An Integrated Seismic Interpretation and Rock Physics Attribute Analysis for Pore Fluid Discrimination

Abstract

Accurate prediction of subsurface structures, lithologies and pore fluids, is of great interest for petroleum prospecting and reservoir characterization. Seismic reflection data are widely used to mark subsurface structures and lithologies. However, only seismic data are not sufficient to mark fluid heterogeneities present into the pores. Therefore, the use of integrated approach is vital to map subsurface heterogeneities with more accuracy. Based on seismic interpretation, the limestone of Chorgali Formation present in Ratana area of Northern Potwar, Pakistan is interpreted as reservoir rock. Structural interpretation revealed that the study area lies in compressional regime and structures formed are thrust and popups. The reservoir properties such as lithology, porosity, permeability, depositional environments, shale volume, fluid saturation, net pay thickness are determined from petrophysical analysis which confirms that reservoir characteristics of Chorgali limestone are enough to permit hydrocarbon production. Fluid substitution modeling is used to estimate different rock physics attributes such as compressibility, Lame's parameters and their product with density, P to S-wave velocity ratio, impedances and Poisson's ratio are computed as a function of pore fluid type (oil, gas, brine etc.). Sensitivity analysis is performed to derive fluid indicator coefficient which indicates the most appropriate and sensitive rock physics attribute that can be crossplotted to discriminate the rock saturated with different pore fluids (gas/brine/oil).

Hydrocarbon Mapping on Reservoir Carbonate Using AVO Inversion Method

“…Then super gather is carried out for trace smoothing, which aims to strengthen the amplitude response. The stacking process on seismic PSTM gathers data by adding seismic traces in one CDP after Normal Move Out (NMO) correction [17], [19], [20]. The CDP stack data obtained were then correlated with well seismic tie data.…”