A rotary sweeping plasma jet rock breaking drill bit and drilling method

Abstract

The present invention discloses a rotary sweeping plasma jet rock-breaking drill bit and drilling method, belonging to the field of drilling engineering technology. The method comprises a plasma jet drill bit body, a conductive slip ring, a hollow shaft, and a motor. The plasma jet drill bit body comprises an anode electrode, within which a discharge chamber is disposed. The end of the anode electrode facing the conductive slip ring is fixedly connected to an anode base, and the radially inner side of the anode base is insulated from a cathode base, within which a cathode electrode is disposed. The end of the discharge chamber, away from the cathode electrode, penetrates the jet end of the anode electrode to form an anode nozzle. The central axis of the discharge chamber forms an inclined angle with the central axis of the plasma jet drill bit body. During the drilling process, the plasma ejected from the anode nozzle rotates in a circle to form a dynamic jet, forming a circular ablation trajectory on the rock surface and increasing the rock-breaking aperture.

Description

Technical Field

[0001] The present invention belongs to the technical field of drilling engineering, and in particular relates to a rotary sweeping plasma jet rock breaking drill bit and a drilling method. Background Art

[0002] As global energy demand continues to grow, oil and gas resource development is gradually expanding into deep and ultra-deep formations. However, deep formations often present challenges such as high rock strength (uniaxial compressive strength >160 MPa) and strong heterogeneity (e.g., interbedded granite and flint). Traditional mechanical drilling techniques rely on the mechanical crushing action of roller cone bits or PDC cutters, but face numerous bottlenecks in hard rock formations, such as severe bit wear, low drilling efficiency, and difficulty controlling wellbore quality. Consequently, thermal rock breaking technology has become a research hotspot. Non-transferred arc plasma jets, for example, effectively break hard rock through the coupled thermal erosion and thermal shock effects of a high-temperature (>8000 K) and high-velocity (>500 m / s) jet.

[0003] However, existing plasma rock breaking devices have fundamental flaws. Due to the physical size constraints of the anode nozzle, the jet diameter is usually no more than 30 mm, and the resulting crushing crater diameter is only 20-40 mm, which cannot meet the aperture requirements for continuous drill feed. Static jets acting on a local area for a long time will not only cause nozzle overheating and damage but also increase the rock breaking specific energy, which is the energy required to remove a unit volume of rock.

[0004] Therefore, the development of a new type of plasma rock-breaking drill bit that can increase the rock-breaking diameter and protect the nozzle has become an urgent need for upgrading deep resource development equipment. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and to provide a rotary sweeping plasma jet rock breaking drill bit.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A rotary sweeping plasma jet rock breaking drill bit comprises a plasma jet drill bit body, a conductive slip ring, and a hollow shaft which are coaxially fixedly connected in sequence along the axial direction, wherein the other end of the hollow shaft is coaxially fixedly connected to the output end of the motor;

[0008] The plasma jet drill bit body includes an anode electrode, and a discharge chamber is provided inside the anode electrode;

[0009] One end of the anode electrode facing the conductive slip ring is fixedly connected to the anode base, the radial inner side of the anode base is insulated and connected to the cathode base, and a cathode electrode is fixedly arranged inside the cathode base and extends into the discharge chamber;

[0010] The central axis of the cathode electrode is collinear with the central axis of the discharge chamber;

[0011] One end of the discharge chamber away from the cathode electrode passes through the jet end of the anode electrode to form an anode nozzle;

[0012] The center point of the end of the cathode electrode away from the anode nozzle is located on the central axis of the plasma jet drill body;

[0013] There is an inclined angle between the central axis of the discharge chamber and the central axis of the plasma jet drill body.

[0014] Preferably, the inclination angle ranges from 15° to 45°.

[0015] Preferably, the distance between the intersection of the central axis of the discharge chamber and the anode electrode jet end and the center point of the anode electrode jet end is L1, the length of the discharge chamber is L2, and the ratio of L1 to L2 ranges from 1:8 to 1:6.

[0016] Preferably, the discharge chamber comprises a first cylindrical channel, a frustum channel, and a second cylindrical channel coaxially connected in sequence, wherein the large end of the frustum channel is away from the anode nozzle and connected to the first cylindrical channel;

[0017] The cathode electrode extends from the first cylindrical channel into the frustum channel.

[0018] Preferably, the radial inner side of the anode base is insulated and connected to the cathode base via insulating ceramic in a ring structure.

[0019] Preferably, a cooling cavity is provided inside the cathode electrode, and a cooling water channel and a return water channel connected to the cooling cavity are provided on the cathode base.

[0020] Preferably, the insulating ceramic is provided with a gas channel connected to the discharge chamber.

[0021] The present invention also provides a rotary sweeping plasma jet rock breaking and drilling method.

[0022] A rotary sweeping plasma jet rock breaking drilling method is implemented based on a rotary sweeping plasma jet rock breaking drill bit, comprising the following steps:

[0023] A working medium is input into the discharge chamber, where it is ionized into plasma, which is then ejected through the anode nozzle to form an inclined jet.

[0024] The motor drives the plasma jet drill bit body to rotate through the hollow shaft and conductive slip ring, causing the inclined jet to rotate in a circle to form a dynamic jet, forming a circular ablation trajectory on the rock surface, realizing rotary sweeping plasma jet rock breaking and increasing the rock breaking aperture.

[0025] The beneficial effects of the present invention are:

[0026] (1) The present invention tilts the discharge chamber and the cathode electrode relative to the central axis of the plasma jet drill body so that the intersection of the central axis of the discharge chamber and the anode electrode jet end deviates from the central point of the anode electrode jet end. Combined with the motor's control of the rotation of the plasma jet drill body, during the drilling process, the plasma ejected from the anode nozzle rotates in a circle to form a dynamic jet, forming a circular ablation track on the rock surface. Compared with the existing coaxial arrangement of the anode nozzle and the drill body, under the condition of the same anode nozzle size, the formation of the circular ablation track in the present application increases the rock breaking aperture; the dynamic jet avoids repeated heating of the melted magma in the crushing pit, reduces energy waste, and at the same time expands the range of thermal stress action, increases the growth of cracks in brittle rocks such as granite and basalt, and has a significant effect on degraded and damaged rocks.

[0027] (2) The centrifugal force generated by the rotation of the plasma jet drill bit body in the present invention will disperse the heat load of the scattering current, causing the arc root attachment point to jump and move continuously, and cannot be fixed at a certain position, aggravating the ablation, thereby extending the life of the anode nozzle; at the same time, during the rock breaking process, the coaxial static plasma jet will reflect on the drill bit end face after impacting the rock surface, causing serious ablation of the end face, while the inclined dynamic plasma jet can greatly reduce the jet erosion, thereby extending the life of the plasma drill bit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0029] Figure 1 Schematic diagram of the structure of the rotary sweeping plasma jet rock breaking drill bit of the present invention;

[0030] Figure 2 This is a cross-sectional view of the structure of the rotary sweeping plasma jet rock breaking drill bit of the present invention;

[0031] Figure 3 is a diagram of the experimental setup;

[0032] Figure 4 Graphs of experimental results: (a) experimental results of existing plasma jet rock breaking drill bits; (b) experimental results of the rotary sweeping plasma jet rock breaking drill bit of the present application;

[0033] in:

[0034] 1. Plasma jet drill bit body; 11. Anode electrode; 12. Discharge chamber; 121. First cylindrical channel; 122. Cone channel; 123. Second cylindrical channel; 13. Anode base; 14. Cathode base; 15. Cathode electrode; 151. End center point; 152. Cooling chamber; 16. Anode nozzle; 17. Inclined angle; 18. Intersection point; 19. Anode electrode jet end center point; 110. Insulating ceramic; 111. Cooling water channel; 112. Return water channel; 113. Gas channel.

[0035] 2. Conductive slip ring; 3. Hollow shaft; 4. Motor; 5. Coupling;

[0036] 6. Support frame; 7. Cooling system; 8. Air supply system; 9. Power supply system; 10. Rock blocks to be broken; 101. First rock breaking aperture; 102. Second rock breaking aperture; 103. Center console. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] In the present invention, the directions or positional relationships indicated by terms such as "upper", "lower", "bottom", and "top" are based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and cannot be understood as limitations on the present invention.

[0040] In the present invention, terms such as "connected" and "connection" should be interpreted broadly to mean a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediary. Relevant researchers or technicians in this field may determine the specific meanings of these terms in the present invention based on specific circumstances, and they should not be construed as limitations on the present invention.

[0041] The present invention will be further described below with reference to the accompanying drawings and examples.

[0042] Example 1:

[0043] like Figure 1 As shown, a rotary sweeping plasma jet rock breaking drill bit comprises a plasma jet drill bit body 1, a conductive slip ring 2, and a hollow shaft 3, which are coaxially fixedly connected in sequence along the axial direction. The other end of the hollow shaft 3 is coaxially fixedly connected to the output end of the motor 4. The other end of the hollow shaft 3 is coaxially fixedly connected to the output end of the motor 4 via a coupling 5. The plasma gas pipe, coolant inlet pipe, coolant return pipe, and cable pass through the center hole of the hollow shaft 3 and do not rotate with the external structure. An optical fiber strain sensor is integrated in the hollow shaft 3 to monitor the axial pressure of the drill bit in real time. When the pressure exceeds a threshold, the feed speed is automatically reduced. The conductive slip ring 2 serves as a multi-channel integrated rotary joint that can simultaneously handle gas, liquid, and electrical transmission.

[0044] like Figure 2 As shown, the plasma jet drill body 1 includes an anode electrode 11, and a discharge chamber 12 is provided inside the anode electrode 11;

[0045] One end of the anode electrode 11 facing the conductive slip ring 2 is fixedly connected to the anode base 13, and the other end of the anode base 13 is coaxially fixedly connected to the conductive slip ring 2. The radial inner side of the anode base 13 is insulated from the cathode base 14. A cathode electrode 15 is fixedly provided inside the cathode base 14 and extends into the discharge chamber 12.

[0046] The central axis of the cathode electrode 15 is collinear with the central axis of the discharge chamber 12;

[0047] The end of the discharge chamber 12 away from the cathode electrode 15 passes through the jet end of the anode electrode 11 to form an anode nozzle 16;

[0048] The center point 151 of the end of the cathode electrode 15 away from the anode nozzle 16 is located on the central axis of the plasma jet drill body 1; that is, the line connecting the center point 151 of the end of the cathode electrode 15 away from the anode nozzle 16 and the center point 19 of the anode electrode jet end is the central axis of the plasma jet drill body 1;

[0049] There is an inclined angle 17 between the central axis of the discharge chamber 12 and the central axis of the plasma jet drill body 1, so that the intersection 18 of the central axis of the discharge chamber 12 and the jet end of the anode electrode 11 deviates from the center point 19 of the anode electrode jet end.

[0050] Preferably, the inclination angle 17 is in the range of 15° to 45°.

[0051] Preferably, the distance between the intersection of the central axis of the discharge chamber and the anode electrode jet end and the center point of the anode electrode jet end is L1, the length of the discharge chamber is L2, and the ratio of L1 to L2 ranges from 1:8 to 1:6.

[0052] Preferably, the discharge chamber 12 comprises a first cylindrical channel 121, a frustum channel 122, and a second cylindrical channel 123 that are coaxially connected in sequence, wherein the large end of the frustum channel 122 is away from the anode nozzle 16 and connected to the first cylindrical channel 121;

[0053] The cathode electrode 15 extends from the first cylindrical channel 121 into the frustum channel 122 .

[0054] Preferably, the radial inner side of the anode base 13 and the cathode base 14 are insulated and connected via an insulating ceramic 110 having a ring structure.

[0055] Preferably, a cooling cavity 152 is provided inside the cathode electrode 15 , and a cooling water channel 111 and a return water channel 112 connected to the cooling cavity 152 are provided on the cathode base 14 .

[0056] The cooling water channel 111 is connected to the cooling liquid inlet pipe, and the return water channel 112 is connected to the cooling liquid return pipe.

[0057] Preferably, the insulating ceramic 110 is provided with a gas channel 113 connected to the discharge chamber 12. The gas channel 113 is connected to the plasma gas pipe.

[0058] Example 2:

[0059] A rotary sweeping plasma jet rock breaking drilling method is implemented based on the rotary sweeping plasma jet rock breaking drill bit in Example 1. The drilling method is as follows:

[0060] A working medium is fed into the discharge chamber 12 through the gas channel 113 , and the working medium is ionized into plasma in the discharge chamber 12 , and the plasma is ejected through the anode nozzle 16 to form an inclined jet;

[0061] The motor 4 drives the plasma jet drill body 1 to rotate through the hollow shaft 3 and the conductive slip ring 2, so that the inclined jet rotates in a circle to form a dynamic jet, forming a circular ablation track on the rock surface, realizing the rotary sweeping plasma jet rock breaking and increasing the rock breaking aperture.

[0062] In the present application, the discharge chamber 12 and the cathode electrode 15 are tilted relative to the central axis of the plasma jet drill bit body 1, so that the intersection 18 of the central axis of the discharge chamber 12 and the jet end of the anode electrode 11 deviates from the center point 19 of the jet end of the anode electrode. Combined with the control of the rotation of the plasma jet drill bit body 1 by the motor 4, during the drilling process, the plasma ejected by the anode nozzle 16 rotates in a circle to form a dynamic jet, forming a circular ablation track on the rock surface. Compared with the existing coaxial arrangement of the anode nozzle and the drill bit body, when the anode nozzle size is the same, the formation of the circular ablation track in the present application increases the rock breaking aperture. The centrifugal force generated by the rotation of the plasma jet drill bit body 1 will disperse the scattered heat load, causing the arc root attachment point to jump and move continuously, and it cannot be fixed at a certain position, aggravating the ablation, thereby extending the life of the anode nozzle 16. At the same time, during the rock breaking process, the coaxial static plasma jet will reflect on the drill bit end face after impacting the rock surface, causing serious ablation of the end face, while the inclined dynamic plasma jet can greatly reduce the jet back erosion, thereby extending the life of the plasma drill bit; at the same time, the rotation of the plasma jet drill bit body 1 causes the plasma jet to form a dynamic jet. The dynamic jet avoids repeated heating of the melted magma in the crushing pit, reducing energy waste. At the same time, the range of thermal stress action is expanded, which increases the growth of cracks inside brittle rocks such as granite and basalt, and has a significant effect on degraded and damaged rocks.

[0063] In view of the effect of the drill bit of the present application on increasing the rock breaking aperture, a rock breaking experiment was conducted to verify the effect. The experimental device is as follows: Figure 3 As shown, it includes a support frame 6 for supporting the drill bit, a cooling system 7 for providing cooling circulating water, an air supply system 8 for providing a medium for plasma jet generation, a power supply system 9 for powering the drill bit, a rock block to be broken 10, and a set of existing plasma jet rock breaking drill bits and a set of rotary sweeping plasma jet rock breaking drill bits of the present application, wherein the cooling system 7, the air supply system 8, and the power supply system 9 are all connected to the central console 103 to control the relevant flow rate and current size, and the water pipe, gas pipe, and cable output from the central console 103 are integrated in a conveying pipe and connected to the hollow shaft 3.

[0064] The central axis of the cathode electrode 15 and the discharge chamber 12 in the plasma jet drill bit body 1 of the present application is changed to be collinear with the central axis of the drill bit body, which is the existing plasma jet rock breaking drill bit.

[0065] Experiments were conducted using existing plasma jet rock breaking drill bits:

[0066] The existing plasma jet rock breaking drill bit is vertically arranged on the support frame 6 so that the distance between the jet end and the rock block 10 to be broken is 50 mm, wherein the diameter of the anode nozzle 16 in the existing plasma jet rock breaking drill bit is 8 mm;

[0067] Connect the cooling system 7 to the cooling water channel 111 and the return water channel 112 of the existing plasma jet rock breaking drill bit, connect the gas supply system 8 to the gas channel 113 of the existing plasma jet rock breaking drill bit, connect the positive output of the power supply system 9 to the anode base 13 of the existing plasma jet rock breaking drill bit, and connect the negative output to the cathode base 14 of the existing plasma jet rock breaking drill bit;

[0068] The output current of the power supply system 9 is set to 200A, the continuous rock breaking time is set to 40s, the working medium is input through the gas channel 113, and the input flow rate is 40slm. The experimental results are as follows Figure 4 As shown: the first rock breaking aperture 101 is 25mm, the removed mass is 15g, and the rock breaking specific energy is 65kJ / cm 3 .

[0069] Experiments were conducted using the rotary swept plasma jet rock breaking drill bit of this application:

[0070] The rotary sweeping plasma jet rock breaking drill bit of the present application is set on the support frame 6 in the vertical direction so that the distance between the jet end and the rock block 10 to be broken is 50 mm, wherein the diameter of the anode nozzle 16 is 8 mm;

[0071] Connect the cooling system 7 to the cooling water channel 111 and the return water channel 112, connect the gas supply system 8 to the gas channel 113, connect the positive output of the power supply system 9 to the anode base 13, and connect the negative output to the cathode base 14;

[0072] The power supply system 9 is set to output current of 200A, the continuous rock breaking time is set to 40s, the working medium is input through the gas channel 113 and the motor 4 is started to control the rotation of the plasma jet drill body 1, wherein the input flow rate is 40slm and the speed of the motor 4 is 6rpm. The experimental results are shown as follows Figure 4 As shown: the second rock breaking aperture 102 is 76mm, the removed mass is 48g, and the rock breaking specific energy is 31kJ / cm 3 .

[0073] Through comparison, it was found that the rotary sweeping plasma jet rock breaking drill bit of the present application has a rock breaking aperture increased by 204%, a removal mass increased by 220%, and a rock breaking specific energy decreased by 52.31% compared with the existing plasma jet rock breaking drill bit.

[0074] In this application, the calculation formula of rock breaking specific energy is as follows:

[0075] (1);

[0076] in, is the rock breaking specific energy; For time Total energy consumption within is the volume of rock removed; The energy consumed by the plasma drill to discharge; Energy taken away by the cooling system; is the energy consumption of the motor; is the real-time voltage in the power supply system; is the real-time current in the power supply system; is the density of water; The flow rate of water in the cooling system is monitored by a flow sensor; is the specific heat of water; The temperature difference between the water in the cooling water channel 111 and the return water channel 112 is monitored by a temperature sensor; is the continuous rock breaking time; the real-time voltage and real-time current in the power supply system are monitored by power sensors.

[0077] Among them, when the existing plasma jet rock breaking drill bit is used for the experiment, the energy consumption of the motor is 0; when the rotary sweeping plasma jet rock breaking drill bit of the present application is used for the experiment, the current and voltage of the motor 4 are measured, and the energy consumption of the motor is calculated by multiplying the current and voltage of the motor 4 with the continuous rock breaking time.

[0078] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not a limitation of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A rotary sweeping plasma jet rock breaking drilling method, implemented based on a rotary sweeping plasma jet rock breaking drill bit, characterized in that: The rotary sweeping plasma jet rock breaking drill bit comprises a plasma jet drill bit body, a conductive slip ring, and a hollow shaft that are coaxially fixedly connected in sequence along the axial direction. The other end of the hollow shaft is coaxially fixedly connected to the output end of the motor. The plasma gas pipe, coolant inlet pipe, coolant return pipe, and cable pass through the center hole of the hollow shaft and do not rotate with the external structure. The plasma jet drill bit body includes an anode electrode, and a discharge chamber is provided inside the anode electrode; One end of the anode electrode facing the conductive slip ring is fixedly connected to the anode base, the radial inner side of the anode base is insulated and connected to the cathode base, and a cathode electrode is fixedly arranged inside the cathode base and extends into the discharge chamber; The central axis of the cathode electrode is collinear with the central axis of the discharge chamber; One end of the discharge chamber away from the cathode electrode passes through the jet end of the anode electrode to form an anode nozzle; The center point of the end of the cathode electrode away from the anode nozzle is located on the central axis of the plasma jet drill body; There is an inclined angle between the central axis of the discharge chamber and the central axis of the plasma jet drill body; The distance between the intersection of the central axis of the discharge chamber and the anode electrode jet end and the center point of the anode electrode jet end is L1, the length of the discharge chamber is L2, and the ratio of L1 to L2 is in the range of 1:8 to 1:6; By tilting the discharge chamber and cathode electrode relative to the central axis of the plasma jet drill bit body, the intersection of the central axis of the discharge chamber and the anode electrode jet end is offset from the center point of the anode electrode jet end. Combined with the motor's control of the rotation of the plasma jet drill bit body, during the drilling process, the plasma ejected from the anode nozzle rotates in a circle to form a dynamic jet, forming a circular ablation track on the rock surface, thereby increasing the rock breaking aperture. The drilling method comprises the following steps: A working medium is input into the discharge chamber, where it is ionized into plasma, which is then ejected through the anode nozzle to form an inclined jet. The motor drives the plasma jet drill bit body to rotate through the hollow shaft and conductive slip ring, causing the inclined jet to rotate in a circle to form a dynamic jet, forming a circular ablation track on the rock surface, achieving a rotary sweeping plasma jet to break the rock and increase the rock breaking aperture; The centrifugal force generated by the rotation of the plasma jet drill body will disperse the scattered heat load, causing the arc root attachment point to constantly jump and move, and unable to be fixed in a certain position, aggravating the ablation and extending the life of the anode nozzle; the inclined dynamic plasma jet can greatly reduce the jet back erosion and extend the life of the plasma drill bit; the rotation of the plasma jet drill body causes the plasma jet to form a dynamic jet. The dynamic jet avoids repeated heating of the melted magma in the crushing pit, reduces energy waste, and reduces the rock breaking specific energy. At the same time, the range of thermal stress action is expanded, increasing the growth of cracks inside the brittle rock.

2. The rotary sweeping plasma jet rock breaking and drilling method according to claim 1, characterized in that: The range of the tilt angle is 15° to 45°.

3. The rotary sweeping plasma jet rock breaking and drilling method according to claim 1, characterized in that: The discharge chamber comprises a first cylindrical channel, a frustum channel, and a second cylindrical channel coaxially connected in sequence, wherein the large end of the frustum channel is away from the anode nozzle and connected to the first cylindrical channel; The cathode electrode extends from the first cylindrical channel into the frustum channel.

4. The rotary sweeping plasma jet rock breaking and drilling method according to claim 1, wherein: The radial inner side of the anode base is insulated and connected to the cathode base via insulating ceramic in a ring structure.

5. The rotary sweeping plasma jet rock breaking and drilling method according to claim 1, characterized in that: A cooling cavity is provided inside the cathode electrode, and a cooling water channel and a return water channel connected to the cooling cavity are provided on the cathode base.

6. The rotary sweeping plasma jet rock breaking and drilling method according to claim 4, characterized in that: The insulating ceramic is provided with a gas channel connected to the discharge chamber.

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