Application of seismic inversion in estimating reservoir petrophysical properties: Case study of Jay field of Niger Delta

The conventional approach in reservoir characterization uses an extrapolation of petrophysical properties calculated from well logs in determining the entire field volume. This technique fails to acknowledge the heterogeneity of a reservoir and consequently leads to errors (under or over-estimation) in reservoir capacity quantification. This research employs a deterministic seismic inversion approach in determining the petrophysical properties of each reservoir sand. First, the reservoir sand was identified from intervals of low gamma-ray value with corresponding high resistivity log value. Then, a synthetic seismogram was generated to tie the well to the seismic data and identify events corresponding to the reservoir sands. This was done by convolving the developed reflectivity series, derived from approximated Zeoppritz reflectivity with a zero-phase wavelet generated using the seismic. Acoustic impedance from the well and seismic were analyzed and strongly correlated. The impedance was then constrained with determined petrophysical parameters from the well, and it was used in generating the petrophysics base model used in the inversion. Finally, deterministic seismic inversion was carried out to determine the petrophysical properties such as porosity, the volume of shale, and water saturation associated with the fluids from the seismic volume of Jay-field shallow offshore of Niger Delta.