渤海油田泥页岩地层坍塌失稳机理分析

Study on Collapse Instability Mechanism of Shale Formations in Bohai Oilfield

蔚宝华 谭强 邓金根 范白涛 刘小刚

YU Baohua TAN Qiang DENG Jin'gen FAN Baitao LIU Xiaogang

中国石油大学(北京)油气资源与探测国家重点实验室, 北京昌平 102249; 中海石油(中国)有限公司天津分公司钻完井部, 天津塘沽 300450

State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Changping Beijing 102249, China; Drilling and Completion Department of Tianjin Branch, CNOOC Ltd., Tanggu Tianjin 300450, China

渤海油田钻井中遇到大量由于井壁坍塌失稳造成的复杂问题,主要表现为起泥球、返出掉块、阻卡、憋压、井径扩大等,处理复杂情况影响钻井速度并增加钻井成本,因此有必要从岩石力学和钻井液化学角度进行研究,澄清井壁坍塌失稳机理。通过对渤海部分油田的钻井复杂特点、泥页岩黏土矿物含量和理化性能、井壁坍塌压力随时间的变化关系等进行分析,得出了泥页岩地层井壁坍塌的主导机理。在上部明化镇组,主要是蒙脱石含量较高的泥岩发生水化坍塌,在下部东营组至沙河街组,主要是裂缝发育的硬脆性泥页岩由于存在弱面及钻井液渗流发生坍塌掉块。针对不同地层的失稳机理,提出了相应的钻井技术对策。

There are lots of complex problems due to borehole collapse instability in Bohai oilfield, which include mainly mud ball, fall-blocks returning, stuck pipe, pump suffocation and hole enlargement and so on. The complex problems affect drilling speed and increase drilling spending. Therefore, it is necessary to research wellbore stability from rock mechanics and drilling fluid chemistry, and clarify the instability mechanism of borehole collapse. The dominate mechanism was made clear through analysis of drilling features, clay mineral content and the physical-chemical properties of shales and the relationship between collapse pressure and drill-ing time in some oilfields of Bohai Sea region. In the upper member of Minghuazhen Fm, the main mechanism is that mudstone with high content of montmorillonite is easy to collapse due to hydration. From the lower member of Dongying formation to Shahejie formations, the hard brittle shales with cracks are easy to fall blocks due to weak plane and drilling fluid seepage. For the different instability mechanism, the corresponding countermeasures of drilling technology were put forward.

中海石油总公司项目"渤海油阳提升钻井效率系统优化研究及其应用"(YXKY-2010-TJ-04)。

https://doi.org/10.3969/j.issn.1008-2336.2013.02.101