3D data interpretation petro physical Analysis and reservoir Modeling through Inversion and Rock Physics Modeling

Abstract

There are many special techniques in geophysics that are implied to delineate the under surface natural resources of any area. To untapped the hydrocarbon reserves seismic reflection method is widely used technique. To map potential of reservoir in a comprehensive way 3D data is more feasible because it gives high resolution of subsurface. To measure and evaluate the hydrocarbon strength and sand channels of area this study has gone through on Sawan field. Here 3D seismic interpretation, Rock physics, and Seismic Inversion techniques with Petrophysical analysis for the interpretation purpose of study area. 3D data is given as in-lines from 720-860 and cross lines are given as 880-1000 with three wells as Sawan-01, Sawan-07 and Sawan-08 as gas producing. The work is gone through proper sequence as with generation of synthetic seismogram with (0.718) correlation and then three horizons of interest are picked as Lower Goru, D-Interval and finally C-Interval as reservoir. To overview the depth variations of these horizons time contour maps are created and it is clear that sand interval (2190ms to 2260ms ) of Lower Goru formation of age cretaceous age are proven as strong reservoir that is present in middle and lower indus basin but specially in Sawan area these are much deep and heterogeneous. Petrophysical analysis is also taken into account for calculation of reservoir properties that are as volume of shale (Vsh=20%), Porosity (Ф=17.3%), Average effective Porosity (Ф=11.4%) Resistivity of water formation (Rw=66%), Saturation of water (Sw=66%), Saturation of hydrocarbon (Sh=34%) that definitely incorporated help in identification of potential zones by evaluation of reservoir properties by well logs. Reservoir sand is clearly dominating by facies trend and porosity variations are defined by cross plots. Seismic Inversion is initiated by acoustic impedance that undoubtedly played an important role. Model based inversion of 3D data is performed for the recognition of dimensional dispersion of acoustic impedance in potential zone. Actually, Acoustic impedance gives a reflection between layer property and suitable interface property. It is a vast level translator so from well position a zero phase wavelet is calculated by the help synthetic trace and seismic trace contrasting filter. Then, by the translated horizon and well log data a low impedance model is built. Using acoustic impedance to predict porosity far from the well position by the help of seismic inversion. Core objective of Seismic backward modeling is to get high determination from low determination seismic info. Furthermore, Inversion technique combines rock physics and model based inversion. Undoubtedly seismic inversion is a non-unique problem and always ambiguities are associated with this method. Keeping in mind an equation is obtained which found that clean C sand is shown by acoustic impedance and porosity. Successfully results are demonstrating the porosity, density bulk and shear moduli as well as P and S velocity in the prospect zone.