Investigation And Project Design Of CO₂Flooding In Low Permeability Reservoir

Yi34block of Bonan oilfield belongs to ultra-low permeability reservoir, whosedevelopment mode is injection energy development. But the injection pressure is veryhigh and the injection effect is very poor. The key to improve the effect of the34block is how to effective complement the formation energy. CO2flooding is theimportant method to enhance oil recovery, especially to the low permeability oilrecovery.In this paper, we complete CO2flooding reservoir engineering design by CO2and formation oil system phase feature research, CO2flooding miscible pressureresearch and CO2flooding into the way and the oil displacement efficiency researchand gas injection development feasibility evaluation. The results show that, CO2in theformation of the crude oil has a strong dissolving capacity. the solubility of CO2incrude oil increases with the injection pressure increasing. Because CO2can easilydissolved in the crude oil, oil volume will greatly expansion with the injection ofcarbon dioxide, and oil viscosity will decrease significantly. Yi34block of Bonanoilfield can realize CO2miscible flooding according to the thin tube experimentresults. According to the reservoir low permeability core three undersecretary coredisplacement test results, it is known that in the present formation temperature andpressure, the CO2injection oil displacement can obtain much higher than waterflooding oil recovery. In conclusion, the sooner carrying out carbon dioxide miscibleflooding test, the better. Finally according to the block reservoir characteristics, weoptimize the design of the CO2flooding plan and scheme in the index prediction.