A fast method of waterflooding performance forecast for large-scale thick carbonate reservoirs

Abstract Due to the severe heterogeneity of carbonate reservoirs, the traditional reservoir engineering methods for waterflooding performance forecast, mainly including the material balance equation, waterflooding characteristic curve and production decline curve, suffer from less reliability. The fine-scale reservoir numerical simulation is extremely time-consuming, because petrophysical properties in carbonate geological models change so drastically. To predict the development performance rapidly, a new method for large-scale thick carbonate reservoirs is proposed. By combining the geological characteristics and dynamic performance of each well, vertical stacking pattern of the reservoir are classified, and also good insights into the lateral distribution of typical stacking patterns are also gained. The stacking pattern distributions are further projected onto the waterflooding well pattern, followed by rapid evaluation of production and injection rate of every block. Based on the simulation results for typical stacking pattern blocks, type curves of water flooding on different stacking pattern reservoirs are workout. Then the waterflooding performance for the whole carbonate reservoir is step-by-step quickly predicted at a constant liquid rate so as to keep the reservoir injection-production balance with voidage replacement ratio 1. Finally, a large-scale thick porous carbonate reservoir in the Middle East is taken as an example to show the workflow of the proposed method. The accuracy is further validated by comparing the predicted results from numerical simulation, indicating that the proposed method can save a lot of calculation time while ensuring the accuracy of performance forecast.