The traps must form early, because biogenic gas can only accumulate when it can migrate as a free gas phase. A free gas state results when biogenic gas generation exceeds the gas solubility in the pore fluid or when gas exsolution from pore water is caused by reduction of the hydrostatic pressure. Exsolution of gas can be a consequence of falling sea level or uplift and erosion. The composition of natural gas readily reveals whether it is biogenic or thermogenic. Furthermore, the composition of a thermogenic gas reveals the thermal maturity of the source rock that generated the gas.
Biogenic gas is also drier than many thermogenic gases.
Integrating gas geochemical data with engineering and geological information to solve specific problems can also be a straightforward process. At OilTracers, L.L.C., we work with clients to design projects that integrate these discrete data types to solve a variety of exploration and development problems. Ph.D. thesis, Technische Universitat Clausthal. Erdol Erdgas Kohle, v. 103, p. 210-218. AAPG Bulletin, v. 67, p. 2225-2238.