Self-pressurization type rotary control head for vehicle-mounted drilling rig in coal mine area and drilling operation method

Abstract

The invention provides a self-pressurization type rotary control head for a vehicle-mounted drilling machine in a coal mine area and a drilling operation method. The rotary control head comprises a hanging ring, a gland, a rubber core, a rotary main shaft, an upper disc bearing, a lower disc bearing, a bearing shell, a lubricating grease injection port, a seal, a lower lubricating grease injection port, a three-way pipe fitting and a connecting flange. The method comprises the step that in the drilling operation process, connecting pipelines of the three-way pipe fitting are different according to different matched drilling technologies of a vehicle-mounted drilling machine in a coal mine area. The problems that the wellhead of the truck-mounted drilling rig in a coal mine area cannot be sealed and works under pressure are solved, the wellhead of the truck-mounted drilling rig has the functions of complete sealing, blowout prevention, pressure building, flow guiding and the like, the truck-mounted drilling rig can be matched with various advanced and efficient drilling technologies such as slurry drilling, underbalanced drilling and air drilling, the application range of the truck-mounted drilling rig is further expanded, and the application range of the truck-mounted drilling rig is expanded. The overall performance of the truck-mounted drilling rig is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of drilling, relates to a rotary control head, and particularly relates to a self-pressurized rotary control head for a vehicle-mounted drill rig in a coal mining area and a drilling operation method. Background Art

[0002] The fully hydraulic vehicle-mounted drill rig for ground drilling in a coal mining area is a drilling equipment that highly integrates a diesel engine, a drilling system, a hydraulic system, etc. on a special vehicle chassis. It has high integration and intelligence levels, a good operating environment, and strong construction capabilities, and is widely used in fields such as emergency rescue large-diameter holes in coal mining areas, coalbed methane horizontal wells, and water control directional wells. The rotary control head, also known as a rotary blowout preventer, is a dynamic sealing device used for air, mud, foam, and underbalanced drilling. It plays a sealing role between the wellbore annulus and the drill string and can provide safe and effective pressure control. At the same time, it has the function of guiding the wellbore return fluid away from the wellhead, and is an essential supporting equipment for the drilling operation of the vehicle-mounted drill rig in the coal mining area.

[0003] Currently, there are mainly two types of rotary control heads used at home and abroad. One type is the high-pressure rotary control head for oil drilling. This type of rotary control head has a high pressure level, mature technology, complete functions, and stable performance, and is widely used in various types of oil tower rigs. However, this type of rotary control head has a complex structure, large external dimensions, large weight, and high price. Due to space position limitations, it cannot be installed on the fully hydraulic vehicle-mounted drill rig for coal mining area drilling. The other type is the low-pressure control head developed for air DTH drilling in the geological exploration industry. Air DTH drilling breaks rocks in a high-frequency impact and slow rotation manner. The sealing method of this type of control head is mainly static sealing. The sealing rubber core is fixed on the housing and does not rotate with the drill pipe. The designed sealing pressure is low, the function is single, and the applicable range is small, and it cannot meet the multiple drilling processes required for the supporting of the fully hydraulic vehicle-mounted drill rig.

[0004] Currently, there is no multifunctional rotary control head for vehicle-mounted drill rigs in coal mining areas on the market, resulting in the following deficiencies in the construction of vehicle-mounted drill rigs: (1) During mud drilling, mud grooves and mud pits need to be dug around the drill rig, causing serious soil pollution, high labor intensity of workers, large consumption of mud materials, and difficult treatment of waste slurry; (2) During air drilling, a large amount of dust is ejected at high speed from the wellhead, causing serious environmental pollution, poor operating environment, and threatening the physical health of on-site construction workers; (3) Since rotary sealing cannot be achieved at the wellhead, the vehicle-mounted drill rig cannot adopt advanced and efficient underbalanced drilling technology; (4) During the treatment of drilling accidents, especially when drilling through a lost circulation formation, during the plugging process, due to the inability to build pressure at the wellhead, an efficient squeeze plugging process cannot be adopted, resulting in plugging failure. Summary of the Invention

[0005] Aiming at the defects and deficiencies existing in the prior art, the purpose of the present invention is to provide a self-pressurized rotary control head for a vehicle-mounted drill in a coal mining area and a drilling operation method, so as to solve the technical problems such as large safety hazards, serious environmental pollution, inability to apply some high-efficiency drilling processes, low drilling efficiency, and high drilling costs caused by the inability to seal under pressure at the wellhead during the operation of a fully hydraulic vehicle-mounted drill in a coal mining area.

[0006] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0007] A self-pressurized rotary control head for a vehicle-mounted drill in a coal mining area, comprising a three-way pipe fitting; the main body of the three-way pipe fitting is a hollow cylindrical structure, and the joint arranged along the radial direction on the outer wall of the main body of the three-way pipe fitting is a union joint; a connecting flange is fixedly arranged at the bottom end of the three-way pipe fitting, a bearing housing is installed at the top end of the three-way pipe fitting, and a bearing housing end cover is fixedly connected to the top end of the bearing housing; an upper disc bearing and a lower disc bearing are fixedly installed in the bearing housing, and a rotary main shaft is rotatably installed in the upper disc bearing and the lower disc bearing; the top of the rotary main shaft extends out of the bearing housing end cover, the bottom of the rotary main shaft extends into the three-way pipe fitting, and a set of seals is arranged between the outer wall of the rotary main shaft and the inner wall of the three-way pipe fitting; a rubber core is coaxially installed inside the top of the rotary main shaft, and the top end of the rubber core is flush with the top end of the rotary main shaft; a gland is coaxially installed on the top end of the rotary main shaft, the rotary main shaft and the gland are connected by a threaded structure, and the gland is in close contact with the top end of the rubber core.

[0008] The present invention also has the following technical features:

[0009] The rubber core is made of nitrile rubber. The rubber core is integrally provided with a large rubber core end and a small rubber core end from top to bottom. The large rubber core end is a hollow cylindrical structure; the small rubber core end is a hollow frustum structure, and its outer diameter gradually decreases from top to bottom; the cavity at the top of the rotary main shaft matches the shape of the rubber core.

[0010] Central holes are opened at the centers of the rotary main shaft, the rubber core and the gland. The central hole of the gland, the central hole of the rubber core, the central hole of the rotary main shaft, the inner cavity of the three-way pipe fitting and the central hole of the connecting flange are connected and communicate with each other to jointly form the inner cavity of the rotary control head.

[0011] A plurality of upper grease inlets are opened at the top of the bearing housing, and the plurality of upper grease inlets are evenly arranged along the circumferential direction. The horizontal plane where the upper grease inlets are located is close to the upper disc bearing; a plurality of lower grease inlets are opened at the top of the three-way pipe fitting, and the plurality of lower grease inlets are evenly arranged along the circumferential direction. The horizontal plane where the lower grease inlets are located is close to the seal.

[0012] A pair of lifting rings are fixedly arranged on the top surface of the gland.

[0013] The three-way pipe fitting described above is a high-pressure three-way; the connecting flange described above is a high-pressure flange; the high-pressure three-way, high-pressure flange, bearing housing, and bearing housing end cover are all made of alloy steel.

[0014] The seal described above is a V-shaped skeleton seal. The V-shaped skeleton seal and the rotating main shaft are designed with an interference fit, and the mating surface between the V-shaped skeleton seal and the rotating main shaft is lubricated with grease.

[0015] The upper disc bearing and the lower disc bearing described above are both tapered roller bearings, and the upper disc bearing and the lower disc bearing are arranged opposite to each other up and down.

[0016] The present invention also protects a drilling operation method using the self-pressurized rotary control head for a vehicle-mounted drill rig in a coal mining area as described above. During the drilling operation process of this method, according to different drilling technologies supporting the vehicle-mounted drill rig in the coal mining area, the connecting pipelines of the three-way pipe fitting are also different. Specifically: during the construction of a coalbed methane horizontal well, the three-way pipe fitting connects to a high-pressure pipeline; during air down-the-hole hammer drilling, the three-way pipe fitting connects to a low-pressure pipeline; during underbalanced drilling operation, it is ensured that the wellhead seal can realize normal drilling operation under the condition of wellbore pressure; during high-concentration bridge plugging operation, the three-way pipe fitting connects to a high-pressure gate valve.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] (Ⅰ) The self-pressurized rotary control head for a vehicle-mounted drill rig in a coal mining area of the present invention is composed of a rotary assembly and a fixed assembly, and includes a lifting ring, a gland, a rubber core, a rotating main shaft, an upper disc bearing, a lower disc bearing, a bearing housing, a grease injection port, a seal, a lower grease injection port, a three-way pipe fitting, and a connecting flange. The present invention solves the problems of the inability to seal the wellhead and pressure-bearing operation of the vehicle-mounted drill rig in the coal mining area, enables the wellhead of the vehicle-mounted drill rig to have functions such as complete sealing, blowout prevention, pressure holding, and diversion, realizes that the vehicle-mounted drill rig can be equipped with various advanced and efficient drilling technologies such as mud drilling, underbalanced drilling, and air drilling, further expands the applicable range of the vehicle-mounted drill rig, and improves the overall performance of the vehicle-mounted drill rig.

[0019] (Ⅱ) The self - pressurized rotary control head for vehicle - mounted drill rigs in coal mine areas of the present invention has strong pressure - bearing capacity and good rotary sealing effect. The gland and the rotary main shaft are connected by threads. The inner side of the upper part of the rotary main shaft is inverted - conical. By gradually tightening the threads, the rubber core is squeezed simultaneously from above and below, causing the lateral deformation of the rubber core to compensate for the wear of the rubber core and realizing self - pressurized sealing. A set of seals is designed at the lower part of the rotary main shaft, and the pressure - bearing capacity of the seals reaches 7 MPa, protecting the bearing assembly and realizing dust - proof sealing. The bearing assembly is designed as two sets of thrust roller bearings installed in opposite directions, solving the problem that the rotating parts repeatedly and alternately bear axial tension and compression, and realizing the high - speed and stable rotation of the control head. The self - pressurized rotary control head for vehicle - mounted drill rigs in coal mine areas produced according to the present invention has been continuously operated for 1295.50 h, and no damage has been found in the rotary assembly, no abnormal noise in the bearing group, and no leakage in the rotary seal.

[0020] (Ⅲ) The self - pressurized rotary control head for vehicle - mounted drill rigs in coal mine areas of the present invention has small external dimensions, light weight, and is convenient for installation, disassembly and maintenance, and is applicable to the vehicle - mounted drill rigs for coal mine area drilling existing in the current market. At present, the working platform height of imported and domestic vehicle - mounted drill rigs for coal mine area drilling in the market is about 1.5 m, and the maximum opening diameter of the platform is about 750 mm. The designed total height of the rotary control head of the present invention is 900 mm, the maximum outer diameter is 450 mm, and the weight is 350 kg. During the operation process, it can be hoisted integrally by the drill rig winch, directly passed through the working platform and lowered to the wellhead for installation. There is no need to rent a crane for installation on site, and the drill rig working platform does not need to be disassembled. The installation, disassembly and maintenance are simple and convenient, reducing the drilling auxiliary time and saving the drilling cost.

[0021] (Ⅳ) The self - pressurized rotary control head for vehicle - mounted drill rigs in coal mine areas of the present invention has complete functions and wide application range, and can meet the requirements of various advanced and efficient drilling process technologies such as air, mud, under - balanced and foam. In the construction of coal - bed methane horizontal wells, the rotary control head is used to hold back the pressure of the returned mud at the wellhead and send it to the solids control system, realizing that the mud does not land, reducing soil pollution, lowering the labor intensity, and saving mud materials. In air DTH drilling, the rotary control head is used to directly discharge a large amount of cuttings and dust returning from the well to the waste mud pit far away from the operation area, reducing environmental pollution, improving the operation environment, and ensuring the physical health of the staff. In under - balanced drilling operations, it ensures the wellhead seal and bears a certain pressure, realizing rotary sealing, so that the drilling operation can be carried out normally under the condition of wellhead pressure. In high - concentration bridge plugging operations, it realizes wellhead pressure holding and injection, ensuring that the plugging material is smoothly injected into the lost zone to achieve the plugging effect. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the overall structure of the self - pressurized rotary control head for vehicle - mounted drill rigs in coal mine areas.

[0023] The meanings of the reference numerals in the figure are as follows: 1 - three-way pipe fitting, 2 - connecting flange, 3 - bearing housing, 4 - bearing housing end cover, 5 - upper disc bearing, 6 - lower disc bearing, 7 - rotating main shaft, 8 - seal, 9 - rubber core, 10 - gland, 11 - upper grease injection port, 12 - lower grease injection port, 13 - lifting ring.

[0024] The technical solution of the present invention will be further described below in conjunction with embodiments. Specific embodiments

[0025] In the present invention, the meaning of "self-pressurized" is as follows: when the rubber core 9 is worn, the gland 10 is rotated to squeeze the rubber core 9 downward to ensure the sealed connection between the drill pipe and the rubber core 9. "Multi-functional" means that the designed rotary control head of the present invention can be used in a variety of drilling processes.

[0026] It should be noted that all the components used in the present invention are components known in the art without special instructions.

[0027] Following the above technical solution, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solution of the present application fall within the protection scope of the present invention.

[0028] Embodiment 1:

[0029] This embodiment provides a self-pressurized rotary control head for a vehicle-mounted drill in a coal mine area, as Figure 1 shown, including a three-way pipe fitting 1; the main body of the three-way pipe fitting 1 is a hollow cylindrical structure, and the fitting provided on the outer wall of the main body of the three-way pipe fitting 1 along the radial direction is a union fitting. The union fitting of the three-way pipe fitting 1 is used to connect a high-pressure pipeline, a low-pressure pipeline or a high-pressure gate valve.

[0030] In this embodiment, during the drilling operation, according to the different drilling technologies supported by the vehicle-mounted drill rig in the coal mining area, the connecting pipelines of the three-way pipe fitting 1 are also different: First, during the construction of a coalbed methane horizontal well, the three-way pipe fitting 1 is connected to the high-pressure pipeline to send the backflow pressure at the wellhead to the solids control system, realizing that the mud does not land, reducing the pollution of the well site, lowering the labor intensity, and saving mud materials; Second, during air DTH drilling, the three-way pipe fitting 1 is connected to the low-pressure pipeline to directly discharge a large amount of cuttings and dust returning from the well into the waste mud pit far away from the operation area, reducing environmental pollution, improving the operation environment, and ensuring the health of the staff; Third, during underbalanced drilling operation, ensure that the wellhead seal can realize normal drilling operation under the condition of wellbore pressure; Fourth, during high-concentration bridge plugging operation, the three-way pipe fitting 1 is connected to the high-pressure gate valve to realize wellhead pressure buildup and injection, ensuring that the plugging material is smoothly injected into the lost zone to achieve the plugging effect and realizing that the rotating control head has functions such as sealing, blowout prevention, pressure buildup, and diversion. By connecting different equipment and pipelines through the union joint of the three-way pipe fitting 1, it meets the requirements of various drilling technologies such as mud drilling, underbalanced drilling, and air drilling, and at the same time realizes safe, environmentally friendly, and efficient drilling.

[0031] As Figure 1 shown, a connecting flange 2 is fixedly arranged at the bottom end of the three-way pipe fitting 1, a bearing housing 3 is installed at the top end of the three-way pipe fitting 1, and a bearing housing end cover 4 is fixedly connected to the top end of the bearing housing 3; an upper disc bearing 5 and a lower disc bearing 6 are fixedly installed in the bearing housing 3, and a rotating main shaft 7 is rotatably installed in the upper disc bearing 5 and the lower disc bearing 6; the top of the rotating main shaft 7 extends outside the bearing housing end cover 4, the bottom of the rotating main shaft 7 extends into the three-way pipe fitting 1, and a set of seals 8 are arranged between the outer wall of the rotating main shaft 7 and the inner wall of the three-way pipe fitting 1; a rubber core 9 is coaxially installed inside the top of the rotating main shaft 7, and the top end of the rubber core 9 is flush with the top end of the rotating main shaft 7; a gland 10 is coaxially installed on the top end of the rotating main shaft 7, the rotating main shaft 7 and the gland 10 are connected by a threaded structure, and the gland 10 is in close contact with the top end of the rubber core 9.

[0032] In this embodiment, the three-way pipe fitting 1, the connecting flange 2, the seal 8, the bearing housing 3, four grease injection ports 12, and four lower grease injection ports 12 together form a fixed assembly. The characteristics of this fixed assembly are: compact structure and light weight; the height of the rotating control head formed with the rotating assembly is lower than the working platform of the vehicle-mounted drill rig, and the outer diameter is smaller than the maximum opening diameter of the platform.

[0033] In this embodiment, the upper disc bearing 5, the lower disc bearing 6, the rotating main shaft 7, the rubber core 9, the gland 10, the bearing assembly (including the bearing housing 3 and the bearing housing end cover 4), and the lifting ring 13 together form a rotating assembly, and the rotating main shaft 7 can rotate stably at high speed relative to the bearing housing 3; the characteristics of this rotating assembly are: small external dimensions, capable of passing through the wellhead round bushing, and realizing maintenance without pulling out the drill string.

[0034] As a specific solution of this embodiment, the rubber core 9 is made of nitrile rubber; the rubber core 9 is successively an integrally arranged large rubber core end part and a small rubber core end part from top to bottom. The large rubber core end part is a hollow cylindrical structure; the small rubber core end part is a hollow frustum structure, and its outer diameter gradually decreases from top to bottom; the cavity at the top of the rotating main shaft 7 matches the shape of the rubber core 9.

[0035] In this embodiment, during the drilling process, the forces on the rubber core 9 are intricate. It rotates at a high speed for a long time, and is simultaneously subjected to tensile and compressive forces in the axial and longitudinal directions in a staggered manner. The rubber core 9 is prone to wear, causing relative rotation among the drill pipe, the rubber core 9, and the rotating main shaft 7. Firstly, it affects the sealing effect and has low pressure resistance. Secondly, the high-frequency axial swing of the drill tool is likely to damage the entire rotary control head. To slow down the wear of the rubber core 9 and extend its service life, the present invention is optimized from two aspects: Firstly, the structure of the rubber core 9 is optimized and the material is preferably selected. The rubber core 9 is a conical nitrile rubber core, which has good elasticity, large fluidity, wear resistance, heat resistance, etc. Through the interference fit with the drill pipe and the extrusion with the inner side of the rotating main shaft 7, the sealing of the drill pipe is achieved; the inner diameter of the rubber core 9 is 10 - 15 mm smaller than the outer diameter of the matching drill pipe, and the outer taper of the rubber core 9 is designed to be the same as the taper of the rotating main shaft 7. By pressurizing, the clamping force between the rubber core 9 and the drill pipe and the adhesion force between the rubber core 9 and the rotating main shaft 7 are improved. Secondly, the gland 10 and the rotating main shaft 7 are designed to be threadedly connected. The upper part of the rotating main shaft 7 is an inverted cone. During use, as the rubber core 9 wears, by gradually rotating the gland 10 clockwise, the gland 10 moves downward and squeezes the upper end face of the rubber core 9. The deformation of the lower part of the rubber core is restricted, and the rubber core is simultaneously squeezed from top and bottom, so that the outer side of the rubber core 9 is squeezed, squeezing the drill pipe, achieving the sealing effect, and realizing the self-pressurizing seal with the rotating main shaft 7.

[0036] As a specific solution of this embodiment, central holes are provided at the centers of the rotating main shaft 7, the rubber core 9, and the gland 10. The central hole of the gland 10, the central hole of the rubber core 9, the central hole of the rotating main shaft 7, the inner cavity of the three-way pipe fitting 1, and the central hole of the connecting flange 2 are connected and communicate with each other to jointly form the inner cavity of the rotary control head. In this embodiment, the external fluid flows into the inner cavity of the rotary control head from the opening at the bottom end of the three-way pipe fitting 1, and then flows out from the opening of the union joint on the side wall of the three-way pipe fitting 1.

[0037] As a specific solution of this embodiment, a plurality of upper grease inlets 11 are provided on the top of the bearing housing 3, and the plurality of upper grease inlets 11 are uniformly arranged along the circumferential direction. The horizontal plane where the upper grease inlets 11 are located is close to the upper disc bearing 5. A plurality of lower grease inlets 12 are provided on the top of the tee fitting 1, and the plurality of lower grease inlets 12 are uniformly arranged along the circumferential direction. The horizontal plane where the lower grease inlets 12 are located is close to the seal 8. In this embodiment, during the drilling operation, the wellhead working conditions are poor. To reduce the failures of the rotary control head, the lower grease inlets 12 are designed. The number of both the upper grease inlets 11 and the lower grease inlets 12 is four. Lubricating oil is injected through the four upper grease inlets 11 and the four lower grease inlets 12 to improve the working environment of the bearing assembly and the seal 8, slow down the wear, extend the service life, and ensure the efficient and stable operation of the rotary control head.

[0038] As a specific solution of this embodiment, a pair of lifting rings 13 are fixedly arranged on the top surface of the gland 10. In this embodiment, the lifting rings 13 are used to lift the rotary control head from the wellhead.

[0039] As a specific solution of this embodiment, the tee fitting 1 is a high-pressure tee; the connecting flange 2 is a high-pressure flange; the high-pressure tee, the high-pressure flange, the bearing housing 3, and the bearing housing end cover 4 are all made of alloy steel, with high rigidity and strong load-bearing capacity.

[0040] As a specific solution of this embodiment, the seal 8 is a V-shaped skeleton seal. The V-shaped skeleton seal and the rotary main shaft 7 are designed to have an interference fit, and the mating surface of the V-shaped skeleton seal and the rotary main shaft 7 is lubricated with grease. In this embodiment, during the drilling operation, a large amount of mud, cuttings, dust and other pasty substances are returned from the wellhead. If these pasty substances enter the bearing assembly, the wear of the upper disc bearing 5 and the lower disc bearing 6 will be accelerated, affecting the service life of the entire rotary control head. To ensure that the bearing assembly is not damaged by the mud, cuttings, and dust returned from the wellhead and extend the service life of the upper disc bearing 5 and the lower disc bearing 6, the present invention designs a group of V-shaped skeleton seals with a sealing capacity of 7 MPa, which can effectively prevent mud and dust from entering the bearing assembly and causing bearing damage, meet the sealing pressure required for various matching processes of the vehicle-mounted drill in the coal mining area, and achieve dust-proof sealing.

[0041] As a specific solution of this embodiment, both the upper disc bearing 5 and the lower disc bearing 6 are tapered roller bearings, and the upper disc bearing 5 and the lower disc bearing 6 are arranged opposite to each other up and down (i.e., installed in reverse). In this embodiment, the drilling operation includes processes such as normal drilling, tripping, and reaming circulation. During the operation process, the force states of the upper disc bearing 5 and the lower disc bearing 6 are complex, and they are repeatedly and alternately subjected to tension and compression. At the same time, they also need to have the function of self-aligning and coaxial. In this embodiment, the advantages of designing the bearings as tapered roller bearings are as follows: First, it can bear a large combined axial load; second, it has a large axial load-bearing capacity; third, the limiting speed can meet the high-speed requirements of the drilling rig. The advantage of installing the two bearings in reverse is that during the drilling operation, when the drill string moves upward, the lower disc bearing 6 transmits the axial tension to the bearing housing 3, and when the drill string moves downward, the upper disc bearing 5 transmits the axial pressure to the bearing housing 3, solving the problems of axial compression and tension in the rotating part and realizing the high-speed and stable rotation of the control head.

[0042] Embodiment 2:

[0043] This embodiment provides a drilling operation method, which is realized by using the self-pressurized rotary control head for a vehicle-mounted drilling rig in a coal mining area in Embodiment 1; the method specifically includes the following steps:

[0044] Step 1, during the drilling operation, after the installation of the surface casing or the hole opening pipe in the first stage is completed, a bottom flange with the same structural dimensions as the connecting flange 2 is welded to the top end of the surface casing or the hole opening pipe in the first stage. When welding, a carbon dioxide shielded welding machine and high-strength welding wires are used to ensure the welding quality.

[0045] Step 2, before starting the second stage of drilling, assemble the rotary control head in advance. In the axial direction of the rotary control head, from top to bottom in sequence are: gland 10, rotary main shaft 7, bearing assembly, bearing housing 3, fixed assembly (including seal 8, tee fitting 1, connecting flange 2). Considering that the drill bit needs to be lowered to the bottom of the well before starting drilling, the rubber core 9 is not installed here temporarily, and all other components are installed normally.

[0046] Step 3, use the auxiliary winch of the vehicle-mounted drilling rig to lift the rotary control head through the lifting ring 13, and directly lower it through the wellhead platform of the vehicle-mounted drilling rig to a position 5 cm away from the surface casing hole flange in the first stage. Manually assist in rotating the rotary control head to align the threaded holes of the connecting flange 2 with the threaded holes of the hole flange, install the sealing ring, and at the same time fix the rotary control head with high-strength bolts.

[0047] Step 4, connect the gland 10 and the rotary main shaft 7 by thread. To ensure that the drill bit can pass through the rotary control head smoothly and facilitate the installation of the rubber core 9 in the later stage, disassemble the gland 10 from the rotary control head and place it near the wellhead.

[0048] Step Five: Connect the drill string and the drill bit and start lowering the drill. Pass the drill bit through the central hole of the rotary main shaft 7 and lower it into the hole. Connect drill pipes in accordance with the normal drilling operation process. When the drill is lowered to a depth of 5 - 15 m from the bottom of the hole, use the kelly bushing and elevators at the wellhead to suspend the drill string in the hole. The gland 10 and the rubber core 9 are successively passed through the male thread of the drill pipe to be lowered. The inner side of the rubber core 9 is squeezed and deformed, generating frictional force with the drill pipe body, thus relatively fixing the gland 10, the rubber core 9 and the drill pipe body. Connect this drill pipe and continue to lower the drill. The rubber core 9 enters the rotary main shaft 7 along with the drill pipe, and the gland 10 is fixedly connected to the rotary main shaft 7 through threads. The self - pressurized rotary control head for the vehicle - mounted drill in the coal mining area is completely installed.

[0049] Step Six: During the drilling operation, the downward pressure of the drill pipe and the gland 10 causes the inner and outer sides of the rubber core 9 to be squeezed and deformed. First, the inner side of the rubber core 9 tightly holds the drill pipe. Second, a large frictional force is generated between the outer side of the rubber core 9 and the inner wall of the rotary main shaft 7, achieving a tight fit. During the drilling operation, the drill pipe rotates at high speed, driving the rubber core 9 and the rotary main shaft 7 to rotate. The three are relatively fixed and there is no relative rotation.

[0050] Step Seven: During the drilling operation, as the rubber core 9 wears, tighten the gland 10 to move downward, causing the rubber core 9 to be squeezed and deformed again, achieving self - pressurized sealing and reaching the sealing effect.

[0051] Step Eight: During the drilling operation, connect the tee fitting 1 to the specific pipeline according to the different drilling technologies supporting the vehicle - mounted drill in the coal mining area.

[0052] Step Nine: During the drilling operation, use the time of connecting drill pipes or shift change to inject lubricating oil through the grease injection port 12 and the lower grease injection port 12.

[0053] Step Ten: After the drilling operation is completed, disassemble the high - strength bolts of the kelly bushing and the connecting flange 2 at the wellhead of the vehicle - mounted drill. Use the auxiliary winch equipped on the mast of the vehicle - mounted drill to lift the rotary control head from the wellhead through the sling 13 and place it near the wellhead to complete the entire operation.

Claims

1. A self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine, characterized in that: It comprises a three-way pipe fitting (1); the main body of the three-way pipe fitting (1) is a hollow cylindrical structure, and the joint arranged along the radial direction on the outer wall of the main body of the three-way pipe fitting (1) is a union joint; The bottom end of the three-way pipe fitting (1) is fixedly provided with a connecting flange (2); the top end of the three-way pipe fitting (1) is provided with a bearing housing (3); the top end of the bearing housing (3) is fixedly connected with a bearing housing end cover (4); an upper plate bearing (5) and a lower plate bearing (6) are fixedly installed in the bearing housing (3); a rotating main shaft (7) is rotatably installed in the upper plate bearing (5) and the lower plate bearing (6); the top of the rotating main shaft (7) extends out of the bearing housing end cover (4); the rotating main shaft (7) The bottom of the rotating main shaft (7) extends into the three-way pipe fitting (1), and a group of seals (8) are arranged between the outer wall of the rotating main shaft (7) and the inner wall of the three-way pipe fitting (1); a rubber core (9) is coaxially installed in the top of the rotating main shaft (7), and the top of the rubber core (9) is flush with the top of the rotating main shaft (7); a pressure cover (10) is coaxially installed on the top of the rotating main shaft (7), and the rotating main shaft (7) and the pressure cover (10) are connected by a threaded structure, and the pressure cover (10) is in close contact with the top of the rubber core (9).

2. The self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area as claimed in claim 1, characterized in that: The rubber core (9) is made of nitrile rubber. The rubber core (9) is composed of an integrated rubber core large end and a rubber core small end from top to bottom. The rubber core large end is a hollow cylindrical structure; the rubber core small end is a hollow truncated cone structure, and its outer diameter gradually decreases from top to bottom; the cavity at the top of the rotating main shaft (7) matches the shape of the rubber core (9).

3. The self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area according to claim 1, characterized in that: The rotating main shaft (7), the rubber core (9) and the pressure cover (10) are all provided with a center hole at their centers. The center hole of the pressure cover (10), the center hole of the rubber core (9), the center hole of the rotating main shaft (7), the inner cavity of the three-way pipe fitting (1) and the center hole of the connecting flange (2) are connected to form the inner cavity of the rotating control head.

4. The self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area as claimed in claim 1, characterized in that: The top of the bearing housing (3) is provided with a plurality of upper grease injection ports (11), which are evenly arranged along the circumferential direction, and the horizontal plane where the upper grease injection ports (11) are located is close to the upper plate bearing (5); the top of the three-way pipe fitting (1) is provided with a plurality of lower grease injection ports (12), which are evenly arranged along the circumferential direction, and the horizontal plane where the lower grease injection ports (12) are located is close to the seal (8).

5. The self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area as claimed in claim 1, characterized in that: A pair of hanging rings (13) are fixedly arranged on the top surface of the gland (10).

6. The self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area as claimed in claim 1, characterized in that: The three-way pipe fitting (1) is a high-pressure three-way pipe fitting; the connecting flange (2) is a high-pressure flange; the high-pressure three-way pipe fitting, the high-pressure flange, the bearing housing (3), and the bearing housing end cover (4) are all made of alloy steel.

7. The self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area as claimed in claim 1, characterized in that: The seal (8) is a V-shaped skeleton seal, and the V-shaped skeleton seal and the rotating main shaft (7) are designed to be interference fit, and the matching surfaces of the V-shaped skeleton seal and the rotating main shaft (7) are lubricated with grease.

8. The self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area as claimed in claim 1, characterized in that: The upper plate bearing (5) and the lower plate bearing (6) are both tapered roller bearings, and the upper plate bearing (5) and the lower plate bearing (6) are arranged opposite to each other up and down.

9. A drilling operation method using the self-pressurizing rotary control head for a vehicle-mounted drilling rig in a coal mine area as claimed in any one of claims 1 to 8, characterized in that: During the drilling operation, the connection pipelines of the three-way pipe fitting (1) are different according to the different drilling processes of the vehicle-mounted drilling rig in the coal mine area. Specifically, in the construction of coalbed methane horizontal wells, the three-way pipe fitting (1) is connected to the high-pressure pipeline; in the air down-the-hole hammer drilling, the three-way pipe fitting (1) is connected to the low-pressure pipeline; in the underbalanced drilling operation, it is ensured that the wellhead seal can realize normal drilling operation under the pressure state in the well; in the high-concentration bridge plugging operation, the three-way pipe fitting (1) is connected to the high-pressure gate valve.

10. The drilling method according to claim 9, characterized in that: The method specifically comprises the following steps: Step 1, during the drilling operation, after the installation of an open casing or orifice pipe is completed, a bottom flange having the same structural dimensions as the connecting flange (2) is welded to the top of the open casing or orifice pipe, using a carbon dioxide shielded welding machine and high-strength welding wire; Step 2: Before drilling, assemble the rotary control head in advance. Except for the rubber core (9), all other parts are installed normally. Step 3: Use the auxiliary winch of the vehicle-mounted drilling rig to lift the rotating control head through the lifting ring (13), pass through the wellhead platform of the vehicle-mounted drilling rig and directly lower it to a position 5 cm away from the orifice flange of the casing, manually assist in rotating the rotating control head, align the threaded hole of the connecting flange (2) with the threaded hole of the orifice flange, install the sealing ring, and fix the rotating control head with high-strength bolts; Step 4: Connect the gland (10) to the rotating main shaft (7) by threading, remove the gland (10) from the rotating control head, and place it near the wellhead; Step 5, connect the drilling tool and the drill bit to start drilling, pass the drill bit through the center hole of the rotating main shaft (7) and lower it into the hole, connect a single drill according to the normal drilling operation process, and when the drilling tool is 5 to 15 meters away from the bottom of the hole, use the wellhead core and the hanging card to hang the drilling tool in the hole at the wellhead, and the gland (10) and the rubber core (9) are passed through the male buckle of the drill pipe to be lowered in turn, and the gland (10), the rubber core (9) and the drill pipe body are relatively fixed, and the drill pipe is connected to continue drilling, and the rubber core (9) enters the rotating main shaft (7) with the drill pipe, and the gland (10) and the rotating main shaft (7) are fixed by threaded connection, and the self-pressurizing rotary control head for the vehicle-mounted drilling rig in the coal mine area is completely installed; Step 6: During the drilling operation, the pressure from the drill pipe and the pressure from the gland (10) causes the inner and outer sides of the rubber core (9) to be squeezed and deformed, so that the drill pipe, the rubber core (9) and the rotating main shaft (7) are tightly combined. During the drilling operation, the drill pipe rotates at a high speed, driving the rubber core (9) and the rotating main shaft (7) to rotate. The three are relatively fixed and do not rotate relative to each other. Step 7: During the drilling operation, as the rubber core (9) wears, the pressure cap (10) is tightened and moved downward, so that the rubber core (9) is compressed and deformed again, and a self-pressurized seal is achieved to achieve a sealing effect; Step 8, during the drilling operation, according to the different drilling processes of the vehicle-mounted drilling rig in the coal mining area, the three-way pipe fitting (1) is connected to a specific pipeline; Step nine, during the drilling operation, injecting lubricating oil through the grease injection port (12) and the lower grease injection port (12); Step 10, after the drilling operation is completed, remove the wellhead bushing of the vehicle-mounted drilling rig and the high-strength bolts of the connecting flange (2), use the auxiliary winch on the mast of the vehicle-mounted drilling rig to lift the rotating control head from the wellhead through the lifting ring (13), and place it on the wellhead attachment to complete the entire operation.

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