Rock burst drilling tool and rock burst rock blasting method

Abstract

The invention relates to the field of drilling engineering, in particular to a rock burst drilling tool and a rock burst rock blasting method. The rock burst drilling tool mainly comprises a bypass valve assembly, a liquid distribution valve assembly, a metal motor assembly, a torque limiter assembly, a transmission shaft assembly and a rock burst drill bit, the rock burst drilling tool is of an all-metal structure and is resistant to high temperature, and in the drilling process of a 10000-meter deep part, under the condition of high crustal stress, the rock burst drilling tool can work normally. According to the rock burst drilling tool, the crustal stress of the rock under the drill bit is periodically unloaded, the rock is induced to release energy, and the rock is subjected to tensile failure and rock burst, so that the rock breaking efficiency is improved, the deeper the well is, the larger the rock burst energy is, and the critical geothermal drilling becomes easier.

Description

Technical Field

[0001] The present invention relates to the field of drilling engineering, and more specifically, to a rock burst drilling tool and a rock bursting method. Background Art

[0002] Geothermal energy is gradually formed after the decay of the earth's molten lava and radioactive materials. It is clean, renewable, and very abundant. Moreover, the geothermal energy at a depth of 10,000 meters gradually tends to be evenly distributed, with a temperature of up to 200-500°C, which is very suitable for large-scale power generation. Critical geothermal energy is the key to replacing fossil fuels. Water is a supercritical fluid when the pressure exceeds 22 MPa and the temperature is higher than 374°C. Compared with non-supercritical power plants, power plants using supercritical water as a working fluid can extract up to 10 times more useful energy from each drop of water. At present, the parameters of the subcritical unit of a thermal power plant are to reach 538°C. Using critical geothermal energy to heat the power plant, according to the geothermal gradient of 3°C / 100 meters, critical geothermal drilling requires more than 18,000 meters.

[0003] Low-cost drilling of 10,000-meter geothermal and critical geothermal is the key to achieving carbon-free energy to replace fossil fuels. The high cost of geothermal development is almost included in the initial investment, especially the cost of drilling 10,000-meter deep wells, which accounts for more than half of the entire project. Conventional rotary drilling rock breaking methods and drilling tools cannot solve the problem of critical geothermal drilling.

[0004] First, for conventional drilling and rock-breaking methods, the deeper the well, the more difficult it is to drill. As the well depth increases, the rock in the deep formation becomes harder and harder, and at the same time, the plasticity becomes greater and greater, and the formation has poor drillability. During the drilling process of hard and brittle formations, the stick-slip phenomenon is more serious, accelerating the wear of the drill bit and even breaking the teeth. In addition, the higher the formation temperature, the greater the decrease in the hardness of the drill bit, the worse the wear resistance of the drill bit, and the greater the life of the drill bit; the wellbore structure size of ultra-deep wells is larger, the drilling efficiency is lower, and the mechanical drilling speed is slow. The problem of well deviation in deep wells is also becoming increasingly prominent. The deeper the well, the more difficult it is to drill, which seriously restricts the exploration and development process. New rock-breaking methods are urgently needed to significantly improve the rock-breaking efficiency.

[0005] Secondly, the existing downhole power tools are no longer applicable. The stator rubber of conventional screw drills is not resistant to high temperatures, and the working environment temperature is less than 120°C; even if the stator rubber is modified, it can only work in an environment below 180°C, and its life is very short. With the increase in drilling depth and the continuous increase in downhole temperature, when the bottom hole temperature is greater than 180°C, the temperature resistance limitations of elastic rubber cause screw drills to be unable to meet drilling needs. However, my country is currently trying to drill to a depth of more than 10,000 meters, and the predicted temperature is over 180°C, so there are no power drills available. The downhole temperature of critical geothermal wells reaches 600°C, and high-temperature resistant power drills are urgently needed.

[0006] In summary, with the advancement of global drilling technology and people's thirst for mineral resources, searching for deep earth resources has become an important direction for global prospecting. At present, worldwide, 10,000-meter deep drilling and critical geothermal development are still in the stage of experimental and demonstration projects, far from reaching the level of large-scale application. my country is trying to break through the 10,000-meter ultra-deep drilling, and has not yet carried out exploratory research on critical geothermal drilling. Therefore, it is necessary to develop rock burst drilling equipment and rock bursting methods for 10,000-meter deep drilling and critical geothermal development to solve the bottleneck of current critical geothermal drilling technology. Summary of the invention

[0007] The object of the present invention is to provide a rock burst drilling tool and a rock blasting method for solving the above problems.

[0008] In order to achieve these purposes and other advantages according to the present invention, a rock burst drilling tool is provided, including a bypass valve assembly, a metal motor assembly, a transmission shaft assembly and a rock burst drill bit arranged in sequence from top to bottom, the metal motor assembly including a shell, the bypass valve assembly is connected to the upper end of the shell, N metal motors with rotors connected in series are arranged in sequence from top to bottom in the shell, N ≥ 3, a liquid distribution valve assembly connected to the first metal motor is provided in the shell, a liquid inlet channel is provided between each metal motor and the shell, the liquid distribution valve assembly distributes drilling fluid evenly to each metal motor, the Nth metal motor is connected to the transmission shaft assembly through a torque limiter assembly, and the rock burst drill bit is connected to the transmission shaft assembly.

[0009] The beneficial effect of the present invention is that the rockburst drilling tool of the present invention adopts a liquid distribution valve assembly to evenly distribute the drilling fluid to each metal motor connected in series, thereby reducing the displacement of each motor, thereby greatly reducing the length of the single-stage rotor and reducing the output speed of the power tool to within the engineering technical requirements.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows:

[0011] Furthermore, the metal motor comprises a stator and a rotor, two adjacent stators are sealed and connected, the rotor is coaxially arranged in the stator with a cavity between the two, the upper and lower ends of the rotor are respectively provided with an upper seal and a lower seal corresponding to the cavity, two stator symmetrical holes are arranged on the inner side of the stator, a large sealing cylinder is vertically arranged in the stator symmetrical holes, two rotor symmetrical holes are arranged on the outer side of the rotor, a small sealing cylinder is vertically arranged in the rotor symmetrical holes, the large sealing cylinder and the small sealing cylinder separate the cavity into two independent high-pressure cavities and two low-pressure cavities, and the stator of each metal motor is The weighing holes and the symmetrical holes of the rotor are staggered along the circumferential direction. N groups of vertical slots are evenly distributed along the circumferential direction on the outer side of the first stator, and each group of vertical slots includes two vertical slots arranged oppositely. The outer side of the i-th stator is provided with N-(i-1) groups of vertical slots, i is a positive integer between 2 and N, and any vertical slot has a vertical slot connected to it above, so that N liquid inlet channels are formed between the shell and multiple stators, and multiple stator inner holes are evenly distributed vertically on the inner wall of the vertical slot at the bottom of each liquid inlet channel. The rotor is hollow inside, and is provided with multiple rotor inner holes that are equal to the number of stator inner holes and correspond one to one.

[0012] The beneficial effect of adopting the above further scheme is: in this further scheme, two adjacent stators are sealed and connected, so that each cavity is independent of each other, and the upper end openings of N liquid inlet channels are evenly distributed along the circumferential direction, corresponding to each metal motor respectively. The liquid distribution valve assembly evenly distributes the drilling fluid to each liquid inlet channel, and the drilling fluid in each liquid inlet channel enters the corresponding cavity from the multiple stator inner holes on the inner wall of the lowest vertical groove. Two large sealing cylinders and two small sealing cylinders are arranged between the rotor and the stator, and the cavity between the rotor and the stator is divided into a high-pressure chamber, a low-pressure chamber, a high-pressure chamber and a low-pressure chamber in sequence. The pressure of the drilling fluid in the high-pressure chamber is greater than the pressure of the drilling fluid in the low-pressure chamber, so that one side of the rotor is high pressure and the other side is low pressure, generating a torque that causes the rotor to rotate clockwise, and the drilling fluid in the cavity enters the interior of the rotor through the multiple rotor inner holes on the rotor, and finally falls into the rock burst drill bit and is discharged.

[0013] Furthermore, in the rock burst drilling tool, a spline sleeve and a sliding bearing are provided in sequence at the lower end of the lower seal, and the outer sides of the lower seal body, the spline sleeve and the sliding bearing are provided with connecting grooves corresponding to the liquid inlet channel, and the upper and lower stators are in contact with the lower seal body and the sliding bearing respectively, the upper rotor passes through the lower seal body downward, and the lower rotor passes through the sliding bearing upward and is connected to it, and the upper and lower rotors are connected by a spline sleeve.

[0014] The beneficial effect of adopting the above further solution is: in this further solution, connecting grooves corresponding to the liquid inlet channels are provided on the outer sides of the lower sealing body, the spline sleeve and the sliding bearing to ensure the penetration of each liquid inlet channel.

[0015] Furthermore, in the rock burst drilling tool described above, the liquid distribution valve assembly includes an upper valve plate and a lower valve body, the lower valve body is connected to the stator of the first metal motor, a stepped hole is coaxially provided on the lower valve body, the rotor of the first metal motor extends upward into the stepped hole and is rotatably fitted with the lower valve body, and 2N guide grooves are evenly distributed circumferentially on the lower valve body and vertically penetrate the lower valve body, and two opposite guide grooves form a group, and the N groups of guide grooves correspond one by one to the N groups of vertical grooves on the outside of the first stator. A baffle is provided on the upper valve plate, and the lower end of the upper valve plate extends into the stepped hole and is connected to the rotor of the first metal motor, and the baffle is slidably fitted with the upper end of the lower valve body. When the upper valve plate rotates with the rotor, the two blades can simultaneously seal any group of guide grooves.

[0016] The beneficial effect of adopting the above further scheme is: in this further scheme, there is a point in the rotor's rotation process, at which time multiple stator inner holes and multiple rotor inner holes correspond one to one, overlap on the same straight line, and the drilling fluid entering the cavity at the stator inner hole directly flows out from the rotor inner hole into the rotor, and the drilling fluid does not produce torque on the rotor, so this part of the drilling fluid is wasted. At this time, if the corresponding flow groove can be sealed, no drilling fluid will enter the liquid inlet channel, and the loss of this part of the drilling fluid can be avoided. When the drilling fluid drives the motor to rotate, the rotor drives the upper valve plate to rotate together, and the two blades on the upper valve plate successively seal each group of flow grooves during the rotation process, thereby periodically closing each group of flow grooves of the upper valve plate. It is ensured that when the blades seal the upper opening of a group of flow guide grooves, the multiple stator inner holes and multiple rotor inner holes of the corresponding metal motor are located on the same straight line and overlap. At this time, the flow guide grooves are closed, and the drilling fluid enters other metal motors through other flow guide groove holes on the lower valve body, thereby reducing the loss of drilling fluid.

[0017] Furthermore, in the rock burst drilling tool, an internal spline nut, a preload spring and a nut are provided in the stepped hole, the internal spline nut is connected to the rotor of the first metal motor, the upper valve plate slides through the internal spline nut, the nut is arranged at the lower end of the upper valve plate, and the preload spring is sleeved on the upper valve plate, and its two ends respectively contact with the internal spline nut and the nut.

[0018] The beneficial effect of adopting the above further scheme is: in this further scheme, by arranging a preload spring on the upper valve plate, the preload spring is compressed. Since the height of the internal spline nut is constant, the preload spring will exert a downward force on the nut and the upper valve plate, thereby ensuring that the two blades on the upper valve plate are tightly fitted with the upper end of the lower valve body during the sliding process, ensuring the sealing effect of the blade guide groove.

[0019] Furthermore, in the rock burst drilling tool, the torque limiter assembly includes a spline shaft, a spring, an overload actuator, a ball and a threaded shaft, the spline shaft is connected to the lower end of the Nth rotor, the threaded shaft and the spline shaft are tightly connected by the ball, the spring and the overload actuator are arranged on the spline shaft, and the spring applies a force toward the ball to the overload actuator.

[0020] The beneficial effect of adopting the above further scheme is: in this further scheme, the torque limiter connects the rotor and the transmission shaft, and its main function is overload protection: when the rock burst drill bit is stuck or mechanical failure occurs, causing the required torque to exceed the set value, the steel ball will leave the pit, causing slippage between the active end component and the driven end component, and when the overload situation disappears, the connection will be restored automatically to avoid damage and loss of equipment parts.

[0021] Furthermore, in the rockburst drilling tool, the transmission shaft assembly includes an outer shell and a core shaft, and an upper TC outer sleeve and a lower TC outer sleeve are respectively provided at the openings at the upper and lower ends of the outer shell. The core shaft is hollow inside, and it penetrates the outer shell and is respectively connected to the upper TC outer sleeve and the lower TC outer sleeve through the upper TC inner sleeve and the lower TC inner sleeve. The two ends of the core shaft are respectively connected to the torque limiter assembly and the rockburst drill bit, and a plurality of accommodating holes are evenly distributed along the circumferential direction at the lower end of the lower TC outer sleeve, and cylindrical rollers are arranged to roll in the accommodating holes.

[0022] The beneficial effect of adopting the above further scheme is: in this further scheme, the interior of the mandrel is hollow and connected with the interior of the rotor, and the drilling fluid inside the rotor flows through the interior of the mandrel and finally enters the rockburst drill bit. The upper end of the mandrel extends into the torque limiter and is fixed to it through the upper fixing nut, and its lower end is fixed to the lower TC inner sleeve through the lower fixing nut; end covers are respectively arranged at the lower end of the upper TC outer sleeve and the upper end of the lower fixing nut, and multiple inner rings and outer rings sleeved on the mandrel are arranged between the two end covers in an upper and lower staggered manner, and a spacer sleeve is sleeved on the inner ring.

[0023] Furthermore, in the rock burst drilling tool, the rock burst drill bit includes an annular drill bit, a core drill bit and a water eye nozzle. The annular drill bit is hollow inside, and its upper end corresponds to the lower end of the lower TC sleeve. The upper end of the annular drill bit is provided with an arc surface corresponding to multiple cylindrical rollers. The core drill bit can be slid up and down in the annular drill bit, and its upper end is connected to the lower end of the core shaft. The water eye nozzle is arranged on the core drill bit.

[0024] The beneficial effect of adopting the above further scheme is: in this further scheme, the core drill bit and the annular drill bit can slide up and down relatively to each other, and the core drill bit is connected to the core shaft and rotates therewith during the drilling process, thereby driving the annular drill bit to rotate together, and at the same time, high-frequency up and down reciprocating motion occurs between the annular drill bit and the core drill bit. Multiple arc surfaces at the upper end of the annular drill bit form a wave surface. During the rotation of the annular drill bit, the cylindrical roller at the lower end of the lower TC casing does not rotate. The upper end of the annular drill bit moves upward to the wave surface and contacts the multiple cylindrical rollers at the lower end of the lower TC casing. Controlled by the wave surface, when the annular drill bit moves downward, the drilling pressure gradually increases, and at the same time, the core drill bit moves upward, and the drilling pressure gradually unloads to zero; when the annular drill bit moves upward, the drilling pressure decreases rapidly and gradually unloads to zero, and at the same time, the core drill bit moves downward, and the drilling pressure gradually increases to the maximum value; during the drilling process, the annular drill bit and the core drill bit are unloaded alternately. When the annular drill bit has the maximum drilling pressure, the drilling pressure of the core drill bit is zero; when the drilling pressure of the core drill bit is the maximum and the drilling pressure of the annular drill bit is zero; when the drilling pressure unloading decreases, the rock follows and unloads rapidly. When unloading in one direction, the rock undergoes elastic bulging deformation, which manifests as tensile failure. The rock is resistant to compression but not to tension, and its tensile strength is only 1 / 8 of its compressive strength, making it easier to break. The deep rock is subjected to forces in three axes and six directions, storing a large amount of elastic strain energy. When the single-sided load is suddenly unloaded, after the unidirectional expansion deformation occurs, the stress in other directions will also be unloaded successively, accelerating the bulging deformation in the unidirectional unloading direction. The rock is instantly destroyed by the excess energy, causing rock bursts, making deep drilling easier. When the drilling pressure is unloaded, making the compression energy of the rock equal to the tensile failure energy, only destruction occurs; when the stress of the rock compression deformation is much greater than the tensile strength, the rock is quickly unloaded, and the rock undergoes tensile deformation, which is instantly destroyed. The stored excess elastic strain energy is released, causing rock bursts, making deep drilling easier. The annular drill bit and the core drill bit are connected by a keyway, and multiple strip grooves are evenly distributed along the circumference on the inner wall of the annular drill bit. Splines are set up to slide up and down in the strip grooves, and the splines are connected to the core drill bit, realizing the keyway connection between the annular drill bit and the core drill bit.

[0025] The present invention also provides another rockburst drilling tool, comprising a bypass valve assembly, a screw motor assembly, a universal shaft assembly, a transmission shaft assembly and a rockburst drill bit which are sequentially connected from top to bottom.

[0026] The beneficial effect of adopting the above further scheme is: in this further scheme, a screw motor assembly and a universal shaft assembly are used to replace the metal motor assembly and the torque limiter assembly, and the existing screw motor assembly is used as a power source to drive the rockburst drill bit to rotate, which is mainly used for speeding up conventional drilling at temperatures below 150°C.

[0027] The present invention also provides a rock blasting method, using a rock blasting drilling tool as described in any one of the above, comprising the following steps:

[0028] S1, drilling the rockburst drilling tool down to the bottom of the well, and connecting the bypass valve assembly to the drilling pump;

[0029] S2, start the drilling pump and inject high-pressure drilling fluid into the rockburst drilling tool. After the drilling fluid passes through the liquid distribution valve assembly, it is evenly distributed to the liquid inlet channels of each metal motor of the metal motor assembly. Each metal motor starts to rotate and drives the rockburst drill bit to rotate through the torque limiter assembly and the transmission shaft assembly. After the pump is turned on normally, record the displacement and pump pressure;

[0030] S3. Drill further down. After the rockburst drill bit contacts the bottom of the well, gradually increase the pressure, adjust to the expected mechanical drilling speed, and record the pump pressure.

[0031] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of a rockburst drilling tool according to an embodiment of the present invention;

[0033] Figure 2 for Figure 1 Sectional views at AA, BB, CC and DD;

[0034] Figure 3 is a schematic structural diagram of the metal motor of the present invention;

[0035] Figure 4 It is a structural schematic diagram of the stator according to the present invention;

[0036] Figure 5 is a cross-sectional view of the stator according to the present invention;

[0037] Figure 6 is a schematic structural diagram of the rotor according to the present invention;

[0038] Figure 7 is a cross-sectional view of the rotor according to the present invention;

[0039] Figure 8 is a cross-sectional view of the liquid dispensing valve assembly of the present invention;

[0040] Fig. 9 It is a structural schematic diagram of the upper valve plate of the present invention;

[0041] Fig.10 It is a structural schematic diagram of the lower valve body of the present invention;

[0042] Fig.11 A top view of the lower valve body of the present invention;

[0043] Fig.12 It is a schematic diagram of the connection between the torque limiter assembly, the transmission shaft assembly and the rock burst drill bit according to the present invention;

[0044] Fig.13 It is a three-dimensional structural schematic diagram of the contact state of the TC sleeve under the transmission shaft, the cylindrical roller and the upper end surface wave surface of the annular drill bit according to the present invention;

[0045] Fig.14 It is a structural schematic diagram of the rockburst drill bit of the present invention;

[0046] Fig.15 is a side view of the rockburst drill bit of the present invention;

[0047] Fig.16 It is a structural schematic diagram of the annular drill bit of the present invention;

[0048] Fig.17 It is a structural schematic diagram of the core drill bit of the present invention;

[0049] Fig.18 It is a schematic diagram of the connection between the annular drill bit and the core drill bit of the present invention;

[0050] Fig.19 It is a schematic structural diagram of a rockburst drilling tool according to another embodiment of the present invention.

[0051] Wherein, the reference numerals represent:

[0052] 1. Bypass valve assembly; 2. Liquid dispensing valve assembly; 201. Upper valve plate; 202. Lower valve body; 203. Internal spline nut; 204. Preload spring; 205. Nut; 3. Metal motor assembly; 301. Compression spring; 302. Upper seal; 303. Housing; 304. Stator; 305. Rotor; 306. Large sealing cylinder; 307. Small sealing cylinder; 308. Lower sealing body; 309. Spline sleeve; 310. Sliding bearing; 4. Torque limiter assembly; 401. Spline shaft; 402. Spring; 403. Overload action body; 404. Ball bearing ; 405, threaded shaft; 5, transmission shaft assembly; 501, upper fixing nut; 502, upper TC inner sleeve; 503, upper TC outer sleeve; 504, housing; 505, end cover; 506, outer spacer; 507, inner ring; 508, outer ring; 509, inner spacer; 510, support sleeve; 511, lower fixing nut; 512, lower TC inner sleeve; 513, lower TC outer sleeve; 514, cylindrical roller; 515, mandrel; 6, rock burst drill bit; 601, annular drill bit; 602, core drill bit; 603, water eye nozzle; 7, screw motor; 8, universal shaft assembly. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0054] It should be noted that, in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and 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 a limitation on the present invention.

[0055] like Figure 1 As shown, an embodiment of the present invention provides a rockburst drilling tool, comprising a bypass valve assembly, a metal motor assembly, a transmission shaft assembly and a rockburst drill bit which are arranged in sequence from top to bottom, the metal motor assembly comprising a shell, the bypass valve assembly is connected to the upper end of the shell, four metal motors with rotors connected in series are arranged in sequence from top to bottom in the shell, a liquid distribution valve assembly connected to the first metal motor is provided in the shell, a liquid inlet channel is provided between each metal motor and the shell, the liquid distribution valve assembly distributes the drilling fluid evenly to each metal motor, the fourth metal motor is connected to the transmission shaft assembly through a torque limiter assembly, and the rockburst drill bit is connected to the transmission shaft assembly.

[0056] Among them, Figure 3 As shown, the metal motor includes a compression spring, an upper seal, a stator, a rotor, a large sealing cylinder, a small sealing cylinder, a lower sealing body, a spline sleeve and a sliding bearing; sliding bearings and a lower sealing body are arranged on both sides of the stator, the inside of the stator is a rotor, and the lower sealing body supports the lower shaft of the first rotor; the first rotor is connected to the second rotor through a spline sleeve, and the second rotor is connected to the third rotor through a spline sleeve, and the third rotor is connected to the fourth rotor through a spline sleeve; the stator and the rotor, two adjacent stators are sealed and connected, the rotor is coaxially arranged in the stator and there is a cavity between the two, and the rotor structure is as shown in Figure 6-Figure 7 As shown, the upper and lower ends of the rotor are respectively provided with an upper seal and a lower seal corresponding to the cavity, such as Figure 2As shown, two stator symmetrical holes are provided on the inner side of the stator, and a large sealing cylinder is vertically provided in the stator symmetrical hole. Two rotor symmetrical holes are provided on the outer side of the rotor, and a small sealing cylinder is vertically provided in the rotor symmetrical hole. The large sealing cylinder and the small sealing cylinder divide the cavity into two independent high-pressure chambers and two low-pressure chambers. The stator symmetrical holes and the rotor symmetrical holes of each metal motor are staggered along the circumferential direction. Two adjacent stators are sealed and connected, so that each cavity is independent of each other. The upper openings of the eight liquid inlet channels are evenly distributed along the circumference and correspond to each metal motor. The liquid distribution valve assembly evenly distributes the drilling fluid to each liquid inlet channel. The drilling fluid in each liquid inlet channel enters the corresponding cavity from the multiple stator inner holes on the inner wall of the lowest vertical groove. Two large sealing cylinders and two small sealing cylinders are arranged between the rotor and the stator, and the cavity between the rotor and the stator is divided into a high-pressure chamber, a low-pressure chamber, a high-pressure chamber and a low-pressure chamber in sequence. The pressure of the drilling fluid in the high-pressure chamber is greater than the pressure of the drilling fluid in the low-pressure chamber, so that one side of the rotor is high pressure and the other side is low pressure, generating a torque that causes the rotor to rotate clockwise. The drilling fluid in the cavity enters the inside of the rotor through the multiple rotor inner holes on the rotor, and finally falls into the rock burst drill bit and is discharged. A spline sleeve and a sliding bearing are provided at the lower end of the lower seal in sequence. The outer sides of the lower seal body, the spline sleeve and the sliding bearing are provided with connecting grooves corresponding to the liquid inlet channel. The upper and lower stators are in contact with the lower seal body and the sliding bearing respectively. The upper rotor passes through the lower seal body downward, and the lower rotor passes through the sliding bearing upward and is connected to the sliding bearing. The upper and lower rotors are connected by a spline sleeve. The outer sides of the lower seal body, the spline sleeve and the sliding bearing are provided with connecting grooves corresponding to the liquid inlet channel to ensure the penetration of each liquid inlet channel.

[0057] like Figure 5 As shown in (1), the outer side of the first stator is evenly distributed with four groups of vertical slots along the circumferential direction, which are slot a1, slot b1, slot c1, slot d1, slot a2, slot b2, slot c2 and slot d2, respectively, wherein slot a1 and slot a2 are connected to the interior of the first stator through a plurality of stator inner holes; Figure 5 As shown in (2), three groups of vertical slots are arranged on the outer side of the second stator, namely slot b1, slot c1, slot d1, slot b2, slot c2 and slot d2, and slot b1 and slot b2 are connected to the inside of the second stator through a number of stator inner holes; Figure 5 As shown in (3), two groups of vertical slots are arranged along the circumferential direction on the outer side of the third stator, namely slot c1, slot d1, slot c2 and slot d2, and slot c1 and slot c2 are connected to the inside of the third stator through a number of stator inner holes; Figure 5As shown in (4), a group of vertical slots are arranged on the outside of the fourth stator, namely slot d1 and slot d2, which are connected to the inside of the fourth stator through a number of stator inner holes; the slots d1 and slot d2 on the four stators are located on the same straight line in the vertical direction, and after being connected, two liquid inlet channels of the fourth stator are formed. Similarly, after all the slots c1 and slot c2 are connected, two liquid inlet channels of the third stator are formed. After all the slots b1 and slot b2 are connected, two liquid inlet channels of the second stator are formed. Slot a1 and slot a2 form two liquid inlet channels of the first stator.

[0058] like Figure 8-Figure 11 As shown in the figure, the liquid dispensing valve assembly mainly includes an upper valve plate, a lower valve body, an internal spline nut, a preload spring and a nut. The upper part of the upper valve plate is a flow guide structure, the middle part is two symmetrical fan-shaped baffles, and the lower part is a central axis. The middle and lower parts of the central axis are splines and the end is a thread. The upper end face of the lower valve body is a porous structure, and the upper end face of the lower valve body is 8 fan-shaped liquid dispensing valve holes evenly distributed along the circumferential direction, as shown in the figure. Fig.11 As shown, they are hole A1, hole B1, hole C1, hole D1, hole A2, hole B2, hole C2, and hole D2 in sequence. Meanwhile, connecting grooves corresponding to the eight liquid distribution valve holes are evenly distributed on the outer side of the lower valve body, and the connecting grooves extend downward to the lower end of the lower valve body. The eight liquid distribution valve holes correspond to the eight vertical grooves on the first stator in a one-to-one manner. The liquid distribution valve holes are connected to the corresponding connecting grooves to form flow guide grooves. The flow guide grooves and the corresponding connecting grooves together constitute flow guide grooves. The flow guide grooves are connected to the corresponding vertical grooves, so that the groove a1 is connected to the hole A1, the groove b1 is connected to the hole B1, the groove c1 is connected to the hole C1, the groove d1 is connected to the hole D1, the groove a2 is connected to the hole A2, the groove b2 is connected to the hole B2, the groove c2 is connected to the hole C2, and the groove d2 is connected to the hole D2. A stepped hole is set in the center of the lower valve body, and the inner surface is made of hard alloy layer. The central axis of the upper valve plate passes through the central hole of the lower valve body and the internal spline nut. A preload spring is set on the central axis of the upper valve plate and is fixed on the central axis of the upper valve plate through a nut. The baffle of the upper valve plate fits tightly with the porous upper surface of the lower valve body. When the upper valve plate rotates with the rotor, the two blades can seal any group of diversion grooves at the same time.

[0059] In the above embodiment, there is a point in the rotation process of the rotor, at which time the multiple stator inner holes and the multiple rotor inner holes correspond to each other one by one, overlap on the same straight line, and the drilling fluid entering the cavity at the stator inner hole directly flows out from the rotor inner hole into the rotor, and the drilling fluid does not generate torque on the rotor, so this part of the drilling fluid is wasted. At this time, if the corresponding flow guide groove can be sealed, no drilling fluid will enter the liquid inlet channel, and the leakage of this part of the drilling fluid can be avoided. When the drilling fluid drives the motor to rotate, the rotor drives the upper valve plate to rotate together, and the two blades on the upper valve plate seal each group of flow guide grooves in turn during the rotation process, thereby periodically closing each group of flow guide grooves of the upper valve plate. It is ensured that when the blade seals the upper end opening of a group of flow guide grooves, the multiple stator inner holes and the multiple rotor inner holes of the corresponding metal motor are exactly located on the same straight line and overlap, and the flow guide groove is closed at this time, and the drilling fluid enters other metal motors through other flow guide groove holes on the lower valve body, thereby reducing the leakage of drilling fluid. Taking a 172mm four-stage metal motor as an example, the drilling fluid displacement is 32L / s, and the drilling fluid flow rate allocated to each stage of the metal motor is 8L / s, which is only 1 / 4 of the total flow rate. The output speed of the power tool is still 200 rpm, but the length of the single-stage rotor is only 750mm, and the output torque is more stable, thereby greatly improving the life of the rotor.

[0060] Preferably, as another embodiment of the present invention, Fig.12 As shown, the torque limiter assembly includes a spline shaft, a spring, an overload actuator, a ball and a threaded shaft. The spline shaft is connected to the lower end of the lowest rotor, the threaded shaft and the spline shaft are tightly connected by the ball, the spring and the overload actuator are arranged on the spline shaft, and the spring applies a force toward the ball to the overload actuator.

[0061] In the above embodiment, the torque limiter connects the rotor and the transmission shaft, and its main function is overload protection: when the rock burst drill bit is stuck or mechanical failure occurs, causing the required torque to exceed the set value, the steel ball will leave the pit, causing slippage between the active end component and the driven end component, that is, slippage between the rotor and the core shaft of the transmission shaft assembly. When the overload situation disappears, the connection is automatically restored to avoid damage and loss of equipment parts.

[0062] Preferably, as another embodiment of the present invention, Figure 13-14 As shown, the transmission shaft assembly includes a shell and a core shaft, and an upper TC outer sleeve and a lower TC outer sleeve are respectively provided at the openings at the upper and lower ends of the shell. The core shaft is hollow inside, penetrates the shell and is connected to the upper TC outer sleeve and the lower TC outer sleeve respectively through the upper TC inner sleeve and the lower TC inner sleeve. The two ends of the core shaft are respectively connected to the torque limiter assembly and the rock burst drill bit. The lower end of the lower TC outer sleeve has 18 accommodating holes evenly distributed along the circumferential direction, and cylindrical rollers are rolled in the accommodating holes to contact the upper wavy surface of the annular drill bit.

[0063] In the above embodiment, the interior of the mandrel is hollow and communicated with the interior of the rotor, and the drilling fluid in the rotor flows through the interior of the mandrel and finally enters the rockburst drill bit. The upper end of the mandrel extends into the torque limiter and is fixed to it through the upper fixing nut, and its lower end is fixed to the lower TC inner sleeve through the lower fixing nut; end covers are respectively arranged at the lower end of the upper TC outer sleeve and the upper end of the lower fixing nut, and a plurality of inner rings and outer rings sleeved on the mandrel are arranged between the two end covers in an upper and lower staggered manner, and a spacer sleeve is sleeved on the inner ring.

[0064] Preferably, as another embodiment of the present invention, Figure 14-18 As shown, the rock burst drill bit includes an annular drill bit, a core drill bit and a water nozzle. The annular drill bit is hollow inside, and its upper end corresponds to the lower end of the lower TC sleeve. The core drill bit is slidably arranged in the annular drill bit, and its upper end is connected to the lower end of the core shaft. The water nozzle is arranged on the core drill bit. The annular drill bit and the core drill bit are connected by a keyway. A plurality of strip grooves are evenly distributed along the circumference on the inner wall of the annular drill bit. A spline is arranged to slide up and down in the strip groove. The spline is connected to the core drill bit, so that the annular drill bit and the core drill bit are connected by a keyway.

[0065] The beneficial effect of adopting the above further scheme is: in this further scheme, the core drill bit and the annular drill bit can slide up and down relatively to each other, and the core drill bit is connected to the core shaft and rotates therewith during the drilling process, thereby driving the annular drill bit to rotate together, and at the same time, high-frequency up and down reciprocating motion occurs between the annular drill bit and the core drill bit. Multiple arc surfaces at the upper end of the annular drill bit form a wave surface. During the rotation of the annular drill bit, the cylindrical roller at the lower end of the lower TC casing does not rotate. The upper end of the annular drill bit moves upward to the wave surface and contacts the multiple cylindrical rollers at the lower end of the lower TC casing. Controlled by the wave surface, when the annular drill bit moves downward, the drilling pressure gradually increases, and at the same time, the core drill bit moves upward, and the drilling pressure gradually unloads to zero; when the annular drill bit moves upward, the drilling pressure decreases rapidly and gradually unloads to zero, and at the same time, the core drill bit moves downward, and the drilling pressure gradually increases to the maximum value; during the drilling process, the annular drill bit and the core drill bit are unloaded alternately. When the annular drill bit has the maximum drilling pressure, the drilling pressure of the core drill bit is zero; when the drilling pressure of the core drill bit is the maximum and the drilling pressure of the annular drill bit is zero; when the drilling pressure unloading decreases, the rock follows and unloads rapidly. When unloading in one direction, the rock undergoes elastic bulging deformation, which manifests as tensile failure. The rock is resistant to compression but not to tension, and its tensile strength is only 1 / 8 of its compressive strength, making it easier to break. Deep rocks are subjected to forces in three axes and six directions, storing a large amount of elastic strain energy. When the single-sided load is suddenly unloaded, after unidirectional expansion deformation occurs, stresses in other directions will also be unloaded successively, accelerating the bulging deformation in the direction of unidirectional unloading. The rock is instantly destroyed by the excess energy, causing rock bursts, making deep drilling easier. When the drilling pressure is unloaded, making the compression energy of the rock equal to the tensile failure energy, only damage occurs; when the stress of the rock compression deformation is much greater than the tensile strength, the rock is quickly unloaded, and the rock undergoes tensile deformation, which causes instantaneous destruction of the rock. The stored excess elastic strain energy is released, causing rock bursts, making deep drilling easier.

[0066] The present invention also provides a rock blasting method, which uses the above-mentioned rock blasting drilling tool and comprises the following steps:

[0067] Step 1: Set the motor output speed:

[0068] According to the rotor torque strength requirements, the single-stage rotor length is set within a certain range; then according to the rockburst drill bit's speed requirements, the motor stages are selected, and the liquid distribution valve assembly is used to evenly distribute the drilling fluid to each stage of the metal motor, reducing the displacement of each stage of the motor and reducing the speed of the power tool output to within the range required by engineering technology.

[0069] Step 2: Set the rockburst drill bit parameters:

[0070] The shorter the unloading time, the faster the compressive stress is converted into tensile stress, and the larger the peak value; the drill bit frequency is close to the natural frequency of the rock, and the formation absorbs the maximum external energy, so the alternating unloading frequency of the rockburst drill bit is set to above 40Hz; then according to the mechanical drilling speed requirements, the drill bit footage of each unloading is converted, and the amplitude of the up and down reciprocating motion of the annular drill bit and the core drill bit is set.

[0071] Step 3: Rockburst drilling operation:

[0072] Drilling the rockburst drilling tool down to the bottom of the well, and connecting the bypass valve assembly to the drilling pump;

[0073] Turn on the drilling pump and inject high-pressure drilling fluid into the rockburst drilling tool. After the drilling fluid passes through the distribution valve assembly, it is evenly distributed to the liquid inlet channels of each metal motor of the metal motor assembly. When the high-pressure drilling fluid enters the cavity between the stator and the rotor through the distribution valve assembly. The large sealing cylinder in the symmetrical groove of the stator and the small sealing cylinder in the symmetrical groove on the rotor divide the cavity between the stator and the rotor into four chambers, which are high-pressure chamber, low-pressure chamber, high-pressure chamber and low-pressure chamber respectively. One side of the rotor is high pressure and the other side is low pressure, which generates a torque that causes the rotor to rotate clockwise. The rotor transmits the torque to the core drill bit through the torque limiter assembly and the core shaft. The core drill bit transmits the torque to the annular drill bit through the keyway at the bottom of the annular drill bit, so that the annular drill bit and the core drill bit rotate synchronously. At the same time, the annular drill bit is controlled by the wave surface at the upper end of the annular drill bit during the rotation relative to the lower TC sleeve, and reciprocates up and down relative to the core drill bit in the axial direction;

[0074] Each metal motor starts to rotate and drives the rockburst drill bit to rotate through the torque limiter assembly and the drive shaft assembly. After the pump is turned on normally, the displacement and pump pressure are recorded;

[0075] Step 4: Rock blasting and rock drilling:

[0076] As the drill goes down further, after the rockburst drill bit touches the bottom of the well, the pressure is gradually increased, adjusted to the expected mechanical drilling speed, and the pump pressure is recorded.

[0077] During the drilling process, high-frequency up-and-down reciprocating motion occurs between the annular drill bit and the core drill bit. When the annular drill bit moves downward under the control of the wave surface, the drilling pressure gradually increases, while the core drill bit moves upward, and the drilling pressure gradually unloads to zero; when the annular drill bit moves upward, the drilling pressure decreases rapidly, and the drilling pressure gradually unloads to zero, while the core drill bit moves downward, and the drilling pressure gradually increases to the maximum value;

[0078] During the drilling process, the annular drill bit and the core drill bit are unloaded alternately. When the drilling pressure of the annular drill bit is at its maximum, the drilling pressure of the core drill bit is zero; when the drilling pressure of the core drill bit is at its maximum, the drilling pressure of the annular drill bit is zero;

[0079] When the drilling pressure is reduced, the rock will unload quickly. When unloading in one direction, the rock will undergo elastic bulging deformation, which is manifested as tensile failure. The rock is resistant to compression but not tension, and its tensile strength is only 1 / 8 of its compressive strength, making it easier to break. Deep rocks are subjected to forces in three axes and six directions, storing a large amount of elastic strain energy. When the single-sided load is suddenly unloaded, when expansion deformation occurs in one direction, stresses in other directions will also be unloaded successively, accelerating the bulging deformation in the direction of unidirectional unloading. The rock is instantly destroyed by the excess energy, causing rock bursts, making deep drilling easier.

[0080] When the drilling pressure is unloaded, making the compression energy of the rock equal to the tensile failure energy, only damage occurs; when the stress of the rock compression deformation is much greater than the tensile strength, the rock is quickly unloaded, the rock undergoes tensile deformation, the rock is instantly destroyed, the excess elastic strain energy stored is released, and rock burst occurs, making deep drilling easier.

[0081] Taking the design of rock blasting method at a well depth of 15,000 meters as an example, an 8 1 / 2 rock blasting drill bit is used, with a resonance frequency of 45 Hz, a rock density of 3.0, a mud density of 1.6, and a drilling pressure of 8 tons. That is, when the maximum drilling pressure of the annular drill bit is 8 tons, the drilling pressure of the core drill bit is zero; when the maximum drilling pressure of the annular drill bit is zero, the drilling pressure of the core drill bit is 8 tons.

[0082] The criterion for rock blasting is that the elastic strain energy released by the rock is greater than the energy required for the tensile failure of the rock, that is:

[0083] ΔE=(∫σ0dε-∫σ y dε-∫σ z dε)-∫σ L dε>0

[0084] Where ΔE is the energy released by rockburst; σ0 is the elastic strain energy stored in rock; σ y is the hydraulic energy generated by the drilling fluid; z is the pressure energy generated by the drill teeth; σ L The energy required to overcome tensile failure of rock.

[0085] After finishing, we get:

[0086] σ z <σ0-σ y -σ L

[0087] According to the design parameters: σ0=450MPa, σ y =240MPa,σ L =30MPa, substituting into the above formula, we get:

[0088] σ z <180(MPa)

[0089] Therefore, when the annular drill bit moves downward, the drilling pressure gradually increases, while the core drill bit moves upward, and the drilling pressure gradually unloads. When the compressive stress of the formation rock directly below the drill bit is less than 180MPa, the rock will release stress and rock burst will occur; when the core drill bit moves downward, the drilling pressure gradually increases to the maximum value, and when the annular drill bit moves upward, the drilling pressure decreases rapidly and the drilling pressure is unloaded. When the compressive stress of the drill bit on the formation rock is less than 180MPa, the rock will release stress and rock burst will occur. In short, during the 15,000-meter deep drilling process, the annular drill bit and the core drill bit are alternately unloaded, and rock burst will definitely occur. Moreover, the deeper the formation, the more elastic energy the rock stores, the greater the elastic energy released, and the easier it is to drill.

[0090] In summary, the present invention has the following advantages:

[0091] 1. The rockburst drilling tool is of all-metal structure, resistant to high temperature, with a good speed range, good matching with the rockburst drill bit, high efficiency, and large torque. It can be used for 10,000-meter deep wells and critical geothermal drilling.

[0092] On the one hand, downhole power drilling tools need to increase the mechanical penetration rate of the drill bit to reduce drilling costs. On the other hand, they need to be all-metal, high-temperature resistant, high-torque, and long-life to complete ultra-deep well drilling projects. In recent decades, there has been no breakthrough in the development of downhole power drilling tools. The widely used downhole power drilling tools are mainly screw drilling tools, whose stators are rubber parts with poor high-temperature resistance and cannot adapt to ultra-deep well high-temperature and high-pressure drilling; while turbine drilling tools have low efficiency, high pressure loss, high speed, and no suitable PDC drill bits. Traditional downhole power drilling tools are no longer able to adapt to ultra-deep wells and critical geothermal wells in terms of operability, reliability, and adaptability to the working environment. Now there are no power tools available for 10,000-meter drilling and critical geothermal drilling.

[0093] 2. Compared with conventional drilling methods, the deeper the well, the higher the elastic energy stored in the formation, the higher the efficiency of the rock blasting method, and the mechanical drilling speed is significantly improved, thereby greatly reducing the cost of drilling 10,000 meters.

[0094] Low-cost acquisition of supercritical geothermal energy is the key to achieving large-scale application of carbon-free energy. The deeper the well, the higher the cost of drilling. Efficient rock breaking technology is one of the important factors to improve rock breaking efficiency, reduce drilling time and safely and quickly reduce drilling costs; conventional drilling practice shows that if the drilling efficiency is doubled, the total drilling cost can be reduced by about 1 / 4. The quality of rock breaking efficiency directly determines the drilling speed and cost, and even determines the economic benefits of drilling projects. Improving drilling efficiency is the best way to reduce exploration and development costs.

[0095] For conventional drilling and rock breaking methods, the deeper the well, the more difficult it is to drill. As the well depth increases, the rock in the deep formation becomes harder and harder, and at the same time, the plasticity becomes greater and greater, and the formation has poor drillability. During the drilling process of hard and brittle formations, the stick-slip phenomenon is more serious, accelerating the wear of the drill bit and even breaking the teeth. In addition, the higher the formation temperature, the greater the decrease in the hardness of the drill bit, the worse the wear resistance of the drill bit, and the greater the decrease in the life of the drill bit; the wellbore structure size of ultra-deep wells is larger, the drilling efficiency is lower, and the mechanical drilling speed is slow. The problem of well deviation in deep wells is also becoming increasingly prominent. The deeper the well, the more difficult it is to drill, which seriously restricts the exploration and development process.

[0096] Rockburst is a common dynamic destructive phenomenon during the construction of deep underground projects. It often causes serious damage to the excavation face, equipment damage and casualties, and has become a global problem in the field of rock underground engineering and rock mechanics.

[0097] A large number of practices have shown that whether it is granite, sandstone, or shale, when the burial depth reaches a certain condition, sufficient elastic strain energy is stored in the rock mass, and rock burst is prone to occur. The conditions for rock burst are different in different projects, mainly because the strength of different rocks is different. In addition, the overlying strata are ever-changing, and the distribution of ground stress at the same burial depth is different. The strength of different rocks is different, and the critical depth of rock burst is different.

[0098] The mechanical mechanism of rockburst is extremely complex, and the research on rockburst theory is mostly at the hypothesis and experience stage. At present, most of the research focuses on the deep original rock stress field, the physical and mechanical properties of deep buried rock mass and its constitutive relationship, the prediction theory and method of rockburst incubation mechanism and its tendency, and the research on rock stratum control and support methods under high stress.

[0099] At present, this destruction process is still very unclear, and it is a challenging problem faced by rock mechanics researchers. It is even difficult to reach a consensus on the definition of rock burst. Currently, many research centers around the world are conducting research to explain the rock burst problem. Its progress will represent the development and major breakthrough of the discipline of rock mechanics.

[0100] Rockburst inducing conditions: Rockburst occurs under the following conditions:

[0101] (1) Internal factors: the rock mass stores a large amount of elastic strain energy;

[0102] Considering the three factors of elastic deformation energy E stored in the rock mass, drilling depth h and rock compressive strength σ, the formula for rock storage strain energy is established. It can be seen that different rock compressive strength and burial depth will store different elastic strain energy.

[0103] (2) Rockbursts must be induced by external factors, such as some additional loads.

[0104] The process of air drilling is a typical process of constantly inducing rock bursts: the drill bit opens new rock layers, the air density is low, the rock directly below the drill bit is suddenly unloaded in one direction, and the elastic strain energy is released, making it easier for the drill bit to break the rock, and the mechanical drilling speed is high. Air drilling is 3-10 times faster than conventional drilling machinery, but air drilling is only suitable for shallow layers, formations that do not produce water and do not contain hydrogen sulfide, and cannot be widely used, let alone for drilling 10,000 meters.

[0105] The rock blasting method refers to the process of medium-deep drilling. In the process, sufficient elastic strain energy is stored in the rock mass. Through the rock burst drilling tool, the local rock under the drill bit is stimulated to produce resonance. The ground stress near the drill bit is periodically unloaded, and tensile force is formed during the unloading rebound, which induces the rock to release energy, causing rock bursts and rapidly reducing the rock strength, thereby improving the rock breaking efficiency and making 10,000-meter drilling easier. It is a new method that is expected to significantly increase the mechanical drilling speed.

[0106] The principle of rock burst drilling is as follows: during the drilling process, the drilling fluid drives the rock burst power tool, so that high-frequency up and down reciprocating motion can occur between the annular drill bit and the core drill bit. When the core drill bit moves downward, the drilling pressure gradually increases, and at the same time the annular drill bit moves upward, and the drilling pressure gradually unloads to zero; when the core drill bit moves upward, the drilling pressure decreases rapidly, the rock is unloaded rapidly, and bulging deformation occurs. Since the tensile strength is only 1 / 8 of the compressive strength, these bulging areas quickly release the stored elastic strain energy. When the compression energy is equal to the tensile failure energy, only damage occurs; when the compression energy is greater than the tensile failure energy. For example, when the compressive stress is between the tensile strength and the compressive strength, the stress of the compressive deformation is much greater than the tensile strength, and when the rock is unloaded rapidly, the rock undergoes tensile deformation, the rock is instantly destroyed, and the stored excess elastic strain energy is released, resulting in rock burst. The energy stored in the rock mass is large enough, but the drilling pressure is not fully unloaded, and the critical condition for inducing rock burst cannot be reached, and the rock mass will not experience rock burst. Only when the one-way unloading is sufficient and the released energy is greater than the tensile failure energy, will the rock mass experience rock burst.

[0107] Rockburst undergoes a stress evolution process: it is subjected to stress in three axes and six directions, storing elastic strain energy. When unloaded in one direction, the rock undergoes elastic swelling deformation, which manifests as tensile failure. The rock is compressive but not tensile, and releases enough energy to make the tensile stress of the rock much greater than the tensile failure strength, causing the rock to explode.

[0108] Furthermore, under the three-way six-sided stress state, σ1 is suddenly unloaded in one direction. Assuming that the stresses σ2 and σ3 in the other two directions remain unchanged, expansion deformation occurs in the σ1 direction. At this time, the stresses in the three directions are unbalanced, and then the stresses σ2 and σ3 in the other two directions are successively unloaded, causing σ1 to recover to a certain extent and accelerating the bulging deformation in the σ1 direction. The above unloading process is then repeated until the elastic strains of the rocks in the three directions are completely released and a rock burst occurs.

[0109] According to the rock bursting theory, contrary to conventional drilling methods, during the drilling process, as the drilling depth increases, the higher the elastic strain energy stored in the formation, the easier it is to induce rock burst, the greater the elastic energy released, the more severe the rock burst, the easier it is to drill, the higher the mechanical drilling speed, and the lower the drilling cost.

[0110] In short, the critical geothermal drilling costs must be significantly reduced before it can become a practical resource with the same economic value as fossil energy.

[0111] 3. Rock burst drilling tools and rock blasting methods promote the energy revolution and change the world's economic and political landscape.

[0112] In September 2005, the U.S. Department of Energy established an 18-member assessment team to conduct a detailed assessment of the deep geothermal development system and the corresponding key technologies and economic feasibility. The team concluded that "whoever solves the economic problem of deep geothermal mining will seize the initiative in carbon-free energy and influence the world's energy and economic landscape."

[0113] Rock burst drilling tools and rock blasting methods are key technologies for achieving critical geothermal development. It is expected that low-cost drilling and production of critical geothermal energy will be achieved within 3-5 years, providing abundant and stable carbon-free energy for coal-fired thermal power plants.

[0114] Critical geothermal development is of strategic significance and will completely overturn the energy landscape. The era of fossil energy will soon be over. The energy that renewable energy sources such as hydropower, solar energy, and wind energy can provide to mankind will be extremely limited, and it will be difficult to replace the gap in fossil energy. The large-scale use of nuclear energy will also be subject to various restrictions. In the future, critical geothermal energy at a depth of 10,000 meters on the earth is a clean, carbon-free, abundant, widespread, safe, high-quality, and highly efficient renewable energy source. It is expected to become the main source of my country's basic load power generation capacity in 2050, and is the right direction to solve the long-term energy needs of mankind in the future.

[0115] (1) Critical geothermal resources are very abundant and extensive.

[0116] According to the calculation, the temperature of the earth's depth of 15,000 to 25,000 meters generally exceeds 374°C, and even reaches 700°C. Based on the calculated deep temperature results of my country's land area, the volume method is used to estimate the reserves of hot dry rock resources in my country's land area in the relevant GIS software. The potential of hot dry rock resources at a depth of 10km is calculated. The results are shown in Table 2. The reserves and distribution area of ​​hot dry rocks at a depth of 10,000 meters in my country's land area. It can be seen from the figure that the reserves of hot dry rocks at a depth of 10,000 meters between 9 and 10 km and the temperature between 150°C and 350°C are huge, about 5.3×1024J. Even if only 2% of its reserves are developed, 1.06×1023J of thermal energy will be obtained. It can be estimated that the total amount of hot dry rock resources at a depth of 10.0 to 20.0 km inland of my country is 5.3×1025J, totaling 180×105 billion tons of standard coal. According to the plan, my country's total energy consumption in 2025 will be 4.6 billion tons of standard coal. Calculated at 2% of the exploitable resources, it is equivalent to 390,000 times the total energy consumption planned for 2025.

[0117] (2) High energy utilization coefficient and power generation efficiency

[0118] Critical geothermal energy is thermal energy buried 10,000 meters deep. It is relatively stable and not easily affected by time and climate change. The energy utilization coefficient (or capacity factor) of geothermal energy is above 0.70, which is about 5 times that of photovoltaic power generation, 4 times that of wind power generation, and 1.5 times that of biomass power generation. Compared with wind power and photovoltaic power generation technologies, geothermal power generation technology has a high energy utilization coefficient. Critical geothermal directly provides critical state water for the generator set, and the power generation efficiency is high.

[0119] (3) Carbon-free energy generation, small environmental impact

[0120] Geothermal power generation causes almost no pollution to the environment, and is more competitive than hydropower generation, thermal power generation and other technologies. When the pressure pump presses water into the hot dry rock reservoir tens of thousands of meters underground, the formation temperature is close to 500°C, and the water will be heated and pressurized in the casing container to reach a critical state, and then input into the ground heat exchanger through the pipeline to drive the steam turbine generator to convert thermal energy into electrical energy. The hot water extracted by pipeline pressure can be input into the underground heat exchange again after doing work. The 10,000-meter geothermal power generation system will not produce industrial wastewater and waste gas generated by thermal power generation. It is a truly carbon-free energy source that can reduce greenhouse gas emissions and improve the ecological environment. Therefore, it is expected that China's 10,000-meter deep critical geothermal power generation will develop rapidly in the future, becoming an important force in optimizing the energy structure, responding to climate change, and winning the battle to protect the blue sky, and making greater contributions to high-quality green development and ecological civilization construction.

[0121] (4) my country's energy security will be completely resolved, and all demand parties in my country will be able to obtain clean energy more conveniently and at a lower cost, and will no longer be threatened by the security of international energy transportation lines;

[0122] Energy security has entered a critical period, and low-carbon transformation has entered an important window period. The 10,000-meter critical geothermal energy can be used as a baseload energy source, which is stable and flexible in operation and can provide a series of basic services to ensure the stability and flexibility of the national power grid.

[0124] (5) Comprehensively enhance my country’s international competitiveness and influence the international economic and political landscape.

[0125] Critical geothermal power generation does not require fuel in the later stage, and the daily maintenance cost is low. It is expected to significantly reduce the production and living costs of power generation, industry, transportation and life, thereby systematically improving my country's industrial competitiveness in the world. When conditions are ripe, it can provide carbon-free energy and carbon-free energy services to friendly neighboring countries around my country, which will not only increase international trade and promote economic prosperity, but also increase friendly exchanges with my country, creating a more friendly external environment for my country's development.

[0126] In short, global climate governance is entering a new phase, and the energy system and development model are entering a new stage dominated by non-fossil energy.

[0127] The embodiment of the present invention also provides another rock burst drilling tool, such as Fig.19 As shown, it includes a bypass valve assembly, a screw motor assembly, a universal shaft assembly, a transmission shaft assembly and a rock burst drill bit which are sequentially connected from top to bottom.

[0128] The beneficial effect of adopting the above further scheme is: in this further scheme, a screw motor assembly and a universal shaft assembly are used to replace the metal motor assembly and the torque limiter assembly, and the existing screw motor assembly is used as a power source to drive the rockburst drill bit to rotate, which is mainly used for speeding up conventional drilling at temperatures below 150°C.

[0129] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A rockburst drilling tool, characterized in that: The invention comprises a bypass valve assembly, a metal motor assembly, a transmission shaft assembly and a rockburst drill bit which are arranged in sequence from top to bottom. The metal motor assembly comprises a shell. The bypass valve assembly is connected to the upper end of the shell. N metal motors with rotors connected in series are arranged in sequence from top to bottom in the shell, where N is greater than or equal to 3. A liquid distribution valve assembly connected to the first metal motor is arranged in the shell. A liquid inlet channel is provided between each metal motor and the shell. The liquid distribution valve assembly distributes the drilling fluid evenly to each metal motor. The Nth metal motor is connected to the transmission shaft assembly through a torque limiter assembly, and the rockburst drill bit is connected to the transmission shaft assembly.

2. A rockburst drilling tool according to claim 1, characterized in that: The metal motor comprises a stator and a rotor, two adjacent stators are sealed and connected, the rotor is coaxially arranged in the stator with a cavity between the two, the upper and lower ends of the rotor are respectively provided with an upper seal and a lower seal corresponding to the cavity, two stator symmetrical holes are arranged on the inner side of the stator, a large sealing cylinder is vertically arranged in the stator symmetrical holes, two rotor symmetrical holes are arranged on the outer side of the rotor, a small sealing cylinder is vertically arranged in the rotor symmetrical holes, the large sealing cylinder and the small sealing cylinder divide the cavity into two independent high-pressure cavities and two low-pressure cavities, and the stator symmetrical holes and The symmetrical holes of the rotor are staggered along the circumferential direction. N groups of vertical slots are evenly distributed along the circumferential direction on the outer side of the first stator, and each group of vertical slots includes two vertical slots arranged opposite to each other. The outer side of the i-th stator is provided with N-(i-1) groups of vertical slots, i is a positive integer between 2 and N, and any vertical slot has a vertical slot connected to it above, so that N liquid inlet channels are formed between the shell and multiple stators, and multiple stator inner holes are evenly distributed vertically on the inner wall of the vertical slot at the bottom of each liquid inlet channel. The rotor is hollow inside, and is provided with multiple rotor inner holes that are equal in number to the stator inner holes and correspond one to one.

3. A rockburst drilling tool according to claim 2, characterized in that: A spline sleeve and a sliding bearing are provided at the lower end of the lower seal in sequence, and a connecting groove corresponding to the liquid inlet channel is provided on the outer sides of the lower seal body, the spline sleeve and the sliding bearing. The upper and lower stators are in contact with the lower seal body and the sliding bearing respectively, the upper rotor passes through the lower seal body downward, and the lower rotor passes through the sliding bearing upward and is connected to the sliding bearing, and the upper and lower rotors are connected by a spline sleeve.

4. A rockburst drilling tool according to claim 2, characterized in that: The liquid dispensing valve assembly includes an upper valve plate and a lower valve body. The lower valve body is connected to the stator of the first metal motor. A stepped hole is coaxially arranged on the lower valve body. The rotor of the first metal motor extends upward into the stepped hole and is rotatably fitted with the lower valve body. 2N flow guide grooves are evenly distributed along the circumference of the lower valve body and vertically penetrate the lower valve body. Two opposite flow guide grooves form a group. The N groups of flow guide grooves correspond one by one to the N groups of vertical grooves on the outer side of the first stator. A baffle is arranged on the upper valve plate. The lower end of the upper valve plate extends into the stepped hole and is connected to the rotor of the first metal motor. The baffle is slidably fitted with the upper end of the lower valve body. When the upper valve plate rotates with the rotor, the two blades can simultaneously seal any group of flow guide grooves.

5. A rockburst drilling tool according to claim 4, characterized in that: An internal spline nut, a preload spring and a nut are arranged in the stepped hole. The internal spline nut is connected to the rotor of the first metal motor. The upper valve plate slides through the internal spline nut. The nut is arranged at the lower end of the upper valve plate. The preload spring is sleeved on the upper valve plate, and its two ends respectively contact the internal spline nut and the nut.

6. A rockburst drilling tool according to claim 2, characterized in that: The torque limiter assembly includes a spline shaft, a spring, an overload actuator, a ball and a threaded shaft. The spline shaft is connected to the lower end of the Nth rotor, the threaded shaft and the spline shaft are tightly connected by the ball, the spring and the overload actuator are arranged on the spline shaft, and the spring applies a force toward the ball to the overload actuator.

7. A rockburst drilling tool according to claim 2, characterized in that: The transmission shaft assembly includes a shell and a core shaft. An upper TC outer sleeve and a lower TC outer sleeve are respectively provided at the openings at the upper and lower ends of the shell. The core shaft is hollow inside and passes through the shell and is respectively connected to the upper TC outer sleeve and the lower TC outer sleeve through the upper TC inner sleeve and the lower TC inner sleeve. The two ends of the core shaft are respectively connected to the torque limiter assembly and the rock burst drill bit. A plurality of accommodating holes are evenly distributed along the circumferential direction at the lower end of the lower TC outer sleeve, and cylindrical rollers are rolled in the accommodating holes.

8. A rockburst drilling tool according to claim 7, characterized in that: The rock burst drill bit comprises an annular drill bit, a core drill bit and a water eye nozzle. The annular drill bit is hollow inside, and its upper end corresponds to the lower end of the lower TC sleeve. The upper end of the annular drill bit is provided with an arc surface corresponding to a plurality of cylindrical rollers. The core drill bit is slidably arranged in the annular drill bit, and its upper end is connected to the lower end of the core shaft. The water eye nozzle is arranged on the core drill bit.

9. A rockburst drilling tool, characterized in that: The utility model comprises a bypass valve assembly, a screw motor assembly, a universal shaft assembly, a transmission shaft assembly and a rock burst drill bit which are sequentially connected from top to bottom.

10. A method for breaking rock by blasting, characterized in that: The following steps are involved: S1, drilling the rockburst drilling tool down to the bottom of the well, and connecting the bypass valve assembly to the drilling pump; S2, turn on the drilling pump, inject high-pressure drilling fluid into the rock burst drilling tool, the rock burst drilling tool starts to work, and the rock burst drill bit at its lower end rotates to perform rock breaking operations; wherein, when the rock burst drill bit rotates, the annular drill bit on it performs high-frequency up and down reciprocating motion relative to the core drill bit: when the annular drill bit moves downward relative to the core drill bit, the drilling pressure of the annular drill bit gradually increases, and the drilling pressure of the core drill bit gradually decreases, and when the drilling pressure of the annular drill bit is the maximum value, the drilling pressure of the core drill bit is zero; when the annular drill bit moves upward relative to the core drill bit, the drilling pressure of the annular drill bit gradually decreases, and the drilling pressure of the core drill bit gradually increases, and when the drilling pressure of the annular drill bit is zero, the drilling pressure of the core drill bit is the maximum value; after the pump is turned on normally, record the displacement and pump pressure; S3. Drill further down. After the rockburst drill bit contacts the bottom of the well, gradually increase the pressure, adjust to the expected mechanical drilling speed, and record the pump pressure.

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