A new approach to calculate permeability stress sensitivity in tight sandstone oil reservoirs considering micro-pore-throat structure

• The strain of throats is characterized.
• A new approach to calculate permeability stress sensitivity is presented.
• Reducing throat distribution enlarges permeability stress sensitivity.
• Increasing boundary layer thickness enlarges permeability stress sensitivity.

Permeability stress sensitivity has a significant effect on the development of tight sandstone oil reservoirs. The emphasis of study on mechanism of permeability stress sensitivity currently is microcosmic pore-throat structure instead of macroscopic permeability. However, existing approaches to calculate permeability reduction of stress sensitivity are still the function of permeability. As a result, the existing approaches cannot distinguish the difference of permeability stress sensitivity between different tight oil reservoirs with the same permeability. Therefore, in this paper, based on the characteristics of tight sandstone oil reservoirs, the strain of throats is characterized. Considering the effect of boundary layer and critical throat radius, a new approach to calculate liquid permeability reduction of stress sensitivity is presented. It is found when throat distribution becomes narrower or boundary layer thickness increases, liquid permeability reduction of stress sensitivity increases. Because the tight oil reservoir in Daqing Field has narrower throat distribution and larger liquid permeability reduction, the productivity of the tight oil reservoir in Daqing Field is lower than that in Changqing Field. This paper is significant to the development of tight sandstone oil reservoirs.