Stress Sensitivity Research and Its Application in Extra-low Permeability Reservoirs

A stress sensitivity experiment was made for ultra-low permeability reservoirs in order to investigate the rules of reservoir permeability changes with pressure,and the influence of advanced water injection on reservoir development.The results show that the core from ultra-low permeability reservoir has a strong stress sensitivity,the permeability decreases sharply as the effective pressure increases with the permeability damage more severely of water than that of gas,and advanced water injection at proper time obtains a relatively high oil recovery.The experiments of advanced water injection and synchronous water injection in the ultra-low permeability reservoirs of Well Block SP199 obtain positive results of stable oil production and less production decline rate.