FORMATION EVALUATION OF ORGANIC RICH SOURCE ROCKS

Abstract

Due to the rapid depletion of conventional reservoirs around the world, unconventional resources that are present in abundance all around the world have gained increased attention form small and big exploration and production companies. These organic rich resources are quite complex in terms of its composition and exploitation. In order to calculate the possibility of a deep buried organic-rich source rock in terms of hydrocarbon saturation, concerted efforts are devoted at unravelling the resource potential of these unconventional formations. X-ray Diffraction (XRD), GRI Dean Stark extraction data, and LECO test are some of the measurements that provide ground truth value meant to calibrate the well logs measurements before an effective evaluation of the formation can be performed The workflow for these unconventional resources advocates the concentration of organic content in the grain matrix to be included when computing porosity. The Sondergeld (2010) porosity model is employed in Petrophysical modelling. To upgrade grain density, which is a needed input parameter to produce continuous porosity trend with depth, an empirical relationship between volume percentages of minerals and grain density (without kerogen) has been constructed. The Simandoux model (1963), which employed the volume of shale (Vsh), adjusted for overestimated saturation calculated using Archie's (1942) law, had the best correlation with GRI observed saturation. The petrophysical parameters predicted using logs, such as porosity and saturation, were found to have good correlation with laboratory observations, indicating the model's robustness.