钻井井下爆炸堵漏技术

Downhole explosive plugging technology

现有堵漏方法对渗透性漏失较易解决,对裂缝性漏失,堵漏一次成功率低,处理过程复杂、周期较长、成本高,如近年来苏北盆地有46口井发生裂缝性漏失,平均每口井漏失钻井液641 m^3、损失时间268 h。主要原因是井下裂缝宽度不一、难以确定,造成堵漏材料粒径不匹配,大粒径堵漏材料难以进入地层,小粒径堵漏材料又容易被漏失的钻井液带走,难以在漏失孔喉处形成有效的桥架结构,导致堵漏成功率低。研发了一种针对裂缝性漏失堵漏的新方法——井下爆炸堵漏技术,主要通过堵漏工作原理、堵漏注射器、药盒、胶筒及凝胶配方等方面的研究,形成钻井井下爆炸堵漏技术。该技术主要通过井下爆炸的方式,挤压地层裂缝,减小裂缝宽度,使堵漏材料"进得去、停得住",有效提高裂缝性漏失的堵漏成功率,减少经济损失。该技术通过现场4口井共6个漏失层位的封堵应用,成功堵漏5层、有效1层,堵漏成功率83.33%,有效率100%。钻井井下爆炸堵漏技术为进一步完善堵漏工艺开辟了新的思路和方法。

Existing plugging methods are more suitable for permeable leakage.For fractured leakage,however,their one-time plugging success ratio is low and the treatment process is complex with long cycle and high cost.In recent years,for example,fractured leakage happened in 46 wells in the Subei Basin,with single-well average leakage of 641 m3 and leakage time of 268 h.The reasons for the fractured leakage are as follows.The downhole fracture width is different and cannot be determined,so the grain sizes of lost circulation materials are not matched.The lost circulation materials of large grain size cannot move into the formation easily and those of small grain size are carried easily with the lost drilling fluid.As a result,the effective bridging structure cannot be formed at the leakage pore throat,and consequently the success ratio of plugging is low.In this project,a new method was innovatively developed for plugging the fractured leakage,i.e.,downhole explosive plugging technology,by investigating plugging principle,plugging syringe,chemical box,rubber cylinder and gel formula.By virtue of this technology,the formation fracture is compressed and its width is decreased,so that the lost circulation materials can“move in and stay”.Thus,the plugging success ratio of fractured leakage is improved effectively and the economic loss is reduced.This technology was applied to 6 leakage zones in 4 wells.And 5 zones are plugged successfully and 1 zone is plugged effectively,with plugging success ratio and effectiveness ratio of 83.33%and 100%,respectively.This downhole explosive plugging technology provides a new idea and method for the further improvement of plugging technologies.