碳酸盐岩储层深度酸化的酸液体系实验研究

Experimental Study on Acid System for Deep Acidification of Carbonate Reservoir

碳酸盐岩储层的酸化效果主要取决于酸液体系。针对川深1井钻遇的碳酸盐岩储层,配制含有胶凝剂的酸液体系,进行酸岩反应实验,测试了溶蚀率、氢离子传质系数、酸液动态滤失系数、刻蚀效果及酸蚀裂缝导流能力。实验结果表明,配制的酸液体系对川深1井碳酸盐岩的溶蚀作用较强,溶蚀率可达96%;刻蚀程度较高,酸蚀深度最深达1.9 mm。在低速条件下,碳酸盐岩更易与酸液反应,对氢离子消耗更多。岩心整体刻蚀相对均匀,而酸液出口端比进口端刻蚀程度高。酸蚀裂缝的导流能力随着闭合压力的升高而下降,在闭合压力为35 MPa左右,裂缝的有效导流能力降到最低水平。在压裂酸化施工过程中应加大施工排量,避免酸液在井筒附近快速反应。

The acidification effect of carbonate reservoirs depends mainly on the acid system.For the carbonate reservoirs drilled in the Chuanshen-1 well,an acid liquid system containing a gelling agent is prepared to carry out an acid rock reaction experiment.The dissolution rate,hydrogen ion mass transfer coefficient,acid dynamic fluid loss coefficient,etching effect and acid etching crack conductivity are tested.The experimental results show that the prepared acid liquid system has a strong dissolution effect on the carbonate rock in the Chuanshen-1 well,and the dissolution rate can reach 96%;the etching degree is higher,and the acid etching depth is as deep as1.9 mm.At low speeds,carbonate rocks react more readily with acids and consume more hydrogen ions.The core is relatively uniformly etched,and the acid outlet end is etched higher than the inlet end.The conductivity of the acid-etched crack decreases with the increase of the closing pressure.At the closing pressure of about 35 MPa,the effective conductivity of the crack is reduced to the lowest level.During construction,the construction displacement should be increased to avoid rapid reaction of acid in the vicinity of the wellbore.