TYPES AND RESEARCH DIRECTION OF BIOGENIC GAS IN CHINA
中国生物成因气的类型划分与研究方向

Biogenic gas, originated from the organic matter's alteration by microorganism, is natural gas with high contents of CH4, which may be cosmically large-scale occur. Base on the pathway and mechanism of formation, biogenic gas was divided into five different sorts, as follow :early biogenic gas, low mature gas, late biogenic gas,secondary biogenic gas from degradation of crude oil and upgrading gas from secondary alteration of shallow oil and gas, which belonging to pristine and secondary biogenic gas respectively. Different sorts of biogenic gas may be identified according as the carbon isotope and the character of gas constituents. Because biogenic gas is in the shallow stratum, and easy to do exploitation; furthermore, because of the good quality and the lower exploration cost, biogenic gas should be given a great deal exploration prospecting. Although, there have been found about 30 biogenic gas reservoirs, a lot of them are small gas reservoirs except that in Qaidam basin. The mechanisms of formation and concentrate regulation about biogenic gas don't still understand absolutely. The evaluation of biogenic gas may not only provide the source of shallow gas and make theory of organic geochemistry fuller, but also help to tracing the pathway of oil and gas migration and discover new subtale oil reservoir and source rock. Consequently, along with the farther research of biogenic gas in geology and geochemistry, the scopes of oil and gas exploration prospecting will extend enormously.