TSR反应中地球化学条件的热力学估算  

Physicochemical Estimation of Geochemical Conditions in TSR Reaction

作　　者：谭宇 关平[1] 庞磊 刘沛显 周叶骏 TAN Yu;GUAN Ping;PANG Lei;LIU Peixian;ZHOU Yejun(School of Earth and Space Sciences,Peking University,Beijing 100871)

机构地区：[1]北京大学地球与空间科学学院,北京100871

出　　处：《北京大学学报（自然科学版）》2019年第1期148-158,共11页Acta Scientiarum Naturalium Universitatis Pekinensis

基　　金：国家科技重大专项(2011ZX05009-002-403;2011ZX05004-004-005);国家重点基础研究发展计划(2012CB214801)资助

摘　　要：从化学热力学的角度,通过热力学计算和绘制热力学相图,针对硫酸盐热化学还原反应(TSR反应)和H_2S对碳酸盐岩的溶蚀两个化学反应过程,判别其发生的可能性、方向和物理化学条件,求取不同温度下CaSO_4 (或SO_4^(2-))被直接还原为H_2S的离子浓度、pH和氧化还原条件;指出在地质体系中,当CaCO_3处于沉淀–溶解的边界时,少量酸性流体的加入就会使沉淀转为溶解,而当Ca^(2+)和CO_3^(2-)浓度升高时,又达到新的沉淀–溶解平衡。H_2S对CaCO_3的溶蚀在深度约为1000 m时达到最佳效果,长期、多次的TSR反应才能产生充足的酸性流体(即H_2S),这是溶蚀改造碳酸盐岩储层达到明显效果的必要条件。According to the principle of thermodynamics,thermodynamic phase diagrams are calculated and drawn,the possibility,direction and physicochemical conditions of the two chemical reaction processes of TSR reaction and dissolution of carbonate rocks by H2S are determined,and the direct reduction of CaSO4(or SO4^2﹣)to H2S at different temperatures is obtained.It shows that when CaCO3 is at the boundary between precipitation and dissolution in geological system,a small amount of acidic fluid will make the precipitated CaCO3 dissolved,and when the concentration of Ca^2+and CO3^2﹣increases,a new equilibrium of precipitation and dissolution will be achieved.When the depth of dissolution of CaCO3 is about 1000 m,H2S achieves the best effect.Only long-term and repeated TSR reactions can produce sufficient acidic fluid(H2S),which is the necessary condition for dissolution modification of carbonate reservoirs to achieve obvious results.

关 键 词：TSR反应 H2S 碳酸盐岩储层 热力学相图 

分 类 号：P618.13[天文地球—矿床学]