基于区域地层压力描述的东坪区块井身结构优化

Optimization of casing design of Dongping Block based on regional formation pressure description

东坪区块是青海油田近年来开发的重点区块,由于地质条件复杂和前期对该区块地层压力认识不清,因此井身结构设计存在缺陷,钻井过程中频繁出现漏、喷、塌、卡、断等各种井下复杂情况和事故。针对目前东坪区块地层压力认识不清的问题,首先收集区块内已钻井的测井等资料,利用Eaton法建立已钻井的单井地层压力剖面;然后基于地质统计学和克里金插值法,将地层压力以地层层组为单元外延展开,从而实现地层压力的区域化描述;最后根据区域地层压力的预测结果,对区块内待钻井进行井身结构优化。研究结果为青海油田东坪区块井身结构优化及钻井液密度精细化设计提供了依据,可以有效降低钻井复杂事故的发生频率,对于安全钻井具有重要意义。

Dongping Block has been the focal point of Qinghai Oilfield in recent years. Because of the complex geological condition and the vague understanding of formation pressure in the early stages, there are defects in the casing program design, which led to the frequent occurrence of drilling risks, such as lost, kick, collapse, sticking and tool failure. In order to solve the problem of the vague understanding of the formation pressure in Dongping Block, the logging data and well reports of drilled wells were firstly collected in this paper. And we precisely calculated the formation pressure of drilled wells by the Eaton law. Then based on the geostatistics and Kriging interpolation, the regional formation pressure description had been realized by expanding the formation pressure of drilled wells in one layer group. Finally, casing program design of undrilled wells in the block were optimized according to the established regional formation pressure. The research findings can provide the basis for the optimization of casing program and precise design of drilling fluid density in Dongping Block of Qinghai Oilfield, which can effectively reduce the frequency of occurrence of drilling risks and has great significance to the safety of drilling work.