正电胶磺化混油聚合物钻井液在长裸眼水平井中的应用

针对塔里木油田大部分开发水平井裸眼井段长，地层极易坍塌、渗漏，造成粘附卡钻等复杂问题。对不同的井段、不同地层采用了不同的钻井液体系。即上部地层采用正电胶聚合物钻井液，以防中上部软泥岩地层分散、造浆以及粘附卡钻等复杂情况的发生；下部地层采用正电胶聚磺钻井液，保证钻井液在高温、高压下性能优良，再配合使用稳定处理剂对地层进行封堵，确保了长裸眼井段的井壁稳定；定向水平井段采用正电胶磺化混油钻井液，解决了钻进存在的“岩屑床－流变性－水马力发挥－压耗”等诸多问题，提高了机械钻速，减少了裸眼井壁的浸泡时间，再配合使用油层保护剂及超细碳酸钙，改善泥饼质量，形成屏蔽暂堵层，较好地保护了油气层。经现场50口长裸眼水平井应用表明，该套钻井液体系性能稳定，具有很强的抑制性及悬浮携砂性，钻井施工安全、顺利，无粘附卡钻事故发生，仅套管费用每口井就节约几百万元，取得了非常好的经济效益。

Application of sulfonated and oil-mixed positive gel polymer drilling fluid in the horizontal well with long open hole

Due to the long sections of open hole in the development horizontal wells of Tarim oilfield, as well as the problems of collapsing formations, thief zones and stuck pipe, different drilling fluid systems were used for drilling different intervals. In the upper formation, the positive gel polymer drilling fluid was used to prevent the dispersing and mud making in the soft mudstone, as well as differential pipe stuck. Positive gel polysulfonated drilling fluid was used in the lower formation, to ensure the best drilling fluid performances in HPHT condition, and formation isolation was also achieved with the combination use of stabilizing agent, this ensured the a stabilized hole condition in the long open hole. During drilling the hor- izontal interval, sulfonated and oil mixed positive gel drilling fluid was used. By using this drilling fluid system, ROP was improved and the soaking time of open hole was minimized, while such problems as forming of cutting bed, poor rheology, insufficient hydraulic horse power and pressure drop were effectively solved; with the combination use of reservoir protection agent and super fine calcium carbonate, the mud cake quality was improved and the temporary plugging was also formed, and this effectively protected the oil and gas reservoirs. Field applications in 50 wells of long open hole horizontal wells showed that this set of drilling fluid system has stable performance, strong inhibition, good cuttings transportation and suspension. The drilling operations were safe and smooth and no stuck pipes were encountered, at the same time good economic benefits were obtained as huge amount of cost on casing was saved.