Microstructure and pore system analysis of Barren Measures shale of Raniganj field, India

• Analyse the porosity, permeability, orientation of micro-fractures and their relationship.
• Depict 3D internal structure to analyse the flow media.
• Demonstrate the impact of mineral composition, gas generation and storage potential.
• Explain the fabric heterogeneity.

The parameters of shales in terms of its organic richness, thermal maturity, porosity, permeability, pore & fracture network, orientation of microfractures etc. are the crucial requisites for shale gas exploration and exploitation. In this study, Permian Barren Measures of Raniganj field in Damodar Basin were analysed using thin section petrography, scanning electron microscopy, helium porosimetry, micro computer tomography and x-ray Diffractometer, to assess their petrographic and reservoir characteristics. The Total Organic Content (TOC) of the shale units of Barren Measures ranges from 3.75 to 20.9 wt% with more than 50% quartz content. Carbonaceous silty shales have been analysed using Micro Computed Tomography (μ CT) system to evaluate pore system, fracture network, fabric anisotropy and mineral component of the shale and verified that allocations of pores and mineral grains in Barren Measure shales are highly anisotropic. A porosity range of 3%–5% are achieved by μ CT, where pores are mostly nanopores, micropores, mesopores and macropores. Presence of scattered and pore filling organic matters are analysed in both thin section and SEM images, the morphology and sizes of pores behave a wide range from <10 nm to >100 μm.