Diffusion Process in Reservoir Fluids in Gas Injection Projects

Gas is injected in to reservoir for several purposes including:storage of gas (natural gas), reduction of green houses gases in the atmosphere(i.e.CO2 sequestration) , keeping reservoir oil recovery. As production of oil through conventional methods is in decline , enhanced oil recovery methods are important to extract more oil specially from unconventional iols and reservoirs. gas injection is one of the most commonly used methods of enhanced oil recovery (EOR). In the U.S . gas injection projects may provide billiions of barrels of additional recoverable oil and increasing production life of some existing reservoirs by 20-25 years. in many oil reservoirs waterflooding is no longer as productive because water tends to flow under lower portions of the oil while gas can diffuse into entire portions of the oil . gas injection is useful technique to produce heavy oil and extra heavy oil by increasing oil mobility and viscosity reduction in this case understanding the mechanism of diffusion of gas into oil is important . natural gas CO2 and nitrogen are being used for injection purposes in EOR processes. now some estimates of heavy oils and bitumen in the world give a figure between 5 to 10 trillion barrels comparing to 1.3 trillion barrels of conventional oils and sustainable production of oil will depend on oil recovery from such reservois.

Keywords:

gas injection , enhanced oil recovery , heavy oil , miscible flooding , diffusion process , diffusion coefficients , natural gas , reservoir fluids , experimental technique , reservoir modeling