RESERVOIR MODELING OF LOCKHART FORMATION, CHANDA OIL FIELD, KOHAT SUB-BASIN, PAKISTAN

Abstract

The present study interprets the subsurface structure of Chanda field of Shakardara area. Structural and Stratigraphic interpretation, seismic attribute analysis, Petrophysical analysis and Facies modeling of the area has been done. Navigation data, SEG-Y data and well log data has used for study. In northern Pakistan the shakardara area is the most complex area. OGDCL is the operator of Shakardara block which means seismic data is acquired and processed by OGDCL. For interpreting seismic lines three reflectors and thrust faults were marked on petrel software by using interactive tools. Fault polygon generation, synthetic seismogram, time contour maps and depth contour maps are also the part of seismic data interpretation. The marked horizons were identified using Formation tops by well data and depths were confirmed through correlation with synthetic seismogram from Density log (RHOB) and sonic log. Time and depth contour maps of different horizons that are marked were generated to collect knowledge related to the geometry of structures and nature of geological structures as identified by the seismic section of the area. The tectonic regime of the study area is compressional as thrust faulting is seen on the seismic sections. The Pop-up and Duplex structures formed by thrust faulting are confirmed on interpretation of these seismic lines. Shallower portions or Pop-up portions in the structure are suitable for hydrocarbon traps. Attribute analysis technique is used on seismic sections to enhance and interpret different lithological boundaries and confirmation of subsurface structural disturbance. Petrophysical analysis of Chanda-1, Chanda-Deep1 and Chanda-2 wells revealed that the Datta Formation has good reservoir potential as it has good porosity and Hydrocarbon saturation. In Lockhart Formation the primary porosity is not good, whereas Patala has good shale volume that shows it as a good source of Hydrocarbons. Facies modeling is a good source to identify and confirm the lithology. The facies analysis of these wells revealed that Lockhart Limestone on the basis of secondary porosity and Datta sandstone are good reservoir lithologies of the study area.