Short Communication
Muhammad Hamza Sajid
Abstract
Unconventional reservoirs have been the centre of attention throughout the world as we run out of conventional reserves. In 2016, 69% of US oil and Gas production was from unconventional resources. In Pakistan, conventional reserves are fast depleting and more than 70% of wells are producing water. The paper presents an analytical workflow for evaluation of shale play using conventional logs to counter data limitations in restricted basins. Workflow includes calculation of all the parameters that are important to delineate a shale reservoir. As a first, Toc is calculated using petrophysical methods integration with burial history curves for calculation of thermal maturities. Quantification of Kerogen volume and log maturity index is done and correlated with Toc values. For calculation of kerogen corrected porosity in shale reservoirs, sodergeld equation is calibrated with wards equation for kerogen density. Effective porosities for shale reservoir require accurate vaues of volume of shale which are computed using SGR and N-D method. Saturations are carefully predicted after incorporating the value of shale resistivity and Rw in shales. Smectite to Illite ratio is studied after identifying the type of clays present in the studied formation. Fracking is an integral part in creating permeabilities in shale reservoirs. Brtittleness Index (BI) value is evaluated by converting full waveform sonic responses into Poisson’s ratio/Young’s Modulus cross-plots