Pore Structure Characterization of Shales from Kachchh and Kaladgi Basins

Abstract

Estimating transport and storage properties of shale is a challenging task, due to the lack of under standing of their pore size characteristics. Matrix of shales have micro (pores less than 2 nm diameter) to meso-pores (pores with 2-50 nm diameter) within them. These nano scale pores are mainly associated with clay minerals. The pore structure characteristics of shales viz. surface area, pore size distribution and pore volume, from Kachchh basin of Gujrat and Kaladgi basin of Karnataka, were evaluated using N 2physisorption analyses. The samples were analyzed by applying Brunauer–Emmett–Teller (BET) theory for surface area calculation and Barrett –Joyner–Halenda (BJH) theory for understanding the por e size distribution and pore volume. The pore structural characteristics were compared with the mineral composition obtained from X -ray diffraction analysis. Both sample sets show Bi -modal pore size distribution. Bi -modal pore size distribution is indicati ve of the intra -layer clay pore space. Differential porevolume indicates that porosity is very low in Kaladgi shales in comparison to  Kachchh shales.