Estimation and mapping of vitrinite reflectance from seismic data in South Pars gas field, Persian Gulf

Abstract

Due to the importance of vitrinite reflectance (Ro) data in the evaluation of petroleum basins in terms of thermal maturity of petroleum source rocks, here we estimate Ro from 3D-post-stack seismic data based on a previously developed equation. Three wells drilled into the South Pars gas field, the world's largest non-associated gas field, provide calculated Ro from well-log data and some measured Ro data from core samples. A two steps methodology is followed: 1) at bore-hole scale; and, 2) at 3D seismic scale. Firstly, the Ro is measured in a few samples and also calculated more extensively from well log data applying the recently developed method based on the separation between the cumulative frequency values of resistivity ratio (RR) and sonic log data (the ΔRRS method of Kadkhodaie and Rezaee, 2017). The high correlation coefficient and low-root mean squared error values in measured versus calculated Ro values derived from a blind well in the study area verify the validity of the results. Through the application of the integrated methodology, a 3D-volume of calculated Ro values is generated for use in thermal maturity assessment of potential source rocks both in wellbore (1D) and the field-wide scale (3D).