Laboratory Experimental Study Of Hydrocarbon Gas Injection In Ji Dong Oilfield

Hydrocarbon-gas flooding is one of enhanced oil recovery technologies in low permeability reservoir. It can effectively decrease the interfacial tension and oil viscosity to enhance oil recovery. Therefore this kind of technology was widely applied. The find of Nanpu oilfield provides ample natural gas for Jidong oilfield, it can apply for hydrocarbon-gas flooding and suplement formation energy. So in condition of water flooding has not clear effect, according to Jidong oilfield having the characteristic of low permeability,highly volatile,large inclined angle, carryed out laboratory experimental study of hydrocarbon-gas flooding in Jidong oilfield, having important significance.According to six blocks of Jidong oilfield, the paper carryed out laboratory experiment, including basic data of reservoir fluid, phase behavoir characteristics experiment, slim tube experiment and long core displacement experiment, analyzed different block gas injection flooding regulation. The gas injection phase behavoir characteristics experiment study showed that the value of bubble point pressure largen with mole fraction of gas injection, the bigger crude oil viscosity bubble point pressure have faster rise velocity. The bigger crude oil viscosity viscosity reducing effect was not obviously in the initial stage,but as gas injection increased, viscosity reducing effect was obviously. Minimum miscible pressure experiment showed that shallow light oil reservoir was not miscible,in condition of original reservoir pressure, middle-deep and deep layer medium-low permeability reservoir can achieve near-miscible,in condition of present reservoir pressure,only partial deep layer medium-low permeability reservoir can achieve miscible.Long core displacement test showed that compared with water flooding, water alternating gas injection(WAG) flooding and continuous gas flooding can obviously improve recovery, about percent 30,while WAG flooding is better.On the basic of laboratory experiment, the paper according to Jidong oilfield have large inclined angle and deep depth,carryed out reservoir numerical simulation research.Discussed different formation dip and oil depth WAG flooding enhanced oil recovery mechanism.At the same time, also discussed injection rate and gas-water ratio effect for gas injection.Study showed that formation with or without dip has significant effect on WAG flooding development.When formation have not dip angle,the lower the formation depth,the better the displacement effects. WAG flooding of inclined reservoir can obtain larger and more stable displacement rate than that of horzontal reservoir.For inclined reservoir, the gas-water ratio should not be too small and exist an optimal value, which was 1:1.