CN110541697B - Expansion hose type hydraulic fracturing method for permeability increase of coal seam - Google Patents

Abstract

The invention discloses an expansion hose type hydraulic fracturing method for permeability increase of a coal seam, which comprises five steps of assembling a hydraulic fracturing system, drilling the coal seam, arranging an expansion hose, fracturing and releasing pressure.

Description

Expansion hose type hydraulic fracturing method for permeability increase of coal seam

Technical Field

The invention relates to the technical field of permeability improvement of a coal seam with high gas concentration, in particular to an expansion hose type hydraulic fracturing method for permeability improvement of the coal seam.

Background

The coal in China has poor geological occurrence conditions, low hardness, high gas content and poor air permeability. Along with the increase of the mining depth, the air permeability of the coal seam becomes worse, the difficulty of gas extraction is increased, and the extraction efficiency is lower. Due to the fact that the coal seam is soft, the problems of hole collapse, hole spraying, hole blocking and the like are prone to occurring during gas lottery drilling, and safety production of a mine is seriously affected. The hydraulic fracturing technology can reduce the pressure of a drilled hole, improve the air permeability of a coal bed, enlarge the pressure relief range and be widely applied in recent years. At present, the hydraulic fracturing technology is mainly divided into two modes of bedding drilling and cross-layer drilling. However, when the two schemes are applied to soft coal seams with low air permeability and high gas concentration, on one hand, due to low strength and unstable coal seam stress, phenomena such as drilling collapse, compaction and the like are easy to occur. On the other hand, the combination of high pressure water and soft coal seams in coal seam drilling holes to form coal slurry can also cause hole collapse. Therefore, the effect of implementing a hydraulic fracturing permeability-increasing scheme in the soft coal seam with low air permeability and high gas concentration is not good. In addition, a large amount of water resources are wasted by the two hydraulic fracturing methods, and leaked water is accumulated on a coal face, so that the development of coal mining work is influenced.

Disclosure of Invention

Aiming at the technical defects, the invention aims to provide an expansion hose type hydraulic fracturing method for permeability increase of a coal seam, which utilizes an expansion hose to avoid water from blocking air holes and prevent waste of water resources, thereby solving the problem that the existing soft coal seam gas with low air permeability and high gas concentration is difficult to extract.

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

the invention provides an expansion hose type hydraulic fracturing method for permeability increase of a coal seam, which specifically comprises the following steps:

1) assembling the hydraulic fracturing system; the water tank, the high-pressure pump and the reducing flange are connected in sequence through the main pressure-bearing hose, and the reducing flange is provided with a plurality of reducing ports and is connected with the steel pipe through the auxiliary pressure-bearing hose respectively; a pressure gauge and a pressure relief valve are arranged at the water outlet of the high-pressure pump;

2) opening a hole; a plurality of hydraulic fracturing drill holes are formed in the position, vertical or parallel to the coal seam, of the mining section;

3) arranging an expansion hose; the method comprises the following steps of (1) penetrating a plurality of expansion hoses which have the same diameter as a hydraulic fracturing drill hole and are sealed at one ends into the hydraulic fracturing drill hole, wherein the sealed ends face downwards, and the open ends of the expansion hoses are respectively connected with a steel pipe;

4) and fracturing; connecting a water supply pipe in a mine roadway with a water inlet of a water tank, keeping the water pressure of the water tank stable, starting a high-pressure pump, enabling high-pressure water to enter each expansion hose through a reducing flange, and enabling the expansion hoses to continuously expand and extrude a peripheral coal seam under the condition that the water pressure is continuously increased, so that a coal seam structure is damaged, cracks are formed, and the air permeability of the coal seam is enhanced;

5) releasing pressure; and after the coal seam is damaged to form cracks, opening a pressure relief valve connected with a water outlet of the high-pressure pump, relieving the pressure of the whole system, and pumping out the expansion hose after the pressure relief is finished.

Preferably, the distance between the hydraulic fracturing drill holes is 2-5 m, and the depth of the hydraulic fracturing drill holes is 20-80 m.

Preferably, the pressure range of the high-pressure water at the outlet of the high-pressure pump is 10-60 Mpa.

Preferably, the material of the expansion hose is elastic rubber.

Preferably, the diameter of the hydraulic fracturing drill hole is 8-20 cm.

The invention has the beneficial effects that: the expansion hose in the drill hole is expanded through high-pressure water provided by the high-pressure pump, the fracture structure of the coal bed is damaged under the action of the expansion hose, cracks are formed, and the effects of permeability increasing and pressure relief are achieved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a hydraulic fracturing system provided by an embodiment of the invention;

FIG. 2 is a schematic view of an expanded hose according to an embodiment of the present invention; .

Description of reference numerals:

1. a water tank; 2. a high pressure pump; 3. a main pressure-bearing hose; 4. a variable diameter flange; 5. a steel pipe; 6. hydraulic fracturing drilling; 7. the hose is inflated.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

1-2, an expansion hose type hydraulic fracturing method for coal seam permeability increasing, 1) assembling a hydraulic fracturing system; thewater tank 1, the high-pressure pump 2 and the reducingflange 4 are connected in sequence through the main pressure-bearinghose 3, and the reducingflange 4 is provided with a plurality of reducing ports and is connected with thesteel pipe 5 through the auxiliary pressure-bearing hoses; a water outlet of the high-pressure pump 2 is provided with a pressure gauge and a pressure relief valve; the pressure range of the high-pressure water at the outlet of the high-pressure pump 2 is 10-60 Mpa.

2) Opening a hole; a plurality of hydraulic fracturing drill holes 6 with the diameter of 8-20 cm are formed in the position, vertical or parallel to the coal seam, of the mining section; the distance between the hydraulic fracturing drill holes 6 is 2-5 m, and the depth of the hydraulic fracturing drill holes 6 is 20-80 m.

3) Anexpansion hose 7 made of elastic rubber is arranged; theexpansion hose 7 with the same diameter as the hydraulic fracturing drill hole 6 and one sealed end is inserted into the hydraulic fracturing drill hole 6, the sealed end faces downwards, and the open end of theexpansion hose 7 is connected with thesteel pipe 5;

4) and fracturing; connecting a water supply pipe in a mine roadway with a water inlet of awater tank 1, keeping the water pressure of thewater tank 1 stable, starting a high-pressure pump 2, enabling high-pressure water to enter eachexpansion hose 7 through a reducingflange 4, and enabling theexpansion hoses 7 to continuously expand and extrude a peripheral coal seam under the condition that the water pressure is continuously increased, so that a coal seam structure is damaged, cracks are formed, and the air permeability of the coal seam is enhanced;

5) releasing pressure; and after the coal seam is damaged to form cracks, opening a pressure relief valve connected with the water outlet of the high-pressure pump 2, relieving the pressure of the whole system, and pumping out theexpansion hose 7 after the pressure relief is finished.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (5)

Translated fromChinese

1.一种用于松软煤层增透的膨胀软管式水力压裂方法，其特征在于，具体包括以下步骤：1. a kind of expansion hose type hydraulic fracturing method for the permeability enhancement of soft coal seam, is characterized in that, specifically comprises the following steps:1）、组装水力压裂系统；通过主承压软管依次将水箱、高压泵、变径法兰连接，变径法兰设有若干个变径端口并分别通过副承压软管连接钢管；高压泵的出水口设有压力表和卸压阀；1) Assemble the hydraulic fracturing system; connect the water tank, the high-pressure pump, and the reducing flange in sequence through the main pressure-bearing hose, and the reducing flange is provided with several reducing ports, which are respectively connected to the steel pipe through the auxiliary pressure-bearing hose; The outlet of the high-pressure pump is provided with a pressure gauge and a pressure relief valve;2）、开孔；在开采截面上垂直或平行于煤层的位置开设若干个水力压裂钻孔；2) Opening holes; opening a number of hydraulic fracturing holes on the mining section perpendicular or parallel to the coal seam;3）、设置膨胀软管；将与水力压裂钻孔直径相同且一端密封的膨胀软管深入到水力压裂钻孔内，密封端朝下，膨胀软管开口端分别与钢管连接；3) Set the expansion hose; insert the expansion hose with the same diameter as the hydraulic fracturing borehole and one end sealed into the hydraulic fracturing borehole, with the sealing end facing down, and the open ends of the expansion hose are respectively connected to the steel pipe;4）、压裂；将矿井巷道里的供水管与水箱进水口连接，保持水箱水压稳定，开启高压泵，高压水经过变径法兰进入各个膨胀软管，膨胀软管在水压力不断升高的情况下不断膨胀挤压周边煤层，使得煤层结构遭到破环，形成裂隙，增强煤层透气性；4) Fracturing; connect the water supply pipe in the mine tunnel to the water inlet of the water tank, keep the water pressure of the water tank stable, turn on the high-pressure pump, and the high-pressure water enters each expansion hose through the reducing flange, and the expansion hose continues to rise in water pressure. In the case of high temperature, the surrounding coal seam will be continuously expanded and squeezed, which will destroy the coal seam structure, form cracks, and enhance the coal seam permeability;5）、卸压；在煤层遭到破坏形成裂隙后，打开高压泵出水口连接的卸压阀，对整个系统进行卸压，卸压完成后，将膨胀软管抽出。5) Pressure relief; after the coal seam is damaged to form cracks, open the pressure relief valve connected to the water outlet of the high-pressure pump to relieve the pressure of the entire system. After the pressure relief is completed, pull out the expansion hose.2.如权利要求1所述的一种用于松软煤层增透的膨胀软管式水力压裂方法，其特征在于，步骤2）中，水力压裂钻孔之间的间距为2～5m，水力压裂钻孔的深度为20～80m。2 . The expansion hose type hydraulic fracturing method for increasing permeability of soft coal seams according to claim 1 , wherein, in step 2), the spacing between the hydraulic fracturing boreholes is 2 to 5 m, 2 . The depth of the hydraulic fracturing borehole is 20-80m.3.如权利要求1所述的一种用于松软煤层增透的膨胀软管式水力压裂方法，其特征在于，高压泵的出口处高压水的压力范围为10～60Mpa。3 . The expansion hose type hydraulic fracturing method for increasing the permeability of soft coal seams according to claim 1 , wherein the pressure range of the high-pressure water at the outlet of the high-pressure pump is 10-60 Mpa. 4 .4.如权利要求1所述的一种用于松软煤层增透的膨胀软管式水力压裂方法，其特征在于，步骤3）中，膨胀软管材质采用弹性橡胶。4 . The expansion hose type hydraulic fracturing method for increasing the permeability of soft coal seams according to claim 1 , wherein, in step 3), the material of the expansion hose is elastic rubber. 5 .5.如权利要求1所述的一种用于松软煤层增透的膨胀软管式水力压裂方法，其特征在于，步骤2)中，水力压裂钻孔的直径为8～20cm。5 . The expansion hose type hydraulic fracturing method for increasing the permeability of soft coal seams according to claim 1 , wherein in step 2), the diameter of the hydraulic fracturing borehole is 8-20 cm. 6 .

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