塔中北斜坡鹰山组碳酸盐岩溶蚀的模拟实验研究

Simulation experiment for the dissolution of carbonate rocks of the Yingshan formation on the northern slope of Tazhong uplift

为了研究碳酸盐岩的微观溶蚀机理,本文采用溶蚀实验和镜像观察的方法,研究了塔中北斜坡鹰山组3种类型碳酸盐岩的溶蚀过程及微观溶蚀特征。结果表明:在相同实验条件下,亮晶生屑灰岩、云质灰岩和泥晶颗粒灰岩的溶蚀量基本一致。由于对物质成分和岩石微结构的选择性溶蚀,它们的微观溶蚀特征存在明显差异。亮晶生屑灰岩和泥晶颗粒灰岩样表面整体被溶蚀降低。云质灰岩样表面方解石部分整体被溶蚀降低,形成铸模孔,白云石溶蚀成蜂窝状溶蚀孔,并突出岩石表面,白云石晶间缝溶蚀加大且相互连通,这对油、气和地下水储渗具有重要意义。

Dissolution experiment and microscopic observation are carried out to research micro-corrosion mechanism of carbonate rocks. The corrosion process and micro features of three types of carbonate rocks in the Yingshan formation on the northern slope of Tazhong uplift are studied in this paper. The results show that the dissolution quantities of three kinds of carbonate rocks, sparry bioclastic limestone, dolomitic lime- stone and mud-crystal grain limestone, are almost the same. Because of the selective dissolution for composi- tion and microstructure of rocks, micro-corrosion characteristics of these three kinds of carbonate rocks are significantly different. The surface of sparry bioclastic limestone and mud-crystal grain limestone are overall reduced by corrosion. The calcites of dolomitic limestone are eroded and lowered to form mould pores. The dolomites of dolomitic limestone are eroded into honeycomb-like pores that protruding on the rock surface. The inter-crystal fractures of dolomite are enlarged by dissolution and become interconnected. That is of important significance for reservoir and permeability of oil, gas and groundwater.