Abstract:

Natural gas resources are widespread in terrestrial basins of China.Large or middle size gas fields have been found in southeast sea areas.The terrestrial gas can be divided into five genetic types: biogenetic-thermal overprint gas, near-sapropelic pyrolysis gas, near-humic pyrolysis gas and biological degradation gas.Gas rich depressions include five types: continuously deep buried, pulsative deep buried, continuously mid-deep buried, early slow and late rapid mid-deep buried and continued shallow buried types.Gas richest places are faultedanticline zones within the depressions.They are mostly distributed along paleouplifts, inherited structures or neighbouring places around source-rock sags.Two most advantageous domains of terrestrial gas enrichment are high geotemperature or rich coal measure regions in mid-deep depth and favourible environment for microorganism at middle-shallow depth.