Visual Experimental Study of the Factors Affecting the Stability of Foamy Oil Flow

Abstract

Some of the heavy oil reservoirs in Canada, Venezuela, and China under solution gas drive illustrate important features: low gas–oil ratio, high production rates, and very high ultimate oil recovery. It is generally believed that the foamy oil flow is one of the important mechanisms contributing to these unusual performances. A series of two-dimensional etched glass micromodel experiments was carried out to gain an insight into the processes involved in foamy oil flow. In these experiments, the bubble nucleation, migration, coalescence, breakup, and ultimate generation of a continuous gas phase can be observed continuously. On the basis of the experimental analysis, there are two bubble-point pressures in the foamy oil: One is the true bubble-point pressure, and the other is the pseudo-bubble-point pressure. The greater the difference between these two bubble-point pressures, the more stable the foamy oil flow is and the greater the contribution to oil recovery from the foamy oil drive mechanism is. The visualization experimental results show that there are many factors affecting the stability of the foamy oil, including pressure depletion rate, crude oil viscosity, temperature, dissolved gas–oil ratio, etc.