克拉2号气田盐膏层高压气层钻井液技术

克拉2号气田为国家“西气东输”主力气田之一,位于塔里木盆地南天山造山带南侧库车坳陷北部克拉苏构造上。克拉2号气田下第三系存在大段盐膏层,下第三系和白垩系存在多套压力高、安全密度窗口小的气层,这些地层易缩径、垮塌,易漏易喷。塔里木油田钻井液技术工作者总结克拉苏地区钻探经验,在对克拉苏2号构造带地质情况进一步认识的基础上,引进多元醇等材料,优选出强抑制、强封堵、流变性好、泥饼质量好、滤失量较低的高密度多元醇饱和盐水稀硅酸盐KCl聚磺钻井液配方。经过现场调配,该套钻井液技术在克拉203井和克拉204井应用成功,解决了膏盐层、盐岩层的缩径、垮塌问题,易漏性砂岩地层的防漏问题,同时使用配套工程措施,较好完成了钻井任务,缩短了钻井周期,提高了综合经济效益。

Drilling fluid technology for gypsum salt bed and high pressure gas-bearing formation in gasfield Kela 2

Kela 2 is a main gasfield of "west-east gas transfer engineering" in Tarim Basin. As long gypsum salt bed lies in lower Tertiary and different pressure systems exist in lower Tertiary and Cretaceous formations, hole shrinkage and collapse, lost circulation and well blowout are likely to happen. After summarizing drilling experience on Kelasu zone, and on further knowledge of structural belt in Kela 2, a high density saturated brine drilling fluid system was optimized. Using such materials as polyol and additives such as Barite silicate, cation emulsified asphalt, etc. , the advantages of the fluid include strong inhabitation, strong plugging ability, reasonable rheological characteristic, good mud cake and low filtration. After adjusting the formulation, this fluid was applied in well Kela 203 and well Kela 204 successfully. It solved the problems of hole shrinkage, collapse of salt bed and lost circulation in sandstone formation. Associated with necessary drilling measures, the drilling period was reduced and the comprehensive economic benefit was increased.