断陷盆地斜坡带油气富集差异性及成藏主控因素——以苏北盆地金湖凹陷三河次凹为例

断陷盆地斜坡带紧邻深凹带生烃中心，是油气聚集的有利地区。由于斜坡带断裂系统及沉积体系发育的不均一性，油气成藏往往表现出明显的差异性特征，平面上油气富集程度与规模不同。苏北盆地金湖凹陷三河次凹斜坡带阜宁组二段油气聚集表现为“南富北贫”的特征，油气成藏差异性受多因素控制。通过地球化学测试及测井资料解释分析表明，研究区南部较北部烃源条件优越；纵向上发育下生中储型、自生自储型、上生下储型3种源储配置类型，以上生下储型最为发育，油气最为富集；平面上发育源储叠置型、源储紧邻型、源储分离型3种源储配置类型。北部以源储分离型为主，南部以源储叠置、源储紧邻型为主；南部断裂系统发育、物源丰富、砂体发育，北部远离物源、砂体欠发育。优越的烃源条件、合适的源储配置与良好的输导体系是断陷盆地油气富集的关键因素。 

Differences in oil and gas enrichment in slope belts of rift basins and main controlling factors for hydrocarbon accumulation: a case study of Sanhe Sub-sag in Jinhu Sag,Subei Basin

The slope zone of rift basin is close to the hydrocarbon generation center of deep depression zone, and is favorable area for oil and gas accumulation. Due to the heterogeneity of the development of fault and sedimentary system in slope zone, oil and gas accumulations often show obvious heterogeneity, and the degree and scale of oil and gas enrichment on the plane are different. The oil and gas accumulation of the second member of Funing Formation (E₁f₂) in the slope belt of Sanhe Sub-sag of Jinhu Sag of Subei Basin is characterized by rich in the south and poor in the north, and the hydrocarbon accumulation is controlled by multiple factors. Geochemical test and logging data interpretation showed that the southern part has better source conditions than the northern part in the study area. Three types of source-reservoir configurations were developed vertically: lower-sourced and middle-reserved, self-sourced and self-reserved, as well as upper-sourced and lower-reserved, among which the type of upper-sourced and lower-reserved is the most developed and has the most enriched oil and gas in the studied area. On the plane, there are three types of source-reservoir configurations: stacked source-reservoir type, source-reservoir adjacent type, and source-reservoir separated type. The northern part of the study area is dominated by the source-reservoir separation type, while the southern part is dominated by the stacked source-reservoir type and the source-reservoir adjacent type. The southern part of the study area has well-developed fault system, abundant provenance and sand bodies, while the northern part is far away from provenance and has underdeveloped sand bodies. It is concluded that the superior hydrocarbon source conditions, appropriate source-reservoir configurations and good transport system are the key factors controlling the enrichment of oil and gas in faulted basins.