Numerical Simulation of CO2-N2 Combination Flooding in Low Permeability-Ultra Low Permeability Homogeneous Reservoir

4th International Conference on Energy Equipment Science and Engineering

Chen, Taoping^1 ; Bi, Jiaqi^1 ; Zhao, Bin^1 ; Sun, Wen^1

Enhanced Oil and Gas Recovery Key Laboratory, Ministry of Education, Northeast Petroleum University, Daqing

163318, China^1

关键词: Homogeneous models;    Input-output ratio;    Layer thickness;    Low permeability;    Numerical simulation software;    Permeability increase;    Ultra low permeability;    Ultra-low permeability reservoirs;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/242/2/022035/pdf
DOI  :  10.1088/1755-1315/242/2/022035

来源: IOP

【 摘 要 】

For low permeability, ultra-low permeability reservoir, the CO2 preslug + N2 flooding, using CMG numerical simulation software, the ideal homogeneous model which permeability is 3×10-3 μm2 has been established. The recovery of CO2 flooding under the 11 length-thickness ratios was calculated; the effects of 7 kinds of flooding slug combinations and 4 kinds of permeability on recovery with input-output ratio were analyzed; factors such as length-thickness ratio, permeability and injection slug combination affecting flooding effective were studied deeply. The result shows that: when the length-thickness ratio under the 100, as the increasing of the length-thickness ratio of the model, the oil recovery increased. When the length-thickness ratio reaches to 100, the oil recovery tends to be stabled, that is, when the single oil layer thickness less than 1% of the well spacing, it is more benefit to improve the oil recovery. As the permeability increases, the compound flooding recovery will decrease when the CO2 injection (PV) is a constant and the CO2 slug requires for the combination flooding to achieve the ultimate recovery increases, that is, the lower the permeability is, the more favorable it is for the CO2-N2 combination flooding. In actual oil reservoirs with a lengthen-thickness ratio of 30, the slug composition of CO2-N2 compound flooding should adopt the way of 0.3 PV CO2 slug + subsequent N2.