适合海洋钻井无土相强抑制性钻井液体系的研究

在渤海湾盆地,由于沉积地层存在大段活性软泥页岩,普通聚合物钻井液体系的包被抑制能力不够,封堵能力不强,剪切稀释能力差,在钻遇该泥页岩井段时,经常出现井下复杂情况,并且油层受到一定程度的伤害。为此,研制了无土相强抑制性钻井液体系。从体系中处理剂的防塌抑制机理出发,确定了强抑制性钻井液体系构建的最优组合。研究结果表明该钻井液体系具有强的抑制性,岩屑滚动回收率达到95.6%,接近于油基泥浆;并且具有良好的润滑性、抗温性、抗钻屑污染、抗CaCl2污染、抗MgCl2污染以及良好的储层保护性能,渗透率恢复值能达到85%以上,能够满足大段软泥页岩等复杂地层的钻井要求,具有广阔的应用前景。

Study of clay free phase drilling fluid system with high inhibition for offshore drilling

In the Bohai Bay basin,because of the existence of thick active soft shale in sedimentary formation,downhole problems happen frequently and hydrocarbon reservoir is damaged in a certain degree when drill this shale interval using ordinary polymer drilling fluid system with poor encapsulating ability,weak formation sealing ability,and bad shear thinning property.Therefore,we developed clay free high inhibitive drilling fluid system.Proceeding from mechanism of additives in the drilling fluid system,the most superior combination of the construction is determined.Study results demonstrated that this drilling fluid system has high inhibitive ability,and cuttings roller recovery achieves 95.6% which is close to oil based mud.It has good lubricity,heat tolerance,potential resistance to cuttings contamination,potential resistance to CaCl2 contamination,potential resistance to MgCl2 contamination,as well as good reservoir protection performance,so the return permeability is able to achieve above 85%.The drilling fluid can meet the drilling demands of thick active soft shale complex formation and it has broad application prospect.