Effects of the Strategies of Geological Modelling And Simulation On Scale-up

Abstract

This paper presents results of an investigation of various criteria that can be used for decisions related to reducing the number of layers needed to represent a reservoir in reservoir simulation. One of the approaches towards reducing the number of grid-blocks needed in simulation study is to combine thinner layers represented by scaled petrophysical properties. The Gypsy formation was used to develop three different geological models based on channel identifiers, lithofacies and flow units, respectively. The effect of the criteria used for combining layers on simulation results was studied by conducting scale-up for three different geological models, three different production scenarios and three different boundary conditions. It is observed from the results that the use of lithofacies as a criterion provided the closest match to fine-scale results. Also, results based on three criteria differed significantly only during the early phase of flow. Strategies of geological modeling have a significant impact on scale-up. The channel model and the lithofacies model produce similar results, but flow unit model provides inferior results. Comparing the scale-up results for nine-spot drive, line-drive, and five-spot drive, the line-drive scenario produced the best matches for both water production and reservoir pressure. Comparing the scale-up results obtained for three different boundary conditions, no-flow boundary condition obtained a better results compared to open boundary conditions.