It is a general phenomenon that reservoir fluids interact dynamically with one another under certain geologic and anthropogenic conditions. This interaction brings about variations in rock and pore-fluid properties within such reservoir, which invariably affect its seismic response. The effects of these variations on seismic velocities can be modeled under different geologically plausible scenarios to understand the dynamism within a reservoir during recovery, and to monitor the reservoir throughout its production life history. In this study, rock physics template modeling, constrained by local geology, was employed to carry out time-lapse analysis of a target reservoir (M1) in Moremi Field, Off-shore Niger Delta basin. The aim was to create calibrated charts in form of rock physics templates that can be used as a calibrating device to optimize 4D seismic exploration in the study area. First, static rock physics templates were generated from rock physics cross-plots of the reservoir interval in P-impedance vs Vp/Vs and P-impedance vs S-impedance plains to predict and characterize reservoir M1 in terms of lithology and fluid, as well as diagenetic factors. Dynamic rock physics templates were incorporated to study the reservoir under different geologically plausible scenarios and to correlate relative changes in P-impedance and Vp/Vs to pore pressure, porosity, fluid contact changes and fluid saturation changes that may be anticipated in the reservoir production life history. Through fluid substitution based on Gassman’s theory, 4D well-log and seismic effects were modeled from 4D attribute cross-plots with three variable parameters; porosity, pressure and saturation, to aid the interpretation of time-lapse results. The final results were reported in terms of not only how reservoir fluids would interact under different conditions, but how the resulting impacts on the reservoir properties can be used as a reconnaissance tool to reveal important information prior to conventional 4D seismic survey.
Presentation Date: Tuesday, September 17, 2019
Session Start Time: 1:50 PM
Presentation Start Time: 2:40 PM
Location: Poster Station 13
Presentation Type: Poster