On abiogenic natural gas

Abstract

NATURAL gases usually refer to the inflammable gases dominated by methane from the angle of research on energy gases. Three genetic types of natural gases can be recognized according to the process of methane generation: ( i ) biogenic (bacterial) gas, mainly the gas formed by the decomposition of organic matter in sediments under the action of anaerobic bacteria; ( ii ) thermogenic gas, mainly the gas formed by the degradation of organic matter in sediments under the action of certain temperature and pressure; ( Ill ) abiogenic gas, mainly the primordial gases from the deep earth or the hydrocarbon gases synthetized by inorganic reactions in the deep earth. The biogenic theory is accepted by most geologists, i. e. organic matter in sediments can produce commercial gas reservoirs under the actions of bacteria, temperature and pressure. However, whether the abiogenic hydrocarbons can accumulate into reservoirs has been a debatable problem in the earth scientific circles in the recent 100 years.