Nowadays, oil reservoirs in Vietnam have been put into production and most of them are at the secondary stage of production, as a result, the production rate is decreasing. According to some scientific research results, the remaining reserves can only reach about 5 % of the initial oil in place in the next 10 years. Therefore, it is essential to enhance the oil recovery factor, which needs to clearly understand the status and production situation. In this study, the authors selected the enhanced oil recovery method for 11 reservoirs in the Lower Miocene based on J. J. Taber criteria and artificial intelligence. Then, the authors compared the results from this study with those from the commercial software. The result shows that the developed model is sufficiently reliable in choosing the appropriate enhanced oil recovery method.
The production of oil fields can be divided into three phases: primary, secondary, and tertiary stages. For each production stage, the technology applied to the reservoir will be different. In the primary production stage, when the initial reservoir pressure is greater than the hydrostatic one (or when the initial reservoir pressure is greater than the total pressure loss of the flow from the bottom hole to the surface), the oil will be produced by the natural energy of the reservoir. Commonly used reservoir energy mechanisms are gas cap, water drive, dissolved gas, gravity and mixture mechanisms. In the secondary stage, oil recovery methods are used in order to maintain the reservoir pressure and push oil toward the production well; common ones are water and gas injection. In the tertiary stage, oil recovery methods aim to change the reservoir and fluid properties. Enhanced oil recovery (EOR) methods not only provide reservoir energy but also facilitate oil recovery processes by the interaction of injection fluids with oil and reservoir rock (Lake, 1989; Green and Willhite, 1998; Sheng, 2013).