Offshore heavy oil recovery by periodical injection of steam and flue gas

Based on the results of experimental and numerical simulation,the stimulation principles of cyclic steam and flue gas co-stimulation are investigated including oil viscosity reduction by heating and gas solution,enlargement of heat sweeping efficiency by co-injected gas,which can reduce heat loss,improve sweep efficiency and the synergetic effect of steam and flue gas.Then some significant injection parameters such as temperature of injected steam and flue gas,and ratio of flue gas to steam are optimized.The recommended temperature of injected steam and flue gas is higher than 300℃,and volume ratio of flue gas to steam under atmospheric pressure is 0.4-0.6.The field testing of 4offshore heavy oil wells co-stimulated with steam and flue gas shows that up to 3times of oil production rate in average compared to that of cold production is observed,and the peak oil production is more than 100m 3/day,and cyclic oil production is almost 10 000m 3.In summary,cyclic steam and flue gas co-stimulation is practical and effective to enhance the production rate and recovery factor of offshore heavy oil reservoir,and is potential to be the main thermal production technology for offshore heavy oil reservoirs.