PETROPHYSICAL ANALYSIS AND 2D SEISMIC STRUCTURAL ANALYSIS OF SUBSURFACE GEOMETRIES OF SHAKARDARA AREA, KOHAT SUB BASIN, PAKISTAN

Abstract

The study area Shakardara is situated in District Kohat, Khyber Pakhtunkhwa province, Pakistan. The purpose of the present work is to understand the petrophysical properties of the wells drilled and structural features of Shakardara area. The data used for this research work are seismic data of three dip lines 967-SHD-318, 967-SHD-319, 865- NK-12 oriented N-S direction and one strike line 967-SHD-308 oriented NE-SW direction in SEG Y format for structural interpretation and well logs data of Chanda Deep-01 well and Chanda-01 well were used for the petrophysical analysis. The seismic data and well logs data were processed and acquired by (OGDCL), Oil and Gas Development Company Limited. Petrophysical analysis is carried out with the help of (GEOGRAPHIX DISCOVERY) software while (IHS KINGDOM) software is used for seismic interpretation. The two formations of Chanda Deep-01 namely Lockhart Formation, Datta Formation, while Hangu Formation from Chanda-01 well is petrophysically interpreted. The average Vshl (volume of shale) in zone-A of Lockhart Formation is 14.36% and the effective porosity is 10.66% while the average water saturation Swa is 6.16% and hydrocarbon saturation is 93.84%. The average Vshl in zone-B of Lockhart Limestone is 13.02% and hydrocarbon saturation is 96.69%. The Vshl (volume of shale) in zone-C of Lockhart Formation is 8.61% and hydrocarbon saturation is 96.58%.The average volume of shale in zone-D of Datta formation is 5.03% while in zone-E average Vshl is 20.96% and hydrocarbon saturation is 57.47% whereas the average hydrocarbon saturation in zone-D is 54.57%.The effective porosity in zone-D is 6.40% while in zone-E phiE (effective porosity) is 5.41%.Both Lockhart Limestone and Datta Sandstone shows high net pay saturation and hence considered as an excellent producing reservoir in the area. The average Vshl (volume of shale) in zone A of Hangu Formation of Chanda-01 well ranges upto 7.70% while the effective porosity is 5.18% and the hydrocarbon saturation is 88.58% acts as a good to better producing reservoir in the well. For the seismic interpretation three reflectors and thrust faults are marked on seismic time section. The seismic interpretation confirms that thrust fault propagation fold is present in the area which leads to compressional tectonic regime. Seismic section shows that structural traps are present in the area which is best for the accumulation of hydrocarbon. Both time and depth contour maps are generated which shows thrusted anticlinal structure. Seismic interpretation confirms that both wells are drilled on thrust anticlinal structure.