in contact with the outer side wall surface of the ball protection sheets 3. The return spring 4 is arranged on the inner side wall surface of the ball protection sheets 3 and one end is connected to the ball protector assembly 2. A pressure relief channel is arranged on the side wall of the ball protection sheet. The ball protection plate can rotate and move closer to the shaft in a shrinking diameter manner. Its minimum shrinking diameter can be equal to the diameter of the sheath. The shrinking diameter range is large, expanding the application range of this process. When this ball protector is used, it is respectively connected to the pipe string tubing and the sand washing tip, and is used in pairs, which can ensure that the blocking ball is always in the perforated well section during the downward movement of the sand washing pipe string and the circulation of the sand washing fluid, accurately and quickly block the perforated holes, avoid the leakage of the sand washing fluid, and realize efficient, fast and pollution-free sand washing measures. An axial liquid passage groove 3-3 is arranged in the large diameter section of the first section of the conical cylinder. Its pressure relief channel is on the ball protection plate. The equivalent diameter of the flow passage area is large, which has no influence on the sand washing circulation and will not form a sand bridge locally and cause blockage.

[0028] In the specific implementation process, the outer wall of the above-mentioned ball protector assembly 2 is successively provided with first, second, third, and fourth step structures from top to bottom. Among them, the first and fourth steps are externally provided with threads and are respectively connected to the coupling 1 and the sand washing tip. A number of axial blade slots 2-1 are opened along the circumferential array at the positions of the second and third steps, and a rotating shaft slot 2-2 is provided at the third step. The retaining ring 5 is arranged below the third step. The above-mentioned ball protector blades 3 are arranged along the circumferential array and are divided into three sections as a whole from top to bottom after combination. The first section is cylindrical, the second section is conical with a larger upper part and a smaller lower part, and the third section is cylindrical. By replacing and adjusting the length of the ball protector plate, the maximum outer diameter is adjusted, so as to be applicable to casings of different specifications.

[0029] In the specific implementation process, the maximum outer diameter of the above-mentioned first cylindrical section is the same as the inner diameter of the wellbore casing, and a connecting step is arranged along the width at the connection between the first cylindrical section and the second conical section. The width of the connecting step decreases from top to bottom and its size is the same as the width of the blade slot 2-1. An outer rotating shaft ball 3-2 is arranged on the outer wall at the connection between the cylindrical part of the third section and the conical part of the second section of the ball protector blade 3, and an inner rotating shaft ball 3-1 is arranged on the inner side wall surface. Among them, the ball protector blade 3 is installed in the blade slot 2-1, and the rotating shaft ball 3-1 matches the rotating shaft slot 2-2. The ball protector blade 3 is radially fixed by sleeving on the ball protector assembly 2 and the sheath 6, circumferentially fixed by the blade slot 2-1, and axially fixed by the rotating shaft slot 2-2. The ball protector plate is reduced in diameter by rotating towards the axis with the inner rotating shaft as the axis, and its minimum reduced diameter can be equal to the diameter of the sheath. The necking range is large, expanding the application range of this process.

[0030] To sum up, this ball protector can ensure that the blocking ball is always in the perforated interval during the downward movement of the sand washing string and the circulation of the sand washing fluid, accurately and quickly block the perforation holes, avoid the leakage of the sand washing fluid, and realize efficient, fast, and pollution-free sand washing measures. Since the ball protector can keep the blocking ball always in the perforated interval, the loss of the blocking ball is avoided, one-time ball throwing is realized, accurate and efficient blocking is completed, the entire sand washing process is quickly completed, the process is simplified, the cost is reduced, and the process success rate is improved; the ball protector plate is reduced in diameter by rotating towards the axis with the inner rotating shaft as the axis, and its minimum reduced diameter can be equal to the diameter of the sheath. The necking range is large, expanding the application range of this process; the maximum outer diameter can be adjusted by replacing and adjusting the length of the ball protector plate, so as to be applicable to casings of different specifications; its pressure relief channel is on the ball protector plate, and the equivalent diameter of the flow channel area is large, which has no influence on the sand washing cycle and will not form a sand bridge locally to cause blockage; the structure of the present invention is simple, easy to process, easy to maintain, has a low production cost, and due to the rationality of its structure, its performance is necessarily reliable.

[0031] The above technical solutions only reflect the preferred technical solutions of the technical solutions of the present invention. Some changes that those skilled in the art in this technical field may make to some parts thereof all reflect the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A ball protector, characterized in that, The ball protector is composed of a coupling (1), a ball protector assembly (2), ball protector shims (3), a return spring (4), a retaining ring (5), and a sheath (6). The upper end of the coupling (1) is connected to the tubing string. The upper end of the ball protector assembly (2) is connected to the coupling (1), and the lower end is connected to a wash-over bit. The ball protector shims (3) are arranged in a circular array, and the lower ends are rotatably inserted into the ball protector assembly (2). The sheath (6) is axially fixedly connected to the ball protector assembly (2) through threads and the retaining ring (5). The sheath (6) is sleeved outside the ball protector shims (3), and the upper end is in contact with the outer wall surface of the ball protector shims (3). The return spring (4) is arranged on the inner wall surface of the ball protector shims (3), and one end is connected to the ball protector assembly (2). A pressure relief channel is arranged on the side wall of the ball protector shims (3).

2. The ball protector according to claim 1, characterized in that, The outer wall of the ball protector assembly (2) is successively provided with first, second, third, and fourth stepped structures from top to bottom.

3. A ball protector according to claim 2, characterized in that, Threads are provided on the outside of the first and fourth steps and are respectively connected to the coupling (1) and the wash-over bit. A number of axial shim grooves (2-1) are arranged in a circular array at the positions of the second and third steps, and a rotating shaft groove (2-2) is arranged at the third step. The retaining ring (5) is arranged below the third step.

4. The ball protector according to claim 3, characterized in that, The ball protector shims (3) are arranged in a circular array and are divided into three sections as a whole from top to bottom. The first section is cylindrical, the second section is conical with a larger upper part and a smaller lower part, and the third section is cylindrical.

5. The ball protector according to claim 4, characterized in that, The maximum outer diameter of the cylindrical first section is the same as the inner diameter of the wellbore casing. At the junction of the cylindrical first section and the conical second section, a connecting step is arranged along the width. The width of the connecting step decreases from top to bottom and is the same as the width of the shim groove (2-1). An outer rotating shaft ball (3-2) is arranged on the outer wall at the junction of the cylindrical third section and the conical second section of the ball protector shims (3), and an inner rotating shaft ball (3-1) is arranged on the inner wall surface.

6. The ball protector according to claim 5, characterized in that, The ball protector shims (3) are installed in the shim grooves (2-1). The inner rotating shaft ball (3-1) matches the rotating shaft groove (2-2). The ball protector shims (3) are fixed radially by being sleeved in the ball protector assembly (2) and the sheath (6), fixed circumferentially by the shim grooves (2-1), and fixed axially by the rotating shaft groove (2-2).

Images