Estimating Shale Brittleness Index based on Mineral Content using Wireline Log

Abstract

Summary A brittle region subjected to the same hydraulic pressure will produce fractures more easily and frequently as compared to a ductile region. The analysis of shale brittleness, in principle, gives a better understanding of its ability to hydraulic fracking, an important technique in shale gas production. The brittleness index (BI) depends on the brittle mineral content, such as quartz, dolomite and calcite. In this research, the brittleness index was calculated using modified Wang and Gale’s (2009) method. This method is based on the ratio of brittle mineral content (quartz, feldspar, calcite and dolomite) to the bulk mineral composition of shale. The mineralogical results are based on data obtained through X-ray diffraction (XRD) technique. Based on brittleness index log modeling, the brittleness index of shale in the study area ranges from 0.3–0.85 representing fair to good quality shale for hydraulic fracturing.