Well drilling method suitable for hard rock stratum

Abstract

The invention provides a well drilling method suitable for a hard rock stratum. The well drilling method comprises the steps that preparation is conducted before construction; digging a pilot hole; a drilling machine, a drilling rod and a drill bit are installed, the distance between the drill bit and the well bottom meets the requirement of gas lift reverse circulation, and the length of the slurry discharging device is adjusted according to the height of the gas driving device; a drilling machine is controlled to drill under the condition of gas lift reverse circulation, and slag stone slurry is treated through a well washing and slag discharging system; after the drilling stroke is finished, the drill bit is overhauled, if the drill bit meets the next gas lift reverse circulation condition, a drill rod is added, the next drilling stroke is carried out, if not, the drill bit is adjusted or maintained, and then the drill rod is added for the next drilling stroke; and after drilling to the target depth, hole measuring operation is carried out, and if the shaft does not meet the requirement, hole sweeping operation is carried out until the parameters of the shaft meet the requirement. By means of the well drilling method, through reasonable arrangement of procedures and preparation of the well washing and slag discharging system, the efficiency and quality of slag stone treatment are improved, and the comprehensive efficiency of well building is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of well drilling, and in particular to a drilling method suitable for hard rock stratum. BACKGROUND

[0002] With the development of the national economy, there is a strong demand for the construction of deep vertical shafts in the fields of gold mines, copper mines, iron mines, and phosphate mines. In particular, the secondary well construction in underground tunnels is limited by the limited construction space. Currently, drilling methods are usually used for construction. The drilling method is a relatively safe well construction method of "drilling without lowering the well". The drilling method provides power to the ground, uses a drill bit to drill down, and at the same time provides liquid to the wellbore. The slag and stones excavated are wrapped in mud and discharged from the wellbore through the drill bit, drill pipe, and slurry discharge pipe, and then are returned to the wellbore after sedimentation treatment.

[0003] In the construction of deep vertical shafts by the drilling method in hard rock stratum, the comprehensive efficiency of the drilling method is not high, the drill bit is easily damaged, the drill bit maintenance cycle is long, and the cost of the drilling tool is high due to the comprehensive influence of various factors such as equipment capacity, drill pipe, and drill bit. Moreover, the area of the sedimentation tank is limited, and the slag liquid cannot flow for a long distance to rely on the self-weight for the sedimentation of solid particles.

[0004] Therefore, it is necessary to design a drilling method suitable for hard rock stratum to solve one of the above problems. SUMMARY

[0005] The present application provides a drilling method suitable for hard rock stratum, which can improve the construction efficiency of the vertical shaft drilling machine in hard rock stratum.

[0006] In order to achieve the above purpose, the technical scheme provided by the present application is as follows: The present application provides a drilling method suitable for hard rock stratum, wherein the drilling method comprises: Preparation before construction, including preparation of a well washing and slag discharging system, the well washing and slag discharging system comprising a slag liquid separation device, a sedimentation tank, and a slurry discharge device; Digging a pilot hole, the depth of the pilot hole being not greater than 18 meters; Installing a drilling machine and assisting in installing a drill pipe and a drill bit by using a platform car, the distance between the drill bit and the well bottom satisfying the requirement of gas lift reverse circulation, adjusting the length of the slurry discharge device according to the height of the gas driving device, and installing the slurry discharge device on the drill pipe at a position matched with the gas driving device; Controlling the drilling machine to drill under the condition of gas lift reverse circulation, the slag slurry generated being transported to the slag liquid separation device for filtration and then being discharged to the sedimentation tank, and the slurry being flowed back to the wellbore after sedimentation; After the drilling process, the drill bit is repaired, if the drill bit meets the next air-lift reverse circulation condition, the drill rod is added, the next drilling process is carried out, if not, the drill bit is disassembled for adjustment or maintenance, then the drill rod is added and the drill bit is installed for the next drilling process; After drilling to the target depth, the construction personnel carry out hole measuring operation, if the wellbore does not meet the requirements, hole sweeping operation is carried out until the parameters of the wellbore meet the requirements.

[0007] Further, the sedimentation tank is located between the residue-liquid separation device and the target lock position, the sedimentation tank comprises a first sedimentation area, a second sedimentation area and a back-slurry channel arranged in sequence and connected in sequence, and the depth of the second sedimentation area is not less than the depths of the first sedimentation area and the back-slurry channel.

[0008] Further, a first dam is arranged in the first sedimentation area, and a second dam is arranged in the second sedimentation area, wherein the first dam is arranged close to the second sedimentation area, and the second dam is located in the second sedimentation area.

[0009] Further, the pilot hole excavation comprises a first pilot stage of 0-6 meters and a second pilot stage of 6-18 meters, the first pilot stage adopts mechanical or blasting excavation mode, and the second pilot stage utilizes a slurry pump to pump the residue slurry in the pilot hole to the residue-liquid separation device.

[0010] Further, the platform car is used to assist in installing the drill bit, which comprises the following steps: first, the cutter head is clamped by the clamp of the platform car, the guide device and the connecting device are successively hoisted and installed on the cutter head, then the drill bit is lowered by the main lifting system, and the guide device and the connecting device are repeatedly installed until the distance between the drill bit and the bottom of the pilot hole meets the air-lift reverse circulation requirement.

[0011] Further, when the submergence ratio is not less than 0.5, the air-lift reverse circulation requirement is met.

[0012] Further, the slurry discharge device comprises a fixed pipe in communication with the residue discharge cavity of the drill rod and an adjusting pipe in sealing cooperation with the fixed pipe and in communication with the residue-liquid separation device, and the adjusting pipe is telescopic relative to the fixed pipe to change the total length of the slurry discharge device.

[0013] Further, the slurry discharge device further comprises a connecting pipe for connecting the drill rod and the fixed pipe, the connecting pipe comprises a main pipe connected with the drill rod, a pair of opposite extending branch pipes and a three-way valve connecting the main pipe and the pair of branch pipes, and the fixed pipe is provided with two and is in communication with the two branch pipes.

[0014] Further, after the parameters of the wellbore meet the requirements, the wellbore is cleaned and washed, and the parameters of the slurry are detected in real time until the slurry parameter detection meets the requirements.

[0015] Further, the slurry water flowing back to the wellbore after precipitation is detected, and if the slurry water does not meet the requirements, a flocculating agent is added in the precipitation tank.

[0016] Compared with the related art, the application has the beneficial effect that the drilling method suitable for hard rock strata is used to reasonably arrange the procedures and prepare the well flushing and residue discharging system, so as to ensure the efficiency and quality of the residue slurry treatment and improve the comprehensive efficiency of well construction. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a flow chart of the drilling method of an embodiment of the drilling method suitable for hard rock strata of the application.

[0018] Figure 2 is Figure 1 is a front view structural schematic diagram of the well flushing and residue discharging system in the application.

[0019] Figure 3 is Figure 2 is a top view structural schematic diagram of the well flushing and residue discharging system in the application.

[0020] Figure 4 is Figure 1 is a three-dimensional structural schematic diagram of the clamp of the platform vehicle in the application.

[0021] In the application, 1 is a drilling tool, 11 is a drill pipe, 12 is a residue discharging cavity, 13 is a gas driving device, 2 is a pilot hole, 3 is a wellbore, 4 is a well flushing and residue discharging system, 41 is a slurry discharging device, 411 is a fixed pipe, 412 is an adjusting pipe, 413 is a connecting pipe, 4131 is a main pipe, 4132 is a branch pipe, 4133 is a three-way valve, 414 is an auxiliary pipe, 415 is a rotary connecting pipe, 42 is a residue separation device, 421 is a slurry discharging port, 43 is a precipitation tank, 431 is a first precipitation tank, 432 is a second precipitation tank, 433 is a slurry returning channel, 434 is a first soil dam, 435 is a second soil dam, 51 is a clamp, 51 is a first clamping assembly, 52 is a second clamping assembly, 53 is a clamping space, 54 is an upper clamping piece, 541 is a base area, 542 is a reinforcing area, 543 is a boss, 55 is a lower clamping piece, 56 is a locking assembly, 561 is a fixing pin, 562 is a connecting plate, 563 is a fixing hole, 57 is a first driving device, and 58 is a second driving device. DETAILED DESCRIPTION

[0022] In order for those skilled in the art to better understand the technical solutions in the application, the technical solutions in the embodiments of the application will be clearly and completely described below in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the application.

[0023] It should be noted that the terms "upper", "lower" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application, and do not indicate or imply that the device referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application. Specifically, in the present application, the direction towards the ground is downward, and conversely, the direction away from the ground is upward, and other orientation descriptions are defined based on "upper" and "lower".

[0024] In various drawings of the present application, certain dimensions of structures or parts may be exaggerated relative to other structural parts for ease of illustration, and therefore are only used to illustrate the basic structure of the present application.

[0025] The present application provides a drilling method suitable for hard rock formation. Due to the particularity of hard rock formation, the drilling sludge liquid needs to be filtered into large sludge stones first, and then small sludge stones and soil dust are precipitated, so as to ensure the effect and efficiency of processing sludge liquid.

[0026] As shown in Figure 1 , the drilling method comprises pre-construction preparation, digging a pilot hole 2, installing a drilling machine, a drill rod 1 and a drill bit, controlling the drilling machine to drill under the condition of gas lift reverse circulation, processing the wellbore 3 after drilling to the target depth, until the parameters of the wellbore 3 meet the requirements, and the drilling work is completed.

[0027] Specifically, the pre-construction preparation includes collecting wellbore center cross line base pile, geological and hydrological report, wellbore excavation construction drawing original and other data, then according to the wellbore design parameters and geological conditions, analyzing the formation characteristics of the lock port, combining with the equipment and process conditions, determining the structure type and site layout of the lock port, and finally checking the bearing capacity of the lock port and constructing the crane track foundation.

[0028] The pre-construction preparation also includes configuring a well washing and sludge discharging system 4, which includes a sludge discharging device 41, a sludge liquid separation device 42 and a sedimentation tank 43. In the pre-construction preparation stage, according to the design, the sludge liquid separation device 42 is first installed on the side of the sedimentation tank 43 away from the wellbore 3, one end of the sludge discharging device 41 is installed on the sludge liquid separation device 42, and the other end is to be installed on the drill rod 1. After the drill rod 1 is installed in place, the sludge discharging device 41 is installed according to the height position of the gas driving device 13.

[0029] The sludge liquid separation device 42 separates large sludge stones and small particle sludge stones through a vibrating screen and a plurality of cyclones matched with the vibrating screen, thereby improving the separation efficiency of sludge stones.

[0030] As shown in Figure 2 and Figure 3As shown, the sedimentation tank 43 is located between the residue-liquid separation device 42 and the target lock position, the sedimentation tank 43 comprises a first sedimentation area 431, a second sedimentation area 432 and a reflux channel 433 arranged in sequence and connected in sequence, the slurry outlet 421 of the residue-liquid separation device 42 is projected in the first sedimentation area 431 along the up-down direction, the depth of the second sedimentation area 432 is not less than the depths of the first sedimentation area 431 and the reflux channel 433, the depth of the second sedimentation area 432 is deeper, which is beneficial to the sedimentation of some small particles and dust at the bottom of the second sedimentation area 432, and meanwhile does not affect the slurry entering the reflux channel 433, the sludge sedimented at the bottom is cleaned in time, and the efficiency of sedimentation is improved.

[0031] The first sedimentation area 431 is provided with a first dam 434, and the second sedimentation area 432 is provided with a second dam 435, wherein the first dam 434 is arranged close to the second sedimentation area 432, the first dam 434 is arranged close to the second sedimentation area 432, and the first dam 434 can block the slurry from directly flowing into the second sedimentation area 432, so that the slurry is preliminarily deposited in the first sedimentation area 431 and then flows into the second sedimentation area 432.

[0032] The second dam 435 is located in the middle of the second sedimentation area 432, and the height of the second dam 435 is not less than the height of the first dam 434, the slurry flowing in continues to deposit in the second sedimentation area 432, and the second dam 435 can also reduce the impact of the slurry.

[0033] The slurry discharge device 41 comprises a fixed pipe 411 in communication with the residue discharge cavity 12 of the drill rod 1 and an adjusting pipe 412 in sealing cooperation with the fixed pipe 411 and in communication with the residue-liquid separation device 42, the adjusting pipe 412 is telescopic relative to the fixed pipe 411 to change the total length of the slurry discharge device 41, when the slurry discharge device 41 is installed at different positions of the drill rod 1, the total length of the slurry discharge device 41 can be changed to connect the residue discharge cavity 12 and the residue-liquid separation device 42.

[0034] The slurry discharge device 41 is arranged downwardly inclined along the direction from the drill rod 1 to the residue-liquid separation device 42, which facilitates the transportation of the residue-stone slurry.

[0035] The outer diameter of the adjusting pipe 412 is smaller than the inner diameter of the fixed pipe 411, and part of the structure of the adjusting pipe 412 is located inside the fixed pipe 411 to change the total length of the adjusting pipe 412 and the fixed pipe 411, that is, the total length of the adjusting pipe 412 and the fixed pipe 411 is adjusted by adjusting the length of the adjusting pipe 412 extending into the fixed pipe 411.

[0036] The inner diameter of the adjusting tube 412 is larger than the outer diameter of the fixed tube 411, and part of the structure of the fixed tube 411 is located inside the adjusting tube 412 to change the total length of the adjusting tube 412 and the fixed tube 411, that is, the total length of the adjusting tube 412 and the fixed tube 411 is adjusted by adjusting the length of the adjusting tube 412 to accommodate the fixed tube 411.

[0037] The slurry discharge device 41 also includes a limiting structure for limiting the axial movement of the adjustment tube 412. The limiting structure includes a protrusion provided on one of the fixed tube 411 and the adjustment tube 412, and a groove provided on the other. It is understood that the limiting structures include several pairs, and are spaced apart along the axial direction of the fixed tube 411.

[0038] like Figure 3 As shown, the slurry discharge device 41 also includes a connecting pipe 413 for connecting the drill rod 1 and the fixed pipe 411. The connecting pipe 413 includes a main pipe 4131 connected to the drill rod 1, a pair of branch pipes 4132 extending in opposite directions, and a three-way valve 4133 connecting the main pipe 4131 and the pair of branch pipes 4132. There are two fixed pipes 411, which are respectively connected to the two branch pipes 4132. The entire connecting pipe 413 is in an eight-shaped shape, which improves the efficiency of conveying slag slurry and ensures that the drilling rig itself is in a force-balanced state.

[0039] The slurry discharge device 41 also includes a pair of auxiliary pipes 414 for connecting to the slag-liquid separation device 42, and a rotating connecting pipe 415 for connecting the auxiliary pipe 414 and the adjusting pipe 412. The setting of the rotating connecting pipe 415 facilitates the rotation of the adjusting pipe 412 during the adjustment process, thereby improving the efficiency of the operation.

[0040] The connection between the fixed pipe 411 and the branch pipe 4132 is set in an arc shape, and the regulating pipe 412 and the auxiliary pipe 414 are also set in an arc shape, so as to avoid the slag slurry from getting stuck at the connection and improve the smoothness of conveying the slag slurry.

[0041] The slurry discharge device 41 further includes a seal provided between the regulating pipe 412 and the fixed pipe 411 to prevent the slag-rock slurry from leaking from the joint between the regulating pipe 412 and the fixed pipe 411 .

[0042] The slurry discharge device 41 also includes a grease injection hole provided on the adjusting tube 412 or the fixed tube 411, which facilitates the injection of grease into the overlapping portion of the adjusting tube 412 and the fixed tube 411, thereby improving the smoothness of adjusting the adjusting tube 412. The grease injection hole is provided on the pipe outside the overlapping portion of the adjusting tube 412 and the fixed tube 411, which facilitates operation.

[0043] Further, the pilot hole 2 is excavated, and the depth of the pilot hole 2 is not greater than 18 meters due to the high strength of the hard rock bottom layer. Since the depth of the pilot hole 2 is not enough, the requirement of the air-lift reverse circulation for the residue removal cannot be met. In order to reduce the workload of the on-site blasting operation, the slurry pump and the slurry pipe are used to directly transport the residue slurry to the residue liquid separation device 42 for separation and treatment, and the residue liquid is returned to the foundation pit of the pilot hole 2 after sedimentation.

[0044] Preferably, the pilot hole is excavated by the mechanical method or the blasting method when the depth of the pilot hole 2 is 0-6 meters, and the low propulsion speed is used to continue excavating the pilot hole when the depth of the pilot hole 2 is 6-18 meters, and then the slurry pump and the slurry pipe are used to remove the residue slurry in the pilot hole 2.

[0045] After the pilot hole 2 is excavated, the drilling machine, the drill pipe 1 and the drill bit are installed. The platform vehicle is used to assist the installation or disassembly of the drilling machine and the adjustment of the verticality of the drilling machine.

[0046] As shown in Figure 4 the fixture 5 includes a first clamping assembly 51, a second clamping assembly 52 which is butted with the first clamping assembly 51 along a first direction to form a clamping space 53 for the drilling machine, and a locking assembly 56 for locking the first clamping assembly 51 and the second clamping assembly 52. The first clamping assembly 51 and the second clamping assembly 52 each include an upper clamping piece 54 and a lower clamping piece 55 located below the upper clamping piece 54. One of the upper clamping piece 54 and the lower clamping piece 55 is provided with a sliding rail extending along a second direction, and the other is provided with a sliding groove 131 sliding along the sliding rail. The second direction is perpendicular to the first direction.

[0047] The first clamping assembly 51 and the second clamping assembly 52 have sufficient adjustment space within a certain range, and can be properly adjusted according to the central position of the drilling machine, thereby improving the precision of the drilling machine adjustment, reducing the adjustment time of the fixture 5 and the center of the drilling machine, and improving the work efficiency.

[0048] It can be understood that the first direction is the opening and closing direction of the lower clamping piece 55, and the second direction is the adjustment direction of the upper clamping piece 54. The upper clamping piece 54 does not move relative to the lower clamping piece 55 in the first direction, and the upper clamping piece 54 moves together with the lower clamping piece 55 in the first direction.

[0049] The side surface of the upper clamping piece 54 close to the clamping space has an upper arc surface 132, and the two upper arc surfaces of the first clamping assembly 51 and the second clamping assembly 52 are arranged to form an upper opening, that is, the upper opening is located at the upper part of the clamping space 53.

[0050] Correspondingly, the lower clamping member 55 has a lower arc surface near the side of the clamping space 53, and the two lower arc surfaces of the first clamping assembly 51 and the second clamping assembly 52 surround a lower opening, that is, the lower opening is located at the lower part of the clamping space 53, and the diameter of the lower opening is greater than that of the upper opening. When the clamp 5 clamps the drilling tool, the strength of the upper clamping member 54 mainly supports the drilling tool.

[0051] In order to improve the strength of the upper clamping member 54, the upper clamping member 54 has a base area 541, a boss 543 close to the upper opening 151, and a reinforcing area 542 between the base area 541 and the boss 543. The thickness of the boss 543 is greater than that of the reinforcing area 542, and the thickness of the reinforcing area 542 is greater than that of the base area 541, that is, the closer to the upper opening, the thicker the thickness of the upper clamping member 54, effectively improving the structural strength of the upper clamping member 54.

[0052] The boss 543 is provided with a step, and the thickness of the upper clamping member 54 decreases in turn from the edge of the upper opening boss 543, thereby improving the rigidity of the upper clamping member 54 and improving the stability of the clamp 5 clamping the drilling tool.

[0053] The area of the lower clamping member 55 is greater than that of the upper clamping member 54, that is, the upper clamping member 54 is laid on the lower clamping member 55 to support the upper clamping member 54.

[0054] The slide rail is preferably provided on the lower clamping member 55, and the slide groove is preferably provided on the upper clamping member 54, which facilitates the mutual cooperation of the upper clamping member 54 and the lower clamping member 55 and smooth sliding.

[0055] The clamp 5 includes two locking assemblies 56, which are respectively arranged on both sides of the clamping space 53 along the second direction. The locking assembly 56 includes a fixed pin 561 arranged on one of the upper clamping members 54, a connecting plate 562 pivotally connected with the other upper clamping member 54, and a fixed hole 563 arranged on the connecting plate 562 for cooperation with the fixed pin 561, facilitating the installation and disassembly between the first clamping assembly 51 and the second clamping assembly 52.

[0056] Two of the connecting plates 562 are staggered with the two fixing pins 561, that is, one of the connecting plates 562 is connected to the upper clamping piece 54 of the first clamping assembly 51, and the corresponding fixing pin 561 is installed on the upper clamping piece 54 of the second clamping assembly 52; correspondingly, the other connecting plate 562 is connected to the upper clamping piece 54 of the second clamping assembly 52, and the fixing pin 561 is installed on the upper clamping piece 54 of the first clamping assembly 51, so that the installation directions of the two locking assemblies 56 are opposite, preventing the locking assembly 56 from loosening during construction.

[0057] Preferably, the two locking assemblies 56 are fixed to the reinforced area 542 of the upper clamping piece 54, improving the overall strength of the clamp 5.

[0058] The clamp 5 further comprises at least one first driving device 57 for driving each of the upper clamping pieces 54. In the embodiment, two first driving devices 57 are provided, which are arranged on the two sides of the upper clamping piece 54 in the first direction, and force balance is achieved when the upper clamping piece 54 is moved, which is more labor-saving.

[0059] Specifically, the first driving device 57 comprises a first connecting piece fixed to the upper clamping piece 54, a first driving piece fixed to the lower clamping piece 55, and a first guide rod for connecting the first connecting piece and the first driving piece, the length of the first guide rod being in the second direction. In the second direction, the first driving piece drives the upper clamping piece 54 to move to achieve adjustment of the upper clamping piece 54.

[0060] Preferably, the first driving piece is installed on the edge of the lower clamping piece 55, increasing the adjustment range of the first driving piece.

[0061] The clamp 5 further comprises at least one second driving device 58 for driving each of the lower clamping pieces 55. In the embodiment, two second driving devices 58 are provided, which are arranged on the lower clamping piece 55 in the second direction, and force balance is achieved when the lower clamping piece 55 is moved, which is more labor-saving.

[0062] The structure of the second driving device 58 is the same as that of the first driving device 57, which will not be described in detail.

[0063] In the present application, the first driving piece 57 and the second driving piece 58 are both hydraulic oil cylinders, which ensure that the entire transmission process is relatively stable.

[0064] The drilling head is installed by using the platform vehicle, including: first clamping the cutter head by the clamp 5 of the platform vehicle, hoisting the guide device and the connecting device in sequence and installing them on the cutter head, then lowering the drilling head by the main lifting system, and repeatedly installing the guide device and the connecting device until the distance between the drilling head and the bottom of the pilot hole meets the requirement of the air-lift reverse circulation. During the installation of the drilling head, if the drilling tool is not in a vertical downward state, the state of the drilling tool can be adjusted by adjusting the upper clamping piece 54 or the lower clamping piece 55.

[0065] The gas cavity is located outside the residue discharging cavity 12, and the distance between the gas cavity and the residue discharging cavity 12 is not greater than the width of the gas cavity, so that the high-pressure gas can carry the residue and the slurry into the residue discharging cavity 12. Specifically, the high-pressure air enters the gas cavity through the air inlet of the gas driving device 13, flows from top to bottom, and finally mixes with the slurry in the residue discharging cavity 12 of the guide device with the air hole, and is pressed into the liquid in the upper residue discharging cavity 12 of the high-pressure air. The density of the liquid is much smaller than the density of the liquid in the wellbore, so that a pressure difference is formed between the inside and outside of the drilling tool, forcing the liquid in the residue discharging cavity 12 to flow upward and enter the residue and slurry separation device 42 through the slurry discharging device 41. When the submergence ratio is not less than 0.5, the requirement of the air-lift reverse circulation is met, and the residue and slurry are discharged from the wellbore 3 while the drilling head is drilling.

[0066] The periphery of the guide device is symmetrically provided with a plurality of guide rollers, which can guide the drilling path to be in a straight line state during the drilling of the drilling head.

[0067] The connecting device is provided with a counterweight, so that the stability of the drilling head during drilling can be improved.

[0068] The distance between the drilling head and the well bottom meets the requirement of the air-lift reverse circulation, the slurry discharging device 41 is installed at the position of the gas driving device 13 of the drill rod 1 by adjusting the degree of the slurry discharging device 41 according to the height of the gas driving device; The drilling machine is controlled to drill under the condition of air-lift reverse circulation, the residue and slurry generated are discharged to the sedimentation tank 43 after passing through the slurry discharging device 41 and the residue and slurry separation device 42, and then the slurry flows to the wellbore 3 again; After the drilling process of the drilling head is completed, the drilling head is overhauled, including checking whether the cutting teeth are worn, whether the bolts are loose, whether the structural parts are damaged, whether the tool seal is failed, etc. If all the above problems do not exist, the drilling head meets the next air-lift reverse circulation condition, then the drill rod is increased, and the next drilling process is carried out. If any of the above problems exists, the drilling head does not meet the next air-lift reverse circulation condition, and needs to be repaired or maintained accordingly, then the drilling head is adjusted or maintained, and then the drill rod 1 is increased for the next drilling process.

[0069] The drilling process is repeated until the target depth is reached, and during the entire drilling process, the drill bit passes the cuttings slurry through the gas lift reverse circulation process to the slurry separation device 42, and then the slurry is deposited in the settling tank 43. The slurry is then returned to the wellbore 3, and the slurry flows into the space between the cutter head and the bottom of the wellbore through the backflow holes arranged on the side of the cutter head. On the one hand, this avoids the vacuum between the bottom of the wellbore and the cutter head, and on the other hand, it also plays a role in flushing the cuttings on the periphery of the cutter head to the center.

[0070] In this application, in order to prevent the small dust or small particles contained in the slurry returned to the wellbore 3 from settling in the wellbore, it is necessary to detect the slurry returned to the wellbore 3. If the slurry does not meet the requirements, a flocculating agent or other chemical agent is added to the settling tank 43 to deposit dust, so that the mud returned to the wellbore 3 meets the requirements, and the small particles that have not settled in the wellbore 3 are avoided, reducing the difficulty of well flushing.

[0071] After drilling to the target depth, the operator performs a hole detection operation to detect whether the wellbore 3 is vertical and whether the diameter of the wellbore meets the requirements. If the wellbore 3 meets the requirements, a hole cleaning operation is performed to remove the drill cuttings, small debris and cement blocks deposited in the well, trim the well wall, and expand the diameter of the wellbore 3 in the part that does not meet the requirements, until the parameters of the wellbore 3 meet the requirements. A regular wellbore 3 and a smooth well wall meet the requirements of subsequent construction.

[0072] Since the drilled formation is a medium-hard rock formation, if the solid particle separation effect of the well flushing and cuttings removal system 4 is poor, after the wellbore 3 parameters meet the requirements, the well flushing operation is performed on the wellbore 3, that is, the cuttings or dust and other debris in the wellbore 3 are removed, and the parameters of the wellbore 3 mud are detected in real time. If the mud contains too much debris, the well flushing operation is repeated until the mud parameter detection meets the requirements.

[0073] After the wellbore 3 parameters meet the requirements, the drill bit and the drill pipe 1 are removed in sequence by the platform car. After the above work is completed, the drilling work is completed.

[0074] In summary, by using the drilling method suitable for hard rock formations in this application, the process is arranged reasonably, and the well flushing and cuttings removal system is prepared to ensure the efficiency and quality of the cuttings slurry treatment, thereby improving the overall efficiency of well construction.

[0075] It should be understood that although the present specification is described in terms of examples, each example does not contain only one independent technical solution. The description of the specification is for the sake of clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in each example can also be combined to form other examples that can be understood by those skilled in the art.

[0076] The above detailed description is merely exemplary in nature and is not intended to limit the scope and spirit of the application as defined by the appended claims.

Claims

1. A drilling method suitable for hard rock formations, characterized in that: The drilling method comprises: Pre-construction preparations include the preparation of a well-washing and slag-discharging system, which includes a slag-liquid separation device, a sedimentation tank, and a slurry discharge device; digging a pilot hole, the depth of the pilot hole being no more than 18 meters; Install the drilling rig and use a platform truck to assist in installing the drill pipe and drill bit. The distance between the drill bit and the bottom of the well meets the requirements of gas lift reverse circulation. Adjust the length of the slurry discharge device according to the height of the gas drive device and install the slurry discharge device on the drill pipe at a position that matches the gas drive device. The drilling rig is controlled to drill under the condition of gas lift reverse circulation. The generated slag slurry is transported to the slag-liquid separation device through the slurry discharge device for filtration and then discharged to the sedimentation tank. After sedimentation, the slurry flows back into the wellbore; After the drilling process is completed, the drill bit is inspected and repaired. If the drill bit meets the conditions for the next gas lift reverse circulation, drill rods are added and the next drilling process is carried out. If not, the drill bit is removed for adjustment or maintenance, and then drill rods are added and the drill bit is installed to carry out the next drilling process. After drilling to the target depth, the construction personnel will conduct hole measurement operations. If the wellbore does not meet the requirements, they will carry out hole sweeping operations until the wellbore parameters meet the requirements.

2. The drilling method applicable to hard rock formations according to claim 1, characterized in that: The sedimentation tank is located between the slag-liquid separation device and the target lock position. The sedimentation tank includes a first sedimentation area, a second sedimentation area, and a slurry return channel that are arranged in sequence and connected. The depth of the second sedimentation area is not lower than the depth of the first sedimentation area and the slurry return channel.

3. The drilling method applicable to hard rock formations according to claim 2, characterized in that: A first retaining dam is provided in the first sedimentation area, and a second retaining dam is provided in the second sedimentation tank. The first retaining dam is provided close to the second sedimentation area, and the second retaining dam is located in the second sedimentation tank.

4. The drilling method applicable to hard rock formations according to claim 1, characterized in that: The excavation of the pilot hole includes the first pilot stage of excavation of 0-6 meters and the second pilot stage of 6-18 meters. The first pilot stage adopts mechanical or blasting excavation methods, and the second pilot stage uses a mud pump to extract the slag slurry from the pilot hole to the slag-liquid separation device.

5. The drilling method applicable to hard rock formations according to claim 1, characterized in that: Using a platform truck to assist in installing the drill bit includes: first clamping the cutterhead with the platform truck's clamp, sequentially hoisting the guide device and the connecting device and installing them on the cutterhead, then lowering the drill bit through the main lifting system, and repeatedly installing the guide device and the connecting device until the distance between the drill bit and the bottom of the pilot hole meets the requirements of gas lift reverse circulation.

6. The drilling method applicable to hard rock formations according to claim 5, characterized in that: When the sinking ratio is not less than 0.5, the requirements of gas lift reverse circulation are met.

7. The drilling method applicable to hard rock formations according to claim 1, characterized in that: The slurry discharge device includes a fixed pipe connected to the slag discharge cavity of the drill pipe, an adjustment pipe sealed with the fixed pipe and connected to the slag-liquid separation device, and the adjustment pipe is retractable relative to the fixed pipe to change the total length of the slurry discharge device.

8. The drilling method applicable to hard rock formations according to claim 7, characterized in that: The slurry discharge device also includes a connecting pipe for connecting the drill pipe and the fixed pipe. The connecting pipe includes a main pipe connected to the drill pipe, a pair of branch pipes extending towards each other, and a three-way valve connecting the main pipe and the pair of branch pipes. There are two fixed pipes, which are respectively connected to the two branch pipes.

9. The drilling method applicable to hard rock formations according to claim 1, characterized in that: After the wellbore parameters meet the requirements, the wellbore is cleaned and well washing operations are carried out, and the mud parameters are tested in real time until the mud parameters meet the requirements.

10. The drilling method applicable to hard rock formations according to claim 1, characterized in that: Test the slurry water that flows back to the wellbore after sedimentation. If the slurry water does not meet the requirements, add flocculants into the sedimentation tank.

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