Abstract: The deep subsag areas of lacustrine basin exhibit significant potential for both conventional and unconventional hydrocarbon exploration, yet challenges persist in unclear understanding of hydrocarbon accumulation mechanisms and undetermined exploration targets. Based on exploration practices in the deep subsag areas of Huanghua depression, as well as the comprehensive analysis results of core samples of 1 100 meters and logging data, this study reveals orderly hydrocarbon accumulation in the Whole Petroleum System under the coupling effect of multiple factors including tectonic structure, source rock and reservoir in the deep subsag areas of Huanghua depression as below. (1)The subsag area has excellent source rock conditions, with total organic carbon content of 1.6 % to 3.4 % and the majority kerogen types of Ⅰ to Ⅱ₁. (2)The sedimentary facies show stratified differentiation, corresponding to river delta sandstones in the outer circle, prodelta sandstone and mudstone interbeds in the middle circle, and deep-lacustrine shale in the inner circle. (3)The diagenetic process exhibits distinctive features, such as inhibited compaction under overpressure, and significantly enhanced porosity owing to organic acid dissolution. Research indicates that hydrocarbon migration and accumulation are under the dual control of source-reservoir coupling and dynamic differential driving, forming a continuous reservoir sequence of conventional oil and gas in the outer circle, tight oil and gas in the middle circle, and shale oil and gas in the inner circle. Exploration practices have confirmed that the main far-shore underwater fan channel in the Member 3 of Shahejie Formation in Qikou deep subsag, the braided delta front sands and high-frequency laminated shales in the Member 2 of Kongdian Formation in Changzhuang deep subsag are key targets for subsequent exploration. The orderly distribution pattern of conventional-unconventional petroleum resources in deep subsag areas has not only guided explorations to achieve great breakthroughs in the study area, but also provided a valuable reference for exploring similar deep subsag areas of lacustrine basin.

Key words: integrated conventional-unconventional petroleum resources, hydrocarbon enrichment regularity, petroleum exploration, Huanghua depression, Paleogene, deep subsag areas of lacustrine basin

摘要： 湖盆深凹区展现出常规与非常规油气富集的巨大勘探潜力,但存在成藏机理认识不清、勘探方向待明确等挑战。基于黄骅坳陷深凹区的油气勘探实践,以及1 100 m系统取心和测井/录井综合分析结果揭示,黄骅坳陷深凹区“构造-源岩-储层”多要素耦合控制的全油气系统有序聚集规律为:①烃源岩条件优越(其总有机碳含量为1.6 % ~3.4 %,干酪根以Ⅰ型—Ⅱ₁型为主);②沉积相带呈圈层分异(外圈为辫状河三角洲砂岩,中圈为前三角洲砂岩-泥岩互层,内圈为深湖页岩);③成岩作用特殊(异常高压抑制压实作用,有机酸溶蚀增孔效应显著)。研究结果表明,油气的运聚受“源-储耦合配置”与“动力差异驱动”双重控制,形成“外圈常规油气—中圈致密油气—内圈页岩油气”的连续成藏序列。勘探实践证实,歧口深凹沙河街组三段远岸水下扇主水道、常庄深凹孔店组二段辫状河三角洲前缘砂体和深凹区高频纹层页岩相是接续勘探的重点领域。深凹区常规与非常规油气有序分布的模式不仅指导了工区勘探取得重大突破,更为类似湖盆深凹区的油气勘探提供了借鉴。

关键词: 常-非一体, 油气富集规律, 油气勘探, 黄骅坳陷, 古近系, 湖盆深凹区