多套烃源岩联合供烃下的原油成藏特征及其与压力的耦合关系:以东濮凹陷濮城地区沙河街组为例

Characteristics of Oil Reservoiring and Its Relationship with PressureEvolution of Shahejie Formation in Pucheng Area

目前对濮城地区沙河街组一至四段的成藏整体研究仍存在空白.利用流体包裹体系统分析方法,结合原油实测数据对东濮凹陷濮城地区沙河街组的成藏特征进行研究.结果表明总体上多套烃源岩联合供烃控制着濮城地区沙河街组原油成熟度的垂向分布,压力演化作为成藏的驱动因素与各期成藏耦合完好.濮城地区沙河街组原油存在三期成藏:第一期约30.9~25.3 Ma;第二期约22.3~14.8 Ma;第三期约3.2~1.4 Ma.垂向上巨厚的烃源岩同一时期生成不同成熟度的原油,此外,同一层位烃源岩随时间推移依次生成低熟、成熟、高熟油,使得濮城地区沙河街组各段均存在不同成熟度原油同期成藏的特征.古压力模拟结果表明第一期成藏为超压驱动,第二期成藏为泄压驱动,第三期成藏兼具前两期的特点.

The whole Shahejie Formation has not been treated as one target for reservoiring research.So in this study,fluid inclusion systematic analysis conducted on samples from Shahejie Formation in Pucheng area,Dongpu depression,combined with the crude oil data,indicates that the vertical distribution of oil maturity is under control of petroleum generation of multiple sets of source rocks.The pressure evolution process considered to be a driving factor was in agreement with the reservoiring stages.Three reservoiring stages were identified in Pucheng area:the first was from 30.9—25.3 Ma,the second was from 22.3—14.8 Ma,the third was from 3.2—1.4 Ma.The source rocks with huge vertical thickness produced crude oil with different maturities at the same time.Moreover,different maturities of oil were generated from the same set of source rock over time,which made the Shahejie Formation in Pucheng area had characteristics of simultaneous reservoiring of crude oil with different maturity.The results of paleopressure simulation show that the first stage was driven by overpressure,the second stage was driven by pressure relief and the third stage had the combined features of the former two stages.