摘要
The occurrence of the Quaternary,where located the largest biologic gas field,in the Sanhu area of Qaidam Basin is a product of migration of basin depositional center from west to east under the tectonic movements at the end of Tertiary.The main geological characteristics of Quaternary in Sanhu area include low diagenesis,thin interbed between sand and shale,difficulties in differentiation of source from reservoir,continuous gas generating and strong hydrodynamic action from south to north.Consequently,a special biogenic gas reservoir model for this area comes into being.For example,source rock generates hydrocarbon consistently and dissolved gas in water accumulates dynamically.For the biogenic gas in this area,measures should be taken by paying attention to low amplitude structural trap and strengthening the handling of 2D seismic data around north slope area so as to discover low amplitude structure target.Simultaneously,investigation and research of lithologic gas reservoir should be reinforced.On the basis of definiting favorable area and establishing stratigraphic framework,effective gas detection methods should be taken to determine the lithologic target.