Variation law of roof stress and permeability enhancement effect of repeated hydraulic fracturing in low‐permeability coal seam

Liangwei, Li; Wu, Wei

doi:10.1002/ese3.909

Cited by 5 publications

(3 citation statements)

References 31 publications

(32 reference statements)

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“…These cracks gradually expand and extend with an increase in the fracturing time, and the amount of fracture damage gradually increases. This damage further causes the cracking, expansion, and extension of secondary cracks, so that the fracturing fluid can enter the secondary cracks. , Practices and research show that compared with other permeability enhancement techniques, hydraulic fracturing technology has many advantages such as simplicity and ease, cost effectiveness, and practicality. This technology can not only increase the overall permeability of the coal seam but also solve the problem of the overall mechanical properties of coal rock bodies.…”

Section: Current Status Of Research On Hydraulic Coal and Gas Outburs...mentioning

confidence: 99%

Current Status of Research on the Coal and Gas Outburst Control Technology of Hydration and Anhydrous

Zhang,

Wang,

Chen

2023

ACS Omega

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China is one of the countries with the most frequent coal and gas outburst accidents in the world. In the early years of the founding of New China, coal and gas outburst accidents occurred frequently, causing serious casualties, equipment damage, and economic losses. In recent years, some scholars have tried to simulate the coal and gas outburst phenomenon using physical models to study the mechanisms of its occurrence. However, due to the complexity and nonreproducibility of coal and gas outburst disasters, the study of coal and gas outburst mechanisms is still in the hypothesis stage. In order to effectively reduce the risk of coal and gas outburst accidents, coal and gas outburst prevention and control technology have emerged and achieved remarkable results, and the probability of coal and gas outburst accidents has been greatly reduced. Among coal and gas protrusion outburst and control technologies, hydraulic and anhydrous prevention and control technologies are widely used. The purpose of this paper is to briefly explain the mainstream hypothesis of coal and gas outburst, analyze the action principle of hydration and anhydrous control technologies, discuss the current status of research on hydration and anhydrous control technologies, and put forward the problems of current technologies and future development trends.

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Section: Current Status Of Research On Hydraulic Coal and Gas Outburs...mentioning

confidence: 99%

Current Status of Research on the Coal and Gas Outburst Control Technology of Hydration and Anhydrous

Zhang,

Wang,

Chen

2023

ACS Omega

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“…Many coal seams in China have limited permeability, which has a negative impact on direct gas extraction efficiency and raises production costs. To raise the permeability of coal seams and increase the effectiveness of gas extraction, artificial approaches must be used [12][13][14][15][16]. Hydraulic fracturing is a technology for extracting gas.…”

Section: Introductionmentioning

confidence: 99%

Research on Hydraulic Fracturing Technology of Long Boreholes along Strata of High Vast Thick Coal Seam

Wang,

Li,

Liu

et al. 2024

Advances in Civil Engineering

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Gas extraction is a major technique for regional gas regulation and coal and gas comining in China. Assuring effective gas extraction operations is a crucial step in ensuring the supply of energy. The effect range of extraction drilling, pressure relief degree, and standard period of gas extraction are all constrained because of the geological constraints affecting coal gas permeability and occurrence. Combined with the advantages of directional drilling and high-efficiency pumping technology and antireflection enhanced pumping technology of hydraulic fracturing, directional long-drilling hydraulic fracturing can effectively improve the efficiency of gas control and expand the scale of gas control. The present study focuses on the exploration of directional long-hole hydraulic fracturing technique in thick coal seams with high gas content using Dafosi Mine as a case study. The research findings demonstrate that hydraulic fracturing contributes to the enlargement of pore size, pore density, and pore connectivity in coal seams. In-depth research was conducted on the expansion of coal seam fractures during the hydraulic fracturing process using the RFPA3D-flow numerical simulation program. Additionally, a comprehensive analysis of stress distribution around the fractures under the flow-solid coupling condition was performed. To further improve the effectiveness of hydraulic fracturing technique, the research team optimized the fracturing tools and construction processes in the four coal seams of Dafosi Mine. The impact of segmented hydraulic fracturing in coal seam bare hole drilling was also studied. Furthermore, an investigation method specific to the coal seam bare hole segmented hydraulic fracturing effects applicable to Dafosi Mine was developed. The maximum fracture extension pressure, minimum fracture closure pressure, and fracture morphology change characteristics during drilling and fracturing were measured, and the fracturing influence radius of coal seam was determined to be 46−58 m, the gas extraction concentration after fracturing increased by 2.20–4.22 times, and the 100-m extraction flow increased by 4.93–11.03 times. It gives other mines technical assistance so they can keep advocating and utilizing the horizontal directional long-drilling stage hydraulic fracturing technique.

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“…With the increase in coal mining intensity and the rapid growth of mining depth, the problems of gas outbursts are becoming more serious [1][2][3]. Terefore, the predraining boreholes are required to prevent gas outbursts [4][5][6]. Directional drilling technology (DDT) has the advantages of a controllable track, a long efective extraction distance, multiple branch holes, and a large concentrated extraction area, as well as the advantages of a lower drilling construction cost and high-efciency gas extraction [7].…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of the Stress Distribution and Concentration Factors of the Tool Joint of the Directional Drill Pipe

Shu

Zhao

Mei

et al. 2023

Mathematical Problems in Engineering

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With the wide application of directional drilling technology in coal mine predraining boreholes, the failure problem of the tool joint of the directional drill pipe has become one of the main factors restricting the drilling efficiency. The main reason for the failure problem of the tool joint of the directional drill pipe is the stress concentration. The stress test rig for the tool joint of the directional drill pipe is designed based on the resistance strain measurement method, and the stress of the tool joint of the directional drill pipe is tested. The tool joint’s 3D finite element model was established based on nonlinear contact theory. The experiment verified the accuracy of this model. The stress distribution of the tool joint of the directional drill pipe was obtained. The research shows that the stress of the tool joint of the directional drill pipe is concentrated at the root between the third and the fourth turn of the engaged thread. The work presented in this study is a reliable guide to the design and field use of the tool joint of the directional drill pipe.

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Variation law of roof stress and permeability enhancement effect of repeated hydraulic fracturing in low‐permeability coal seam

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 5 publications

References 31 publications

Current Status of Research on the Coal and Gas Outburst Control Technology of Hydration and Anhydrous

Current Status of Research on the Coal and Gas Outburst Control Technology of Hydration and Anhydrous

Research on Hydraulic Fracturing Technology of Long Boreholes along Strata of High Vast Thick Coal Seam

Numerical Analysis of the Stress Distribution and Concentration Factors of the Tool Joint of the Directional Drill Pipe

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