欠平衡钻井完井液技术(I)--概念及损害机理

欠平衡钻井完井技术是保护油气层、提高采收率、克服各种钻井复杂问题的重要技术措施。介绍了欠平衡钻井的概念以及优点和缺点，阐述了欠平衡钻井对地层的损害机理为由于缺少起保护作用的滤饼，临时的超平衡造成对地层的损害；天然渗析效应；抛光、表面损害以及其它损害。

Completion fluid technology for under-balanceddrilling (part one)--Its concept and formationdamage mechanism

Under-balanced drilling (UBD) technology has beenwidely used in oil drilling to improve oil recovery,minimize formation damage and eliminate drillingtroubles, while completion fluid technology is one ofthe key technologies. This paper describes the con-cept of UDB, together with its advantages and disad-vantages, and demonstrates the formation damagemechanism during UBD, e.g. , the lack of filter cakeprotection, temporary over-balanced condition, pol-ishing effect and surface damage caused by frictionbetween bit and hole wall and poor cooling, and otherdamages, etc.