Studies show positive shifts of inorganic and organic carbon isotope values (δ 13Ccarb and δ 13Ckerogen) from +0.43 (‰ V-PDB) to +3.54 (‰ V-PDB) and from ?2
The potentials of gas generation by kerogen in the late period and by crude oil cracking are closely related to the origin of natural gas in the high- to over m