黄骅坳陷歧北斜坡油气成藏机制与成藏模式

挠曲坡折带油气资源前景广阔，已成为陆相湖盆中的勘探开发与研究热点。由于古地貌或古构造的差异造成多阶挠曲型斜坡地层发生多个折曲变形，同时，由于斜坡结构及构造特征、沉积特征和烃源岩特征等均存在较大的差异，导致复杂的油气分布和油气成藏过程。以多阶挠曲型斜坡——黄骅坳陷歧北斜坡为例，通过研究斜坡形成和演化过程中古地貌和断层耦合下的斜坡结构和构造特征、输导体系、油气运移路径和运移动力等特征，揭示了多阶挠曲斜坡的油气成藏机制。结果表明，歧北斜坡长轴和短轴方向上的古地形、断层及组合样式、砂体成因类型与延伸范围、与烃源岩接触关系、油气运移动力与路径等方面均存在较大差异。长轴方向具有以下特点：以挠曲坡折构造为界，高、中、低斜坡分异；大型断层不发育且三角洲砂体范围局限，中、低斜坡以近源砂体输导为主，砂体连通性好；形成了坡折背景的"缓坡-双边断脊优势-源控型"成藏模式。短轴方向特点为：以滨海断层、港东断层、南大港断层为边界，发育近东西走向的断层坡折构造，次级断层发育，剖面和平面上呈多种组合方式；水下扇砂体连通性好，与一系列断层形成阶梯状输导路径；形成了"近源-阶梯状输导-断控型"成藏模式。

Hydrocarbon Accumulation Mechanism and Accumulation Model of Qibei Slope in Huanghua Depression

The hydrocarbon resource of flexure slope break zone as a broad prospect has become a hot spot of exploration, development and research in continental lacustrine basin. Due to the differences of paleogeomorphology or paleostructure, multiple flexural deformations occur in the multi-stage flexural slope strata. Meanwhile, there are great differences in structural and tectonic characteristics, sedimentary characteristics and source rock characteristics. All of these factors in the study area result in complex hydrocarbon distributions and hydrocarbon accumulation processes. Taking the multi-order flexure slope-Qibei slope in Huanghua depression for example, a good understanding of the characteristics of slope structure and tectonic, transport system, hydrocarbon migration path and force under the coupling of paleogeomorphology and faults during the formation and evolution of the slope could be used to reveal the hydrocarbon accumulation mechanism in multi-order flexure slope. The results show that there are great differences between the long and short axis direction of Qibei slope in paleogeography, fault and assemblage style, genetic type and extension range of sand body, contact relationship between sand body and source rock, hydrocarbon migration power and path, etc. Thereby, the long and short axis direction equip with the following characteristics, respectively. The high, medium and low slopes are differentiated by the flexure slope break structure. The large-scale faults are not developed and the range of delta sand bodies is limited. The medium and low slopes are mainly appeared as hydrocarbon transportation of near source sand bodies, in which the sand bodies possess a good connectivity. The hydrocarbon accumulation model of "advantage of bilateral ridge fault on gentle slope-source control type" is formed in the background of slope break. Additionally, the short axis direction is bounded by Binhai fault, Gangdong fault and Nandagang fault. The slope break structure of the fault near the east-west direction is developed, and the secondary fault and their combinations are also developed. The underwater fan sandbody has good connectivity, and forms a ladder transport path with a series of faults. Therefore, the hydrocarbon accumulation model of "near source-step transport-fault control" has been formed.