Petrophysical logs contribute in appraising productive sands of Lower Goru Formation, Kadanwari concession, Pakistan

Abstract

The interpretation of petrophysical logs unveil the reservoir traits and augment an intuition of hydrocarbon (gas) bearing zones. This study focused on interpretation of petrophysical signatures (encountered in Kadanwari-01, 03, 10 and 11) of Lower Goru Formation (LGF). LGF composed of shoreface sands and near shelf shale, deposited in Cretaceous age in middle and lower Indus basins, Pakistan. The results upshot the reservoir potential tapped in interbeded sand packages of LGF. The petrophysical attributes such as shale content from radioactivity tools (GR, SGR), effective porosity from NPHI-RHOB response and average porosity, derived fluids saturation of porous sand reservoir pockets by averaging, the Wyllie–Rose permeability of the selected producing zones and matching of respective resistivity responses (LLD, LLS) quantified in LGF. Lithology indicator (M–N plots) and mineral identification (MID) plot provide a basis to classify the lithology of potential sands derived by neutron, density and sonic logs. The isoperimetric surfaces depict the spatial distribution of derived results of the corresponding prospect zone (PZ). A correlation from NE to SW of study area yields a lateral profile of physical characters and distribution of PZs. Prospect Zone-3 results exhibit good quality of reservoir sands (30–37 m thick), characterizing ϕND from 0.12 to 0.23 and Shc 0.36–0.6. PZ-3 and PZ-4 are evaluated best prospect zones in this study and may be recommended for drilling.