Definition - What does Adsorbed Gas mean?
Adsorbed Gas is natural gas, mostly methane and ethane, which gets trapped in the shale gas reservoirs. Adsorbed Gas which is trapped in the shale matrix has the same properties of natural gas which is produced from a hydrocarbon reservoir. In order to extract this Adsorbed Gas from shale rocks or tight gas sands, horizontal drilling and hydraulic fracturing techniques are used.
Petropedia explains Adsorbed Gas
In a shale reservoir, Adsorbed Gas is present in the same proportion as the organic content of the shale. We can refer Adsorbed Gas as shale gas because it is trapped in the shale rock and needs hydraulic fracturing and horizontal drilling techniques to extract it from the shale reservoir. Within the shale reserves, natural gas is present as a free gas along with Adsorbed Gas.
Original Gas in Place (OGIP) estimation in the tight sand and shale gas reserves is done by:
- Conventional volumetric calculations with the help of reservoir porosity, rock volume, reservoir pressures and fluid saturation.
- Langmuir Isotherms which are used to calculate volume of Adsorbed Gas in the reservoir.