Experiments on gas and water injection for enhanced oil recovery in porous carbonate reservoir

In Middle-East area,there are some porous carbonate reservoirs with low permeability,few fractures and relatively poor fluid properties.Taking S reservoir as example,the gas and water injection experiments were carried out,and microscope seepage mechanism of EOR was researched.The results show that under formation conditions,miscible associated gas flooding is not achieved easily because of high minimum miscible pressure.The flooding efficiency of hydrocarbon gas injection is higher than that of water injection,especially in the condition of miscible flooding.The immiscible flooding efficiency of gas injection is relatively high,because gas flooding makes oil volume expanse and viscosity decrease,and then oil mobility is improved.In the experiments,water injection and gas injection mainly displace mobile oil in micropore,so changing displacement manner should be considered to improve flooding efficiency further.