江汉盐湖盆地油气形成与运聚特征

为厘清陆相盐湖盆地油气形成和运聚特征，以江汉盆地潜江凹陷潜江组为研究对象，通过岩芯分析的古生物、地球化学测试数据等，恢复盐湖古环境，分析盐湖沉积特征，厘定烃源岩发育及其演化特征，探讨油气排烃及运聚特征。研究结果表明，盐湖干湿交替周期变化的古气候，造成了湖盆咸淡交替，形成了碎屑岩、碳酸盐岩、蒸发岩有规律地韵律沉积，沉积岩性为成分复杂的混积岩；盐湖优质烃源岩发育在咸淡转化期，盐湖烃源岩演化相对滞后，发育未熟低熟油演化阶段；特殊的盐湖沉积特征导致了烃源岩排烃效率低，形成了规模巨大的烃源岩油藏；油气主要沿侧向运移，常规砂岩油藏具有顺层、近源、砂控、源控的特点。陆相盐湖盆地的沉积、油气形成与运聚特征与海相或淡水湖盆具有明显差异性，在勘探中应当引起重视。

Characteristics of Hydrocarbon Formation,Migration, and Accumulation in the Jianghan Saline Lake Basin

The Qianjiang Formation in the Qianjiang Depression in the Jianghan Basin is investigated for the unique hydrocarbon formation, migration, and accumulation patterns of a continental saline lake basin. Using paleontological and geochemical test data from core analyses, this study reconstructs the paleoenvironment and examines the saline lake sedimentation characteristics. It also investigates the hydrocarbon source rock and its evolution, as well as characteristics of the expulsion, migration, and accumulation of hydrocarbon in the basin. The analysis reveals that the paleoclimate of alternating dry and wet periods in the saline lake leads to alternating saline and freshwater in the lake basin. Such cyclic sediments, which consist of clastic rocks, carbonate rocks, and evaporites, can be defined as a lithologically hybrid sedimentary rock with complex compositions. High-quality source rocks in the basin developed during the transition between saline and freshwater periods but evolved quite slowly, so that they are still in the immature-low maturity stage. This unique sedimentation pattern results in low rates of hydrocarbon expulsion and, thereby, the formation of vast oil reservoirs. The hydrocarbon migrates mainly in lateral directions. The conventional sandstone oil reservoir is distributed along stratigraphic facies and near source rocks, being controlled by sandstones and source rocks. Continental saltine lake basins are significantly different from marine and freshwater lake basins in terms of sedimentation and hydrocarbon formation, migration, and accumulation. This difference should be specially considered during reservoir exploration.