A multi-stage reamer while drilling and its operation method

Abstract

The present invention discloses a downhole multi-stage reamer and its operation method, belonging to the technical field of drilling and exploration. It includes an upper sub, an upper mandrel, a secondary piston, a limit slip, a rupture valve, a cylinder body, upper and lower limit blocks, upper and lower stoppers, cutter bodies, a thrust piston, a lower mandrel, a lower ball seat, and a lower sub. The present invention also discloses an operation method for the downhole multi-stage reamer. When at low pressure, through the first ball drop, the first-stage thrust piston is opened to push the cutter body to a small reaming hole diameter, and the cutter body is locked by the limit slip. When at high pressure, the rupture valve opens to form a new hydraulic channel to push the secondary piston downward, the limit slip contracts and returns to its original position, and the cutter body continues to move upward and expand to a large reaming hole diameter, thereby continuously expanding the wellbore, reducing the tripping time, and being suitable for popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of oilfield drilling engineering, and relates to a downhole multi-stage reamer and an operation method thereof. Background Art

[0002] During the oil and gas exploration process, it is found that more and more proven oil and gas resources are buried in deep formations. Deep wells and ultra-deep wells have become a trend in oil and gas development. However, during the drilling of deep wells, ultra-deep wells, and horizontal wells with long horizontal sections, due to the complex and diverse formations drilled, and the presence of easily creep and neck-down formations such as salt gypsum layers, complex accidents such as stuck pipe often occur.

[0003] To solve this problem and improve the safety of deep well drilling operations, the method of reaming while drilling is often used to increase the annulus size. However, the currently commonly used downhole reamers mainly have the following deficiencies in practice: 1. The currently commonly used downhole reamers are divided into nozzle backpressure type and ball-drop type. The expansion cutter wings of the nozzle backpressure type reamer are easier to control in terms of expansion and retraction, but the reliability is poor, and the cutter wings are often difficult to retract, resulting in downhole stuck pipe. The control of the cutter wings of the ball-drop type downhole reamer is more complex, and the operation process is more, which is not convenient for on-site use. However, its reliability and stability are relatively high, and it is more widely used on-site. At present, there is a lack of a reaming tool solution that is convenient to use, has a simple operation process, and has high tool reliability and safety. 2. Most of the existing reaming tools have a fixed reaming size, which is fixed during production and often only targets the same type of well or even a certain well, with poor applicability. It is impossible to achieve on-demand reaming. However, during the drilling of deep wells and ultra-deep wells, due to the more complex formations drilled compared to conventional wellbores, and the relatively common presence of easily creep and neck-down formations such as salt gypsum layers, the reaming requirements for different well sections of the same well are also different. It is difficult for the existing reaming tools to meet the multi-stage different size reaming requirements.

[0004] In the prior art, there is an urgent need for a downhole multi-stage reamer and an operation method thereof. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects existing in the prior art, and provide a downhole multi-stage reamer and an operation method thereof to solve the problem of poor adaptability of the existing reaming tools with fixed reaming sizes. Multi-stage reaming can achieve on-demand reaming, and the reaming size increases with the increase of the reaming level, which can meet the reaming requirements of different formations and different wells of the same well, reduce the complexity of drilling accidents in unconventional reservoirs, greatly improve the drilling speed and quality, shorten the well construction period, reduce production costs, and promote cost reduction and efficiency increase in drilling in deep and unconventional complex formations.

[0006] In order to achieve the above technical purpose, the embodiments of the present invention are implemented as follows:

[0007] On the one hand, an embodiment of the present invention provides a downhole multi-stage reamer, comprising an upper sub, an upper mandrel, a secondary piston, a limit slip, a rupture valve, a cylinder body, upper and lower limit blocks, upper and lower stoppers, a cutter body, a thrust piston, a lower mandrel, a lower ball seat and a lower sub. The upper sub is connected to a drill pipe through a sub thread provided at the upper part. The lower part of the upper sub is successively provided with an upper mandrel, a cylinder body, a cutter body and a lower sub. The lower sub is connected to a lower drill tool through a sub thread for torque transmission. The upper mandrel is fixed to the upper sub by a shear pin. A rupture valve and a spring positioning ring are installed on the upper mandrel by threads. The secondary piston and a first-stage limit slip are installed in the annulus between the upper mandrel and the cylinder body. The upper part of a return spring contacts the spring positioning ring, and the lower part of the return spring contacts the upper limit block. The upper limit block and the upper stopper are connected by screws and installed in the annulus between the upper mandrel and the cylinder body to be slidable relative to each other. The cutter body is installed in a rectangular slideway of the cylinder body and is slidable relative to the cylinder body. The lower stopper, the lower limit block and the thrust piston are fixed to each other by screws and grooves and installed in the annulus between the upper mandrel and the cylinder body to be slidable up and down, and are provided with sealing rings to isolate internal and external mud. The lower mandrel and the lower ball seat are connected by a shear pin. The upper part of the lower mandrel is connected to the upper mandrel through a sealing ring, and the lower part is connected to the lower sub by a thread.

[0008] Further, the lower mandrel is provided with a flow hole.

[0009] On the other hand, an embodiment of the present invention provides an operation method for a downhole multi-stage reamer, comprising the following steps:

[0010] Comprising the following steps:

[0011] During low pressure, through the first ball dropping, a first-stage thrust piston is opened to push the cutter body to a small reaming hole diameter, and the cutter body is locked by the limit slip; during high pressure, the rupture valve is opened to form a new hydraulic channel to push the secondary piston to move downwards, the limit slip contracts and returns to its original position, and the cutter body continues to move upwards and expand to a large reaming hole diameter, so as to continue to enlarge the wellbore and reduce the tripping time.

[0012] Further, during low pump pressure, a steel ball is put into the wellbore, and when it reaches the lower ball seat, a seal is formed, the shear pin is cut off, the steel ball and the lower ball seat move downwards, a part of the fluid enters the annulus, and a part of the fluid continues to circulate downwards through the flow hole opened in the lower mandrel. The fluid in the annulus generates an upward thrust on the thrust piston to push the cutter body to open. When the end face of the upper limit block moves to the first-stage limit slip, the upper end face of the first-stage limit slip abuts against the upper sub, and the cutter body is limited; at this time, a stable low pump pressure is maintained and drilling continues downwards to achieve the effect of reaming a small wellbore.

[0013] Further, at high pump pressure: When the drilling wellbore needs to be enlarged to a large size, the pump pressure needs to be increased. When the pump pressure is increased to the maximum breaking pressure set by the rupture valve, the rupture valve opens, and the fluid enters the annulus between the second-stage piston and the upper mandrel through the valve hole, generating a downward thrust on the second-stage piston and moving downward. At this time, the first-stage limit slips contract into the second-stage piston card slot under the thrust of the upper limit block and their own elasticity. The upper limit block continues to move upward under the thrust of the thrust piston until the step surface of the upper limit block contacts the groove surface of the cylinder body to form a limit, and the cutter body continues to open to the large wellbore size. At this time, maintain a stable high pump pressure and continue to drill downward to achieve the effect of enlarging the large wellbore.

[0014] Further, after the reamer reaches the reaming hole diameter and depth, it is necessary to retract the cutter body for tripping the drill string. After stopping the pump, under the action of the self-weight of the cutter body and the elastic force of the return spring, the upper stop block is pushed to drive the cutter body to slide downward, and the cutter body is retracted. If the cutter body cannot be normally retracted, a second steel ball needs to be inserted. When the steel ball seat on the upper mandrel cuts the shear pin, the steel ball and the upper mandrel move downward, and the step on the upper mandrel pushes the upper stop block to forcibly drive the cutter body to move downward and contract, so as to retract the cutter body. When the lower end of the upper mandrel contacts the step of the lower mandrel, it is limited. At this time, the upper fluid continues to flow downward through the flow holes on the upper mandrel to ensure normal circulation.

[0015] The beneficial effects of the embodiments of the present invention are:

[0016] The technical solution of the present invention can provide a hydraulic multi-stage reamer, and its greatest advantage is that the multi-stage reaming system can ream different sizes according to different formation requirements, realizing different reaming requirements in different well sections of the whole well, and achieving the expansion and speed increase and efficiency improvement of the wellbore structure in deep wells and ultra-deep wells.

[0017] The present invention realizes the technology of reaming on demand. The specially designed multi-stage reaming system can ream different sizes according to different formation requirements, realizing different reaming requirements in different well sections of the whole well. The multi-stage reaming system is hydraulically controlled, and the stability and practicability of the tool are well guaranteed, which helps to improve the safety of deep well drilling operations and the wellbore quality, achieve the speed increase and efficiency improvement of deep wells and ultra-deep wells, improve the adaptability to different target formations, shorten the well construction period, improve the wellbore quality, create good wellbore conditions for subsequent electric logging and casing running, and is suitable for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0019] Figure 1 is a schematic structural diagram of the multi-stage reamer while drilling of the present invention;

[0020] Figure 2 is a partial enlarged view of the rupture valve;

[0021] Figure 3 is a structural diagram of the first-stage limit slip;

[0022] Figure 4 is a schematic diagram of the low pump pressure working principle;

[0023] Figure 5 is a schematic diagram of the high pump pressure working principle;

[0024] Figure 6 is a schematic diagram of the forced retraction principle of the tool body;

[0025] In the figure: 1 - upper sub; 2 - shear pin; 3 - upper mandrel; 4 - rupture valve; 5 - secondary piston; 6 - first-stage limit slip; 7 - spring positioning retaining ring; 8 - cylinder body; 9 - return spring; 10 - upper limit block; 11 - upper stop block; 12 - tool body; 13 - lower stop block; 14 - lower limit block; 15 - thrust piston; 16 - lower mandrel; 17 - shear pin; 18 - lower ball seat; 19 - lower sub; 20 - first steel ball; 21 - second steel ball; 22-28 - sealing rings; 29 - screw; 30 - annulus; 31 - step surface; 32 - step. Specific embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0027] Refer to Figure 1 As shown, the present invention discloses a hydraulic downhole variable diameter reamer, including an upper sub 1, the upper sub 1 is connected to the drill pipe through the sub thread provided in the upper part, the lower part of the upper sub 1 is successively provided with an upper mandrel 3, a cylinder body 8, a tool body 12, and a lower sub 19. The lower sub 19 is connected to the lower drill string through the sub thread for torque transmission. The upper mandrel 3 is fixed to the upper sub 1 by a shear pin 2. A rupture valve 4 ( Figure 2 ), a spring positioning ring 7 are installed on the upper mandrel 3 by threads. The secondary piston 5 and the first-stage limit slip 6 ( Figure 3) It is installed in the annulus between the upper mandrel 3 and the cylinder body 8. The upper part of the return spring 9 contacts the spring positioning ring 7, and the lower part contacts the upper limit block 10. The upper limit block 10 and the upper stop block 11 are connected by screws and installed in the annulus between the upper mandrel 3 and the cylinder body 8 to be slidable relative to each other. The cutter body 12 is installed in the rectangular slideway of the cylinder body 8 and is slidable relative to each other. The lower stop block 13, the lower limit block 14, and the thrust piston 15 are fixed to each other by screws and the grooves and installed in the annulus control between the upper mandrel 3 and the cylinder body 8 to be slidable up and down, and are equipped with sealing rings to isolate the internal and external mud. The lower mandrel 16 and the lower ball seat 18 are connected by a shear pin 17. The upper part of the lower mandrel 16 is connected to the upper mandrel 3 through a sealing ring, and the lower part is connected to the lower sub 19 through a thread. The lower mandrel 16 is provided with a flow hole.

[0028] Embodiment 1

[0029] At low pump pressure, the first steel ball 20 is put into the wellbore. As Figure 4 it reaches the lower ball seat 18 to form a seal, the shear pin 17 is cut off. The first steel ball 20 and the lower ball seat 18 move down to Figure 3 the position. Part of the fluid enters the annulus 30, and part of it continues to circulate downward through the flow hole 31 opened in the lower mandrel 16. The fluid in the annulus control 30 generates an upward thrust on the thrust piston 15 to push the cutter body 12 to open. When the end face of the upper limit block moves to the first-stage limit slip 6, the upper end face of the first-stage limit slip 6 abuts against the upper sub 1, and the cutter body 12 is limited; at this time, the stable low pump pressure continues to drill downward, achieving the effect of reaming a small wellbore.

[0030] Embodiment 2

[0031] At high pump pressure: When the drilling wellbore needs to be enlarged to a large size, the pump pressure needs to be increased. When the pump pressure is increased to the maximum rupture pressure set by the rupture valve 4, the rupture valve 4 opens, and the fluid enters the annulus between the second-stage piston 5 and the upper mandrel 3 through the valve hole, generating a downward thrust on the second-stage piston 5 and moving downward to Figure 5 the position. At this time, the first-stage limit slip 6 contracts into the card slot of the second-stage piston 5 under the thrust of the upper limit block 10 and its own elasticity. The upper limit block 10 continues to move upward under the thrust of the thrust piston 15 until the step surface 31 of the upper limit block 10 contacts the groove surface of the cylinder body 8 to form a limit, and the cutter body 12 continues to open to the large wellbore size; at this time, the stable high pump pressure continues to drill downward, achieving the effect of reaming a large wellbore.

[0032] Embodiment 3

[0033] Retracting the cutter blades: When the reamer reaches the reaming hole diameter and depth, it is necessary to retract the cutter body 12 to facilitate the tripping of the drill string. After stopping the pump, under the self-weight of the cutter body 12 and the elastic force of the return spring 9, it pushes the upper stop block 11 to drive the cutter body 12 to slide downward, and the cutter body 12 is retracted. If the cutter body 12 cannot be normally retracted, it is necessary to put the second steel ball 21 and lower it to Figure 6When shearing the shear pin 2 at the ball seat of the upper mandrel 3 in position, the second steel ball 21 and the upper mandrel 3 move downward, and the step 32 on the upper mandrel 3 pushes the upper stop block 11 to forcibly drive the tool body 12 to move downward and contract, thereby retracting the tool body 12. When the lower end of the upper mandrel 3 abuts against the step of the lower mandrel 16, it is limited. At this time, the upper part of the three-dimensional body continues to circulate downward through the flow hole on the upper mandrel 3.

[0034] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.

Claims

1. A multi-stage reamer while drilling, characterized in that, It includes an upper sub, an upper mandrel, a secondary piston, a first-stage limit slip, a rupture valve, a cylinder body, a return spring, upper and lower limit blocks, upper and lower stoppers, a cutter body, a thrust piston, a lower mandrel, a lower ball seat and a lower sub. The upper sub is connected to the drill pipe through the sub thread provided at the upper part. The lower part of the upper sub is successively provided with an upper mandrel, a cylinder body, a cutter body and a lower sub. The lower sub is connected to the lower drill string through the sub thread for torque transmission. A rupture valve and a spring positioning ring are installed on the upper mandrel through threads. The secondary piston and the first-stage limit slip are installed in the annulus between the upper mandrel and the cylinder body. The upper part of the return spring contacts the spring positioning ring, and the lower part of the return spring contacts the upper limit block. The upper limit block and the upper stopper are connected by screws and installed in the annulus between the upper mandrel and the cylinder body. The cutter body is installed in the rectangular slideway of the cylinder body. The lower stopper, the lower limit block and the thrust piston are fixed to each other by screws and the grooves and installed in the annulus between the upper mandrel and the cylinder body, and sealing rings are installed to isolate the inner and outer mud. The lower mandrel and the lower ball seat are connected by shear pins.

2. The multi-stage hole opener while drilling according to claim 1, characterized in that The lower mandrel is provided with a flow hole.

3. The multi-stage reamer while drilling according to claim 2, characterized in that, The upper mandrel and the upper sub are fixed by shear pins.

4. The multi-stage reamer while drilling according to claim 3, characterized in that The upper part of the lower mandrel is connected to the upper mandrel through a sealing ring.

5. The multi-stage reamer while drilling according to claim 4, characterized in that, The lower part of the lower mandrel is connected to the lower sub through threads.

6. A method for operating the multi-stage hole opener while drilling according to claim 5, characterized in that, It includes the following steps: At low pressure, through the first ball injection, the thrust piston is pushed to open the cutter body to a small reaming hole diameter, and the cutter body is locked by the first-stage limit slip; at high pressure, the rupture valve opens to form a new hydraulic channel to push the secondary piston to move downward, the first-stage limit slip contracts and returns to its original position, and the cutter body continues to move upward and open to a large reaming hole diameter.

7. The operating method of the multi-stage reamer while drilling according to claim 6, wherein At low pump pressure, a steel ball is put into the wellbore and reaches the lower ball seat to form a seal, so that the pressure is built up to shear the shear pins. The steel ball and the lower ball seat move downward. Part of the fluid enters the annulus, and part of the fluid continues to circulate downward through the flow hole opened in the lower mandrel. The fluid in the annulus generates an upward thrust on the thrust piston to push the cutter body to open. When the end face of the upper limit block moves to the first-stage limit slip, the upper end face of the first-stage limit slip abuts against the top of the upper sub, and the cutter body is limited; at this time, a stable low pump pressure is maintained and drilling continues downward to achieve the effect of reaming a small wellbore.

8. The operating method of the multi-stage reamer while drilling according to claim 6, characterized in that At high pump pressure: when the drilling wellbore needs to be enlarged to a large size, the pump pressure needs to be increased. When the pump pressure is increased to the highest rupture pressure set by the rupture valve, the rupture valve opens, and the fluid enters the annulus between the secondary piston and the upper mandrel through the valve hole, generating a downward thrust on the secondary piston and moving downward. At this time, the first-stage limit slip contracts into the card slot of the secondary piston under the thrust of the upper limit block and its own elasticity. The upper limit block continues to move upward under the thrust of the thrust piston until the step face of the upper limit block contacts the groove face of the cylinder body to form a limit, and the cutter body continues to open to the large wellbore size; at this time, a stable high pump pressure is maintained and drilling continues downward to achieve the effect of reaming a large wellbore.

9. The operating method of the multi-stage reamer while drilling according to claim 7, characterized in that, When the reamer reaches the reamed hole diameter and depth, it is necessary to retract the cutter body to tripping the drill string. After stopping the pump, under the self-weight of the cutter body and the elastic force of the return spring, the upper stop block is pushed to drive the cutter body to slide downward, and the cutter body is retracted. If the cutter body cannot be retracted normally, a second steel ball needs to be inserted. When it reaches the ball seat of the upper mandrel, the shear pin is cut off. The steel ball and the upper mandrel move downward, and the step on the upper mandrel pushes the upper stop block to forcibly drive the cutter body to move downward and contract, so as to retract the cutter body. When the lower end of the upper mandrel contacts the step of the lower mandrel, it is limited. At this time, the upper fluid continues to circulate downward through the flow hole on the upper mandrel.

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