阅读说明：本技术 一种梳状穿层定向长钻孔分支孔煤层段精准水力压裂工艺 (Accurate hydraulic fracturing process for comb-shaped layer-through directional long-drilling branch hole coal seam section ) 是由 李文 黄旭超 王广宏 赵坤 欧聪 于 2021-05-31 设计创作，主要内容包括：本发明属于煤层增透技术领域。涉及一种梳状穿层定向长钻孔分支孔煤层段精准水力压裂工艺,包括如下步骤：S1：梳状穿层定向长钻孔：利用定向钻进设备对待掘工作面进行梳状穿层定向长钻孔施工；S2：安装压裂设备：退出定向钻进设备,并利用定向钻进设备,采用分支孔重入技术将压裂封孔器送至分支孔中指定位置；S3：利用定向钻进设备中的高压水,将压裂封孔器打开,并对梳状分支孔进行压裂；S4：退出压裂封孔器及导向筛管,重复S2、S3步骤,对其余梳状分支孔进行压裂。本发明将封孔位置设于梳状分支孔中煤层与岩层交界处,高压水直接作用于煤层本身,避免了高压水能量的损失,使增加煤层的透气性,使煤层瓦斯易于流出。(The invention belongs to the technical field of coal bed permeability improvement. Relates to a comb-shaped crossing directional long drilling branch hole coal seam section accurate hydraulic fracturing process, which comprises the following steps: s1: comb-shaped layer-penetrating directional long drilling: performing pectinate layer-penetrating directional long drilling construction on a working surface to be excavated by utilizing directional drilling equipment; s2: installing a fracturing device: withdrawing the directional drilling equipment, and conveying the fracturing hole packer to a specified position in the branch hole by utilizing the directional drilling equipment and adopting a branch hole reentry technology; s3: opening the fracturing hole packer by using high-pressure water in the directional drilling equipment, and fracturing the comb-shaped branch hole; s4: and (4) withdrawing the fracturing hole packer and the guide screen pipe, repeating the steps S2 and S3, and fracturing the rest comb-shaped branch holes. According to the invention, the hole sealing position is arranged at the junction of the coal bed and the rock stratum in the comb-shaped branch hole, and high-pressure water directly acts on the coal bed, so that the loss of high-pressure water energy is avoided, the air permeability of the coal bed is increased, and the coal bed gas is easy to flow out.)

1. The accurate hydraulic fracturing process for the comb-shaped layer-through directional long drilling branch hole coal seam section is characterized by comprising the following steps of:

s1: comb-shaped layer-penetrating directional long drilling: performing pectinate layer-penetrating directional long drilling construction on a working surface to be excavated by utilizing directional drilling equipment; the comb-shaped crossing directional long drilling is to perform main hole directional drilling in a coal seam top and bottom plate rock stratum, then penetrate the coal seam top and bottom plate rock stratum through the main hole, and perform comb-shaped branch hole directional drilling in the coal seam;

s2: installing a fracturing device: after the construction of the comb-shaped crossing directional long drilling hole is finished, withdrawing the directional drilling equipment, and conveying the fracturing hole packer to a specified position in the branch hole by utilizing the directional drilling equipment and adopting a branch hole reentry technology;

s3: opening the fracturing hole packer by using high-pressure water in the directional drilling equipment, and setting the comb-shaped branch hole; fracturing the comb-shaped branch holes by using high-pressure water in the directional drilling equipment;

s4: and (4) withdrawing the fracturing hole packer and the guide sieve tube, repeating the steps S2 and S3, and sequentially fracturing the other comb-shaped branch holes by adopting a forward type or a backward type.

2. The accurate hydraulic fracturing process for comb-shaped through-layer oriented long drilling branch hole coal seam sections according to claim 1, characterized in that: in step S1, the directional drilling equipment includes a high-pressure water pipe, a high-pressure water tail, a cabled drill rod, an upper non-magnetic drill rod, a probe pipe, a lower non-magnetic drill rod, a hole bottom motor, and a drill bit, which are connected in sequence.

3. The accurate hydraulic fracturing process for comb-shaped through-layer oriented long drilling branch hole coal seam sections according to claim 2, characterized in that: in step S2, when the directional drilling equipment is withdrawn, the hole bottom motor and the drill bit in the directional drilling tool are replaced by a fracturing hole packer and a guiding screen pipe; the fracturing hole packer is connected with a lower non-magnetic drill rod through threads or a reducing joint, and the guide sieve tube is connected with the fracturing hole packer.

4. The precise hydraulic fracturing process for comb-shaped through-layer directional long drilling branch hole coal seam sections according to claim 3, characterized in that: in the step S3, the branch hole re-entry technique is to send the fracturing hole packer into the comb-shaped branch hole through the main hole along the drilling trajectory of the comb-shaped branch hole again according to the drill rod azimuth angle and inclination angle parameters measured in the comb-shaped branch hole directional drilling construction process in the step S1.

5. The precise hydraulic fracturing process for comb-shaped through-layer directional long drilling branch hole coal seam sections according to claim 4, characterized in that: the fracturing hole packer is guided to be positive through a guide sieve tube in the process of feeding the fracturing hole packer into the comb-shaped branch holes from the main hole; the guide sieve tube comprises a horizontal section and an elbow section, the horizontal section is connected with the fracturing hole packer, and the front end of the elbow section is connected with a drill bit through threads; the elbow section is connected with the horizontal section, and the elbow section and the horizontal section form an included angle of 170-178 degrees.

6. The precise hydraulic fracturing process for comb-shaped through-layer directional long drilling branch hole coal seam sections according to claim 5, characterized in that: and the horizontal section is provided with sieve pores which are uniformly distributed on the horizontal section.

7. The precise hydraulic fracturing process for comb-shaped through-layer directional long drilling branch hole coal seam sections according to claim 3, characterized in that: in step S3, the injection pressure of the high-pressure water pump is greater than or equal to 30MPa, and the hole sealing pressure is greater than or equal to 30 MPa.

8. The accurate hydraulic fracturing process for comb-shaped through-layer oriented long drilling branch hole coal seam sections according to claim 1, characterized in that: in step S3, the designated location is a boundary between a coal seam and a rock formation.

9. The accurate hydraulic fracturing process for comb-shaped through-layer oriented long drilling branch hole coal seam sections according to claim 1, characterized in that: in step S1, the aperture of the comb-shaped layer-penetrating directional long drilling hole is 96-102 mm, and the length of the main hole is 100-500 m.

10. The accurate hydraulic fracturing process for comb-shaped through-layer oriented long drilling branch hole coal seam sections according to claim 1, characterized in that: in step S1, the coal seam structure is original structure coal or cracked coal, the hardness coefficient of the coal seam is more than 0.6, and the fracture initiation pressure of the coal seam is less than 20 MPa.

Technical Field

The invention belongs to the technical field of coal seam permeability improvement, and relates to a comb-shaped layer-penetrating directional long-drilling branched-hole coal seam section accurate hydraulic fracturing process.

Background

The large amount of gas generated along with the coal mining process poses a significant threat to the safety production of coal mines, particularly for coal and gas outburst coal seams. The method for pre-pumping coal bed gas by using the drill hole before mining is an important and effective means for controlling the gas problem in China at present. At present, with the development and progress of underground directional drilling extraction technology and equipment, the directional long-drill hole pre-extraction coal seam gas technology is widely applied, wherein for broken soft coal seams, due to poor hole forming performance, long-distance bedding drilling is difficult to achieve, directional long-drill hole main hole drilling is mostly implemented in a coal seam top and bottom plate rock stratum, and then comb-shaped through-layer branch holes are constructed to the coal seam through the main holes, so that large-range advanced extraction of the coal seam gas is achieved.

In recent years, in order to further improve the gas treatment effect of a broken soft, low-permeability and high-gas outburst coal seam, the hydraulic fracturing technology for directional long drilling is widely applied and researched, at present, the hydraulic fracturing of the comb-shaped through-layer directional long drilling mainly adopts the integral fracturing of a main hole and a branch hole, the hole sealing depth is about 100m, so that most of high-pressure water acts on rocks, only a small amount of high-pressure water acts on the coal seam, and therefore, the hydraulic fracturing has the following defects:

1) because fractures develop in the top and bottom floor strata of the coal seam, particularly in areas of complex construction. Along with the increase of pressure in the water injection process, water can be lost from rock stratum cracks, the pressure maintaining difficulty of comb-shaped crossing directional long drilling is caused, the pressure of fluid in holes is difficult to rise, and the coal bed fracturing effect is poor.

2) Because the coal seam has very strong heterogeneity, in the whole fracturing process, the high-pressure water body firstly acts on the weak part of the coal seam, and once the weak part of the coal seam is broken to form an advantageous channel, the high-pressure water body is difficult to act on the non-weak part of the coal seam again, so that the fracturing effect of the coal seam is uneven.

Disclosure of Invention

In view of the above, the invention aims to overcome the defects of the existing hydraulic fracturing process for comb-shaped through-layer directional long drilling, improve the hydraulic fracturing effect of a coal seam, and provide the accurate hydraulic fracturing process for the branch hole coal seam section of the comb-shaped through-layer directional long drilling.

In order to achieve the purpose, the invention provides the following technical scheme:

a comb-shaped through-layer directional long-drilling branch hole coal seam section accurate hydraulic fracturing process comprises the following steps:

s1: comb-shaped layer-penetrating directional long drilling: carrying out comb-shaped layer-penetrating directional long drilling construction on a working surface to be excavated by utilizing directional drilling equipment; the comb-shaped crossing directional long drilling is to perform main hole directional drilling in a coal seam top and bottom plate rock stratum, and then perform comb-shaped branch hole directional drilling in the coal seam by the main hole crossing the coal seam top and bottom plate rock stratum;

s2: installing a fracturing device: after the construction of the comb-shaped crossing directional long drilling hole is finished, withdrawing the directional drilling equipment, and conveying the fracturing hole packer to a specified position in the branch hole by utilizing the directional drilling equipment and adopting a branch hole re-entering technology;

s3: opening the fracturing hole packer by using high-pressure water in the directional drilling equipment, and setting the comb-shaped branch hole; fracturing the comb-shaped branch holes by using high-pressure water in the directional drilling equipment;

s4: and (4) withdrawing the fracturing hole packer and the guide sieve tube, repeating the steps S2 and S3, and sequentially fracturing the rest comb-shaped branch holes by adopting a forward type or a backward type.

This basic scheme sets up the fracturing hole packer in the assigned position, makes the high pressure water act on locally, has avoided the loss of high pressure water energy, and high pressure water energy utilization improves, has improved coal seam fracturing effect.

Further, in step S1, the directional drilling equipment includes a high-pressure water pipe, a high-pressure water tail, a cabled drill rod, an upper non-magnetic drill rod, a probe pipe, a lower non-magnetic drill rod, a hole bottom motor, and a drill bit, which are connected in sequence.

Further, in step S2, when the directional drilling equipment is withdrawn, the hole bottom motor and the drill bit in the directional drilling tool are replaced by a fracturing hole packer and a guiding sieve tube; the fracturing hole packer is connected with the lower nonmagnetic drill rod by threads or reducing joints, and the guide sieve tube is connected with the fracturing hole packer.

Further, in step S3, the branch hole re-entry technique is to send the fracturing hole packer into the comb-shaped branch hole through the main hole again along the drilling trajectory of the comb-shaped branch hole according to the azimuth angle and inclination angle parameters of the drill stem measured in the comb-shaped branch hole directional drilling construction process in step S1.

Further, the fracturing hole packer is guided by a guide sieve tube in the process of feeding the fracturing hole packer into the comb-shaped branch holes from the main hole; the guide sieve tube comprises a horizontal section and an elbow section, the horizontal section is connected with the fracturing hole packer, and the front end of the elbow section is connected with a drill bit through threads; the elbow section is connected with the horizontal section, an included angle of 170-178 degrees is formed between the elbow section and the horizontal section, the front end of the guide sieve tube is connected with a drill bit, and the guide sieve tube can drill in a rotating mode when slight hole collapse or hole drilling reducing occurs in the reentry process of the branch hole; the included angle of 170-178 degrees is convenient for entering the comb-shaped branch holes from the main hole.

Furthermore, sieve pores are arranged on the horizontal section and are uniformly distributed on the horizontal section.

Further, in step S3, the injection pressure of the high-pressure water pump is not less than 30MPa, and the sealing pressure is not less than 30 MPa.

Further, in step S3, the designated location is a boundary between the coal seam and the rock formation.

Further, in step S1, the aperture of the comb-shaped layer-penetrating directional long drill hole is 96-102 mm, and the length of the main hole is 100-500 m

Further, in step S1, the coal seam structure is original structure coal or cracked coal, the hardness coefficient of the coal seam is greater than 0.6, and the fracture initiation pressure of the coal seam is less than 20 MPa.

The invention has the beneficial effects that:

1) according to the invention, the hole sealing position is arranged at the junction of the coal bed and the rock stratum in the comb-shaped branch hole, and high-pressure water directly acts on the coal bed, so that the loss of high-pressure water energy is avoided, the air permeability of the coal bed is increased, and the coal bed gas is easy to flow out.

2) The traditional process adopts a common fracturing tool string, and high-pressure water is conveyed through a fracturing steel pipe.

3) The guide sieve tube is used for guiding a drill rod when the drill rod enters the comb-shaped branch hole, and the guide sieve tube is combined with the branch hole reentry technology, so that the positioning is accurate, and the comb-shaped branch hole position is easier to find.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram of the position of a fracturing packer in a comb-shaped branch hole in the invention;

FIG. 2 is a schematic diagram of a comb-shaped branching hole fracturing process in the present invention;

FIG. 3 is a schematic diagram of conventional comb-shaped branch hole fracturing;

FIG. 4 is a schematic illustration of the installation of a frac packer in a drilling apparatus;

FIG. 5 is a schematic view of a guide screen configuration.

Reference numerals: 1-a rock formation; 2-coal bed; 3-a main hole; 4-comb branch holes; 5-fracturing the tube; 6-high pressure water pipe; 7-fracturing hole packer; 8-guiding a sieve tube; 9-high pressure water tail; 10-a cable-passing drill pipe; 11-installing a non-magnetic drill rod; 12-a probe; 13-lower non-magnetic drill rod; 81-horizontal segment; 82-a bend section; 83-mesh.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

Example 1

Referring to fig. 1 to 2, a comb-shaped perforating directional long drilling branched coal seam section accurate hydraulic fracturing process includes the following steps:

s1: comb-shaped layer-penetrating directional long drilling: carrying out comb-shaped layer-penetrating directional long drilling construction on a working surface to be excavated by utilizing directional drilling equipment; the comb-shaped through-layer directional long drilling is to perform directional drilling on a main hole 3 in a top floor rock stratum 1 of a coal seam 2, wherein the diameter of the main hole 3 is 98mm, the length of the main hole 3 is 300m, and then the main hole 3 penetrates through the top floor rock stratum 1 of the coal seam 2 to perform directional drilling on a comb-shaped branch hole 4 in the coal seam 2;

s2: installing a fracturing device: after the construction of the comb-shaped crossing directional long drilling hole is finished, withdrawing the directional drilling equipment, and conveying the fracturing hole packer 7 to the junction of the coal seam 2 and the rock stratum 1 in the branch hole by utilizing the directional drilling equipment and adopting a branch hole re-entry technology;

s3: opening the fracturing hole packer 7 by using high-pressure water in the directional drilling equipment, and setting the comb-shaped branch hole 4; and the comb-shaped branch hole 4 is fractured by using high-pressure water in the directional drilling equipment; wherein, the injection pressure of the high-pressure water pump is more than or equal to 30MPa, and the hole sealing pressure is more than or equal to 30 MPa.

S4: and (4) withdrawing the fracturing hole packer 7 and the guide sieve tube 8, repeating the steps S2 and S3, and sequentially fracturing the rest comb-shaped branch holes 4 by adopting a retreating mode.

Referring to fig. 4, the directional drilling equipment includes a high-pressure water pipe 6, a high-pressure water tail 9, a cable-passing drill rod 10, an upper nonmagnetic drill rod 11, a probe pipe 12, a lower nonmagnetic drill rod 13, a hole bottom motor, and a drill bit, which are connected in sequence; in step S2, when the directional drilling equipment is withdrawn, the hole bottom motor and the drill bit in the directional drilling tool are replaced by the fracturing hole packer 7 and the guide sieve tube 8; the fracturing hole packer 7 is connected with a lower non-magnetic drill rod 13 by threads, and the guide sieve tube 8 is connected with the fracturing hole packer 7.

In the embodiment, the branch hole reentry technology is that according to the azimuth angle and inclination angle parameters of the drill rod measured in the directional drilling construction process of the comb-shaped branch hole 4 in S1, the track is drilled along the comb-shaped branch hole 4 again, and the fracturing hole packer 7 is sent into the comb-shaped branch hole 4 through the main hole 3; the fracturing packer 7 is guided by the guide sieve tube 8 in the process of feeding from the main hole 3 to the comb-shaped branch hole 4.

Referring to fig. 5, the guiding screen pipe 8 includes a horizontal section 81 and an elbow section 82, the horizontal section 81 is connected with the fracturing hole packer 7, the elbow section 82 is connected with the horizontal section 81, and an included angle of 178 degrees is formed between the elbow section 82 and the horizontal section 81; the horizontal section 81 is provided with sieve holes 83, and the sieve holes 83 are uniformly distributed on the horizontal section 81.

In this embodiment, the structure of the coal seam 2 is original structure coal or cracked coal, the hardness coefficient of the coal seam 2 is greater than 0.6, and the fracture initiation pressure of the coal seam 2 is less than 20 MPa.

Comparative examples

Referring to fig. 3, a schematic view of a conventional comb-shaped branch hole 4 fracturing process is shown, which is different from embodiment 1 in that: the fracturing hole packer 7 is used for setting and sealing the main hole 3, high-pressure water is introduced into the comb-shaped branch hole 4 through the fracturing pipe 5, the main hole 3 and the comb-shaped branch hole 4 are integrally fractured, most of high-pressure water acts on rocks in the process, and only a small amount of high-pressure water acts on the coal bed 2.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all that should be covered by the claims of the present invention.