The application of steam injection in different forms of processes is widely used for thermal heavy oil recovery. Several studies have been carried out to evaluate the effect of injecting steam with gaseous additives such as, Hexane, Nitrogen, Carbon Dioxide, Propane and air. However there is very little literature about addition of methane or natural gas to steam in order to improve steam injection process.
This experimental study, investigates the effect of methane as an additive to steam. A consolidated core sample of an Iranian carbonate heavy oil reservoir (12°API) was used. The experiments involved injecting steam with methane in various methane/steam ratios ranging from 0:100 to 10:100 at reservoir conditions pressure and fluid saturations. Superheated steam was injected at 1200 psi which is higher than reservoir pressure at datum depth. Oil production rates, pressure drops and methane/steam ratios were measured to compare the effect of methane on oil recovery and other parameters at various fluid injection rates as well as steam temperatures.
With optimum methane/steam ratio it was noticed that oil production is accelerated, steam injectivity is increased and also recovery is higher when compared to injection of pure steam.