SUBSURFACE STRUCTURAL INTERPRETATION AND PETROPHYSICAL ANALYSIS OF PIRKOH AREA, CENTRAL INDUSBASIN, PAKISTAN

Abstract

For the hydrocarbon exploration, study has been carried out in Pirkoh located in Sulaiman fold belt, sub part of central Indus basin Pakistan. Tectonically, Pirkoh structure is an attractive anticline, located in the northeast of Sulaiman foredeep. In Pirkoh the drilling has been done from Kirthar Formation of Eocene age up to Mughalkot Formation of upper Cretaceous age. Logging suite which includes caliper log, spontaneous potential log, gamma ray log, dual Laterolog, neutron log, density log, sonic log and micro spherically focused log has been run from depth of 2169 to 2354 m encountering Lower Ranikot Formation of lower Paleocene age, Pab sandstone and Mughalkot Formation of upper Cretaceous age. One zone of interest has been marked as Pab Sandstone till the well bottom. According to present research work, Pab Sandstone has been concluded as reservoir, the zones not only showed good porosity and hydrocarbon saturation but also bear acceptable volume of shale. For the study we have been given the segy files, navigation file, the well tops file for our research. For seismic interpretation, first the files are added to the software and a base map is generated, then since there is difference between the data types, a tie needs to be created and for that a synthetic seismogram is generated after which the horizons are marked and then faults are marked and finally after the horizons have been marked, a time contour map and depth contour map are plotted for interpretation. Now for petrophysical analysis, after the logs are added, the zone of interest is marked which in this case is Pab Sandstone and since is no clear separation between the resistivity curves, entire thickness of Pab Sandstone is evaluated for petrophysical analysis. Then volume of shale is calculated and volume of sand after which the porosities are calculated which are average and effective porosity respectively. After the results are calculated, it is concluded that petrophysical analysis confirms Pab Sandstone has good effective porosity and hydrocarbon saturation. Entire zone in Pab Sandstone has been evaluated for petrophysical analysis which shows that the sands of Pab Sandstone have the potential of being a reservoir.