Seismic based structural interpretation and Reservoir characterization along with pore Pressure studies of Dhodak area, center Indus basin, Pakistan (T-1446) (MFN 7097)

Abstract

The present study pertains to the modeling of the productive zones by using seismic and well log datain the study area, since the study area had abnormal pressure conditions encountered in the wells that were drilled in the past. These studies were carried out using Seismic lines, 795-SK-06, 795-SK-07, 795-SK-05, 795-SK-IIA, 805-SK-18, 805-SK-19, 805-SK-20 and well log data of Dhodak-O 1 and Dhodak-05 provided by the Directorate General of Pakistan concession. Seismic data was used to delineate subsurface structure in the study area for hydrocarbon entrapment, since the study area lies in the Northern compressional tectonic regime, So, the main entrapping structure in the study area was pop up anticline. The log data of both the wells were used for analyzing hydrocarbon producing zones from the formations including Lower Ranikot Formation and Pab Sandstone through petrophysical analysis. Seismic data in collaboration with well data was used to predict porosity values at well locations as well as Inter well region using empirical relationships between acoustic impedance and porosity at well locations and then predicting porosities on seismic sections using that empirical relationship. Well log data was also used to conduct pore pressure studies in the study area using Eaton's velocity method through Sonic, density and GR logs, since Dhodak gas field had experienced high pressures while drilling few wells and mainly a blow out in Dhodak-O 1 well. The pore pressure results confirm high pressure conditions in compared with the hydrostatic pressure gradient of the study area. These results can be used to estimate the overall pressure conditions in the study area to define pre drill pressures and adjusting the mud weights accordingly for further drilling of wells in the study area.