东营北带深井钻井主要工程地质问题及对策

近年来,胜利油田深层勘探主要集中在东营北带,该区由于目的层埋藏深,纵向上普遍存在多压力系统,同时还存在膏岩、盐岩集中段等易蠕变地层,给钻井设计和施工造成困难。不能预见的工程地质问题导致设计与实钻不相符及钻井复杂情况的发生,不仅制约了钻井速度,而且严重危及钻井工程安全和地质目标的实现。建议在以下几方面开展工作:加强工程与地质的结合,跟踪优化井身结构。利用地层自然造斜特性解决大倾角地层防斜打直问题,减少井斜控制难度,提高机械钻速。加强岩石可钻性分析,做好钻头选型工作。开展深层岩石可钻性研究,研制和引进适合深层砂砾岩体的高效钻头。这是缩短钻井周期、降低钻井成本的重要途径。开展扩展安全密度窗口钻井液技术研究,解决多压力层系、低压易漏和不稳定易塌地层并存导致的恶性漏失/井塌/井涌等技术难题。

Engineering Geology Problems of Deep Drilling and Their Countermeasures in Northern Slope,Dongying Sag

In recent years,northern slope in Dongying sag has become the focus of deep exploration of Shengli oilfield.Deep burial depth of the intended zones in this area results in multiple pressure systems and easily-to-creepage formations of concentrated intervals of gypsum and salt rocks in the vertical.It makes drilling design and operation difficult.Unforeseeable engineering geology problems make the discrepancy of real drilling and design,and result in drilling complication.It not only restricts the improvement of drilling speed,but also seriously endangers safety drilling engineering and realization of geologic target.Effective measures are proposed as following.Engineering and geology should be integrated and the hole configuration should be traced and optimized.The behavior of angle build-up naturally of the formation should be used for solving the issues of hole deviation control in big-dip formations,which can make hole deviation control be easier and enhance rate of penetration.Drillable analysis of the rocks should be strengthened and bit type selection should be well done.Drillability of the rocks in deep zones should be researched and effective bit fits for deep glutenite should be developed and introduced.It is the important way for shortening drilling cycle and decreasing the drilling cost.The drilling fluid technology of extending the safe density windows should be studied,which can solve the technical difficulties of mud losses,borehole sloughing and well kick resulted from the multi-pressure,easily-to-loss at low-pressure and unstable formations.