Low Permeability Gas-Bearing Sandstone Reservoirs Characterization from Geophysical Well Logging Data: A Case Study of Pinghu Formation in KQT Region, East China Sea

The Pinghu Formation is a low permeability sandstone reservoir in the KQT Region, East China Sea. Its porosity ranges from 3.6 to 18.0%, and distributed 0.5 251.19 mD. relationship between was poor due strong heterogeneity. This led difficulty of quantitatively evaluating effective reservoirs identifying pore fluids by using common methods. In this study, effectively evaluate sandstones structure first characterized nuclear magnetic resonance (NMR) logging based on piecewise function calibration (PFC) method. Effective formation classification criteria were established indicate “sweet spot”. Afterwards, several methods proposed calculate petrophysical parameters, e.g., porosity, permeability, water saturation (Sw), irreducible (Swirr). Finally, two techniques, crossplots mean value apparent resistivity (Rwam) versus variance (Rwav)—Sw Swirr—were adopted distinguish hydrocarbon-bearing formations saturated layers. Field applications different regions illustrated that techniques widely applicable. Computed parameters matched well with core-derived results, obviously identified. These valuable improving characterization.