Evaluation of reservoir potential for unconventional hydrocarbon, Potwar Basin, Pakistan (Late Palaeocene Patala and Early Jurassic Datta Formations): Insights from sedimentological, geochemical and petrophysical analyses

These days, despite of technological advances, the world’s conventional hydrocarbons reserves continue to be depleted at high rate as our reliance on it is increasing day by day. However, the recent successful recoveries of hydrocarbons from unconventional reservoirs such as shale gas/oil plays has tremendously increased the world’s interest towards these unconventional hydrocarbons. Thus, the current research project aims to evaluate the conventional and unconventional hydrocarbon potential of the Late Paleocene Patala Formation, in the petroliferous Potwar Basin of Pakistan. Conventionally, the formation is acting as a proven source rock to charge the reservoirs of Potwar Basin. However, it also possess prospects to act as source for unconventional hydrocarbons such as shale gas/oil and tight gas reservoir. The strata is mainly comprised of, in descending order of their abundance, shale, limestone, sandstone, marl and coal lithofacies. The shale and coal lithofacies are organic rich and possess prospectivity to be assessed for shale gas/oil potential of these strata. In general, shale constitute two thirds of all the sedimentary rocks and can act as source for conventional and reservoir for unconventional hydrocarbons when stimulated. However, yet they are amongst the least understood of all clastic sedimentary rocks. Likewise, about 60% of the world reservoirs are contained in carbonate rocks but their reservoir complexity is often not fully understood. The limestone of Patala Formation is bituminous as well as nodular in nature and possess suitability for conventional and unconventional reservoir potential. Overall, in this project an integrated sedimentological, organic geochemical, mineralogical and petrophysical approach will be applied to investigate the paleo-depositional and diagenetic environments in relation to the conventional and unconventional reservoir potential of the formation. The sedimentary and diagenetic attributes encountered will be figured out and their impact on tight reservoir architecture will be addressed. X-ray diffraction, major & trace geochemical and petrographic techniques will be applied to investigate the mineralogy, elemental composition, lithological characteristics and heterogeneity of the lithofacies. These techniques will also help to understand the physical framework such as clay mineralogy, clay fabric, pore size distribution and percentages of brittle minerals such as silica that are critical for successful fracturing of the tight shale gas reservoirs. Likewise, total organic carbon (TOC), Rock Eval pyrolysis and vitrinite reflectance (VR) analyses will be carried out to assess organic richness, thermal maturity and hydrocarbon generation potential of the formation. Finally, in this PhD project in order to investigate petrophysical characteristics such as porosity, permeability and complex pore networks, scanning electron microscopy (SEM), computed tomography (CT) scan, mercury injection capillary pressure (MICP) and nuclear magnetic resonance (NMR) analyses will be performed on rock samples to understand the reservoir potential of the targeted unit.