增强型地热系统(EGS)土酸化学刺激剂对热储层的改造

Effectiveness of using mud acid as stimulation agent for enhanced geothermal systems(EGS) reservoir

以我国潜在EGS工程靶区热储层-松辽盆地营城组凝灰岩为目标层,通过化学刺激剂岩心流动仪模拟高温环境下土酸注入热储层过程中的化学刺激剂-热储层相互作用。通过TOUGHREACT软件建立反应性溶质运移模型,模拟上述实验的化学反应过程。研究结果表明:加入颗粒稳定剂的低浓度土酸对热储层具有良好的化学刺激效果,岩心裂隙渗透率增加6.7倍。岩体渗透率的增加主要源自于钠长石、钾长石的溶解,石英的溶蚀作用不明显,矿物表面出现次生矿物,即无定型二氧化硅的沉淀。

Experiments were conducted in a high-temperature core flow instrument to evaluate HF-rock （aquifer plus aquitard） reactions that may impact the reservoir of the EGS in the Songliao Basin, China. The chemical reactions in the experiments were simulated through reactive transport modeling by using TOUGHREACT and the information currently available for the solution chemical composition. The results show that the permeability of core fracture increases by 6.7 times at the end of experiments, indicating the good chemical stimulation effect of mud acid with particle stabilizer. Increases of permeability of core are mainly caused by K-feldspar and albite dissolution while the dissolution of quartz is weakened. Amounts of secondary amorphous silica are generated.