Shale gas potential of Sembar Formation, Punjab Platform, Pakistan: Insights for a possible shale gas reservoir of economic quantity

The increasing demand for natural gas in Pakistan has intensified interest in evaluating unconventional shale gas resources as a supplement to declining conventional reserves. This study presents the first integrated geochemical and petrophysical assessment of the Sembar Formation in the Ahmedpur Oilfield, Punjab Platform Basin, with the objective of determining its shale gas generation and storage potential. Twenty-three cutting samples were analysed using TOC, Rock-Eval pyrolysis, and vitrinite reflectance to characterise organic richness, kerogen type, and thermal maturity. TOC values ranges from 1.35 to 2.92 wt% and S2 ranges from 5.25 to 7.88 mg HC/g rock and HI values of 180–397 mg HC/g TOC indicating mixed Type II/III kerogen. Tmax ranges from 437 to 444 °C and vitrinite reflectance 0.71–0.83 %Ro confirm that formation lies in early-to-mid gas window. Petrophysical analysis using density, neutron, SP and resistivity logs shows average porosity of ∼12 %, water saturation of 37.28 % and hydrocarbon saturation of 62.71 %, these demonstrates favourable reservoir characteristics as per the standard values. Integration of geochemical parameters with polar shale gas risk plot shows that Sembar Formation meets key criteria for an economically viable shale gas reservoir. Overall results suggest that Sembar Formation possesses adequate gas generation potential and suitable storage capacity highlighting its significance as a prospective shale gas target in Punjab Platform Basin. • First integrated geochemical, petrophysical and polar risk-plot study of Sembar Formation in Ahmedpur field. • TOC, S2, HI and Tmax data confirm good generative potential and thermal maturity. • Mixed Type II/III kerogen supports gas generation within Ahmedpur oilfield sediments. • Petrophysical data show average 12 % porosity and 63 % hydrocarbon saturation. • Results validate Sembar Formation as a potential shale gas reservoir in Punjab Platform.