A self-adjusting element for a PDC bit with pressure increase and decrease functions and its installation method

Abstract

The present invention relates to the field of oil and geological drilling, and particularly relates to a PDC bit self-adjusting element capable of increasing and decreasing pressure and an installation method thereof. The self-adjusting element is installed inside the PDC bit, and the tooth column at the end is exposed outside the bit, and can automatically extend or retract according to the change of the external pressure. When the bit drills stably, the tooth column retracts to achieve a larger cutting depth and improve the drilling speed; when the bit drills unstably and is subjected to an instantaneous impact load, the tooth column quickly pops out to resist the external impact force to protect the cutting teeth of the PDC bit. The sizes of the two pistons and the piston cylinders for realizing the pressure increasing and decreasing function can be appropriately enlarged or reduced as needed to achieve the magnification adjustment of the pressure increase under different drilling environments. The connecting pipeline of the pressure increasing and decreasing part can be appropriately changed according to the different internal structures of the bit to achieve the flexible installation configuration of the self-adjusting element inside the bit.

Description

Technical Field

[0001] The present invention relates to the field of oil and geological drilling, and particularly to a pressure-increasing and -decreasing PDC bit self-adjusting element and an installation method thereof. Background Art

[0002] The sticking and sliding phenomenon of PDC bits has always been a major challenge faced by the oil and geological drilling industry. The instability caused by sticking and sliding can lead to premature damage of the bit, limit the bit life, increase the number of trips in and out of the well, extend the drilling cycle, and increase the drilling cost. The cutting depth control technology is an important symbol of the progress of bit technology. This technology mitigates the sticking and sliding vibration and broadens the application range of PDC bits. However, the fixed cutting depth control technology sacrifices some rate of penetration. The cutting depth self-adjusting PDC bit has greatly enhanced adaptability to different formations and drilling conditions. Currently, for the cutting depth self-adjusting PDC bit, it is necessary to study a pressure-increasing and -decreasing PDC bit self-adjusting element that can automatically adjust the cutting depth with the change of the drilling environment to improve the functionality of the self-adjusting element. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a pressure-increasing and -decreasing PDC bit self-adjusting element and an installation method thereof.

[0004] The technical solution is as follows:

[0005] A pressure-increasing and -decreasing PDC bit self-adjusting element includes a tooth column, a pressure-increasing and -decreasing device, and a self-adjusting device. The pressure-increasing and -decreasing device mainly consists of a first piston, a first piston cylinder, a second piston, and a second piston cylinder. The first piston and the second piston are respectively arranged in the first piston cylinder and the second piston cylinder. The tooth column is arranged on the first piston. The bore diameter of the first piston cylinder is larger than that of the second piston cylinder. The first piston cylinder and the second piston cylinder are connected and communicated through a connecting pipeline.

[0006] The self-adjusting device mainly consists of a self-adjusting piston cylinder, a self-adjusting piston, a return spring, and a flow control device. The self-adjusting piston is arranged in the self-adjusting piston cylinder. A first self-adjusting piston chamber and a second self-adjusting piston chamber are respectively arranged at both ends of the self-adjusting piston. One end of the self-adjusting piston is connected to the second piston through a connecting rod passing through the first self-adjusting piston chamber and the self-adjusting piston cylinder. A return spring is arranged in the second self-adjusting piston chamber. A flow control device is arranged inside the self-adjusting piston. The flow control device connects and communicates the first self-adjusting piston chamber and the second self-adjusting piston chamber. The connecting rod and the pressure distribution rod are in sliding and sealing fit with the self-adjusting piston cylinder.

[0007] A pressure distribution rod is arranged at the other end of the self-adjusting piston. One end of the pressure distribution rod is connected to the self-adjusting piston, and the other end extends outside the self-adjusting piston cylinder. The return spring is sleeved on the pressure distribution rod.

[0008] Further, the flow control device is a one-way flow control valve.

[0009] Further, the flow control device mainly consists of a self-regulating piston bleed hole, an internal piston flow channel, a steel ball cavity, a check valve steel ball, a pressure distribution rod bleed hole, and a check valve spring. The self-regulating piston bleed hole is opened on the side wall of the self-regulating piston. There is a flow gap on the side wall of the self-regulating piston. The self-regulating piston bleed hole communicates with the first self-regulating piston cavity through the flow gap. The self-regulating piston bleed hole communicates with the steel ball cavity through the internal piston flow channel. The steel ball cavity communicates with the pressure distribution rod bleed hole. The pressure distribution rod bleed hole communicates with the second self-regulating piston cavity. The pressure distribution rod bleed hole is opened on the side wall of the pressure distribution rod. The check valve steel ball is arranged in the steel ball cavity. The check valve steel ball is placed at the mouth of the internal piston flow channel, and its diameter is larger than that of the internal piston flow channel, leaving a gap between it and the mouth of the internal piston flow channel. The check valve spring is arranged between the check valve steel ball and the inner wall of the steel ball cavity.

[0010] Further, the connecting pipeline is a straight pipe; the connecting pipeline is a rigid pipeline. Sealing rings are provided between the first piston and the first piston cylinder, between the second piston and the second piston cylinder, between the connecting rod and the self-regulating piston cylinder, and between the pressure distribution rod and the self-regulating piston cylinder.

[0011] Based on the above installation method of the self-regulating element of the PDC bit capable of increasing and decreasing pressure, the self-regulating element of the PDC bit capable of increasing and decreasing pressure is installed at the position of the rear row teeth of the PDC bit, and the tooth column 1 is exposed behind the main cutting teeth of the PDC bit.

[0012] Further, the self-regulating element of the PDC bit capable of increasing and decreasing pressure is installed inside the PDC bit, and the tooth column at the end is exposed behind the cutting teeth of the bit.

[0013] Further, the PDC bit is a full-face drilling matrix PDC bit or a full-face drilling steel body PDC bit.

[0014] The beneficial effects of the present invention are:

[0015] The self-regulating element is installed inside the PDC bit, and the tooth column at the end is exposed behind the cutting teeth of the bit. It can automatically extend or retract according to the change of the external pressure. When the bit drills stably, the tooth column retracts to achieve a larger cutting depth and improve the drilling speed; when the bit drills unstably and is subjected to an instantaneous impact load, the tooth column quickly pops out to resist the external impact force to protect the cutting teeth of the PDC bit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure;

[0017] Figure 2Schematic structural diagram of the flow control device;

[0018] Figure 3 Schematic assembly position diagram;

[0019] In the figure: 1. Tooth column, 2. Piston 1, 3. Piston cylinder 1, 4. Connecting pipeline, 5. Piston cylinder 2, 6. Piston 2, 7. Self-regulating piston cylinder, 8. Self-regulating piston, 9. Flow control device, 10. Return spring, 11. Pressure distribution rod, 12. Sealing ring, 13. Self-regulating piston cylinder chamber 1, 14. Self-regulating piston cylinder chamber 2, 15. Piston cylinder chamber 2, 16. Piston cylinder chamber 1, 17. Self-regulating piston drain hole, 18. Check valve steel ball, 19. Pressure distribution rod drain hole, 20. Check valve spring, 21 Connecting rod, 22 Flow gap, 23 Internal flow channel of the piston, 24 Steel ball accommodating cavity, 25 Position 1, 26 Position 2, 27 Rear row teeth, 28 Main cutting teeth. Specific embodiments

[0020] The technical solution of the present invention will be further elaborated in detail below in conjunction with the embodiments.

[0021] Embodiment 1:

[0022] As Figure 1 shown, a self-regulating element of a PDC bit that can increase and decrease pressure includes a tooth column 1, a pressure increasing and decreasing device, and a self-regulating device.

[0023] The pressure increasing and decreasing device mainly consists of a piston 1 2, a piston cylinder 1 3, a piston 2 63, and a piston cylinder 2 5. The piston 1 2 and the piston 2 63 are respectively arranged in the piston cylinder 1 3 and the piston cylinder 2 5 and are in sliding seal fit with the piston cylinder. The upper end of the piston 1 2 extends out from the inside of the piston cylinder 1 3, and the tooth column 1 is arranged on the upper end surface of the piston 1 2. A piston chamber 1 is formed between the lower end surface of the piston 1 2 and the piston cylinder. A piston chamber 2 is formed between the upper end surface of the piston 2 63 and the piston cylinder 2 5. The bore diameter of the piston cylinder 1 3 is larger than the bore diameter of the piston cylinder 2 5, so that the volume of the piston chamber 1 is larger than the volume of the piston chamber 2. The piston cylinder 1 3 and the piston cylinder 2 5 are connected through a connecting pipeline 4. The connecting pipeline 4 is a connecting pipe integrally formed with the piston cylinder 1 3 and 2. The lower end of the piston 2 63 extends out from the lower end of the piston cylinder 2 5, and a connecting rod 21 is welded to the lower end surface of the piston 2 63.

[0024] The self-adjusting device mainly consists of a self-adjusting piston cylinder 7, a self-adjusting piston 8, a return spring 10, and a flow control device 9. The self-adjusting piston 8 is arranged in the self-adjusting piston cylinder 7, and the self-adjusting piston 8 is in sliding and sealing fit with the self-adjusting piston cylinder 7. Both ends of the self-adjusting piston 8 are respectively provided with a first self-adjusting piston chamber 13 and a second self-adjusting piston chamber 14. One end 2 of the self-adjusting piston 8 is connected to a second piston 63 through a connecting rod 21 passing through the first self-adjusting piston chamber 13 and the self-adjusting piston cylinder 7. The return spring 10 is arranged in the second self-adjusting piston chamber 14. The flow control device 9 is arranged inside the self-adjusting piston 8, and the flow control device 9 communicates the first self-adjusting piston chamber 13 and the second self-adjusting piston chamber 14; the connecting rod 21 and the pressure distribution rod 11 are in sliding and sealing fit with the self-adjusting piston cylinder 7.

[0025] The other end of the self-adjusting piston 8 is welded with a pressure distribution rod 11. One end of the pressure distribution rod 11 is connected to the self-adjusting piston 8, and the other end extends outside the self-adjusting piston cylinder 7. The return spring 10 is sleeved on the pressure distribution rod 11, and the pressure distribution rod 11 is in sliding and sealing fit with the self-adjusting piston cylinder 7.

[0026] The upper and lower openings of the self-adjusting piston cylinder 7 are provided with inward-extending annular platforms. Sealing grooves are formed on the inner walls of the annular platforms, and sealing rings 12 are embedded in the sealing grooves. The annular platforms are in sliding and sealing fit with the connecting rod 21 and the pressure distribution rod 11. The annular platform, the connecting rod 21, and the upper end face of the self-adjusting piston 8 located in the upper part of the self-adjusting piston cylinder 7 and the self-adjusting piston cylinder 7 form the first self-adjusting piston chamber 13, and the annular platform, the pressure distribution rod 11, and the lower end face of the self-adjusting piston 8 located in the lower part of the self-adjusting piston cylinder 7 and the self-adjusting piston cylinder 7 form the second self-adjusting piston chamber 14.

[0027] The flow control device 9 adopts a one-way flow control valve, and hydraulic oil flows from the first self-adjusting piston chamber 13 to the second self-adjusting piston chamber 14 through the one-way flow control valve.

[0028] The flow control device 9 mainly consists of a self-regulating piston drain hole 17, an internal piston flow channel 23, a steel ball accommodation cavity 24, a check valve steel ball 18, a pressure distribution rod drain hole 19, and a check valve spring 20. The self-regulating piston drain hole 17 is opened on the side wall of the self-regulating piston 8. There is a flow-through gap on the side wall of the self-regulating piston 8. The self-regulating piston drain hole 17 is communicated with the first self-regulating piston cavity 13 through the flow-through gap. The self-regulating piston drain hole 17 is communicated with the steel ball accommodation cavity 24 through the internal piston flow channel 23. The steel ball accommodation cavity 24 is communicated with the pressure distribution rod drain hole 19. The pressure distribution rod drain hole 19 is communicated with the second self-regulating piston cavity 14. The pressure distribution rod drain hole 19 is opened on the side wall of the pressure distribution rod 11. The check valve steel ball 18 is arranged in the steel ball accommodation cavity 24. The check valve steel ball 18 is in clearance fit with the internal piston flow channel 23. The check valve spring 20 is arranged between the check valve steel ball 18 and the inner wall of the steel ball accommodation cavity 24.

[0029] The connecting pipeline 4 is a straight pipe; the connecting pipeline 4 is a rigid pipeline. Sealing rings 12 are provided between the first piston 2 and the first piston cylinder 3, between the second piston 63 and the second piston cylinder 5, between the connecting rod 21 and the self-regulating piston cylinder 7, and between the pressure distribution rod 11 and the self-regulating piston cylinder 7.

[0030] Embodiment 2:

[0031] An installation method of a self-regulating element for a PDC bit capable of increasing and decreasing pressure. The PDC bit is a full-face drilling matrix PDC bit or a full-face drilling steel body PDC bit. The PDC bit mainly consists of a PDC bit body, cutter wings, main cutting teeth, and rear row teeth. Installation holes are machined on the PDC bit body. The inner wall structure of the installation holes is the same as the outer shape of the self-regulating element for the PDC bit capable of increasing and decreasing pressure. The installation holes are opened between the two cutter wings, and can be at position two behind the main cutting teeth or at position one behind the rear row teeth. After being placed, it is fixed with threads.

[0032] Embodiment 3:

[0033] On the basis of Embodiment 1, a cylindrical outer shell is added. External threads are machined on the outside of the outer shell, and internal threads are machined on the inner wall of the above installation holes. The above elements are installed through thread fitting. The first piston cylinder 3, the second piston cylinder 5, and the self-regulating piston cylinder 7 are fixedly sleeved inside the outer shell.

[0034] The working principle of the present invention is:

[0035] The component of the present invention is installed at the position of the rear row of teeth on the blade of the PDC bit and fixed by threads. The tooth column 1 is exposed behind the cutting teeth of the PDC bit. When the tooth column 1 is subjected to a continuous and stable external force, the pressure is reduced through the piston 1 for pressure increase and decrease and the piston 2 for pressure increase and decrease, and then the acting force is transmitted to the self-adjusting piston 8. Under the action of the external force, the self-adjusting piston 8 is gradually compressed, and the compression rate is related to the flow control device 9. At the same time, the return spring 10 is gradually compressed, the height difference between the tooth column 1 and the front row of teeth increases, and the cutting depth of the front row of teeth increases; when the tooth column 1 is not subjected to an external force, the self-adjusting piston 8 quickly pops out under the action of the return force of the return spring 10, and the popping rate is also related to the flow control device 9. The flow control device 9 is designed with a piston drain hole 17, a check valve steel ball 18, a pressure distribution rod drain hole 19, and a check valve spring 20. Through the comprehensive damping effect of the check valve and the drain hole, different rate performances of compression and rebound under different force conditions are realized, and the damping effect is achieved. The rebound acting force is transmitted to the tooth column 1 through the piston 2 for pressure increase and decrease and the piston 1 for pressure increase and decrease; when the tooth column 1 is subjected to an instantaneous impact force from the outside, the pressure is reduced through the pressure increase and decrease part. Due to the damping effect of the flow control device 9, the hydraulic medium cannot instantaneously flow from the cavity 13 into the cavity 14, and the self-adjusting piston cannot be instantaneously compressed. Therefore, the tooth column can withstand the instantaneous impact force without being compressed, realizing the function of protecting the front row of teeth.

[0036] The two cavities of the piston cylinder 1 for pressure increase and decrease and the piston cylinder 2 for pressure increase and decrease in the pressure increase and decrease part are filled with a hydraulic medium, and the hydraulic medium can flow between the two cavities through the connecting pipe 4; the diameter of the piston cylinder 1 for pressure increase and decrease is larger than the diameter of the piston cylinder 2 for pressure increase and decrease. According to the pressure F = pressure P × piston cross-sectional area S, the pressure of the piston 1 for pressure increase and decrease is greater than the pressure of the piston 2 for pressure increase and decrease, so as to achieve the effect of external pressure increase and internal pressure decrease. The piston cylinder 7 of the self-adjusting part is divided into two cavities 13 and 14 by the self-adjusting piston 8. The cavities are filled with a hydraulic medium, and the hydraulic medium flows between the two cavities through the flow control device 9. The two-way flow rates are different and are controlled by the flow control device 9. When the hydraulic medium flows from the cavity 13 into the cavity 14, the check valve is closed, and the medium flows through the overflow gap with a small flow rate and a slow medium flow velocity; when the hydraulic medium flows from the cavity 14 into the cavity 13, the check valve is pushed open, and the instantaneous flow rate increases and the medium flow velocity is fast. By controlling the cross-sectional size of the check valve and the size of the overflow gap, the precise control of the two-way flow rate is achieved. The tooth column 1 is connected to the piston 1 for pressure increase and decrease, and the piston 2 for pressure increase and decrease is connected to the self-adjusting piston 8 through a connecting rod to achieve overall connection and pressure conduction. The function of the pressure distribution rod 11 is to achieve pressure balance with the outside world and be in the same environmental medium as the tooth column 1 to ensure the pressure balance of all the internal cavities of the hydraulic cylinders of the self-adjusting component.

[0037] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, in any aspect, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0038] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A self - adjusting element for a PDC bit with pressure increasing and decreasing function, comprising a tooth column, a pressure increasing and decreasing device, and a self - adjusting device, characterized in that, The pressure increasing and decreasing device is composed of piston 1, piston cylinder 1, piston 2, and piston cylinder 2. Piston 1 and piston 2 are respectively arranged in piston cylinder 1 and piston cylinder 2. The tooth column is arranged on piston 1. The cylinder diameter of piston cylinder 1 is larger than that of piston cylinder 2. Piston cylinder 1 and piston cylinder 2 are communicated through a connecting pipeline. The self-adjusting device is composed of a self-adjusting piston cylinder, a self-adjusting piston, a return spring, and a flow control device. The self-adjusting piston is arranged in the self-adjusting piston cylinder. Self-adjusting piston chambers 1 and 2 are respectively arranged at both ends of the self-adjusting piston. One end of the self-adjusting piston is connected to piston 2 through a connecting rod passing through self-adjusting piston chamber 1 and the self-adjusting piston cylinder. The return spring is arranged in self-adjusting piston chamber 2. A flow control device is arranged inside the self-adjusting piston. The flow control device communicates self-adjusting piston chamber 1 and self-adjusting piston chamber 2. The connecting rod, the pressure distribution rod, and the self-adjusting piston cylinder are in sliding and sealing fit. The flow control device is composed of a self-adjusting piston drain hole, an internal piston flow channel, a steel ball accommodating cavity, a check valve steel ball, a pressure distribution rod drain hole, and a check valve spring. The self-adjusting piston drain hole is opened on the side wall of the self-adjusting piston. A flow-through gap is arranged on the side wall of the self-adjusting piston. The self-adjusting piston drain hole is communicated with self-adjusting piston chamber 1 through the flow-through gap. The self-adjusting piston drain hole is communicated with the steel ball accommodating cavity through the internal piston flow channel. The steel ball accommodating cavity is communicated with the pressure distribution rod drain hole. The pressure distribution rod drain hole is communicated with self-adjusting piston chamber 2. The pressure distribution rod drain hole is opened on the side wall of the pressure distribution rod. The check valve steel ball is arranged in the steel ball accommodating cavity. The check valve steel ball is located at the port of the internal piston flow channel. A gap is left between the check valve steel ball and the port of the internal piston flow channel. The check valve spring is arranged between the check valve steel ball and the inner wall of the steel ball accommodating cavity.

2. The self-adjusting element of the PDC bit capable of increasing and decreasing pressure according to claim 1, characterized in that, A pressure distribution rod is arranged at the other end of the self-adjusting piston. One end of the pressure distribution rod is connected to the self-adjusting piston, and the other end extends outside the self-adjusting piston cylinder. The return spring is sleeved on the pressure distribution rod.

3. The self-adjusting element of the PDC bit capable of increasing and decreasing pressure according to claim 1 or 2, characterized in that, The flow control device is a one-way flow control valve.

4. The self-adjusting element of a PDC bit capable of increasing and decreasing pressure according to claim 3, wherein, The connecting pipeline is a straight pipe.

5. The self-adjusting element of a PDC bit capable of increasing and decreasing pressure according to claim 4, wherein The connecting pipeline is a rigid pipeline.

6. The self - adjusting element of a PDC bit capable of increasing and decreasing pressure according to claim 5, wherein, Sealing rings are arranged between piston 1 and piston cylinder 1, between piston 2 and piston cylinder 2, between the connecting rod and the self-adjusting piston cylinder, and between the pressure distribution rod and the self-adjusting piston cylinder.

7. The installation method of a self-adjusting element of a PDC bit capable of increasing and decreasing pressure according to claim 6, characterized in that, The self-adjusting element of the PDC bit capable of increasing and decreasing pressure is installed inside the PDC bit, and the tooth column at the end is exposed behind the cutting teeth of the bit.

8. The installation method of a self-adjusting element of a PDC bit capable of increasing and decreasing pressure according to claim 7, characterized in that The self-adjusting element of the PDC bit capable of increasing and decreasing pressure is installed at the position of the rear row of teeth of the PDC bit, and the tooth column is exposed behind the main cutting teeth of the PDC bit.

9. The installation method of a self-adjusting element of a PDC bit capable of increasing and decreasing pressure according to claim 7 or 8, characterized in that The PDC bit is a full-face drilling matrix PDC bit or a full-face drilling steel body PDC bit.

Images