复杂砂岩气藏酸化酸液体系优选

砂岩矿物组成的复杂性决定了酸化酸液体系选择困难,采用室内物理模拟实验,结合电镜扫描技术,分析了经验选择的酸液体系对TZ气藏两类典型砂岩储层的酸化效果影响,根据酸化物理模拟实验优选了两类储层的酸液体系。实验结果表明,碳酸盐矿物含量高(大于20%(w))、岩石胶结疏松的储层,仅用15%(w)HCl酸化不能解除钻井液污染,需采用前置酸(15%(w)HCl)与主体酸(12%(w)HCl+1%(w)HF)相结合,并适当减小用酸量;泥质含量高、岩石胶结强度高的储层,采用前置酸(12%(w)HCl)与主体酸(13.5%(w)HCl+2%(w)HF)相结合,适当增加用酸量。实验研究表明,一套酸液体系难以解决复杂砂岩储层的酸化问题。现场应用试验表明,实验优选的酸液体系能较好地解除储层污染,提高酸化效果。

Optimization of acid system for matrix acidizing in complex sandstone gas reservoir

The option of acid system in complex sandstone acidizing was difficult due to the intricacy mineral composition. The influence of acid system on acidizing effect of two types of typical sandstone in TZ gas reservoir was analyzed by physical simulation experiments combining with SEM. Thereby, the acid system of two kinds of sandstone reservoir was optimized. The results showed that because the hydrochloric acid (15wt%) acidification alone could not remove drilling mud pollution in the reservoir, acid system of preflush (15wt%HCl) should be incorporated with main acid (12wt%HCl+1wt%HF) appling to the unconsolidated sand reservoir with high carbonate mineral content (more than 20%), and the amount of acid should be decreased. However, the sandstone reservoir with high argillaceous content and cementation strength should increase the acid amount and integrated the preflush (12wt%HCl) with main acid (13.5wt %HCl+2wt %HF). The experimental results suggest that one set of acid system is difficult to meet the needs of complex sandstone reservoir acidizing. The field application shows that new acid systems can remove the damage easily and improve the acidizing effect.