聚合物酸液稠化剂对储集层的伤害

Damage of Polymer Acid Viscosifier to Reservoirs

酸压措施中常用酸液的稠化剂大多是采用聚丙烯酰胺类的高分子聚合物。这些稠化剂降解后仍然具有一定的黏度,酸压施工后残留在地层中造成储集层伤害,直接影响酸压效果。配制了3类聚合物酸液稠化剂的残酸(胶凝酸、交联酸和温控变黏酸),针对这3类残酸对碳酸盐岩高渗岩心和低渗岩心渗透率伤害进行了实验,实验结果表明,3类酸液的残酸对碳酸盐岩高渗岩心的基质渗透率伤害率要大于对低渗岩心的伤害率,即岩心初始渗透率越大,孔隙越发育,受大分子聚合物降解产物的伤害越严重。3类酸液的残酸所产生的滤饼对岩心渗透率的伤害率都相对较低,不是导致储集层伤害的主要因素。

Commonly-used acid viscosifiers during acid fracturing are mostly high-molecular polymers of polyacrylamide. These viscosifiers still have some viscosity after degradation and remain in formations after acid fracturing, which may cause damages to reservoirs and influence the acid fracturing effect directly. 3 types of residual acids of polymer acid viscosifier （gelled acid, crosslinked acid and temperature-controlled sticking acid ） are prepared, and experiments on the damages of these 3 residual acids to high-permeable and low-permeable carbonate cores are carried out. The results show that all the 3 residual acids have greater damages to matrix permeability of high-permeable carbonate cores than that of low-permeable cores, i.e., the larger the initial core permeability and, the more developed the core pores are, the more serious the damage from products degraded by large-molecule polymers will be. However, the filter cakes produced by the 3 residual acids have relatively low damages to core permeability, which might not be the key factor for the reservoir damage.