CN117627657A - Construction method for large-diameter shaft well reversing drill in soft rock area - Google Patents

Abstract

The invention discloses a construction method for a large-diameter shaft reverse well drill in a soft rock area, which is characterized in that during the reverse well drilling construction, reaming rock slag generated in the reverse well construction is kept to be accumulated upwards along a shaft from a reaming rock slag drop point at the bottom of the shaft, a supporting shaft is carried out from top to bottom, and during the supporting of the shaft, the reaming rock slag is gradually carried away from the reaming rock slag drop point, and the speed of the supporting shaft is matched with the carrying speed of the reaming rock slag. The construction method for the large-diameter shaft reverse drilling overcomes the defects that soft rock is easy to break and deform, effectively prevents the shaft from caving and collapsing holes by controlling the discharge of reaming rock slag, improves the construction efficiency and reduces the construction cost.

Description

Construction method for large-diameter shaft well reversing drill in soft rock area

Technical Field

The invention relates to the technical field of well construction in the coal industry. In particular to a construction method for a reverse well drill of a large-diameter shaft of soft rock.

Background

Soft rocks are distributed in the bottom layers of areas such as Shaanxi province, inner Mongolia autonomous regions and the like, are structurally weak, and have the characteristics of low strength, strong rheological property, easy expansion, high efflorescence and the like in mechanical aspects; during engineering construction, soft rock is easy to crush and loosen, and has the characteristic of water expansion deformation, and the characteristics easily cause instability of coal roadway engineering.

For example, an inner Mongolian autonomous region tower is used for drawing a certain air inlet vertical shaft of a coal mine, the depth of the air inlet vertical shaft is about 220m, a reverse well drilling machine is used for drilling construction, and the diameter of the air inlet vertical shaft is 6.1m after one-time reaming. After reaming, the rock stratum where the shaft is located is found to be weaker in cementing, and the rock stratum is expanded, crushed and burst after meeting water, so that a plurality of well sections of the shaft are severely caving, and the anchor net spraying support process cannot be normally unfolded. The construction method is changed in the follow-up construction, the coal gangue is backfilled in the shaft, then the process similar to the positive well excavation process is adopted, and finally the shaft construction is completed.

Compared with the well-logging excavation process, the well-reversing drilling construction method is safer and easier to operate, but the existing well-reversing drilling construction method cannot be suitable for western soft rock, the well shaft is easy to collapse due to serious caving during construction, and the anchor-spraying net support cannot be normally unfolded, so that not only can the construction period be delayed, but also larger economic loss can be caused.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide a construction method for large-diameter shaft reverse drilling in soft rock areas, which prevents serious caving hole of a shaft by controlling the discharge of reaming rock slag, and can realize gangue-kicking operation in shaft anchor net spray support after reaming is finished, thereby remarkably reducing the construction cost of the shaft.

In order to solve the technical problems, the invention provides the following technical scheme:

the construction method for large-diameter shaft reverse drilling in soft rock area keeps the reaming rock slag generated in reverse drilling from the reaming rock slag drop point at the bottom of the shaft to be accumulated upwards along the shaft, supports the shaft from top to bottom, and gradually conveys away the reaming rock slag from the reaming rock slag drop point in the process of supporting the shaft, wherein the speed of the supporting shaft is matched with the conveying speed of the reaming rock slag. Reaming rock slag generated during the construction of the reverse well drill is accumulated upwards along the shaft from a rock slag drop point at the bottom of the shaft, and temporary support is carried out on the wall of the shaft, so that the hole collapse of the ledge is prevented; the speed of the supporting shaft is matched with the conveying speed of the reaming rock slag, if the conveying speed of the reaming rock slag is too high and the speed of the supporting shaft is too low, the partially exposed shaft may collapse before being supported; if the reaming sludge is carried away too slowly, the accumulated reaming sludge in the wellbore may interfere with the support operation.

The construction method for the large-diameter shaft well reversing drill in the soft rock area comprises the following steps of:

step A: downwards drilling a guide hole at a set position above a lower port roadway by using a well reversing drilling machine, and leading the guide hole into the lower port roadway;

and (B) step (B): installing a reaming bit at the lower end of a drilling rod of a back-up drilling machine positioned in the lower port roadway, and installing a distance measuring device on the reaming bit;

step C: building a reaming slag enclosing wall outside the position corresponding to the guide hole in the lower port roadway, wherein the height of the reaming slag enclosing wall is consistent with that of the lower port roadway, and a closed space is formed in the reaming slag enclosing wall;

step D: mounting slag drawing and discharging equipment on the wall of the reaming slag enclosing wall and extending into the reaming slag enclosing wall;

step E: performing reaming operation, driving the reaming bit to rotate and upwards ream, simultaneously detecting the distance between the reaming rock slag surface and the reaming bit in real time by the ranging device, and synchronously working by the slag drawing and discharging equipment in the upward moving process of the reaming bit, so that the distance between the reaming rock slag surface and the ranging device is always kept within a set range until the reaming operation is completed;

step F: after the reaming operation is completed, taking out the reaming bit, and installing a supporting hanging scaffold at a wellhead to support a shaft; when the shaft is supported, carrying out sectional high supporting operation on the side wall of the shaft from top to bottom, and after each section of high supporting operation is completed, starting to work by the slag drawing and discharging equipment, so that the slag surface height of the reaming rock slag is reduced, and exposing the next section of unsupported free section shaft to be supported until the shaft supporting operation is completed;

step G: taking out the supporting hanging scaffold and removing the reaming slag enclosing wall after the supporting shaft operation is completed; according to the method, the shaft is supported by using the reaming rock slag, so that the operation is convenient and fast, and the safety coefficient is high.

In the construction method for the large-diameter shaft well reversing in the soft rock area, slurry is adopted as drilling fluid in the step A for use; the mud can help the rock scraps produced in the pilot hole drilling process to be smoothly discharged, and meanwhile, the wall of the well is not easy to be chipped by soft rock.

In the construction method for the large-diameter shaft back-drilling in the soft rock area, in the step B, the reaming bit is an air-cooled bit; the plurality of distance measuring devices are respectively and fixedly connected to the bottom center and the bottom edge of the reaming bit; the distance measuring device is used for measuring the distance between the reaming slag and the reaming bit, ensuring that the height of the reaming slag is enough to form support for a shaft, and detecting whether the reaming bit has enough working space or not; the air-cooled drill bit is beneficial to preventing the borehole wall from collapsing due to contact with the cooling water of the drill bit.

In the construction method for the large-diameter shaft inverted well drilling in the soft rock area, in the step C, the wall of the reaming slag enclosing wall forms a closed shape; the upper end and the lower end of the reaming slag enclosing wall are respectively connected with the top wall and the bottom wall of the lower port roadway in a sealing way, and a slag outlet is formed in the lower end of the side surface of the reaming slag enclosing wall; the reaming slag enclosing wall is used for gathering the slag and accumulating the slag in the shaft, the slag outlet is used for being connected with slag drawing and discharging equipment, and the slag drawing and discharging equipment can control the height of the accumulated slag in the shaft.

In the construction method for the large-diameter shaft back drilling in the soft rock area, the step D also comprises a connecting component, and the slag drawing and discharging equipment is connected with the slag outlet on the reaming slag enclosing wall through the connecting component; the size of the connecting part is matched with the maximum rock particle diameter of the rock slag outlet, and the structural strength and the sealing performance of the connecting part are matched with the maximum water and soil pressure of the rock slag outlet.

In the step D, the slag drawing and discharging device comprises a water injection assembly and a water draining assembly which can operate independently, wherein the water injection assembly is used for injecting water and reducing resistance when the flow resistance of the reaming slag is large, and the water draining assembly is used for draining water and reducing pressure when the reaming slag is in a liquid state. When the water injection assembly injects water to the reaming rock slag, the mobility of the reaming rock slag is increased, the reaming rock slag flows out from a rock slag outlet more easily, and the water discharge assembly discharges water and reduces pressure in time when the reaming rock slag shows a liquid state, so that the reaming rock slag pressure is prevented from being too high, and slag discharging equipment and a rock slag enclosing wall are damaged, so that danger is caused.

In the construction method for the large-diameter shaft reverse drilling in the soft rock area, in the step D, the distance between the slag surface of the reaming rock slag and the bottom surface of the reaming bit is 1-2 m. The distance can ensure that the reaming slag forms strong enough support for the shaft and ensure that the reaming bit has safe and enough operation space.

In the construction method for large-diameter shaft back drilling in soft rock areas, in the step F, supporting shaft operation is carried out from top to bottom by using supporting hanging scaffold bearing constructors and construction materials; in the process of supporting the shaft, the height of the shaft of an unsupported free section above the slag surface of the reaming rock slag is less than or equal to 4m. During supporting operation, the height of the free section shaft which is not supported above the slag surface of the reaming rock slag is controlled, so that the height of the free section shaft which is not supported is as small as possible while the operation space is ensured, and the risk of rock wall collapse of the unsupported shaft is avoided.

In the above construction method for large diameter shaft back drilling in soft rock area, in step F, the supporting shaft operation is anchor net spraying operation; and (5) the constructor kicks gangue to perform the anchor net spraying operation. The anchor screen blasting operation is used to permanently support the wellbore.

The technical scheme of the invention has the following beneficial technical effects:

1. the construction method for the large-diameter shaft reverse drilling can overcome the defect that soft rock is easy to break and deform, effectively prevent the shaft from caving and collapsing by controlling the discharge of reaming rock slag, and improve the construction efficiency.

2. The method for supporting the shaft in the large-diameter shaft reverse well drilling construction method provided by the invention can be used for performing gangue kicking supporting operation in the shaft in a soft rock area, so that the shaft construction cost is obviously reduced.

Drawings

FIG. 1 is a schematic diagram of some construction steps of a method for reverse drilling a large diameter wellbore in a soft rock region according to the present invention;

FIG. 2 is a flow chart of a method of large diameter wellbore back drilling construction in soft rock areas of the present invention.

The reference numerals in the drawings are as follows: 1-soft rock; 2-reversing the drill stem of the well drilling machine; 3-a lower port roadway; 4-reaming bit; 5-a distance measuring device; 6-reaming the rock slag enclosing wall; 7-drawing out slag discharging equipment; 8-reaming the rock slag; 9-supporting hanging scaffold.

Detailed Description

Before the reverse well construction, the construction of the lower port roadway 3 is completed first, in this embodiment, the reverse well construction of the vertical well is performed, and the trend of the lower port roadway 3 is perpendicular to the trend of the shaft. In the reverse well construction, the pilot hole is first drilled using a reverse well drill until the pilot hole communicates with the lower mouth roadway 3, as shown in fig. 1 a. Because the soft rock 1 has the characteristic of easy breakage, the problems of drill sticking, hole collapse, difficult slag return and the like can occur during drilling the guide hole, and therefore, the drilling fluid is required to be injected in the drilling construction process so as to achieve the purposes of carrying rock scraps to return slag, balancing stratum pressure, stabilizing the hole wall and the like. In this embodiment, the drilling fluid should be selected from drilling mud, and no clean water should be used, as the clean water may exacerbate the expansion, crushing and collapse of the soft rock formation in which the pilot hole wall is located.

After the pilot hole drilling is completed, the pilot hole drill bit is removed from the end of the backdrilling machine drill pipe 2 and the reamer bit 4 is installed at the end of the backdrilling machine drill pipe 2 as shown in fig. 1 b. The bottom of the reamer bit 4 is also provided with a distance measuring device 5. The reamer bit 4 should be an air-cooled bit and should be as little as possible to avoid collapse due to cooling water. A plurality of distance measuring devices 5 are arranged on the center of the bottom surface and the edge of the bottom surface of the reaming bit 4, at least 1 position of the center and the edge of the bottom surface of the bit is provided with the distance measuring devices 5, and the bearing strength of the shell of the distance measuring devices 5 is required to meet the actual working condition requirement; the ranging device 5 is used for helping technicians to control the distance between the bottom surface of the reaming bit 4 and the slag surface of the reaming slag 8 in the subsequent reaming process, ensuring that the distance is less than 2m, and if the distance is too large, the risk of collapse of the shaft is increased.

After the completion of the connection of the reamer bit 4 with the distance measuring device 5 mounted thereto with the backhoe drill bit 2, the construction of the reamer slag fence 6 is performed as shown in fig. 1 c. When constructing the reaming slag fence 6, parameters such as diameter, depth and the like of a shaft, total volume of the reaming slag 8 and other field conditions are comprehensively considered to determine the size, structural strength and sealing performance of the reaming slag fence 6. The reaming rock slag enclosing wall 6 can completely block the lower port roadway 3, can only surround the circumference direction of the reaming drill bit 4, the top end of the reaming rock slag enclosing wall 6 is propped against the top wall of the lower port roadway 3, a rock slag outlet is reserved on the side wall of the reaming rock slag enclosing wall 6, which is close to the bottom, and the rock slag outlet is connected with a slag drawing and discharging device 7. The slag drawing and discharging equipment 7 comprises a water injection assembly and a water discharge assembly which are mutually independent to each other, and when the flow resistance of the reaming slag 8 is large, the water injection assembly is operated to inject water into the slag pile for reducing resistance; when the rock slag is in a liquid flow state, the water draining assembly starts to operate and conducts water draining and depressurization. The water injection assembly and the water discharge assembly are respectively used for adjusting the flow resistance and the pressure of the reaming rock slag 8, so that the reaming rock slag 8 is guaranteed to have certain fluidity, and can smoothly flow out of a rock slag outlet, and meanwhile, excessive pressure can not be caused on the rock slag enclosing wall 6, so that danger is avoided.

Reaming rock slag generated during inverted well drilling construction is accumulated upwards along a shaft from a rock slag drop point at the bottom of the shaft, and temporary support is carried out on the wall of the shaft, so that hole collapse of the ledge is prevented.

The reaming slag fences 6 may limit the release of the reaming slag 8. During reaming construction, the reaming slag enclosing wall 6 prevents the reaming slag 8 from randomly scattering, so that the reaming slag 8 is piled up only in a certain range below a shaft and gradually accumulated in the drilled shaft; when the hole-enlarging rock slag 8 in the shaft is excessively accumulated, and the distance between the upper surface of the hole-enlarging rock slag 8 and the bottom surface of the hole-enlarging drill bit 4 is smaller than a preset value, the distance measuring device 5 can remind constructors to start the slag-drawing and discharging equipment 7 in time so as to draw out part of the rock slag. In addition, when the supporting shaft is constructed, the slag drawing and discharging equipment 7 is started as required, the reaming rock slag 8 in the shaft is timely discharged, and the reaming rock slag 8 is timely conveyed away, so that the supporting hanging scaffold 9 and the upper surface of the reaming rock slag 8 are ensured to synchronously descend. The speed of the supporting shaft is matched with the slag drawing and discharging speed, if the slag drawing and discharging speed is too high and the speed of the supporting shaft is too low, the partially exposed shaft can collapse before being supported; if the deslagging is too slow, the reaming rock slag accumulated in the shaft may interfere with the support operation.

The slag removing and discharging device 7 is connected with a slag outlet reserved on the side wall of the reaming slag enclosing wall 6 through a connecting part, as shown in d in fig. 1. The size of the connecting part is designed according to the maximum rock particle diameter at the rock slag outlet when the slag drawing and discharging operation is carried out, and the structural strength, the sealing performance and the like of the connecting part are standard in that no leakage occurs at the connecting part when the water and soil pressure at the position of the connecting part reaches the maximum. Under the cooperation of the slag drawing and discharging equipment 7 and the reaming slag enclosing wall 6, the reaming slag 8 can be controllably released.

As shown in fig. 1 e, during the reaming construction, as the reamer bit 4 continuously rises toward the ground, the reaming slag 8 continuously falls toward the lower port roadway 3, and gathers together under the action of the reaming slag enclosing wall 6, and finally piles up inside the shaft expanded by the reamer bit 4. And the slag removing and discharging operation is carried out during the reaming construction, and the distance between the bottom of the reaming bit 4 and the slag surface of the reaming rock slag 8 piled in the shaft is controlled by the distance measuring device 5, so that the distance is kept between 1 and 2m until the reaming is finished. The operation is that the reaming slag 8 is piled up in the shaft, the support is formed for the shaft wall, the collapse of the shaft wall is prevented, and meanwhile, the space required by the normal operation of the reaming bit 4 is ensured.

After the reaming construction is finished, the reverse well drilling machine is disassembled, and a reaming bit is put out to prepare for well wall supporting operation. At this time, a certain space is still reserved between the slag surface of the reaming rock slag 8 and the ground. As shown in fig. 1 f, the support hanging scaffold 9 is lowered into the well bore by means of the derrick and the hoisting equipment, the support hanging scaffold 9 being located within the space formed by the slag surface of the reaming rock slag 8 and the ground. The supporting hanging scaffold 9 carries constructors and construction materials to be continuously lowered into the shaft, and the constructors implement anchor net spraying supporting operation on the shaft from top to bottom. The support operation is implemented in a sectional height manner, the height of each section is preferably not more than 4m, after each section of high support is completed, slag removal operation is carried out in the lower opening roadway 3, when the exposed unsupported shaft height reaches the height of the support section, slag removal is stopped, anchor net spray support is carried out, and anchor net spray support and slag removal circulation are formed. When the slag is drawn and discharged, the slag surface of the reaming rock slag 8 in the shaft keeps a certain height, which is beneficial for constructors to pedal gangue to perform anchor net spraying operation.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While the obvious variations or modifications which are extended therefrom remain within the scope of the claims of this patent application.

Claims (10)

1. The construction method for the large-diameter shaft reverse drilling in the soft rock area is characterized in that reaming rock slag (8) generated in reverse drilling construction is kept to be accumulated upwards along a shaft from a reaming rock slag drop point at the bottom of the shaft, a supporting shaft is carried out from top to bottom, the reaming rock slag (8) is gradually conveyed away from the reaming rock slag drop point in the process of supporting the shaft, and the speed of the supporting shaft is matched with the conveying speed of the reaming rock slag (8).

2. The construction method for large-diameter shaft back drilling in soft rock area according to claim 1, comprising the following steps:

step A: downwards drilling a guide hole at a set position above a lower port roadway (3) by using a well reversing drilling machine, and leading the guide hole into the lower port roadway (3);

and (B) step (B): installing a reaming bit (4) at the lower end of a reverse well drilling rig drill rod (2) positioned in the lower opening roadway (3), and installing a distance measuring device (5) on the reaming bit (4);

step C: building a reaming slag enclosing wall (6) at the outer side of the position corresponding to the guide hole in the lower port roadway (3), wherein the height of the reaming slag enclosing wall (6) is consistent with that of the lower port roadway (3), and a closed space is formed in the reaming slag enclosing wall (6);

step D: the slag drawing and discharging equipment (7) is arranged on the wall of the reaming slag enclosing wall (6) and extends into the reaming slag enclosing wall (6);

step E: performing reaming operation, driving the reaming bit (4) to rotate and upwards ream, simultaneously detecting the distance between the slag surface of the reaming rock slag (8) and the reaming bit (4) in real time by the distance measuring device (5), and synchronously working the slag digging and discharging equipment (7) in the upward movement process of the reaming bit (4) until the distance between the slag surface of the reaming rock slag (8) and the distance measuring device (5) is always in a set range until the reaming operation is completed;

step F: after the reaming operation is completed, taking out the reaming bit (4), and installing a supporting hanging scaffold (9) at a wellhead to support a shaft; when the shaft is supported, the sectional high supporting operation is carried out from top to bottom, after each section of high supporting operation is finished, the slag drawing and discharging equipment (7) starts to work, so that the slag surface height of the reaming rock slag (8) is reduced, and the next section of unsupported free section shaft to be supported is exposed until the shaft supporting operation is finished;

step G: and taking out the supporting hanging scaffold (9) and removing the reaming slag enclosing wall (6) after the supporting shaft operation is completed.

3. The construction method for large diameter shaft back drilling in soft rock area according to claim 2, wherein slurry is used as drilling fluid in the step a.

4. The construction method for large-diameter shaft back-drilling in soft rock areas according to claim 2, wherein in the step B, the reamer bit (4) is an air-cooled bit; the number of the distance measuring devices (5) is multiple, and the distance measuring devices are respectively and fixedly connected to the bottom center and the bottom edge of the reaming bit (4).

5. The construction method for large diameter shaft back drilling in soft rock area according to claim 2, wherein in step C, the wall of the reaming slag enclosing wall (6) forms a closed shape; the upper end and the lower end of the reaming slag enclosing wall (6) are respectively in sealing connection with the top wall and the bottom wall of the lower port roadway (3), and a slag outlet is formed in the lower end of the side face of the reaming slag enclosing wall (6).

6. The construction method for large-diameter shaft back drilling in soft rock area according to claim 5, wherein step D further comprises a connecting component, and the slag removing and discharging device (7) is connected with the slag outlet on the reaming slag enclosing wall (6) through the connecting component; the size of the connecting part is matched with the maximum rock particle diameter of the rock slag outlet, and the structural strength and the sealing performance of the connecting part are matched with the maximum water and soil pressure of the rock slag outlet.

7. The construction method for large-diameter shaft back drilling in soft rock areas according to claim 2, wherein in the step D, the slag drawing and discharging device (7) comprises a water injection assembly and a water discharge assembly which can operate independently, the water injection assembly is used for injecting water and reducing resistance when the flow resistance of the reaming slag (8) is large, and the water discharge assembly is used for discharging water and reducing pressure when the reaming slag (8) presents liquid flow state.

8. The construction method for large diameter shaft back drilling in soft rock area according to claim 2, wherein in step D, the distance between the slag surface of the reaming rock slag (8) and the bottom surface of the reaming bit (4) is 1-2 m.

9. The construction method for large-diameter shaft back drilling in soft rock areas according to claim 2, wherein in the step F, supporting shaft operation is carried out from top to bottom by using supporting hanging scaffold (9) to bear constructors and construction materials; in the process of supporting the shaft, the height of the shaft of an unsupported free section above the slag surface of the reaming rock slag (8) is less than or equal to 4m.

10. The construction method for large diameter shaft back drilling in soft rock area according to claim 2, wherein in step F, the supporting shaft operation is an anchor net spraying operation; and (5) the constructor kicks gangue to perform the anchor net spraying operation.