深部软弱煤层井段应力分析

Stress Analysis of Borehole in Deep Soft Coal Seam

煤层气作为一种被广泛采用的高效清洁能源,通常使用水平定向钻井技术在煤层中钻进并延深,使抽采率提高。由于开采煤层深度不断增大,深部软弱煤层中塌孔失稳时有发生,对开采效率和经济效益影响严重。本文通过Abaqus有限元软件建立井眼的几何模型并分析煤层不同埋深,钻孔不同深度等因素对钻孔的影响,得出了如下结论:(1)随着煤层埋深逐渐增大,地应力增大大。(2)随着钻机打钻深度逐渐加深,应力集中系数缓慢减小,最大应力明显增大。(3)井眼中间段应力最大,为增强钻井稳定性,建议加固井段中间处。

As a widely adopted green energy- with high calorific, CBM increase pumping and extracting rate by horizontal direetionally drilled technology. Because of the depth of coal nfining is increasing, hole collapse problem have a serious impact on nfining and eeononfie ef-ficiency. In this paper, Abaqus finite element software is used to establish the geometric model of borehole and analyze the ilffluenee of differ-ent buried depth of coal seam and different depth of borehole on borehole. The following conclusions are drawn ： （ 1 ） With the increase of coal seam burial depth,the ground stress increases. （2） As drilling depth deepens, the stress concentration factor decreases and the maximum stress increases. （3）The stress in the nfiddle section of the borehole is the largest. In order to enhance drilling stability, it is reeommended to reinforee the nfiddle part of the well.