Porosity Enhancement Potential through Dolomite Mineral Dissolution in the Shale Reservoir: A Case Study of an Argillaceous Dolomite Reservoir in the Jianghan Basin

Abstract

Shale oil has been found in the argillaceous dolomite reservoir of the Paleogene Xingouzui Formation in the Jianghan Basin. However, the shale oil storage mechanism in these rocks remains unclear, considering that increasing attention has been paid to shales instead of argillaceous dolomites. This article illustrated the microscopic pore structure and distribution of the argillaceous dolomite reservoir, discussed the porosity enhancement potential through dolomite mineral dissolution by organic acids, and indicated the contribution of the dolomite mineral dissolution pores to the porosity. Scanning electronic microscopy images show that the argillaceous dolomite reservoirs mainly contain inorganic pores, including intercrystalline pores, intergranular pores, and dissolution pores. However, organic pores are observed to be sporadically distributed. Nano-computed tomography data show that the pores of argillaceous dolomite vary in morphology and size and are unevenly spatially distributed. There are some is...