Sensitivity analysis of changing Reservoir Saturation involving Petrophysics and Rock Physics in ‘Royal G’ field, Niger Delta

Abstract

Adequate reservoir information is needed for accurate reservoir characterization towards enhancement of hydrocarbon recovery. The reservoir petrophysical parameters and elastic (seismic) properties are related to the quantity of reservoir rock fluids as well as the interaction of fluid types in the reservoirs’ pore space. Apart from the usually study of the petrophysical properties, the elastic properties are also vital because they are affected by the pore fluids interchange during hydrocarbon production or extraction. This study is aimed at examining and predicting those elastic properties that are most responsive and sensitive to changes during the fluid substitution. Information from three well logs from the ‘Royal G’ field’ situated in Niger Delta (onshore) were used for the petrophysical analysis and rock physics interpretation. The 3D crossplot outcomes were established by utilising Gassmann's fluid replacement or substitution modelling evident considering 0% oil and 80% brine (full) saturations in the reservoirs. Reservoir A and B have porosity, permeability and hydrocarbon saturation of 10–29%, 285–670 mD and 62–90% respectively. The 3D crossplot of the pseudo elastic logs give descriptive and distinct lithology and definite fluid content separation. Rock properties identified and noted to be extremely sensitive/reactive for lithology as well as fluid differentiation in the probed reservoirs are Acoustic Impedance, Density, Poisson ratio and Lambda-Rho. The outcome will generally enhance production and recovery of hydrocarbon.