中国石油大学学报（自然科学版）2011，Vol.35Issue(2)：69-73,5.DOI:10.3969/j.issn.1673-5005.2011.02.012
井底压差对岩石破碎的影响机制
Mechanism for effect of down hole differential pressure on rock failure
摘要
Abstract
Based on the stresses in formation including drilling fluid pressure at down hole , pore pressure and stress caused by teeth invasion， the expression of teeth invasion depth was developed, and rock failure model for teeth invasion was established according to Morh-Coulomb principle. Using the ratio of error function and depth x as the reference parameters for underbalanced drilling application, invasion depths under all kinds of differential pressures and β/x were calculated, and the variation law was analyzed. The calculation results show that the real pore pressure of formation near down hole is not the original pore pressure because rock has permeability and porosity. The real pore pressure is related with time and location,and its distribution law can be expressed by one dimension unstable filtration theory. The expression of teeth invasion depth can clearly demonstrate respective effect of pressures and fluid on rock failure. This model can explain the mechanism of enhanced rate of penetration in underbalanced drilling, and it can depict the scope of application for dc index method correctly.关键词
压差/岩石破碎/地层压力/欠平衡钻井/dc指数法Key words
differential nressure / rock failure / formation nressure / underbalanced drilling/ dc index method分类
能源科技引用本文复制引用
郑德帅,高德利,张辉..井底压差对岩石破碎的影响机制[J].中国石油大学学报（自然科学版）,2011,35(2):69-73,5.基金项目
国家"973"研究课题(2010CR226703) （2010CR226703）
