西湖凹陷平湖组岩性油气藏形成条件

为深化西湖凹陷岩性油气藏形成条件研究,以主力勘探目的层——平湖组为研究对象,对沉积体时空配置、成藏条件和油气运移聚集特征等进行综合分析。结果表明,平湖组烃源岩丰富,广泛发育暗色泥岩和煤,多期发育的潮坪砂、潮道砂和三角洲前缘席状砂为油气提供了良好的储集空间。平湖组砂泥岩薄互层明显,纵向上形成旋回式生储盖组合,且泥岩累积厚度大、分布稳定,利于形成区域性盖层。平湖组形成于后裂陷期,裂陷期形成的断裂体系为油气运移提供垂向输导,形成了自源—直排式和自源—垂向侧向式岩性油气藏。平湖斜坡带发育的平湖组潮坪及三角洲砂泥岩薄互层有利于形成岩性油气藏,可沿油气运移路径探索砂岩上倾尖灭、透镜状等岩性圈闭。

Hydrocarbon accumulation conditions for lithologic reservoirs in Pinghu formation,Xihu depression

With the development of oil and gas exploration,structural traps which can be explored in Xihu depression is less and less,and lithologic reservoirs in this area will become an important type.This paper studies the space-time configuration of sedimentary bodies,petroleum pool,reservoir-cap combination style,the oil and gas migration and accumulation features.The stability of post-rift tectonic background made the coal strata of Pinghu formation.Through the thickness statistics,we know Pinghu formation’s thin interbed of sandstone and mudstone obviously,this is the result of frequently marine transgression.Sedimentary mudstone and shale are widely and stably distributed,and the vertical combination of reservoir shows cycles.Finally,it points out that the tidal flat-delta thin layer of sand and shale deposition zone in Pinghu Slope are favorable area for the lithologic reservoir.Along hydrocarbon migration pathway,we search for the updip pinch-out,sandstone lens trap or other lithologic trap that may be promising reservoir.