A plasma drill bit with a cluster impact nozzle and a drilling method

Abstract

The invention discloses a plasma drill bit with a cluster impact nozzle and a drilling method, which belongs to the field of drilling engineering technology, and includes a drill bit body; the drill bit body includes a drill bit shell, an anode electrode is coaxially arranged inside the drill bit shell, an annular flow channel is formed between the drill bit shell and the anode electrode, and a cluster impact nozzle is arranged at the bottom end of the drill bit shell; a discharge chamber is arranged in the middle of the anode electrode; an anode base is arranged at the top of the anode electrode, the inside of the anode base is insulated and connected with the cathode base, and a cathode electrode is arranged at the lower end of the cathode base; a high-pressure medium flow channel is arranged on the anode base, and the top of the high-pressure medium flow channel is connected to a high-pressure medium pipe; a spiral groove is arranged on the outer wall of the cathode base, a working medium pipe connected to the spiral groove is arranged at the upper end of the cathode base, and an air film hole is arranged on the anode electrode. When the high-pressure gas is introduced into the present invention, the plasma jet is caused to spin with the vortex, the sweeping area is increased, and the diameter of the crushing pit generated can meet the requirements for the drill bit to enter.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling engineering, and in particular relates to a plasma drill bit with a cluster impact nozzle and a drilling method. Background Art

[0002] With the increasing demand for oil resources, the depth of drilling is also increasing, and the engineering difficulty of rock-breaking drilling is increasing. The traditional mechanical rock-breaking drilling technology has significantly different rock-breaking efficiency when facing different types of rocks, and the tool wear is serious, making it difficult to meet the demanding technical requirements. Plasma rock-breaking technology is a new drilling technology that uses the plasma jet generated by high-voltage ionization to melt and crush rocks. This technology is not affected by the hardness and strength of the rock, and does not require direct contact with the rock, avoiding tool wear. Therefore, it is a new drilling and rock-breaking technology that can replace mechanical rock-breaking technology.

[0003] Traditional plasma jets have high energy density and small diameter. The size of the crushing pits formed on the rock surface is limited, and the plasma drill cannot enter the wellbore. In addition, the plasma drill removes the rock by thermal melting. The molten magma generated accumulates at the bottom of the crushing pit, constantly absorbing the heat transmitted by the plasma jet, hindering the jet from further breaking the rock, reducing energy utilization, and limiting the improvement of rock breaking efficiency. Molten magma has high viscosity and poor fluidity. Traditional chip removal methods, such as gas chip removal and mud chip removal, easily cause the magma to solidify rapidly into a whole, making it impossible to discharge the magma from the well. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a plasma drill with a cluster impact nozzle.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A plasma drill bit with a clustered impact nozzle comprises a drill bit body;

[0007] The drill body comprises a drill shell in an annular structure, an anode electrode is coaxially arranged on the radial inner side of the drill shell, an annular flow channel with a bottom end blocked is formed between the drill shell and the anode electrode, and a plurality of cluster impact nozzles connected to the annular flow channel are evenly arranged along the circumferential direction at the bottom end of the drill shell;

[0008] A discharge chamber is provided in the middle of the anode electrode and penetrates in the axial direction;

[0009] An anode base is provided at the top of the anode electrode, a radially inner lower end of the anode base is fixedly connected to the top of the anode electrode, and a radially outer lower end of the anode base is fixedly connected to the top of the drill bit housing;

[0010] The radial inner side of the anode base is insulated and connected to the cathode base, and a cathode electrode extending downward into the discharge chamber is fixedly arranged at the lower end of the cathode base;

[0011] The anode base is provided with a high-pressure medium flow channel extending in the axial direction, the bottom end of the high-pressure medium flow channel is connected to the annular flow channel, and the top end of the high-pressure medium flow channel is connected to the high-pressure medium pipe;

[0012] A spiral groove is provided on the radial outer side wall of the cathode base, a working medium pipe connected to the spiral groove is provided at the upper end of the cathode base, and a lower end of the spiral groove is connected to the discharge chamber;

[0013] The anode electrode is provided with an air film hole for connecting the annular flow channel with the discharge chamber.

[0014] Preferably, 6 to 8 cluster impact nozzles are evenly arranged along the circumferential direction at the bottom end of the drill bit housing.

[0015] Preferably, the lower end of the discharge chamber is a gradually expanding divergent outlet.

[0016] Preferably, the upper portion of the divergent outlet is a cylindrical hole channel, and the upper portion of the cylindrical hole channel is a tapered inlet;

[0017] The cathode electrode extends into the tapered inlet.

[0018] Preferably, the wall surface of the divergent outlet is a frustum, and the angle between the generatrix of the wall surface of the divergent outlet and the central axis is 30° to 60°.

[0019] Preferably, the end of the air film hole connected to the annular flow channel is higher than the end connected to the discharge chamber.

[0020] Preferably, the angle between the central axis of the air film hole and the central axis of the anode electrode is 45°~75°.

[0021] Preferably, the radial inner side of the anode base is insulated and connected to the cathode base via insulating ceramic in a ring structure.

[0022] Preferably, a cooling cavity is provided inside the cathode electrode, and a cooling water pipe and a return water pipe connected to the cooling cavity are provided on the cathode base;

[0023] The bottom end of the return water pipe is located above the bottom end of the cooling water pipe.

[0024] The invention also provides a plasma drilling method with a cluster impact nozzle.

[0025] A plasma drilling method with a clustered impact nozzle is implemented based on a plasma drill bit with a clustered impact nozzle, comprising the following steps:

[0026] Step 1, closing the cluster impact nozzle;

[0027] The working medium is input through the working medium pipe, and the working medium is ionized into plasma in the discharge chamber;

[0028] High-pressure gas is input through the high-pressure medium pipe, and the high-pressure gas enters the discharge chamber along the high-pressure medium flow channel and the annular flow channel through the gas film hole;

[0029] The plasma current is controlled to gradually increase from the valley current to the peak current, and the high-pressure gas flow rate is gradually increased to the peak flow rate, so that the plasma in the discharge chamber forms a turbulent flow state. The turbulent plasma is ejected from the outlet of the discharge chamber onto the surface of the rock formation, causing thermal cracking and thermal melting of the rock, and producing rock cuttings and molten magma at the bottom of the well;

[0030] Step 2, opening the cluster impact nozzle;

[0031] Stop inputting high-pressure gas, input high-pressure foam fluid through the high-pressure medium pipe, and the high-pressure foam fluid is ejected along the high-pressure medium flow channel and the annular flow channel through the cluster impact nozzle;

[0032] Control the plasma current to a valley current, so that the plasma in the discharge chamber forms a laminar flow state;

[0033] The high-pressure foam fluid flow rate is controlled to gradually increase to the peak flow rate, and the cluster impact nozzle is used to spray and impact the molten magma, so that the molten magma is broken into small particles and cooled to form solid magma particles. The solid magma particles and rock debris are taken away from the annulus by the high-pressure foam fluid;

[0034] Repeat steps 1 and 2 to achieve continuous drilling operations with alternating plasma rock breaking and high-pressure foam fluid chip removal through pulse control of plasma, high-pressure gas, and high-pressure foam fluid.

[0035] The beneficial effects of the present invention are:

[0036] (1) When high-pressure gas is introduced into the present invention, it flows into the wall of the discharge chamber from the gas film hole through the pressure-holding effect to form a turbulent flow field, so that the plasma jet ejected from the discharge chamber outlet spins along with the vortex, increasing the scanning area, and the diameter of the crushing pit generated can meet the requirements for the entry of the drill bit.

[0037] (2) The present invention realizes continuous drilling operations of alternating plasma rock breaking and high-pressure foam fluid chip removal through pulse control of plasma, high-pressure gas and high-pressure foam fluid, that is, energy utilization is improved through timely discharge of magma.

[0038] (3) The plasma drill bit with a cluster impact nozzle of the present invention can remove magma and use high-pressure and high-speed foam fluid to break up the magma generated in the rock breaking process into small particles, which is convenient for the discharge of magma and improves the rock breaking efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0040] Figure 1 It is a schematic structural diagram of a plasma drill bit with a cluster impact nozzle according to the present invention;

[0041] Figure 2 It is a working principle diagram of a plasma drill bit with a cluster impact nozzle according to the present invention;

[0042] in:

[0043] 1-drill bit housing, 2-anode electrode, 3-annular flow channel, 4-bunching impact nozzle, 5-discharge chamber, 51-divergent outlet, 52-cylindrical hole channel, 53-converging inlet, 6-anode base, 7-cathode base, 8-cathode electrode, 81-cooling chamber, 9-high-pressure medium flow channel, 10-high-pressure medium pipe, 11-spiral groove, 12-working medium pipe, 13-air film hole, 14-insulating ceramic, 15-cooling water pipe, 16-return water pipe;

[0044] 101- rock debris, 102- molten magma, 103- turbulent plasma, 104- laminar plasma, 105- high-pressure foam fluid, 106- solid magma particles. DETAILED DESCRIPTION

[0045] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0046] 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, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0047] In the present invention, the directions or positional relationships indicated by terms such as "upper", "lower", "bottom", "top", etc. 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.

[0048] In the present invention, terms such as "connected" and "connection" should be understood in a broad sense, indicating that the connection can be fixed, integral or detachable; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meaning of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0049] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0050] Embodiment 1:

[0051] like Figure 1 As shown, a plasma drill bit with a clustered impact nozzle comprises a drill bit body;

[0052] The drill body comprises a drill housing 1 in an annular structure, an anode electrode 2 is coaxially arranged on the radial inner side of the drill housing 1, an annular flow channel 3 with a bottom end blocked is formed between the drill housing 1 and the anode electrode 2, and a plurality of cluster impact nozzles 4 connected to the annular flow channel 3 are evenly arranged at the bottom end of the drill housing 1 along the circumferential direction;

[0053] A discharge chamber 5 is provided in the middle of the anode electrode 2 and penetrates in the axial direction;

[0054] An anode base 6 is provided at the top of the anode electrode 2, a radially inner lower end of the anode base 6 is fixedly connected to the top of the anode electrode 2, and a radially outer lower end of the anode base 6 is fixedly connected to the top of the drill housing 1;

[0055] The radial inner side of the anode base 6 is insulated and connected to the cathode base 7, and a cathode electrode 8 extending downward into the discharge chamber 5 is fixedly disposed at the lower end of the cathode base 7;

[0056] The anode base 6 is provided with a high-pressure medium flow channel 9 extending in the axial direction, the bottom end of the high-pressure medium flow channel 9 is connected to the annular flow channel 3, and the top end of the high-pressure medium flow channel 9 is connected to the high-pressure medium pipe 10;

[0057] A spiral groove 11 is provided on the radial outer side wall of the cathode base 7, a working medium pipe 12 connected to the spiral groove 11 is provided at the upper end of the cathode base 7, and the lower end of the spiral groove 11 is connected to the discharge chamber 5;

[0058] The anode electrode 2 is provided with an air film hole 13 for connecting the annular flow channel 3 and the discharge chamber 5 .

[0059] Preferably, 6 to 8 cluster impact nozzles 4 are evenly arranged at the bottom end of the drill housing 1 along the circumferential direction. Specifically, the aperture of the cluster impact nozzle 4 is 3 to 5 mm.

[0060] Preferably, the lower end of the discharge chamber 5 is a gradually expanding divergent outlet 51 .

[0061] Preferably, the upper portion of the divergent outlet 51 is a cylindrical hole channel 52, and the upper portion of the cylindrical hole channel 52 is a tapered inlet 53;

[0062] The cathode electrode 8 extends into the tapered inlet 53 .

[0063] Specifically, the walls of the divergent outlet 51 and the tapered inlet 53 are both frustum surfaces, the upper small end of the divergent outlet 51 is connected to the lower end of the cylindrical hole channel 52 , and the upper end of the cylindrical hole channel 52 is connected to the lower large end of the tapered inlet 53 .

[0064] Preferably, the angle between the generatrix of the frustum of the divergent outlet 51 and the central axis is 30° to 60°.

[0065] Preferably, the end of the air film hole 13 connected to the annular flow channel 3 is higher than the end connected to the discharge chamber 5 .

[0066] Preferably, the angle between the central axis of the air film hole 13 and the central axis of the anode electrode 2 is 45°~75°. Specifically, the number of the air film holes 13 is 30~40, and the air film holes 13 are evenly distributed along the circumferential direction of the anode electrode 2.

[0067] Preferably, the radial inner side of the anode base 6 is insulated and connected to the cathode base 7 via an insulating ceramic 14 having a ring-shaped structure.

[0068] Preferably, a cooling cavity 81 is provided inside the cathode electrode 8, and a cooling water pipe 15 and a return water pipe 16 connected to the cooling cavity 81 are provided on the cathode base 7;

[0069] The bottom end of the water return pipe 16 is located above the bottom end of the cooling water pipe 15 .

[0070] Embodiment 2:

[0071] A plasma drilling method with a clustered impact nozzle is implemented based on the plasma drill bit with a clustered impact nozzle in Example 1, comprising the following steps:

[0072] Step 1, closing the cluster impact nozzle 4;

[0073] The working medium is input through the working medium pipe 12, and the working medium is ionized into plasma in the discharge chamber 5;

[0074] High-pressure gas is input through the high-pressure medium pipe 10, and the high-pressure gas enters the discharge chamber 5 along the high-pressure medium flow channel 9 and the annular flow channel 3 through the gas film hole 13;

[0075] The current of the plasma is controlled to gradually increase from the valley current to the peak current, and the high-pressure gas flow rate is gradually increased to the peak flow rate, so that the plasma in the discharge chamber 5 forms a turbulent flow state, and the turbulent plasma 103 is ejected onto the surface of the rock formation through the outlet of the discharge chamber 5, so that the rock undergoes thermal spallation and thermal melting, and rock cuttings 101 and molten magma 102 are generated at the bottom of the well;

[0076] Step 2, opening the cluster impact nozzle 4;

[0077] The input of high-pressure gas is stopped, and high-pressure foam fluid 105 is input through the high-pressure medium pipe 10. The high-pressure foam fluid 105 is ejected along the high-pressure medium flow channel 9 and the annular flow channel 3 through the cluster impact nozzle 4;

[0078] The plasma current is controlled to drop to a valley current, so that the plasma in the discharge chamber 5 forms a laminar flow state. The laminar plasma 104 can ensure continuous heat transfer to the rock formation with a low power output, so that the magma is in a low-viscosity flow state, and can also prevent the impact damage to the plasma power supply caused by continuous arcing and arc breaking;

[0079] The high-pressure foam fluid 105 is controlled to gradually increase its flow rate to a peak flow rate, and is sprayed by the cluster impact nozzle 4 to impact the molten magma 102, so that the molten magma 102 is broken into small particles, which are cooled to form solid magma particles 106, and the solid magma particles 106 and the rock debris 101 are taken away from the annulus by the high-pressure foam fluid 105;

[0080] Repeat steps 1 and 2 to achieve continuous drilling operations with alternating plasma rock breaking and high-pressure foam fluid chip removal through pulse control of plasma, high-pressure gas, and high-pressure foam fluid.

[0081] Specifically, Figure 2As shown, in the plasma rock breaking stage, the working medium is input through the working medium pipe 12, and the working medium is ionized into plasma in the discharge chamber 5; the cluster impact nozzle 4 is closed, and high-pressure gas is injected into the high-pressure medium pipe 10, and the high-pressure gas flows through the air film hole 13 into the discharge chamber 5 under the action of holding pressure, and forms a cold air protection layer on the wall of the discharge chamber 5; because the air film hole 13 is at an inclined angle, the high-pressure gas will form a turbulent flow field in the discharge chamber 5, causing the flow state of the plasma to become turbulent; the turbulent plasma 103 is sprayed onto the surface of the rock formation through the divergent outlet 51; under the action of the turbulent plasma 103, the rock undergoes thermal cracking and thermal melting, and rock cuttings 101 and molten magma 102 are generated at the bottom of the well;

[0082] After the plasma rock breaking stage, the chip removal stage begins; high-pressure foam fluid 105 is injected into the high-pressure medium pipe 10, and the cluster impact nozzle 4 is opened. Due to the small aperture of the air film hole 13, the high-pressure foam fluid 105 cannot enter the discharge chamber 5; at this stage, the plasma current enters the valley stage, the arc plasma length is shortened, and in the absence of the turbulent cold air layer on the wall of the discharge chamber 5, the arc plasma becomes laminar plasma 104 and is ejected from the divergent outlet 51; the laminar plasma 104 can ensure continuous heat transfer to the rock formation with a low-power output, so that the magma is in a low-viscosity flow state, and can also prevent The impact damage to the plasma power supply caused by continuous arcing and arc breaking is stopped; the high-pressure foam fluid 105 is sprayed by the cluster impact nozzle 4 at the front end of the drill bit to impact the molten magma 102; the molten magma 102 is broken into small particles and cooled to become solid magma particles 106; the solid magma particles 106 and the rock cuttings 101 are taken away from the annulus by the high-pressure foam fluid 105; at this time, a turbulent-laminar plasma adaptive switching cycle ends, and then the above steps are repeated to achieve continuous drilling operations with alternating plasma rock breaking and high-pressure foam fluid chip removal through pulse regulation of plasma, high-pressure gas and high-pressure foam fluid.

[0083] Although the above describes the specific implementation mode 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 creative work are still within the protection scope of the present invention.

Claims

1. A plasma drill bit with a cluster impact nozzle, comprising a drill bit body; characterized in that: The drill body comprises a drill shell in an annular structure, an anode electrode is coaxially arranged on the radial inner side of the drill shell, an annular flow channel with a bottom end blocked is formed between the drill shell and the anode electrode, and a plurality of cluster impact nozzles connected to the annular flow channel are evenly arranged along the circumferential direction at the bottom end of the drill shell; A discharge chamber is provided in the middle of the anode electrode and penetrates in the axial direction; An anode base is provided at the top of the anode electrode, a radially inner lower end of the anode base is fixedly connected to the top of the anode electrode, and a radially outer lower end of the anode base is fixedly connected to the top of the drill bit housing; The radial inner side of the anode base is insulated and connected to the cathode base, and a cathode electrode extending downward into the discharge chamber is fixedly arranged at the lower end of the cathode base; The anode base is provided with a high-pressure medium flow channel extending in the axial direction, the bottom end of the high-pressure medium flow channel is connected to the annular flow channel, and the top end of the high-pressure medium flow channel is connected to the high-pressure medium pipe; A spiral groove is provided on the radial outer side wall of the cathode base, a working medium pipe connected to the spiral groove is provided at the upper end of the cathode base, and a lower end of the spiral groove is connected to the discharge chamber; The anode electrode is provided with an air film hole for connecting the annular flow channel and the discharge chamber; In the plasma rock breaking stage, the working medium is input through the working medium pipe, and the working medium is ionized into plasma in the discharge chamber; the cluster impact nozzle is closed, and high-pressure gas is injected into the high-pressure medium pipe. Under the action of pressure holding, the high-pressure gas flows through the air film hole into the discharge chamber, and forms a cold air protective layer on the wall of the discharge chamber; due to the inclined angle of the air film hole, the high-pressure gas will form a turbulent flow field in the discharge chamber, causing the flow state of the plasma to become turbulent; the turbulent plasma is ejected onto the surface of the rock formation through the divergent outlet; under the action of the turbulent plasma, the rock undergoes thermal cracking and thermal melting, and rock cuttings and molten magma are produced at the bottom of the well; After the plasma rock breaking stage, the chip removal stage begins; high-pressure foam fluid is injected into the high-pressure medium pipe, and the cluster impact nozzle is opened. Due to the small aperture of the air film hole, the high-pressure foam fluid cannot enter the discharge chamber.

2. The plasma drill bit with a cluster impact nozzle according to claim 1, characterized in that: The bottom end of the drill bit housing is evenly provided with 6 to 8 cluster impact nozzles along the circumferential direction.

3. The plasma drill bit with a cluster impact nozzle according to claim 1, characterized in that: The lower end of the discharge chamber is a gradually expanding divergent outlet.

4. The plasma drill bit with a cluster impact nozzle according to claim 3, characterized in that: The upper part of the divergent outlet is a cylindrical hole channel, and the upper part of the cylindrical hole channel is a tapered inlet; The cathode electrode extends into the tapered inlet.

5. The plasma drill bit with a cluster impact nozzle according to claim 3, characterized in that: The wall surface of the divergent outlet is a frustum, and the angle between the generatrix of the wall surface of the divergent outlet and the central axis is 30° to 60°.

6. The plasma drill bit with a cluster impact nozzle according to claim 1, characterized in that: The end of the air film hole connected to the annular flow channel is higher than the end connected to the discharge chamber.

7. The plasma drill bit with a cluster impact nozzle according to claim 6, characterized in that: The angle between the central axis of the air film hole and the central axis of the anode electrode is 45°~75°.

8. The plasma drill bit with a cluster impact nozzle according to claim 1, characterized in that: The radial inner side of the anode base is insulated and connected to the cathode base via insulating ceramic in a ring structure.

9. The plasma drill bit with a cluster impact nozzle according to claim 1, characterized in that: A cooling cavity is arranged inside the cathode electrode, and a cooling water pipe and a return water pipe connected to the cooling cavity are arranged on the cathode base; The bottom end of the return water pipe is located above the bottom end of the cooling water pipe.

10. A plasma drilling method with a cluster impact nozzle, implemented based on the plasma drill bit with a cluster impact nozzle according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, closing the cluster impact nozzle; The working medium is input through the working medium pipe, and the working medium is ionized into plasma in the discharge chamber; High-pressure gas is input through the high-pressure medium pipe, and the high-pressure gas enters the discharge chamber along the high-pressure medium flow channel and the annular flow channel through the gas film hole; The plasma current is controlled to gradually increase from the valley current to the peak current, and the high-pressure gas flow rate is gradually increased to the peak flow rate, so that the plasma in the discharge chamber forms a turbulent flow state. The turbulent plasma is ejected from the outlet of the discharge chamber onto the surface of the rock formation, causing thermal cracking and thermal melting of the rock, and producing rock cuttings and molten magma at the bottom of the well; Step 2, opening the cluster impact nozzle; Stop inputting high-pressure gas, input high-pressure foam fluid through the high-pressure medium pipe, and the high-pressure foam fluid is ejected along the high-pressure medium flow channel and the annular flow channel through the cluster impact nozzle; Control the plasma current to a valley current, so that the plasma in the discharge chamber forms a laminar flow state; The high-pressure foam fluid flow rate is controlled to gradually increase to the peak flow rate, and the cluster impact nozzle is used to spray and impact the molten magma, so that the molten magma is broken into small particles and cooled to form solid magma particles. The solid magma particles and rock debris are taken away from the annulus by the high-pressure foam fluid; Repeat steps 1 and 2 to achieve continuous drilling operations with alternating plasma rock breaking and high-pressure foam fluid chip removal through pulse control of plasma, high-pressure gas, and high-pressure foam fluid.

Images