Stress sensitivity characteristics and influencing factors of different types of sandstone reservoirs in gas storage

Abstract

The storage capacity and productivity of gas storage are affected by many factors, among which porosity and permeability are the main factors. To reveal the variation characteristics of porosity and permeability of different types of sandstone reservoirs in gas storage, five different types of sandstone samples were collected from the S gas storage in the Liaohe Depression, Bohai Bay Basin, and stress sensibility comparative experiments were carried out. The results show that the porosity and permeability decrease with the increase of effective stress, which affects the storage capacity and productivity of the gas storage. The porosity and permeability damage rate can be used to characterize the damage degree of the storage capacity and productivity. A damage factor characterizing storage capacity and productivity was proposed for the first time, which can be used to quantitatively evaluate storage capacity and productivity of gas storage under alternating load conditions. The porosity and permeability damage rate of the S gas storage increase linearly with the increase of effective stress. The porosity stress damage rate of the argillaceous siltstone reservoir is the largest, and the porosity stress damage rate of the medium-grained sandstone reservoir is the lowest. The argillaceous siltstone reservoir also has the largest permeability damage rate and its own permeability is too low, so it contributes less during emergency supply assurance. The medium-grained sandstone reservoir has the smallest permeability damage rate, and it has little influence on the capacity of peak regulating and supply assurance. Through this study, the quantified damage degree of stress to gas storage capacity was determined. According to the damage rate of different types of reservoirs, the storage capacity and productivity of gas storage can be maximized by optimizing the operation condition of gas storage reasonably.

Keywords

• underground gas storage
• overburden pressure
• porosity
• permeability
• stress sensitivity