Infill Opportunities Validation for a Mature Niger Delta Reservoir: Lessons Learned and Best Practices

Abstract

Abstract Infill opportunity identification in a mature reservoir has some unique challenges because of the uncertainties in exact fluid front movement. These uncertainties are magnified for waterflood or gas-flood reservoirs. The reservoir of interest is a saturated oil reservoir with 54 years of production history and under waterflood. The aim of this study was to validate with a dynamic simulation model, infill opportunities proposed from using a combination of map-based assessment and current reservoir production data. High-resolution reservoir characterization was done to properly capture the different stratigraphic units in the reservoir. Insights from production and pressure behavior formed part of the input during the characterization phase. Results of the characterization step were used for earth modelling to generate a base case earth model for the reservoir used for history matching. Pro-cycling of the model was done during the history matching process, enabling the narrowing of fluid-in-place uncertainties during history matching. This resulted in a high-quality history-matched model that replicated over 80 percent of the fluid contact movement observed over the production life of the reservoir. This model was then utilized to validate two proposed infill opportunities in the reservoir. A key lesson identified during the process is that the use of high-resolution reservoir characterization methods prior to the earth modelling stage ensures better tracking of fluid-front movement and better replicates observed historical data. Rapid cycling between the earth modeler and simulation engineer also delivers significant value, by helping to resolve history-matching challenges early on and ensuring alignment between the dynamic model and the static interpretation of the reservoir.