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.