Experimental Analysis of Adsorption Capacities and Behaviors of Shale Samples

In recent years, the amounts of conventional hydrocarbon reserves have been decreasing. Hence, unconventional reserves such as shale gas and coal-bed methane reservoirs have become a major alternative source of energy in Turkey as in the world. It is known that Turkey has shale gas potentials especially in the southeastern and Thrace region. In shale gas reservoirs, significant amounts of natural gas exist as conventional “free” gas in porous spaces as well as “adsorbed” gas on shale matrix. Hence, understanding the adsorption capacities and behaviors of shale gas reservoirs may help the exploitation and resource evaluation. In order to calculate initial gasin place, the determination of adsorption capacity of a shale gas reservoir is very crucial because it is important both for feasibility and reservoir management studies. In this study, experimental adsorption measurements for shale samples in Turkey were conducted at various pressures and temperatures by using pure methane. The effects of temperature and pressure on adsorption were observed. By using Langmuir model and Ono-Kondo models, adsorption experimental results were evaluated and adsorption isotherms were constructed. The advantages and disadvantages of these models were compared. It was concluded that Ono-Kondo monolayer model are really capable of fitting adsorption isotherms, especially at high pressures. For initial gas-in place calculations, the equations used by the help of Langmuir model were modified for Ono- Kondo models, and then initial-gas in place calculations for the cases in this study were made.