In-house Laboratory Investigation Of CO₂-water Alternative Drive In Heterogeneous Reservoir

Gas-water alternative flooding technology is a very effective way to improve the recovery of oil and gas.Gas-water alternative injection improves the mobility control,slow down the trend of water and gas breakthrough,and the combination of the lighter gas and heavy water improve the vertical displacement efficiency of reservoir.By this way,you can get higher oil recovery,and the foreign oil fields use it more extensively.In the low permeability heterogeneous sandstone reservoir,during water flooding,low-permeability layer use less,and overall development effect is not well.The experiment simulated the conditions of heterogeneous reservoir,to measured recovery,gas breakthrough time,oil production rate,injection pressure,injection gas capacity and so on.By core series,parallel experiment,to compare with CO2 flooding,this paper evaluated the heterogeneity effect on development.Gas-water alternative flooding compared with CO2 flooding,the ultimate recovery of positive rhythm layer increased by 20.56%and the ultimate recovery of anti-rhythm layer increased by 9.3%;High and low permeable layer is placed parallel to the core increased by 17.74%;In high permeable layer,positive rhythm recovery increased by 14.01%,anti-rhythm recovery increased by 13.05%,and high and low permeable recovery increased by placed parallel to the core increased by 12.78%;In low permeable layer,positive rhythm recovery increased by 6.1%,anti-rhythm recovery decreased by 0.168%,and high and low permeable recovery increased by placed parallel to the core increased by 29.51%.Gas-water alternative flooding injection pressure is higher 5.12Mpa more than CO2 flooding,and positive rhythm pressure improve to 9.6Mpa,followed by anti-rhythmic layer.Gas-water alternative flooding compared with CO2 flooding,the high permeable layer relative inspiratory capacity is greatly reduced,the anti-rhythm layer is reduced by 5.907%,and the positive rhythm layer is reduced by 8.74%.Regardless of series or parallel core,under the same conditions,Gas-water alternative flooding injection pressure is relatively high,injection capacity is lower,but the rest of the parameters are better than CO2 flooding.For the conditions in the experiment,gas-water alternative flooding effect is significantly better than CO2 flooding,and the positive rhythm effect is better than the anti-rhythm effect and parallel effect.