Hydraulic flushing drilling technology can not only improve the efficiency of high-pressure and low-permeability geological reservoir coalbed methane drainage but also effectively reduce the probability of coal and gas outburst disasters through pressure relief. The main mechanism of this technology is to expand the borehole diameter through hydraulic flushing measures, increase the strain of the coal around the borehole, and increase the development of cracked pores, to improve the permeability of the coal seam and realize the dual reduction of ground and gas pressure. However, in the actual application process, the interaction mechanism among the stress field, the structure field, and the seepage field is still not clear, and there is no clear method to accurately determine the pressure relief range based on the pressure relief mechanism in order to carry out reasonable drilling arrangements. Therefore, this article comprehensively uses laboratory experiments, numerical simulations, and field practices to fully explain the hydraulic flushing pressure relief mechanism and proposes a method to accurately determine the pressure relief range based on the radial line strain law. The results based on radial line strain showed that the effective relief radius expands to 0.86 m once adopting the Φ579 mm hydraulic flushing borehole compared to Φ160 mm; the borehole’s equivalent diameter of drilling field #11 is 2 to 3 times than that of #10 and 1.2 times the average CBM extraction amount. Therefore, as the borehole diameter increases, the permeability and radial line strain of the coal around the borehole increase significantly, but the tendency of the increase in permeability decreases with increasing vertical stress. The findings of this study can help for a better understanding of the pressure relief and permeability enhancement mechanism of hydraulic flushing, and the method of determining the pressure relief range based on radial strain can also provide a new way for other mines to practice ideas.

中文翻译：

---

水力冲洗钻井周围煤体径向位移规律及增透效果研究

水力冲洗钻井技术不仅可以提高高压低渗透地质储层煤层气抽采效率，还可以通过泄压有效降低煤与瓦斯突出灾害的概率。该技术的主要机理是通过水力冲洗措施扩大井眼直径，增加井眼周围煤体的应变，增加裂隙孔隙的发育，提高煤层的渗透性，实现地层的双重减缩。和气体压力。但在实际应用过程中，应力场、结构场、渗流场之间的相互作用机制尚不清楚，并没有明确的方法可以根据泄压机理准确确定泄压范围，从而进行合理的钻井安排。因此，本文综合利用室内实验、数值模拟和现场实践，充分解释了液压冲洗泄压机理，提出了一种基于径向线应变定律的准确确定泄压范围的方法。基于径向线应变的结果表明，一旦采用径向线应变，有效释放半径扩大到 0.86 m。并在现场实践中充分解释了液压冲洗泄压机理，提出了一种基于径向线应变定律的准确确定泄压范围的方法。基于径向线应变的结果表明，一旦采用径向线应变，有效释放半径扩大到 0.86 m。并在现场实践中充分解释了液压冲洗泄压机理，提出了一种基于径向线应变定律的准确确定泄压范围的方法。基于径向线应变的结果表明，一旦采用径向线应变，有效释放半径扩大到 0.86 m。Φ 579 mm 液压冲洗钻孔对比Φ 160 mm；11#钻井的井眼当量直径是#10的2～3倍，是煤层气平均抽取量的1.2倍。因此，随着钻孔直径的增加，钻孔周围煤体的渗透率和径向线应变显着增加，但渗透率增加的趋势随着垂直应力的增加而减小。本研究结果有助于更好地理解水力冲洗卸压增透机理，基于径向应变确定卸压范围的方法也可为其他矿山实践思路提供新思路。