基于测井资料的欠平衡钻井地层适应性分析

ANALYSIS OF UNDERBALANCED DRILLING ADAPTABILITY TO FORMATIONBASED ON LOGGING DATA

欠平衡钻井是保护储层和提高钻速的重要技术之一。在欠平衡钻井过程中,由于工艺措施与常规钻井不同,容易导致卡钻、井涌等复杂钻井事故的发生,影响钻井安全。在钻井设计时对工区地层是否适用欠平衡钻井需作出准确的评估。文章首先分析四川盆地川中地区高石梯构造的构造背景、地质分层及岩性特征,总结分析影响欠平衡钻井安全的地质及工程因素,利用测井资料准确预测地层孔隙压力与坍塌压力等参数,判断实际地层是否适合采用欠平衡钻井,并将该方法应用于四川盆地川中地区高石梯构造多口井钻井设计中,为该地区实施欠平衡钻井提供了可靠的地质依据。

Underbalanced drilling is one of the important technologies to protect the reservoir and improve drilling rate. In underbalanced drilling which is different from conventional drilling, it is easy to cause complicated drilling accidentssuch as sticking and kick. During drilling design, it needs to make an accurate applicable evaluation to underbalanced drilling in the working area. The paper analyses the structure background of Gaoshi siltstones ladder structure in the middle of Sichuan basin, geological stratification and lithological features. It summarizes geological and engineering factors affecting the safety of underbalanced drilling.The formation pore pressure and collapse pressure parameters can be predicted accurately with logging data to distinguish whether the actual formation is suitable for underbalanced drilling.The method has been applied to the underbalanced drilling design in Gaoshi ladder structure of Sichuan basin. It provides reliable geological basis for underbalanceddrilling safely in the region.