This paper was prepared for presentation at the Third Numerical Simulation of Reservoir Performance Symposium of the Society of Petroleum Engineers of AIME to be held in Houston, Tex., Jan, 10–12, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by who the paper is presented. Publication elsewhere after publication in the JOURNAL OF presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.
The use of carbon dioxide in free form or dissolved in water as a flooding agent in secondary and tertiary recovery projects offers several advantages over the use of pure water. Carbon dioxide will dissolve into the oil and increase the oil mobility by reducing its viscosity and by increasing its saturation as a result of swelling. In applying this recovery technique to field practice, a method of predicting reservoir performance is required. predicting reservoir performance is required. The purpose of this paper is to report the development of a numerical model that can be used to predict the reservoir behavior of a carbon dioxide flood in a heterogeneous reservoir. The mathematical model is based upon the transport equations that describe the two-dimensional, simultaneous flow of three phases -oil, water and CO2. Solubility of the CO2 in both water and oil and the development of a free CO2 phase are allowed.
Because of the paucity of reported results of laboratory, field and mathematical model studies, it is only possible to present limited comparison between the results of this model and other results. It is hoped that the results described here will provide the future researcher with a basis of comparison.
Displacement tests, using free CO2 and carbonated water, have been conducted in the laboratory. All of these tests indicated that CO2 flooding results in increased oil recovery in comparison with conventional waterflooding.
There have been at least two attempts to devise mathematical models for predicting the behavior of a CO2 flood. DeNavers presented a model based on Buckley-Leverett flow and Welge's method. This model was one-dimensional, and all the ordinary Buckley-Leverett assumptions were made. Ulanovskii and Levi presented a model of a carbonated waterflood in one dimension. They numerically solved the fractional flow equation along with an equation that accounted for the presence of CO2 in oil and water. They also presence of CO2 in oil and water. They also made most of the assumptions ordinarily made in a Buckley-Leverett model.