Evaluation of Gas Potential in Early Cretaceous Shale Lower Indus Basin, Pakistan

Abstract

The shale gas potential of the early Cretaceous Talhar shale member of the lower Goru Formation in lower
Indus basin of Sanghar district, Sindh province, has been evaluated using 2D seismic and well logs data. Graphical and
empirical techniques were applied to calculate various geochemical parameters for the evaluation of shale plays. Total
Organic Carbon (TOC) is calculated by Passey's (∆LogR) Overlay technique and its values are about 2.44 wt.%. Vitrinite
Reflectance (Ro) is estimated by graphical and empirical relation and the value lies between 0.95-1.0 which implies that
the Talhar shale member is in peak oil and initial gas generation phase. Log-derived Maturity Index (LMI) is calculated
by NPHI, RHOB or density log and uranium logs. The average value is about 0.55 which reflects that the formation is
probably in the initial maturation phase. Kerogen Volume (Vk) is estimated by empirical relation using RHOB log as
input and it is about 13 wt. % which reflects that the formation has enough potential of oil/gas expulsion. The results are
compared and validated with a study of the adjacent field of the same basin. This study reveals that Talhar member of
lower Goru Formation could be the future probable potential unconventional reservoir for exploration in lower Indus
basin of Pakistan.

Keywords: Unconventional, total organic content, Passey's, ∆????????????????, kerogen volume.