彭水区块页岩气水平井防漏堵漏技术探讨

Leak Prevention and Plugging Techniques for Shale Gas Horizontal Wells in Pengshui Block

渝东南彭水区块上部三叠系、二叠系地层灰岩发育,易出现溶洞性漏失;下部目的层志留系龙马溪组裂隙发育,钻进中常发生渗透性漏失及间歇性严重漏失。结合彭页HF-1井、彭页2HF井、彭页3HF井和彭页4HF井的钻井实践,分析了该区块的井漏特点和漏失原因,介绍了防漏堵漏技术和具体的施工措施,探讨了防漏堵漏技术方案。分析认为,彭水区块上部地层利用气体(空气)钻井防漏堵漏效果较好;下部地层漏失层位分布广泛且无规律,宜采用随钻堵漏和分级堵漏措施。进一步分析认为,提高对地质条件的认知程度、优化井身结构、优选钻井方式、使用合理的钻井液密度,可以降低井漏发生率;优选合理的堵漏浆配方、开展堵漏剂评价、制订科学的堵漏措施、规范钻井施工操作是解决漏失的主要手段。

Rich in limestones, Triassic and Permian in Pengshui Block in southeastern Chongqing are prone to circulation lost through cavities; filtrating loss and intermittent severe circulation lost are frequently encountered during drilling through the target formation,Silurian Longmaxi,which is rich in fractures. From drilling practice of Well PY HF-1, PY 2HF, PY 3HF and PY 4HF, the features and reasons of circulation lost in this block were ana lyzed and leak prevention and plugging techniques and specific operation procedure were presented in this paper. A- nalysis showed that air drilling would be favorable for leak prevention and sealing in the upper formations of Peng- shui Block, while leak sealing and layered sealing were suitable for lower formations in this area which has extensive and irregular thief zones. Further analysis indicated that better understanding on the geologic conditions, optimized casing program, drilling mode, and proper mud density could lower the incidence of circulation lost. Proper plugging formula,plugging agent evaluation,scientific plugging measures, and well specified drilling operation are the major means to solve circulation loss issues.