Abstract:

Due to the tight nature of low-permeability reservoir，recoveries from depletion，water flooding and normal EOR methods are greatly limited.However，gases like CO2 with lower viscosity have higher injectivity which can co-optimize oil recovery and CO2 sequestration.In this study，reservoir engineering analysis and simulations are performed to investigate the best injection and production schemes in tight reservoirs among continuous gas injection，water alternative gas injection and producer control according to GOR and average reservoir pressure，periodical injection and production，improved well control production method，etc.The three objective functions are oil recovery，amount of CO2 sequestered and net present value.Result shows that continuous CO2 injection by using directional injectors coupled producers′ well control method according to oil well static pressure and gas oil ratio is the best scheme during CO2 flooding in tight reservoirs，which can give higher oil recovery and the most CO2 sequestration with higher injectivity，shorter developing period

and feasibility.

Key words: tight reservoir, CO2 flooding, EOR, sequestration, injection-production schemes