A Comparison of Hybrid Steam-Assisted Gravity Drainage Models in Top Water Reservoir

Top Water Reservoirs are continually being exploited by oil companies to meet the increasing energy demands. This type of reservoir is considered fragile and requires thorough development strategies to achieve acceptable recovery factors. This study discusses the advantages of the SAGD, Steam Assisted Gravity Drainage, system in the development of Top Water Reservoirs. A literature review shows that SAGD has the edge in cumulative oil recovery in comparison with CSS, Cyclic Steam Stimulation. This is because the SAGD system can maintain a consistent steam injection pressure throughout the production of the Top Water Reservoir. A consistent pressure system is necessary in this type of reservoir to achieve higher oil recovery rates.;The oil industry utilizes different gas mixtures to recover heavy oil and bitumen from top water reservoirs. The different gas mixtures used are: solvent-steam, nitrogen-steam, and methane-Steam gas mixtures. A generic, sink/source, SAGD model was developed using CMG to compare the effects of the three gas mixtures mentioned above on the behavior of the top-water zone and reservoir. The results showed that nitrogen-steam and methane-steam gas mixtures can delay a top water zone collapse. It was found that nitrogen-steam and methane-steam mixtures minimize heat loss to the top-water zone in comparison to the solvent-steam gas injection mixture.