Reservoir Characterization of Kadanwari Gas Field Using Petrophysics and Seismic Inversion Integrated with Seismic Interpretation and Fault Seal Analysis

Abstract

This research work is done for reservoir charactelization of Ka hwru ' --ga's field by using 2D and 3D seismic data along with well data of three wells Kadanwari -08, Kadanwari 10 and Kadanwari-16. It lies in middle Indus basin of Pakistan. Based on well data four horizons are marked which are Upper Gom, Lower Gom, G Sand and E Sand. Then Time contour maps are generated to find the horizons trend and overall stmcture of this area. Then seismic velocities are used to change the time data to depth. Depth contour maps are generated to find the depth of these horizons and their thickness in study area. Seismic interpretation shows that in this area normal faults are present in the form of Horst and Graben. Petrophysical analysis of two wells Kadanwari-08 and Kadanwari-1 0 is done to find out the reservoir zones and pay zone based on volume of shale, Porosity, resistivity, water saturation. Facies modeling is done to differentiate between the shale and sand lithology and to discriminate the gas sand from the Brine sand. Fault seal analysis is used to find the sealing capability of faults which are present in the study area. First Juxtaposition diagram is used to check whether there is seal here due to juxtaposition of different lithologies. Then shale gouge ratio method is used to check that faults itself are acting as a seal or not. Seismic attribute analysis is done to confilm the seismic interpretation done previously. In this different attribute are used such as reflection strength, Phase and average energy. Seismic inversion is used here to characterize the reservoir zone. First P impedance model is computed from the well data and interpretation data and then it is used for inversion to get the impedance section. On impedance section reselvoir zone is picked by low value of impedance. This impedance model is used to find the porosity distribution of G sand in the 3D seismic area. This porosity is compared with the petrophysical results of Kadanwmi-10 to confilm it. Density section is generated and reselvoir zone is marked on it by low value of density. Shear velocities are used to generate the shear impedance model to get the shear impedance section after seismic inversion. This S impedance is used along with P impedance to find the Lambda-Rho and Mu-Rho section. Reservoir zone is picked by low value of Lambda-Rho with cOlTesponding high value of Mu-rho. Compressional wave velocity and shear wave velocity is used to find the Vp/Vs section, reselvoir zone is picked here by low value ofVp/Vs.