Construction method for large-aperture drilling
Technical Field
The invention belongs to the field of mining, and particularly relates to a construction method for large-aperture drilling.
Background
The large-aperture drill hole 1 can be applied to a cable hole, a gas extraction hole, a coal mine lifesaving hole, a coal mine ventilation hole and the like of a coal mine. The construction process generally comprises the steps of constructing a guide hole 10, expanding holes in a grading way, setting a production casing 2 for well cementation and waiting for setting, cleaning cement and a buoyancy plate 21 in the hole, lifting residual cement slurry in the hole and forming the hole. However, the conventional pilot hole 10 construction process generally adopts the conventional rotary drilling technology, and the inclination measurement of the drill hole 1 is carried out in stages, which is defined as the track of the passive control drill hole 1; after the construction of the guide hole 10 is finished, carrying out grading and multiple chambering until the hole diameter meets the requirement, wherein the auxiliary time for tripping is long, and the potential safety hazard is large; in the process of cleaning the cement and the buoyancy plate 21 in the hole, the buoyancy plate 21 is made of metal, so that the drill jamming accident is easily caused, and the drill bit has the risk of damaging the pipe wall of the production casing 2; in the construction process of lifting the residual cement paste in the hole, because the amount of the residual cement paste in the later period is small, the last lifting barrel 3 cannot lift the cement paste in the hole, the final net hole depth is smaller than the preset hole depth, and the existing buoyancy plates 21 are provided with check assemblies (such as check valves) which penetrate through the existing buoyancy plates from top to bottom.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a construction method for drilling a hole with a large aperture, which is convenient to construct, has few working procedures and can meet the requirement of drilling depth.
In order to achieve the purpose, the technical scheme of the invention is as follows: a construction method for large-aperture drilling comprises the following steps:
step 1: drilling a guide hole by adopting a directional drilling process, wherein the depth of the guide hole is 5-20m greater than the preset hole depth, and the hole section of which the lower end is greater than the preset depth is a sand settling section;
step 2: reaming the guide hole to a preset hole diameter of the drilled hole;
and step 3: a production casing is put in, the length of the production casing is consistent with the depth of the drilled hole, a buoyancy plate is fixedly arranged at the position corresponding to the sand settling section in the production casing, and a seepage hole penetrating through the pipe wall of the buoyancy plate is formed in the lower end of the production casing and positioned below the buoyancy plate;
and 4, step 4: adding cement slurry into the production casing, plugging a pipe orifice of the production casing, and then pressurizing the production casing, so that part of the cement slurry in the production casing is immersed below the buoyancy plate through the buoyancy plate, cement slurry entering the lower part of the buoyancy plate through a lifting bucket is infiltrated between the production casing and the wall of the drilled hole through seepage holes under the pressure action, and gaps between the production casing and the wall of the drilled hole are filled;
and 5: and removing part of the cement slurry in the production casing by using a lifting barrel so that the net well depth in the production casing is greater than the preset depth of the guide hole, and finishing the drilling construction.
The beneficial effects of the above technical scheme are that: the depth of the drilled hole is drilled to be 5-15m greater than the preset depth, so that the buoyancy plate is positioned in the sand sinking section after the production casing is lowered, and after cement slurry is added to fill the hole between the production casing and the drilled hole and the lower end of the sand sinking section in the production casing, the drilled hole with the hole depth greater than the preset hole depth can be obtained without damaging the buoyancy plate and the cement slurry layer at the inner lower end of the production casing by using a drill bit again afterwards, and the whole construction process of the construction method is few.
In the technical scheme, the hole depth of the guide hole in the step 1 is 15-20m greater than the preset hole depth.
The beneficial effects of the above technical scheme are that: so that the desilting section can better satisfy the construction requirement of grout grouting.
In the technical scheme, in the reaming process of the guide hole in the step 2, the reaming is performed in a grading manner by adopting a diameter step combined drill.
The beneficial effects of the above technical scheme are that: therefore, the requirements of the reaming process on the drilling equipment are reduced, and the equipment cost is reduced.
In the technical scheme, a plurality of seepage holes are formed in the wall of the production casing in the step 3 and are uniformly distributed on the wall of the production casing.
The beneficial effects of the above technical scheme are that: therefore, cement slurry in the production casing can uniformly seep into a gap between the production casing and the hole wall bracket of the drill hole.
In the technical scheme, the depth of the buoyancy plate in the production sleeve is greater than the sum of the preset depth of the drill hole and the height of the lifting barrel.
The beneficial effects of the above technical scheme are that: therefore, the cement slurry layer can be kept at the upper end of the buoyancy plate, and the upper end of the lifting barrel is below the preset depth when the lifting barrel is required to stand at the upper end of the cement slurry layer.
Drawings
FIG. 1 is a schematic structural diagram of a pilot hole drilled in step 1 of a construction method for large-aperture drilling according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a drill hole after the reaming in step 2 in the construction method of the large-aperture drill hole according to the embodiment of the invention;
FIG. 3 is a schematic structural diagram of the construction method for large-aperture drilling according to the embodiment of the present invention, after a production casing is inserted into the drilling hole in step 3;
fig. 4 is a schematic structural diagram of the large-aperture drilling construction method according to the embodiment of the present invention after cement slurry is added into the drilled hole in step 4 and step 5.
In the figure: 10 pilot holes, 1 drilling hole, 2 production casing pipes, 21 buoyancy plates, 22 seepage holes and 3 buckets.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
The embodiment provides a construction method for large-aperture drilling, which comprises the following steps:
step 1: drilling a guide hole 10 by adopting a directional drilling process, wherein the depth of the guide hole 10 is 5-20m greater than the preset hole depth, and the hole section of the lower end of the guide hole 10, which is greater than the preset depth, is a sand settling section, as shown in figure 1;
step 2: reaming the guide hole 10 to a preset hole diameter of the drill hole 1, as shown in fig. 2;
and step 3: a production casing 2 is put in, the length of the production casing 2 is consistent with the depth of the drill hole 1, a buoyancy plate 21 is fixedly arranged at a position corresponding to a sand sinking section in the production casing 2, and a seepage hole 22 penetrating through the pipe wall of the buoyancy plate 21 is arranged below the lower end of the production casing 2 and positioned below the buoyancy plate 21, as shown in fig. 3;
and 4, step 4: adding cement slurry into the production casing 2, plugging the pipe orifice of the production casing 2, and then pressurizing the production casing 2, so that part of the cement slurry in the production casing 2 is immersed below the buoyancy plate 21 through the non-return component, the cement slurry entering the lower part of the buoyancy plate 21 through the lifting bucket 3 is infiltrated between the production casing 2 and the hole wall of the drill hole 1 through the seepage hole 22 under the pressure effect, and the gap between the production casing 2 and the hole wall of the drill hole 1 is filled;
and 5: and removing part of the cement slurry in the production casing 2 by using the lifting barrel 3, so that the net well depth in the production casing 2 is greater than the preset depth of the guide hole 10, and the construction of the drilling hole 1 is completed. The depth of the drill hole 1 is drilled to be greater than the preset depth by 5-15m, so that the buoyancy plate 21 is positioned in the sand sinking section after the production casing 2 is lowered, and after cement slurry is added to fill the hole between the production casing 2 and the drill hole 1 and the lower end of the sand sinking section in the production casing 2, the drill hole 1 with the hole depth greater than the preset hole depth can be obtained without damaging the buoyancy plate 21 and the cement slurry layer at the inner lower end of the production casing 2 by a drill bit, and the whole construction process of the construction method is few, as shown in fig. 4.
In the technical scheme, the hole depth of the guide hole 10 in the step 1 is 15-20m greater than the preset hole depth, so that the sand settling section can better meet the construction requirement of cement slurry grouting.
In the technical scheme, the reaming process of the guide hole 10 in the step 2 is to perform reaming by adopting the diameter step combined drill bit in a grading manner, so that the requirement of the reaming process on the drilling 1 equipment is reduced, and the equipment cost is reduced.
In the technical scheme, a plurality of seepage holes 22 are formed in the pipe wall of the production casing 2 in the step 3, and the plurality of seepage holes 22 are uniformly distributed in the pipe wall of the production casing 2, so that cement slurry in the production casing 2 can be uniformly seeped into a gap between the production casing 2 and the hole wall support of the drill hole 1.
In the technical scheme, the depth of the buoyancy plate 21 in the production casing 2 is greater than the sum of the preset depth of the drill hole 1 and the height of the lifting barrel 3, so that a cement slurry layer can be reserved at the upper end of the buoyancy plate 21, and when the lifting barrel 3 is required to stand at the upper end of the cement slurry layer, the upper end of the lifting barrel 3 is below the preset depth.
The invention is characterized in that the drill bit is not needed to be reused in the later period to destroy the structures of the buoyancy plates at the inner and lower ends of the drill hole and the cement slurry layers at the upper and lower ends of the buoyancy plates, and in addition, the clean well depth of the drill hole can be ensured to meet the requirements.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.