Unconventional Gas Geochemistry—An Emerging Concept after 20 Years of Shale Gas Development?

Geochemical studies of gases from low-permeability reservoirs have raised new questions regarding the chemical and stable isotope systematics gas hydrocarbons. For instance, possibility thermodynamic equilibrium is recurrently in discussion. However, it not clear whether there anything “unconventional” way these systems continue to be studied. Using molecular carbon data North American unconventional conventional reservoirs, this research has applied two parameters that well describe key transformation stages during generation. The δ13C ethane C2/C3 ratio increase baseline values (<1%Ro, prominent kerogen cracking) until a first inflexion at 1.5%Ro. same leads 13C depletion rapidly increasing as hydrocarbon cracking becomes prominent. transition between proposed crossover non-equilibrium conditions. There no evidence for characteristics limited reservoirs. Unconventional geochemistry should represent an approach acknowledges distributions are ruled by only one mechanism but several specific intervals thermal history.