大直径污水井孔壁失稳与泥浆护壁机理

Hole wall instability and mechanism of slurry protection about large diameter bilge well

采用经典土力学滑动理论,建立某大直径污水井的孔壁失稳滑移轨迹方程及其滑移面安全系数的计算式。研究结果表明:随着凝胶泥浆抗剪强度的提高,孔壁的稳定性增强;对于砾砂或圆砾层,孔壁的稳定性主要取决于泥浆的重度,随着泥浆重度的增大,孔壁稳定性不断增强;对于基岩段,孔壁的稳定与孔壁的深度无关,主要与基岩的结构及其周围的节理或断层面分布状况有关;采用气举反循环分阶段钻进和优质泥浆护壁的施工工艺取得了很好的工程应用效果,具有一定的工程应用价值。

Using classical theory of soil mechanics, wall instability sliding trajectory equations and slip surface safety coefficient calculation formula on large diameter water well hole were established. The results show that with the increase of gel mud shear strength, hole wall stability is enhanced. For the gravel sand or gravel layer, hole wall stability mainly depends on the mud slurry severe, and with the increase of severe, the hole wall stability increases. For bedrock, the stability of the hole wall has nothing to do with its depth, but is mainly related to the structure and its surrounding joints or fault plane distribution status. Using gas lift reverse circulation drilling and good slurry wall construction technology can obtain good application effect, and can achieve valuable effect.