前置酸改善水力压裂效果机理分析

Analysis on Pore Microstructure for Sandstone Acidizing

常规加砂压裂过程中往往会给储层和支撑裂缝带来损害,导致压裂效果有限甚至压裂无效。为了改善压裂增产效果,提出和发展了前置酸液加砂压裂工艺技术,压裂效果显著改善。系统分析了压裂过程中的压裂液残渣损害、压裂液滤失损害和机械杂质引起的损害。还分析了前置酸改善水力压裂效果的机理,即溶解敏感性粘土矿物,减少粘土膨胀和微粒运移、加速压裂液破胶、溶解压裂液滤饼、清洗支撑裂缝杂质损害和促进破乳等。现场应用表明采用该技术可降低压裂过程中的损害,从而提高压裂成功率和有效率,大大改善压裂效果。

Capillary flow porometry was used for analyzing the changes of pore microstructure after acidizing.Experimental results of the core sample conducted with capillary flow porometry both before and after acidization show that acidizing can enlarge the effective pore throat diameter, increase the effective pore throat size and promote the development of pore and throat dramatically.The analysis for reservoir pore microstructure can be used to study the acidizing mechanism from microcosmic aspects.