Mathematical Foundation and Numerical Simulation for Foamy Oil Flow in Porous Media

Southern Methodist University, Dallas TX

Investigators

Abstract

A technical description of the project: Heavy (dense and viscous) oils are considered an alternative energy source because they constitute one of the largest reserves of previously unexploited fossil fuels on earth. The fraction of the original oils in place that can be recovered by solution gas drive decreases with increasing oil viscosity. For heavy oil reservoirs, the expected recovery factor (percentage of the oil in the reservoir that can be recovered) by solution gas drive is typically lower than 5%. However, a number of heavy oil reservoirs under solution gas drive show anomalous primary performance: low production gas-oil ratios, high oil production rates, and high oil recovery. Ultimate oil recovery can be as high as 20% in the primary performance of such heavy oil reservoirs. The oil samples at the wellhead produced from these reservoirs are in the form of oil-continuous foam, which has the appearance of chocolate mousse and contains a certain volume fraction of gas. The term "foamy oil" is often used to describe such oils. The flow behavior of foamy oils is very complex, and remains controversial and poorly understood. This project is directed toward experimental, theoretical, and numerical investigations of the flow behavior of foamy oils. A nontechnical description of the project: The world needs enormous new crude oil reserves. During the next several decades, there is not and there will not be an economical, abundant substitute for crude oil in the economies of industrial countries, even with the price of a barrel of oil over $70. Maintaining the supply needed to support these economies and enable them to grow means that significant additional crude reserves must be developed. The conventional (light and medium) oil resources discovered up to the end of 2002 will last at most 40 years at 2002's production rate. Thus additional development will be primarily in the form of the sole alternative: heavy crudes. Two crucial issues must be addressed before or during the design of any production project for these heavy oils: What is a suitable method for evaluating the foamy oil drive mechanism that plays a major role during such oil recovery, and what is a reasonable percentage of ultimate oil recovery for each project? Unfortunately, these two issues have not been fully addressed and are still not understood. The laboratory experiments, theoretical investigations, and numerical simulations proposed in this project will greatly improve our understanding of these issues.