The injection pattern investigation of hydrocarbon gas enhanced oil recovery in heterogeneous reservoirs

Considering the large difference in physical properties and low water flooding efficiency of heterogeneous reservoirs, the hydrocarbon gas flooding to enhance oil recovery was investigated. Through the rising bubble apparatus experiment, it was determined that the injected gas and crude oil are immiscible under formation conditions. On the other hand, the displacement experiment carried out on a long core was used to perform the effect of hydrocarbon gas flooding. According to displacement experiment, alternative injection of gas as slugs with water slugs can mobilize the residual oil in place in the reservoirs. When the gas injection rate is 0.5 cm3/min, the recovery efficiency of hydrocarbon gas flooding is highest. At the same time, the lower of water content, the better the timing of waterflooding to gas flooding. In experiments with slugs of different gas–water ratios, when the gas–water ratio is 1:1, the oil recovery efficiency is the highest. The water alternate gas in use within limit adaptation could significantly enhance the residual oil recovery and bring more economic benefits.