2D seismic interpretation and petrophysical analysis of Bhangali field (P-1059) (MFN 3034)

Abstract

The seismic lines OX-S88-20, OX-S88-23, OX-S88-36 and Bhangali-01 well, obtained from Directorate General of Petroleum Concessions (DGPC), was shot by Occidental of Pakistan Inc. in the area of Bhangali (Eastern Salt Range/Potwar Plateau). The direction of the dip lines is NorthWest to SouthEast and that of the strike line is SouthWest to NorthEast. Two prominent reflectors namely Chorgali Formation and Basement were marked on the seismic section on the basis of observed reflection events. A fault was marked which continued along the Pre-Cambrian basement. Two more thrust faults were marked which show a fault-propagating fold in the form of the anticline of Bhangali. The TWT picked from the seismic section was posted on the base map to make a time contour map of the Upper Eocene Chorgali Formation, as it was continuing throughout the area. The seismic velocities (Vrms), given in the velocity windows on the seismic section, were used to find the average velocities of the Upper Eocene Chorgali Formation and the Pre-Cambrian basement. These average velocities were then used to find the depths of the formation for the depth contour map of the Upper Eocene Chorgali Formation. Well data of Bhangali-01 was used to mark the thicknesses of the individual formations and to perform petrophysical evaluation. The interpreted seismic sections and the contour maps showed that the area was structurally deformed due to salt decollement and compressional tectonic movements. Traps for hydrocarbons were developed in the anticlines as they truncated against the basement fault. Salt probably moved into these anticlines due to compressional movements. The Bhangali anticline is the prospective zone and is the primary targets for oil exploration, where the depth of the Upper Eocene formation is almost 3600m, favorable for drilling.