GENETIC IDENTIFICATION METHOD OF KEROGEN-CRACKED GASES AND OIL-CRACKED GASES

Natural gas is not only originated from kerogen cracking,but also from oil cracking. For type Ⅰ or Ⅱ kerogen,most of natural gas is derived from cracking of oil generated from source rock during oil generation peak, only part of natural gas is originated from kerogen cracking directly. Genetic identification of kerogen and oil-cracked gases is very important for the study of natural gas sources and area exploration evaluation, especially for high maturity areas. Natural gas genesis in the North and Central Tarim was studied according to ln(C₂/C₃) and (δ¹³ C₂-δ¹³ C₃)of gas composition. The results showed that dry gas in the North Tarim is mainly kerogen-cracked gas,and gas in the Central Tarim is mainly oil-cracked one.