Prediction model of shale gas content with the consideration of moisture and multicomponent gas

A prediction model of shale gas content was established based on the volumetric method. The total gas con- tent of shale includes gas in the adsorbed phase and free phase. The amount of gas in the adsorbed phase was calculat- ed with the consideration of mineral composition of shale,temperature,pressure,moisture and non-methane gas,and in the calculation of gas amount in the free phase the adsorbed phase volume was con-sidered. The model validation was conducted with the experimental data of in-situ desorption of JY-1 well in Fuling Jiaoshiba area. The results show that when the adsorbed phase volume is considered,the gas content calculated by the model is in good agreement with the field desorption data. However,when the adsorbed phase volume is not considered,the gas content is overestimated by 27% -38% . Moisture has little effect on the gas content of shale. Multicomponent gas not only changes the gas content of shale,but also changes the occurrence state of shale gas. The gas content will be overestimated by 5. 6% -31. 8%without the consideration of multicomponent gas. The accuracy of the model greatly depends on the results of indoor ex- periments. To obtain an accurate shale gas content,a further study of adsorption experiments of multicomponent gas on moisture-equilibrated shale should be carried out in the future study.