2D Seismic Data Interpretation and Petro physical Analysis of Sawan Area, Central Indus Basin, Pakistan

Abstract

The study represents the seismic interpretation and petrophysical evaluation of the Sawan Gas Field, situated in the Central Indus Basin of Pakistan. The main objective is to assess the hydrocarbon potential of the Lower Goru Formation, which lies between the depths of 2707 meters and 3635 meters in the Judge-01 well. A total of five 2D seismic lines were interpreted using Kingdom software. Synthetic seismograms were generated to correlate well data with seismic profiles, allowing accurate marking of key horizons and fault structures. The seismic interpretation identified horsts, grabens, and a negative flower structure, reflecting significant tectonic deformation. Time and depth contour maps were created for formations such as Lower Goru, Habib Rahi, and Sui Main Limestone to visualize subsurface geometries and identify potential hydrocarbon traps. Petrophysical analysis was carried out using various logs including gamma ray, resistivity, neutron, density, and sonic logs. Different porosity types—density, neutron, sonic, average, and effective porosity— were calculated. In Zone-1, the average porosity (PHIA) was 5.8% and the effective porosity (PHIE) was 5.3%, while Zone-2 had PHIA of 4.4% and PHIE of 2.7%. The average shale volume (Vsh) was 10% in Zone-1 and 32% in Zone-2, indicating cleaner rock in Zone-1. Water saturation (Sw) intervals were also computed, averaging 37% in Zone-1 and 43% in Zone-2. These results confirm that Zone-1 has better reservoir quality, with higher porosity, lower shale content, and reduced water saturation. Overall, the integration of seismic and petrophysical data provides a clear understanding of the subsurface and highlights the gas-bearing potential of the Lower Goru Formation in the study area.