砂-泥岩界面碳酸盐溶解-沉淀反应及其石油地质意义

CARBONATE DISSOLUTION-PRECIPITATION IN SANDSTONE-SHALE CONTACT AND ITS PETROLEUM GEOLOGICAL MEANINGS

沉积盆地中的砂-泥岩界面发生过强烈的碳酸盐溶解-沉淀反应,这种反应主要取决于相邻泥岩中流体的组成和性质、流体动力环境和砂岩与泥岩之间物理化学条件,如pH、Eh、P(CO2)、化学组成、温度、压力、孔隙度和渗透率、矿物组成和流体动力条件的差异性等。砂-泥岩界面碳酸盐溶解-沉淀反应的石油地质意义主要体现在:①影响储层物性;②影响油气的运移和充注;③有利于形成压力封存箱,对油气的保存具有重要的作用。

A lot of studies had verified that there is strong carbonate dissolution-precipitation in sandstoneshale contact in sedimentary basin, carbonate dissolution-precipitation in sandstone-shale contact are mainly controlled by fluid composition and feature of shale near to sandstone, fluid dynamic environment and physical-chemical conditions between sandstone and shale, such as the differences of pH, Eh,P（CO2）, composition ,temperature ,pressure, porosity, permeability, mineral and fluid dynamics between sandstone and shale. There are three petroleum geological meanings for carbonate dissolution-precipitation in sandstone-shale contact： ①to influence reservoir porosity and permeability; ②to influence oil and gas migration and inject; ③to be favorable to form pressure compartment and to protect oil and gas from escape.