聚合醇饱和盐水钻井液体系室内研究

聚合醇饱和盐水钻井液体系是一种适用于易垮塌、缩径,易漏易喷的大段盐膏层钻井和压力系数高的地层钻井的体系.该体系的主处理剂为聚合醇CFH-2、强封堵剂和抗高温抗盐降滤失剂OCl-PT等,采用密度为5.0 g/cm3的高密度铁矿粉或铁矿粉与重晶石的复配物(复配比例为3∶1)加重.聚合醇CFH-2具有可生物降解性,既能提高体系的抑制性、润滑性及储层保护性能,又可满足环保要求;抗高温降滤失剂OCl-PT能有效地降低饱和盐水体系在高密度(2.32 g/cm3)下的高温高压(130 ℃)滤失量(小于8 mL).聚合醇饱和盐水钻井液具有良好的抑制性、润滑性和储层保护效果,可有效抑制粘土矿物的水化分散,防止盐岩层的溶解,解决大段盐膏层、盐岩层易缩径、垮塌的问题;具有较好的失水造壁性、热稳定性以及悬浮稳定性,抗粘土侵和Ca2 污染的能力强.

Laboratory study on polyalcohol/saturated salt-water drilling fluid

Polyalcohol/saturated salt-water drilling fluid is a fluid suitable for drilling in large body of salt-gypsum layer and high pressure coefficient formation, in which well slough, hole shrinkage, lost circulation and well blowout are easy to occur. In the drilling fluid system, main treating agents include polyalco-hol CFH-2, strong sealing agent and high temperature salt tolerant filtrate reducer OCL-PT, and so on. The weighting material is totally ground iron ore or a mixture of ground iron ore and barite (the ratio is 3 :1). Due to the presence of polyalcohol CFH-2 and filtrate reducer OCL-PT, the fluid system exhibits characteristics as follows: 1) It provides excellent inhibition, lubrication and formation protection, which is good for solving problems of easy shrinkage and collapse in large body of salt-gypsum. 2) It performs excellent filtration control, wall-building property, cuttings suspension and strong tolerance to clay and Ca2+ contamination.