柴达木盆地三湖地区生物气成藏机理与勘探对策

柴达木盆地三湖地区第四系的形成是在新近纪末期新构造运动作用下，盆地沉积中心由西向东整体迁移的产物。三湖地区第四系具有成岩作用弱、砂泥岩薄互层、源储不分、接替接力生气及由南向北水动力条件较强等独有的地质特征。在这一特有的地质背景下，形成了该区特有的生物气成藏模式:烃源岩持续生烃、水溶气动态成藏。针对该区生物气的勘探对策是:以寻找低幅度构造圈闭为主，围绕北斜坡构造发育区带，加强连片二维地震资料目标处理，寻找低幅度构造目标；同时应继续加强岩性气藏的研究与探索，在确定有利区带、建立地层格架的基础上，采取有效的含气检测手段确定有利岩性目标。

Biologic Gas Accumulation Mechanism and Exploration Strategy in Sanhu Area,Qaidam Basin

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.