Numerical Studies of Gas Exsolution in a Live Heavy-Oil Reservoir

Abstract

Abstract Gas phase formation in supersaturated live heavy oil occurs by bubble nucleation and growth. Modeling the dynamics of these processes in cold production is essential, since they are key mechanisms in determining oil recovery. The greatest challenge in field scale simulations of cold production is to quantify the spatial and temporal changes of the gas exsolution and transport processes. This paper describes a new kinetic model which, when coupled with a thermal reservoir simulator, can simulate the dynamics of gas exsolution and transport processes in a heavy oil reservoir. In this model, two relatively simple types of mass transfer equations predict bubble nucleation and growth in a live heavy reservoir. The model structure and parameters were investigated in comparison with a previously published model. The capability of the proposed kinetic model to handle the dynamics of gas phase formation in a heavy oil reservoir was explored in two sets of laboratory experimental data. In set 1, numerical history matches of pressure data were performed for eight constant withdrawal rate experiments. In set 2, numerical history matches of oil and gas production data were performed for four pressure depletion experiments. A close agreement was achieved between numerical simulation and experimental results. The model can be applied in the field scale simulations of cold production to predict gas exsolution and gas builds up in an oil reservoir.