Delineation of Shale Gas Play from Non-Pay Zones Using Elastic and Mechanical Properties of Organic-Rich Shales, Southern Punjab Platform, Pakistan

Abstract

ABSTRACT Energy demand has increased due to socio-economic development, and depletion in conventional hydrocarbon reservoirs. Due to this, unconventional hydrocarbon reservoirs have received considerable attention. Among the variety of unconventional hydrocarbon reservoirs, shale gas is the most significant unconventional alternate energy resource. The Cretaceous organic-rich shales of Sembar Formation are considered a shale gas play however the composition and mineralogy of these shales are extremely heterogeneous in the central parts of the Indus basin, especially in the southern extent of the Punjab Platform. The primary objective of the research is to employ petrophysical analysis to characterize shales to assess their potential for shale gas exploration. To estimate various petrophysical parameters, this study utilizes wire-well logs acquired from the J-01 well. The findings reveal that total organic content (TOC) and kerogen volume are present in significant volume, indicating the shale’s viability as a shale gas play. To evaluate shale brittleness (B) and to differentiate between ductile and brittle behavior, elastic parameters including acoustic impedance, elastic moduli, and Poisson’s ratio (PR) are computed. The cross plot of Young’s modulus and PR indicates elevated brittleness values, pointing to brittle behavior of these shales favorable conditions for fracking and horizontal drilling. Moreover, a set of three logs – neutron porosity log, bulk density log, and gamma-ray log – were used for facies modeling and identification of different lithologies. The facies modeling effectively discriminate shale intervals from other lithologies, demonstrating higher porosity and density. As a result, the organic-rich shale intervals within the Sembar Formation exhibit promising potential as a shale gas play in the southern Punjab Platform.