Seabed shallow long horizontal section composite crushing cavity-building tool

Abstract

The invention discloses a composite crushing cavity-building tool for a long horizontal section of a seabed shallow layer. The device comprises an upper connector, a cavity-making spray head sliding core, an upper outer cylinder, a locking sliding sleeve I, a spring I, a lower outer cylinder, a bearing check block I, an overflowing bearing set I, a hydraulic turbine shaft, an overflowing bearing set II, a bearing check block II, a sealing bearing, a check block III, a lower connector, a composite drill bit, a flow channel plug, a spring II, a locking sliding sleeve II, a drilling spray head sliding core, a check block IV and the like. The drill bit is hydraulically driven to rotate and crush, and a regular borehole is formed; the gradual borehole expansion is realized, the abrasion of the drill bit is reduced, and the service life is prolonged; hydraulic crushing and mechanical crushing are fused, and the problem that the crushing and cavity-building efficiency is low due to the fact that a traditional crushing and cavity-building tool is single in crushing method is solved; self-locking opening of the hydraulic high-pressure jet nozzle is achieved, the problem that the stability of an existing high-pressure jet nozzle is prone to being affected by hydraulic parameters is solved, and the hydraulic high-pressure jet nozzle has the advantages of being low in energy consumption, high in working condition adaptability, high in operation safety and the like on the whole.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas hydrate exploitation and carbon dioxide storage, and in particular to a composite crushing and cavity-making tool with a long horizontal section in a shallow seabed. Background Art

[0002] Natural gas hydrate, also known as combustible ice, solid natural gas or gas ice, is an ice-like crystalline substance formed by the combination of natural gas (mainly methane) and water molecules under high pressure and low temperature conditions. It is regarded as an ideal clean energy source due to its huge reserves, high calorific value and low pollution characteristics. Due to its unique physical properties and huge energy potential, natural gas hydrate has become one of the focuses of global energy research today. At present, the common methods of natural gas hydrate extraction mainly include heat injection, pressure reduction and solid fluidization extraction. The common feature of these methods is that they need to drill large-sized wells to achieve efficient extraction of hydrates.

[0003] Deep-sea carbon dioxide hydrate carbon fixation technology is a technology that converts carbon dioxide into a solid hydrate form and stores it in the deep sea. The general operating procedure is to inject carbon dioxide into seabed sediments, and use the specific temperature and pressure conditions of the deep sea to allow carbon dioxide to form stable solid hydrates, thereby achieving long-term storage of carbon dioxide. The principle of this technology is similar to the formation mechanism of natural gas hydrates. In the deep-sea environment, gases such as methane will interact with water molecules, undergo hydration reactions, and then form hydrates. Similarly, carbon dioxide can also combine with water molecules to form hydrates when certain conditions are met. These carbon dioxide hydrates are relatively stable in deep-sea environments and can store carbon dioxide for a long time.

[0004] According to the investigation, the downhole crushing and cavity-making tools currently used for natural gas hydrate exploitation and carbon dioxide storage mainly include hydrate drill bits, umbrella tools, and pressure-controlled sliding sleeves. However, in actual applications, these tools are difficult to meet the requirements of efficient natural gas hydrate exploitation and carbon dioxide storage. At present, the crushing and cavity-making tools used for solid fluidization exploitation of natural gas hydrates and carbon dioxide storage have the following main deficiencies:

[0005] (1) Traditional hydrate drill bits mainly rely on a rotary drive or a top drive to drive the entire device to perform rotational operations. However, in actual applications, these two drive modes cannot effectively utilize fluid hydraulics during operation, which not only leads to excessive consumption and waste of energy, significantly increasing mining costs, but also affects the overall mining efficiency and carbon dioxide storage process, making it difficult to meet the needs of efficient and low-cost operations;

[0006] (2) In the process of natural gas hydrate extraction and carbon dioxide storage, traditional hydrate drill bits only have the function of drilling. Due to design and structural problems, it is difficult to form a regular wellbore. The irregular wellbore will limit the operating space of subsequent equipment underground, making it difficult to accurately lower, position and operate tools, increasing the probability of accidents such as drill sticking and well wall collapse.

[0007] (3) Traditional hydrate drill bits lack the function of progressive diameter expansion. During drilling, the force is highly concentrated, resulting in severe wear on the drill bit surface. This uneven and high-intensity wear continues to cause cumulative fatigue damage to the material, changing the material's organizational structure and mechanical properties. As the drilling operation continues, the cumulative fatigue damage continues to increase, ultimately resulting in a significant reduction in the service life of the drill bit.

[0008] (4) Existing downhole crushing and cavity-making tools for natural gas hydrate exploitation and carbon dioxide storage only use a single crushing method, without integrating hydraulic and mechanical crushing, resulting in low energy conversion efficiency and hindering exploitation and storage operations and technology development;

[0009] (5) Traditional downhole crushing and cavity making tools rely on hydraulic control to switch the jet nozzles. The stability is greatly affected by the hydraulic parameters. Maintaining the switch requires continuous high hydraulic pressure, which causes heavy load on the hydraulic system components and is prone to failure, endangering the reliability and stability of the system and hindering the crushing and cavity making operation process.

[0010] In summary, the existing downhole crushing and cavity-making tools for natural gas hydrate exploitation and carbon dioxide storage have many shortcomings. In order to ensure the efficiency and safety of shallow non-diagenetic natural gas hydrate exploitation and carbon dioxide storage operations on the seabed, it is urgent to invent a shallow long horizontal section composite crushing and cavity-making tool on the seabed, which combines hydraulic crushing with mechanical crushing, realizes variable pressure control locking sleeve self-locking opening and closing of high-pressure jet nozzle, and converts the linear momentum of water flow into rotational momentum through the turbine blade group on the hydraulic turbine shaft, thereby providing power support for the composite drill bit to rotate and gradually expand the wellbore size. Summary of the invention

[0011] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a composite crushing and cavitation tool for a long horizontal section in a shallow seabed. The present invention adopts a hydraulic turbine shaft to realize hydraulically driven drill bit rotation to crush hydrates, form and regularize wellbores, solve the problem of excessive energy consumption and waste of traditional hydrate drill bits and inability to regularize wellbores, reduce mining costs, and provide more ideal wellbore conditions for subsequent hydrate mining operations; the present invention adopts a progressive drill bit to realize progressive crushing to expand the wellbore size, solve the problem that traditional hydrate drill bits are subjected to concentrated force, severe wear, and easily cause cumulative fatigue damage during drilling, thereby greatly reducing the service life of the drill bit; the present invention combines hydraulic crushing and mechanical crushing methods to solve the problem that traditional crushing and cavitation tools have a single method for crushing hydrate layers, resulting in low crushing and cavitation efficiency; the present invention adopts a variable pressure control sliding sleeve self-locking method to achieve stable and controllable opening and closing of high-pressure jet nozzles, solves the problem that the stability of existing high-pressure jet nozzles is easily affected by hydraulic parameters, and improves the reliability of the entire device.

[0012] The purpose of the present invention is achieved through the following technical solutions: a composite crushing cavity making tool for a long horizontal section of a shallow seabed, characterized in that it includes an upper joint, a cavity making nozzle sliding core, an upper outer cylinder, a locking sliding sleeve I, a spring I, a lower outer cylinder, a bearing stopper I, a flow bearing group I, a hydraulic turbine shaft, a flow bearing group II, a bearing stopper II, a sealing bearing, a stopper III, a lower joint, a composite drill bit, a flow channel plug, a spring II, a locking sliding sleeve II, a drilling nozzle sliding core, and a stopper IV; the upper joint includes a limit The step, high-pressure jet nozzle, slide rail I, self-locking groove I, the cavity nozzle slide core includes a tapered mouth, a slider, and a self-locking convex block, the upper outer cylinder includes an internal thread and an external thread, the locking sliding sleeve I includes a strip-shaped inclined block and an annular groove, the lower outer cylinder includes a shaft shoulder, a limit step I, and a limit step II, the flow bearing group I includes a fluid channel, the hydraulic turbine shaft includes a water outlet, a turbine blade group, a water inlet, a step I, and a step II, the lower joint includes an internal thread, an external thread, a slide rail II, and a self-locking convex block. Locking groove II, positioning step, the composite drill bit includes a crushing wing, a jet nozzle, a jet hole, a spring groove, and a threaded hole. The upper joint is connected to the upper outer cylinder by a thread, the cavity nozzle sliding core is installed in the upper joint, the locking sliding sleeve I is installed outside the cavity nozzle sliding core, the spring I is installed between the locking sliding sleeve I and the upper outer cylinder, the lower outer cylinder is connected to the upper outer cylinder by a thread, the hydraulic turbine shaft is installed in the lower outer cylinder, the flow bearing group I is installed on the step I, the bearing stopper I is installed outside the flow bearing group I by a thread, the flow bearing group II is installed on the step II, the bearing stopper II is installed outside the flow bearing group II by a thread, the stopper IV is installed on the limit step I, the stopper III is installed on the limit step II by a thread, the sealing bearing is installed between the stopper III and the stopper IV, the lower joint is connected to the hydraulic turbine shaft by a thread, the composite drill bit is connected to the lower joint by a thread, the flow channel plug is matched with the threaded hole, and the spring II is installed in the spring groove.

[0013] The upper joint is provided with a limiting step, a high-pressure jet nozzle, a slide rail I and a self-locking groove I. The limiting step 101 is used for axial positioning of the cavity-making nozzle slide core. The high-pressure jet nozzle has circumferentially uniformly distributed injection holes. The slide rail I is used to install the slider. The self-locking groove I realizes self-locking of the locking sleeve I by limiting the strip-shaped inclined block.

[0014] The cavity-making nozzle slide core is provided with a slide block and a self-locking convex block. The slide block moves in the slide rail I. The self-locking convex block contacts the strip-shaped inclined block and pushes the locking slide sleeve I to move to realize self-locking opening and closing.

[0015] The lower outer cylinder is provided with a shaft shoulder, a limit step I and a limit step II, the shaft shoulder is used to realize the axial positioning of the flow bearing group, the limit step I is used to install the stopper III, and the limit step II is used to install the stopper.

[0016] The composite drill bit is provided with a crushing wing, a jet nozzle and a jet hole. The jet nozzle crushes the jet to form a pilot hole. The crushing wing and the jet hole gradually expand the wellbore size on the basis of the pilot hole, and the crushing wing rotates the regular wellbore.

[0017] The hydraulic turbine shaft is provided with step I, step II and a turbine blade group, wherein step I and step II are used to install flow bearing group I and flow bearing group II respectively, and the turbine blade group converts the linear momentum of water flow into rotational momentum to provide power for the rotation of the drill bit.

[0018] The lower joint is provided with a slide rail II, a self-locking groove II and a positioning step. The slide rail II is used for the axial movement of the drilling nozzle slide core. The self-locking groove II realizes self-locking by limiting the movement of the locking sliding sleeve II. The positioning step is used for installing and positioning the composite drill bit.

[0019] The locking sleeve II has a similar characteristic structure to the locking sleeve I, the drilling nozzle slide core has a similar characteristic structure to the cavity making nozzle slide core, and the flow bearing group II is the same as the flow bearing group I.

[0020] The aforementioned composite crushing and cavitation tool for shallow seabed with long horizontal section is characterized in that the method of use comprises the following steps:

[0021] SⅠ, drilling and expansion stage, specifically including the following steps:

[0022] Sa. Pilot hole drilling: Water flows through the jet nozzle at the front end of the composite drill bit to break up the shallow hydrate layer on the seabed and form a pilot hole;

[0023] Sb, progressive diameter expansion: The hydraulic turbine shaft converts the linear momentum of the water flow into rotational momentum, drives the composite drill bit to rotate mechanically to break, and the jet hole sprays hydraulically to break the hydrate layer. The breaking diameter of the breaking wing gradually increases, and the wellbore diameter is gradually expanded;

[0024] Sc, regular wellbore: The composite drill bit rotates to break the hydrate layer to form a wellbore, and the regular wellbore wall is rotated by the horizontal section of the breaking wing, which is conducive to the smooth running of the subsequent operation string;

[0025] SⅡ, the retrieval and cavity creation stage, specifically includes the following steps:

[0026] Sd, pressurized back dragging: After the drilling and expansion is completed, the water flow pressure is increased until the locking sleeve I is self-locked to open the high-pressure jet nozzle, the locking sleeve II is self-locked, the drilling nozzle slide core and the flow channel plug cooperate to close the front end jet nozzle of the composite drill bit, and the crushing cavity making tool is started to be back dragged;

[0027] Se. Crushing and cavity formation: High-pressure water flows through the jet holes evenly distributed around the high-pressure jet nozzle to scour the well wall to form a cavity;

[0028] Sf. Secondary crushing: During the pull-back stage, high-pressure water is sprayed through the jet holes on the composite drill bit to perform secondary crushing on the remaining larger rock particles, thereby improving the efficiency of subsequent fluidized mining operations.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The turbine blade group is used to convert the linear momentum of the water flow into rotational momentum, so that the hydraulically driven composite drill bit can be rotated to crush the hydrate layer and rock blocks, thereby improving the rock breaking efficiency and the secondary crushing and refining of the rock blocks.

[0031] (2) The composite drill bit is used to rotate the regular wellbore, providing more ideal wellbore conditions for subsequent operations such as hydrate extraction and carbon dioxide storage.

[0032] (3) It achieves progressive expansion of the wellbore, reduces drill bit wear, reduces accumulation of fatigue damage, and extends service life.

[0033] (4) It realizes the combination of hydraulic crushing and mechanical crushing, solving the problem that the traditional crushing and cavity making tools have a single method for crushing the hydrate layer, resulting in low crushing and cavity making efficiency.

[0034] (5) The variable pressure control sleeve self-locking opening and closing of the high-pressure jet nozzle is realized, which solves the problem that the stability of the existing high-pressure jet nozzle is easily affected by hydraulic parameters and improves the reliability of the entire device. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic cross-sectional view of a composite crushing and cavity-making tool for a long horizontal section in a shallow seabed according to the present invention;

[0036] Figure 2 It is a three-dimensional view and a half-section view of the upper joint of the present invention;

[0037] Figure 3 It is a front view and a half-section view of the slide core of the cavity-making nozzle of the present invention;

[0038] Figure 4 A three-dimensional diagram of the upper outer cylinder of the present invention;

[0039] Figure 5 A three-dimensional diagram of the locking sliding sleeve I of the present invention;

[0040] Figure 6 It is a three-dimensional diagram of the lower outer cylinder of the present invention;

[0041] Figure 7 A three-dimensional diagram of the flow bearing group I of the present invention;

[0042] Figure 8 A three-dimensional diagram of a hydraulic turbine shaft of the present invention;

[0043] Fig. 9 A half-section view of the lower joint of the present invention;

[0044] Fig.10 The three-dimensional view and half-section view of the composite drill bit of the present invention;

[0045] Fig.11 A half-section view of a long horizontal section composite crushing and cavitation tool for shallow seabed in the drilling stage of the present invention;

[0046] Fig.12 It is a half-section view of a long horizontal section composite crushing and cavity-making tool in shallow seabed of the present invention at the towing back stage.

[0047] In the figure: 1, upper joint; 101 limiting step, 102 high-pressure jet nozzle, 103 slide rail Ⅰ, 104 self-locking groove Ⅰ; 2, cavity nozzle slide core; 201 conical mouth, 202 slider, 203 self-locking convex block; 3, upper outer cylinder; 301 internal thread, 302 external thread; 4, locking sliding sleeve Ⅰ; 401 strip inclined block, 402 annular groove; 5, spring Ⅰ; 6, lower outer cylinder; 601 shaft shoulder, 602 limiting step Ⅰ, 603 limiting step Ⅱ; 7, bearing stopper Ⅰ; 8, flow bearing group Ⅰ; 801 fluid channel; 9, hydraulic turbine shaft; 901 water outlet, 902 turbine blade Plate group, 903 water inlet, 904 step I, 905 step II; 10, flow bearing group II; 11, bearing block II; 12, sealing bearing; 13, block III; 14, lower joint; 1401 internal thread, 1402 external thread, 1403 slide rail II, 1404 self-locking groove II, 1405 positioning step; 15, composite drill bit; 1501 crushing wing, 1502 jet nozzle, 1503 jet hole, 1504 spring groove, 1505 threaded hole; 16, flow channel plug; 17, spring II; 18, locking sleeve II; 19, drilling nozzle slide core; 20, block IV. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] like Figure 1-Figure 12A composite crushing and cavitation tool for shallow long horizontal sections of the seabed, comprising an upper joint 1, a cavity-making nozzle sliding core 2, an upper outer cylinder 3, a locking sliding sleeve Ⅰ4, a spring Ⅰ5, a lower outer cylinder 6, a bearing stopper Ⅰ7, a flow bearing group Ⅰ8, a hydraulic turbine shaft 9, a flow bearing group Ⅱ10, a bearing stopper Ⅱ11, a sealing bearing 12, a stopper Ⅲ13, a lower joint 14, a composite drill bit 15, a flow channel plug 16, a spring Ⅱ17, a locking sliding sleeve Ⅱ18, a drilling nozzle sliding core 19, and a stopper Ⅳ20; the upper joint 1 comprises a limiting step 101, a high-pressure jet nozzle 102, a slide rail Ⅰ103, and a self-locking groove Ⅰ104, the cavity-making nozzle sliding core 2 includes a tapered mouth 201, a slider 202, and a self-locking protrusion 203, the upper outer cylinder 3 includes an internal thread 301 and an external thread 302, the locking sliding sleeve I4 includes a strip-shaped inclined block 401 and an annular groove 402, the lower outer cylinder 6 includes a shaft shoulder 601, a limit step I602, and a limit step II603, the flow bearing group I8 includes a fluid channel 801, the hydraulic turbine shaft 9 includes a water outlet 901, a turbine blade group 902, a water inlet 903, a step I904, and a step II905, the lower joint 14 includes an internal thread 1401, an external thread 1402, a slide rail II1403, and a self-locking groove II1 404, positioning step 1405, the composite drill bit 15 includes a crushing wing 1501, a jet nozzle 1502, a jet hole 1503, a spring groove 1504, and a threaded hole 1505. The upper joint 1 is connected to the upper outer tube 3 by a thread, the cavity nozzle sliding core 2 is installed in the upper joint 1, the locking sliding sleeve I4 is installed outside the cavity nozzle sliding core 2, the spring I5 is installed between the locking sliding sleeve I4 and the upper outer tube 3, the lower outer tube 6 is connected to the upper outer tube 3 by a thread, the hydraulic turbine shaft 9 is installed in the lower outer tube 6, the flow bearing group I8 is installed on the step I904, and the bearing stopper I7 is screwed. The bearing block Ⅱ11 is installed outside the flow bearing group Ⅰ8 through a thread, the flow bearing group Ⅱ10 is installed on the step Ⅱ905, the bearing block Ⅱ11 is installed outside the flow bearing group Ⅱ10 through a thread, the block Ⅳ20 is installed on the limit step Ⅰ602, the block Ⅲ13 is installed on the limit step Ⅱ603 through a thread, the sealing bearing 12 is installed between the block Ⅲ13 and the block Ⅳ20, the lower joint 14 is connected to the hydraulic turbine shaft 9 through a thread, the composite drill bit 15 is connected to the lower joint 14 through a thread, the flow channel plug 16 is connected to the threaded hole 1505, and the spring Ⅱ17 is installed in the spring groove 1504.

[0053] The upper joint 1 is provided with a limiting step 101, a high-pressure jet nozzle 102, a slide rail Ⅰ103 and a self-locking groove Ⅰ104. The limiting step 101 is used for axial positioning of the cavity-making nozzle slide core 2. The high-pressure jet nozzle 102 has circumferentially uniformly distributed injection holes. The slide rail Ⅰ103 is used to install the slider 202. The self-locking groove Ⅰ104 realizes self-locking of the locking sleeve Ⅰ4 by limiting the strip-shaped inclined block 401.

[0054] The cavity-making nozzle slide core 2 is provided with a slider 202 and a self-locking protrusion 203. The slider 202 moves in the slide rail Ⅰ103. The self-locking protrusion 203 contacts the strip-shaped inclined block 401 to push the locking sliding sleeve Ⅰ4 to move to realize self-locking opening and closing.

[0055] The lower outer cylinder 6 is provided with a shaft shoulder 601, a limiting step I 602 and a limiting step II 603, wherein the shaft shoulder 601 is used to realize the axial positioning of the flow bearing group 13, the limiting step I 602 is used to install the stopper III 12, and the limiting step II 603 is used to install the stopper II 10.

[0056] The composite drill bit 15 is provided with a crushing wing 1501, a jet nozzle 1502 and a jet hole 1503. The jet nozzle 1502 performs jet crushing to form a pilot hole. The crushing wing 1501 and the jet hole 1503 gradually expand the borehole size on the basis of the pilot hole, and the crushing wing 1501 rotates a regular borehole.

[0057] The hydraulic turbine shaft 9 is provided with step I 904, step II 905 and turbine blade group 902. Step I 904 and step II 905 are used to install flow bearing group I 8 and flow bearing group II 10 respectively. The turbine blade group 902 converts the linear momentum of water flow into rotational momentum to provide power for the rotation of the drill bit.

[0058] The lower joint 14 is provided with a slide rail II 1403, a self-locking groove II 1404, and a positioning step 1405. The slide rail II 1403 is used for the axial movement of the drilling nozzle slide core 19. The self-locking groove II 1404 realizes self-locking by limiting the movement of the locking sliding sleeve II 18. The positioning step 1405 is used for installing and positioning the composite drill bit 15.

[0059] The locking sleeve II 18 has a similar characteristic structure to the locking sleeve I 4 , the drilling nozzle slide core 19 has a similar characteristic structure to the cavity nozzle slide core 2 , and the flow bearing group II 10 is the same as the flow bearing group I 8 .

[0060] The method for using the long horizontal section composite crushing and cavitation tool in shallow seabed comprises the following steps:

[0061] SⅠ, drilling and expansion stage, specifically including the following steps:

[0062] Sa, pilot hole drilling: water flows through the jet nozzle 1502 at the front end of the composite drill bit 15 to break up the shallow hydrate layer on the seabed and form a pilot hole;

[0063] Sb, progressive diameter expansion: the hydraulic turbine shaft 9 converts the linear momentum of the water flow into rotational momentum, drives the composite drill bit 15 to rotate for mechanical crushing, and the jet hole 1503 sprays hydraulically to crush the hydrate layer. The crushing diameter of the crushing wing 1501 gradually increases, and the wellbore diameter is gradually expanded;

[0064] Sc. Regular wellbore: The composite drill bit 15 rotates to break the hydrate layer to form a wellbore, and the regular wellbore wall is rotated by the horizontal section of the breaking wing 1501, which is conducive to the smooth running of the subsequent operation string;

[0065] SⅡ, the retrieval and cavity creation stage, specifically includes the following steps:

[0066] Sd, pressurized back-dragging: After the drilling and expansion is completed, the water flow pressure is increased until the locking sleeve I4 is self-locked to open the high-pressure jet nozzle 102, the locking sleeve II 18 is self-locked, the drilling nozzle slide core 19 and the flow channel plug 16 cooperate to close the front end jet nozzle 1502 of the composite drill bit 15, and the crushing cavity making tool is started to be back-dragged;

[0067] Se. Breaking and cavity formation: High-pressure water flows through the jet holes uniformly distributed on the circumference of the high-pressure jet nozzle 102 to scour the well wall to form a cavity;

[0068] Sf. Secondary crushing: In the pull-back stage, high-pressure water is sprayed through the jet holes 1503 on the composite drill bit 15 to perform secondary crushing on the remaining larger rock particles, thereby improving the efficiency of subsequent fluidized mining operations.

[0069] The working process of the present invention is as follows:

[0070] like Fig.11 During the drilling stage, a progressive expansion method is used, and the specific operation is as follows: First, the jet nozzle 1502 at the front end of the composite drill bit 15 is used to spray and crush the natural gas hydrate layer to form a pilot hole. Subsequently, the hydrate layer and rock blocks are mechanically and hydraulically crushed by the crushing wings 1501 and the circumferentially uniformly distributed jet holes 1503, and the crushing wings 1501 are used to achieve progressive expansion of the wellbore and rotate the regular wellbore to facilitate the subsequent operation of the pipe string; Fig.12In the pull-back stage, the specific operation is as follows: the hydraulic pressure rises to push the cavity-making nozzle slide core 2 and the drilling nozzle slide core 19 to move, the self-locking protrusion 203 on the cavity-making nozzle slide core 2 pushes the locking sliding sleeve Ⅰ4 to move, the locking sliding sleeve Ⅰ4 self-locks to maintain the stable opening of the high-pressure jet nozzle, and the self-locking protrusion on the drilling nozzle slide core 19 pushes the locking sliding sleeve Ⅱ18 to move until it is self-locked, and finally the drilling nozzle slide core 19 cooperates with the flow channel plug 16 to block the water flow through the front jet nozzle 1502 on the composite drill bit 15, so as to ensure the high-pressure jet crushing cavity. At this time, the high-pressure jet nozzle 102 jets and crushes the wellbore wall to make a cavity. At the same time, the water flows through the jet hole 1503 on the composite drill bit 15 to spray and crush the hydrate layer and larger hard rock particles. The work process of the present invention does not need to repeatedly lift the pipe string, improves the drilling and production efficiency of natural gas hydrates, reduces energy consumption, effectively reduces operating costs, and provides a reliable technical solution for the efficient and safe exploitation of natural gas hydrates.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that this patent can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A composite crushing and cavitation tool for shallow seabed with long horizontal sections, characterized by: It comprises an upper joint (1), a cavity-making nozzle sliding core (2), an upper outer cylinder (3), a locking sliding sleeve I (4), a spring I (5), a lower outer cylinder (6), a bearing stopper I (7), a flow bearing group I (8), a hydraulic turbine shaft (9), a flow bearing group II (10), a bearing stopper II (11), a sealing bearing (12), a stopper III (13), a lower joint (14), a composite drill bit (15), a flow channel plug (16), a spring II (17), a locking sliding sleeve II (18), a drilling nozzle sliding core (19), and a stopper IV (20); The upper joint (1) comprises a limiting step (101), a high-pressure jet nozzle (102), a slide rail I (103), and a self-locking groove I (104); The cavity-making nozzle sliding core (2) comprises a tapered opening (201), a sliding block (202), and a self-locking protrusion (203); the upper outer cylinder (3) comprises an internal thread (301) and an external thread (302); The locking sliding sleeve I (4) comprises a strip-shaped inclined block (401) and an annular groove (402); The lower outer cylinder (6) includes a shaft shoulder (601), a limit step I (602), and a limit step II (603); the flow bearing group I (8) includes a fluid channel (801); and the hydraulic turbine shaft (9) includes a water outlet (901), a turbine blade group (902), a water inlet (903), a step I (904), and a step II (905); The lower joint (14) comprises an internal thread (1401), an external thread (1402), a slide rail II (1403), a self-locking groove II (1404), and a positioning step (1405); The composite drill bit (15) comprises a crushing wing (1501), a jet nozzle (1502), a jet hole (1503), a spring groove (1504), and a threaded hole (1505); The upper joint (1) is connected to the upper outer cylinder (3) by means of threads, the cavity-making nozzle slide core (2) is installed in the upper joint (1), the locking sleeve I (4) is installed outside the cavity-making nozzle slide core (2), the spring I (5) is installed between the locking sleeve I (4) and the upper outer cylinder (3), the lower outer cylinder (6) is connected to the upper outer cylinder (3) by means of threads, the hydraulic turbine shaft (9) is installed in the lower outer cylinder (6), the flow bearing group I (8) is installed on the step I (904), the bearing stopper I (7) is installed outside the flow bearing group I (8) by means of threads, and the flow bearing group II (10) is installed on the step II (90 5), the bearing block II (11) is installed outside the flow bearing group II (10) by means of threads, the block IV (20) is installed on the limit step I (602), the block III (13) is installed on the limit step II (603) by means of threads, the sealing bearing (12) is installed between the block III (13) and the block IV (20), the lower joint (14) is connected to the hydraulic turbine shaft (9) by means of threads, the composite drill bit (15) is connected to the lower joint (14) by means of threads, the flow channel plug (16) is connected to the threaded hole (1505), and the spring II (17) is installed in the spring groove (1504).

2. A long horizontal section composite crushing and cavitation tool for shallow seabed according to claim 1, characterized in that: The upper joint (1) is provided with a limiting step (101), a high-pressure jet nozzle (102), a slide rail I (103) and a self-locking groove I (104); the limiting step (101) is used for axial positioning of the cavity-making nozzle slide core (2); the high-pressure jet nozzle (102) has circumferentially uniformly distributed injection holes; the slide rail I (103) is used for installing a slider (202); and the self-locking groove I (104) realizes self-locking of the locking sleeve I (4) by limiting the strip-shaped inclined block (401).

3. The long horizontal section composite crushing and cavitation tool for shallow seabed according to claim 1, characterized in that: The cavity-making nozzle slide core (2) is provided with a slider (202) and a self-locking protrusion (203); the slider (202) moves in the slide rail I (103); the self-locking protrusion (203) contacts the strip-shaped inclined block (401) to push the locking sliding sleeve I (4) to move, thereby realizing self-locking opening and closing.

4. The long horizontal section composite crushing and cavitation tool for shallow seabed according to claim 1, characterized in that: The lower outer cylinder (6) is provided with a shaft shoulder (601), a limiting step I (602) and a limiting step II (603), wherein the shaft shoulder (601) is used to realize the axial positioning of the flow bearing group (13), the limiting step I (602) is used to install the stopper III (12), and the limiting step II (603) is used to install the stopper II (10).

5. The long horizontal section composite crushing and cavitation tool for shallow seabed according to claim 1, characterized in that: The composite drill bit (15) is provided with a crushing wing (1501), a jet nozzle (1502) and a jet hole (1503); the jet nozzle (1502) crushes the jet to form a pilot hole; the crushing wing (1501) and the jet hole (1503) gradually expand the wellbore size on the basis of the pilot hole, and the crushing wing (1501) rotates the regular wellbore.

6. The long horizontal section composite crushing and cavitation tool for shallow seabed according to claim 1, characterized in that: The hydraulic turbine shaft (9) is provided with a step I (904), a step II (905) and a turbine blade group (902). The step I (904) and the step II (905) are used to install a flow bearing group I (8) and a flow bearing group II (10) respectively. The turbine blade group (902) converts the linear momentum of the water flow into rotational momentum to provide power for the rotation of the drill bit.

7. The long horizontal section composite crushing and cavitation tool for shallow seabed according to claim 1, characterized in that: The lower joint (14) is provided with a slide rail II (1403), a self-locking groove II (1404), and a positioning step (1405); the slide rail II (1403) is used for the axial movement of the drilling nozzle slide core (19); the self-locking groove II (1404) realizes self-locking by limiting the movement of the locking sliding sleeve II (18); and the positioning step (1405) is used for installing and positioning the composite drill bit (15).

8. The long horizontal section composite crushing and cavitation tool for shallow seabed according to claim 1, characterized in that: The locking sleeve II (18) has a similar characteristic structure to the locking sleeve I (4), the drilling nozzle slide core (19) has a similar characteristic structure to the cavity nozzle slide core (2), and the flow bearing group II (10) is the same as the flow bearing group I (8).

9. A long horizontal section composite crushing and cavitation tool for shallow seabed according to any one of claims 1 to 8, characterized in that: The method of use includes the following steps: SⅠ, drilling and expansion stage, specifically including the following steps: Sa, pilot hole drilling: water flows through the jet nozzle (1502) at the front end of the composite drill bit (15) to spray and break up the shallow hydrate layer on the seabed to form a pilot hole; Sb, progressive diameter expansion: the linear momentum of the water flow is converted into rotational momentum through the hydraulic turbine shaft (9), driving the composite drill bit (15) to rotate mechanically to break, and the jet hole (1503) sprays hydraulically to break the hydrate layer, and the breaking diameter of the breaking wing (1501) gradually increases, thereby gradually expanding the wellbore diameter; Sc. Regular wellbore: The composite drill bit (15) rotates to break the hydrate layer to form a wellbore, and the regular wellbore wall is rotated by the horizontal section of the breaking wing (1501), which is conducive to the smooth running of the subsequent operation string; SⅡ, the retrieval and cavity creation stage, specifically includes the following steps: Sd, pressurized back-pulling: After the drilling and expansion are completed, the water flow pressure is increased until the locking sleeve I (4) is self-locked to open the high-pressure jet nozzle (102), the locking sleeve II (18) is self-locked, the drilling nozzle slide core (19) and the flow channel plug (16) cooperate to close the front end jet nozzle (1502) of the composite drill bit (15), and the crushing cavity making tool is started to be back-pulled; Se. Breaking and cavity formation: high-pressure water flows through the high-pressure jet nozzle (102) through the jet holes evenly distributed on the circumference to scour the well wall to form a cavity; Sf. Secondary crushing: During the pull-back stage, high-pressure water is sprayed through the jet holes (1503) on the composite drill bit (15) to perform secondary crushing on the remaining larger rock particles, thereby improving the efficiency of subsequent fluidized mining operations.

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