柴达木盆地三湖地区第四系岩性气藏形成的主控因素

Controlling factors of Q uaternary lithologic gas reservoirs in the Sanhu area,Q aidam Basin

柴达木盆地三湖地区第四系是在第三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,在第四系中发现了世界上最大的生物气田(背斜气田)。近年来,在三湖地区第四系发现了岩性气藏,现已发现的岩性气(层)藏可分为砂岩上倾尖灭型、砂岩透镜体型和物性侧向变化型3种类型。该地区岩性气藏平面上分布受控于流体运移方向和构造背景,纵向上分布受控于砂体类型和埋藏深度,最终能否成藏受控于天然气聚散的动态平衡。

The Quaternary in the Sanhu area of Qaidam Basin,a product of the basin depositional center shifting from west to east under neotectonic movements at the end of Tertiary,has trapped the largest worldwide biologic gas accumulation（an anticline gasfield）.In recent years,3 types of lithologic gas reservoirs,including the updip pinch-out sand,lens sand and sand with lateral change in physical properties,have been identified.It has been found that in the study area the orientation of fluid migration and the tectonic background controlled the lateral distribution of lithologic gas reservoirs while the vertical distribution of these reservoirs was dominated by sand types and burial depths,but it was the dynamic equilibrium between the accumulation and dispersion of natural gases that substantially controlled the final formation of these reservoirs.This study is of theoretical significance in further exploration of lithologic gas reservoirs.