Non-hydrocarbon gas injection followed by steam-gas co-injection for heavy oil recovery enhancement from fractured carbonate reservoirs

摘要

Considerable heavy oil is accumulated in naturally fractured carbonate reservoirs, with very low oil recovery efficiency through costly production techniques. In this experimental study, the effects of different non-hydrocarbon gases on the performance of gas injection process followed by steam-gas co-injection on heavy oil recovery from low permeable full sized carbonate cores were investigated at reservoir conditions in a long fractured laboratory model. Three different gases: pure CO2, pure N-2, and their mixtures as synthetic flue gas were used to study the performance of gas injection process. Also, the tests were continued by steam-gas co-injection process that gas was injected with specific steam/gas ratio at steam saturation temperature condition. In the course of experiments, oil and water productions, pressure and temperature were monitored carefully.