强抑制酸溶钻井(完井)液ASS-1研制与应用

长庆气田上古生界气藏属低压低渗储层。苏平1井、苏平2井水平段采用下筛管完井,酸洗投产,要求完井液性能不仅要满足长裸眼小井眼水平井段钻进的施工要求,还必须对产层伤害小,而且在产层表面所形成的泥饼易被酸溶掉。因此,选择强抑制酸溶聚合物完井液ASS-1体系,进行改进、评价,使之用于这2口井的水平井段钻进。结果表明,ASS-1体系主要特点为:密度低,滤失量低,性能稳定;流变性好,动塑比为O.3～O.5 Pa/mPa·s;钻井液润滑性好。室内分析现场取样,钻井液滤饼酸溶率超过80％;对同井直井段储层岩心进行伤害,经酸洗后岩心渗透率恢复率大干75％。

Development of acid-soluble completion fluid of strong inhibition ASS-1 and its application

The upper Paleozoic reservoir in Changqing gas-field is a low pressure and low permeability reservoir.Screen pipe completion and acid cleaning were used in the horizontal wells of Suping-1 and Suping-2.The completion fluid was required that not only satisfy the drilling requirements in long open hole and slim horizontal section but also cause little damage to the reservoir, meanwhile, the mud cake formed in hole wall can easily be dissolved by acid.Thus acid-soluble polymer completion fluid of strong inhibition ASS-1 system was selected for evaluation and modification.Using of it in horizontal drilling of the two wells showed that the fluid has the following main performances; good rheological property with dynamic plastic ratio of 0.3~0.5 Pa/mPa-s and better lubrication.Field samples were analyzed in laboratory and the results indicated that the acid-soluble ratio of drilling filter cake exceeded 80%, and the permeability recovery value of damaged core in vertical section of the same well reached over 75%.