松科1井(主井)防塌钻井液技术

Anti-Sloughing Drilling Fluid in Main Wellbore of SLCORE-1 Well

松科1井是全球第一口陆相白垩纪科学探井,采用"一井双孔"方案,由南孔和主井(北孔)组成。主井设计井深1 810.00 m,连续取心1 630.00 m,主要钻遇以泥岩和砂岩为主的沉积岩地层,钻进过程中存在防塌、护心、井壁稳定等方面的问题和难点。针对松科1井(主井)的钻井难点,在室内钻井液体系优选的基础上,根据不同地层分别采用了PAM钻井液体系、DFD-LG-CMC钻井液体系和DFD-NH4HPAN-SAKH钻井液体系,同时结合钻井液粘度控制技术、降低钻井液循环压降技术等,解决了松散砂层、水敏性泥岩和硬脆性泥岩中取心钻进的防塌钻井液技术难题,探索出了一条用低钻井液成本进行类似科学钻探工程的成功之路。

SLCORE-1 Well, the first cretaceous continental scientific drilling well in the world, consists of a south and a north wellbore （main wellbore）. The planned depth of the main wellbore was 1 810.00 m with the continuous coring length of 1 630.00m. The main formations are sedimentary zones mainly composed of shale and sand stone. Sloughing, core protection, and wellbore wall instability, etc are the main challenges and difficulties. Based on optimized drilling fluid systems in laboratory, PAM, DFD-LG-CMC, and DFD-NH4HPAN-SAKH drilling fluids were used in different formations combined with viscosity control and reduction of circulation pressure loss. The technical challenges for coring in unsolidated sand, water sensitive mudstone and hard mudstone were solved. A successful way of using low cost drilling fluid for similar scientific drilling project was developed.