Correlation Study Between Minerals Composition and Porosity Evolution of Black Shale Under Different Oxidation Mechanisms

Abstract

The correlation between rock minerals composition and porosity evolution is essential to black shale oxidation,chemical and biological effects may act different roles which is unclear. In present study, the acid solution and Acidithiobacillus ferrooxidans was applied to simulate the chemical and biological effects, the total organic carbon (TOC), pyrite and clay minerals content, porosity characteristics, micro-surfacemorphologyof black shale sampleswere employed to analyze the minerals-porosity correlation. Results showed that the chemical effect led to a greaterdecrease of pyrite and increase of clay minerals content than biological effect, which accompanied by a higherspecific surface areas and pore volume. These difference may attribute to the TOCcontent, which decreasedby acid erosion and led to the increase of macropores in chemical group, then promoted the minerals reactions; whereas the TOC content increased byattached and dead bacteria cell bodies on rock surface, led to the increase of micropores and less minerals reactions in biological group. It suggests that the correlation between minerals composition and porosity evolution is different in chemical and biological effects, is mainly due to the different alter trends of TOC content.