Study of Shale Gas Storage Mechanism and Gas in Place Calculations: New sights

摘要

For shale gas reservoirs, the combined study of adsorbed and absorbed gases provides a better description of gas storage mechanism and characterizes the original gas-in-place. Two shale samples were taken and a series of isothermal gas sorption, porosity and total organic carbon experiments were conducted. Then, gas sorption and stress equations were combined to evaluate the mechanism of gas storage by analyzing the effective porosity of sorbed gas. Absorbed gas is usually linked with adsorbed gas and about 22% is contributing in connection with total gas storage capacity but previous studies had ignored such gas in calculation of total gas storage capacity. Therefore, present study is considered the sorbed gas which is the combination of adsorbed and absorbed gases and presenting new sights to comprehend the gas storage mechanism and to characterize the shale gas-in-place. Results revealed from this study that sorption model is providing better descriptions than Langmuir model and close matched with experimental data. Analysis of effective porosity is important to depict the shale gas reservoirs. Shale gas-in-place was measured using different methods e.g. previous and new proposed method and observed that when using new proposed method the total gas storages were found higher at low pressure because of absorbed gas input as compare to previous methods. Further, the total gas storages capacity is increases further according to the adsorption and absorption behavior as pressure increases. This study presents sorbed gas mechanism and might be useful for characterizing the shale gas reservoirs.