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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。
In order to deepen the formation conditions of lithologic reservoirs in Xihu Depression, taking the main exploration target formation, Pinghu Formation, as a research object, the temporal and spatial distribution of sedimentary bodies, hydrocarbon accumulation conditions and hydrocarbon migration and accumulation characteristics are comprehensively analyzed. The results show that the Pinghu Formation is rich in source rocks, extensively developing dark mudstone and coal, and tidal flat sand, tidal channel sand and delta front sands sand provide good reservoir space for oil and gas development. The sand-mudstone of Pinghu Formation shows a thin interbedded layer with a swirling reservoir-cap assemblage in the vertical direction. The mudstone has a large accumulated thickness and a stable distribution, which is conducive to the formation of a regional caprock. The Pinghu Formation formed in the post-rifting period and the faulted system formed during the rifting provided vertical guidance for the migration of oil and gas, resulting in self-source-in-line and self-source-lateral lateral lithologic reservoirs. The thin interbedded layers of tidal flat and delta sand-mudstone in the Pinghu Formation developed in the Pinghu slope zone are favorable for the formation of lithologic reservoirs. The lithologic traps can be explored such as updip pinnacles and lens-shaped sandstone along the hydrocarbon migration path.