四川盆地深部海相优质储集层的形成机理及其分布预测

四川盆地深部海相碳酸盐岩储集层主要以白云岩为主,其间夹杂发育膏质岩类,且经历过较大的埋深,有利于TSR（硫酸盐热化学还原反应）的发生和H2S的形成与聚集.TSR形成的H2S溶于水后显示出较强的溶蚀性能,在深部储集层中发生流体-岩石相互作用,促进碳酸盐岩次生孔洞的发育和优质储集层的形成,H2 S含量越高,含H2S储集层埋藏越深,储集层性质越好.基于此,可以运用H2S的形成和分布规律来预测深部优质储集层的分布.川东和川西北地区中、下三叠统白云岩储集层都含有一定的硫酸盐岩且经历过较高的温度,目前埋藏较深,是H2S形成的最有利层系,也是优质储集层最发育的层位.图3参36

Formation mechanism and distribution prediction of high-quality marine reservoir in deeper Sichuan Basin

TSR(Thermochemical Sulfate Reduction) and the formation and accumulation of H2S occurred easily in the deep marine sedimentary carbonate reservoir of the Sichuan Basin,because reservoirs there were mostly composed of dolostone,which were interbedded with gypsiferous rocks, and experienced a deeply buried process.Fluid-rock interaction occurred in the deep reservoirs and caused the formation of high-quality reservoirs and secondary pores because H2S of TSR origin exhibited strong corrosion after dissolving in water.Because of the high temperature and high concentrations of hydrogen sulfide,the acid corrosion acted intensely in the deep strata,resulting in the well-developed secondary pores.The porous reservoir with gypsiferous rock was the base of TSR reaction.The occurrence of TSR further optimized the quality of reservoir,and led to the developed pore reservoir complex of high porosity and permeability.Furthermore,the corrosion was more acute in the deeper strata.The corrosion of H2S to reservoir might form larger pores through the reconstruction and dilation of original pores,or form new denudation pores.The formation and distribution of H2S may be used to predict the deep highquality reservoir.