【摘要】 正确认识和有效评价地下复杂的围岩环境,深入探索井壁稳定机理,建立预测理论和控制模型,有效控制钻井过程中的井壁失稳问题,是实现优质、安全、高效和低成本钻井的关键。介绍了敏感性页岩地层、裂缝性地层、流变地层和各向异性地层的失稳机理,分析了构造地应力、井眼轨迹、钻井液造壁性、地层强度、垮塌的几何形态及钻柱振动对地层失稳的影响,总结了地层失稳的研究方法,提出了在完善钻前预测的理论基础上,对当前钻头处地层的井壁稳定性进行实时评价,及对钻头下地层的井壁稳定性进行预测,是当前钻井急需解决的理论和工程难题。更多还原

【Abstract】 Properly identifying and evaluating downhole complex surrounding beds, thoroughly analyzing well-wall stability mechanism, establishing forecast theories and control models, and effectively controlling wall instability during drilling are vital to conduct quality, safe, efficient and low-cost drilling. The paper firstly presents wellbore sloughing mechanisms while drilling sensitive shales, fracture formations, rhemorphic rocks, and nonuniform formations, then analyzes effects of structural earth stress, well path, mud plastering ability, formation strengths, sloughing shapes and drillstring vibrations on formation caving-in, and summarizes research methods for formation sloughing, finally concludes that how to evaluate in real-time the wall stability of the formation being penetrated on the basis of perfecting forecast-before-drilling theory and predict the wall stability of formations to be penetrated is a problem needing urgent solutions in both theory and engineering.更多还原