断陷湖盆可容空间转换与油气分布——以东营凹陷沙三中亚段为例

东营凹陷沙三中亚段层序由湖进体系域和湖退体系域组成,构造沉降为湖进体系域主控因素,可容空间在盆地范围统一增加,欠补偿沉积形成暗色泥岩烃源岩;沉积物供给为湖退体系域主控因素,在盆地缓坡中部和陡坡中部形成可容空间转换带,该带外侧可容空间减小,内侧可容空间增加。平面上,油气藏的形成和分布与可容空间的分布具明显关系,可容空间转换带是油气成藏最有利的地区,特别是岩性油气藏集中分布的地区,可容空间减小带主要为构造–断块油气藏集中分布区,而可容空间增加带主要分布着滑塌浊积砂体形成的油气藏。

The Accommodation Transformation and the Distribution of oil pools in Faulted Lake Basin—An example from the third member of Shahejie formation in Dongying sag

The third member of Shahejie formation in Dongying sag consists of sequences of lacustrine transgression system tract (TST) and regression system tract (RST), of which the TST is the main control factor in tectonic subsidence, resulting in increase of accommodation space in the faulted lake basin and shape of dark shale source rocks from under-compensation deposits; the RST is the main factor in sedimentary material supply, as a result of forming accommodation transformation zone in central ramp and central sdeep slope, decreased accommondation space at outer side and increased accommondation space at inner side of the zone. In plane, the formation and distribution of petroleum reservoirs are closely related to the distribution of accommondation space, indicating that the accommondation transformation zone is the most favorable area for hydrocarbon accumulation, especially, the centralized distribution area for lithologic reservoirs, while the accommondation decreasing zone is the main area for structural-fault block reservoirs, the accommondation increasing zone will become oil reservoirs formed by slump turbidite sand bodies.