Abstract

This study integrates lithofacies analysis, petrography, wireline log interpretation and petrophysical evaluation to understand the depositional environment and reservoir characteristics of Early Jurassic sandstones from two conventional cores of Well A in the Saurashtra Offshore Basin. The multidisciplinary approach highlights the complex depositional history and reservoir heterogeneity of the Early Jurassic succession along the western offshore margin of India. The succession mainly comprises sandstones interbedded with thin shale layers. These sandstones show both textural and compositional maturity, dominated by quartz arenite. SEM and XRD analyses confirm the presence of kaolinite, quartz, microcline and minor muscovite. Sedimentological features and wireline log signatures reveal coarsening and thickening-upward trends, suggesting a prograding deltaic depositional system. Sedimentary structures and facies in cores CC-1 and CC-2 indicate deposition in delta front subenvironments such as pro-delta, mouth bar and distributary channels within a Fan-Delta complex. The stratigraphic cyclicity reflects small-scale sea-level fluctuations and variable sediment supply. Petrophysical analysis shows high porosity and high permeability, with better reservoir quality in CC-2. Permeability variations are controlled by intergranular and microporous pathways, while porosity remains primarily facies-controlled and largely unaffected by kaolinite. Overall, this integrated dataset improves understanding of Early Jurassic clastic reservoirs along the tectonically active western offshore Indian margin and highlights their exploration potential.