陆相湖盆海侵地质事件识别及其对烃源岩形成影响

陆相湖盆一些烃源岩的形成是否与海侵地质作用有关,这在石油地质学的陆相生油理论研究中,是一个具有一定不确定性的重要科学和实践应用问题.为给全面深入理解该问题提供参考,笔者等述评了这一领域的研究现状,并提出了值得进一步深入工作的方向.首先剖析了是否有海侵作用发生,为此分析了海侵的各类识别证据,并主要归纳为生物学、矿物岩石学、地球化学这3个方面,多方面证据指示一些湖相烃源岩在形成过程中的确很可能有海侵地质事件发生.海侵对烃源岩形成具有影响,并主要体现在有机质丰度、类型及烃源岩规模上,且通常使得丰度增高、类型变好、规模变大,优化了烃源岩质量.未来为了进一步深化对该问题的认识,一方面要继续加强对海侵识别宏微观证据的综合研究,另一方面可寻找在沉积环境上具有延续性和过渡性的研究实例,从海相到海侵湖相再到湖相,如中国东南部下白垩统,开展时空上的对比分析.这对全面准确认识烃源岩的形成机制具有重要意义,并可为油气勘探提供参考.

A Review on the Distinguishing of Marine Transgression in Continental Basins and Its Influence on the Formation of Hydrocarbon Source Rocks

The formation of hydrocarbon source rocks in continental basins may be related to marine transgression. This issue is of scientific and practical significance in the theoretical study of hydrocarbon generation in continental basins, but has uncertainties. In order to improve the understanding on the issue more comprehensively and deeply, we conducted a research review, and further suggested the future directions for study. The determination of transgression is the basis for this study. Thus, we investigated the evidence supporting the transgression, which can be divided into three folds including biological, mineralogical and petrological, and geochemical. These multiple lines of evidence indicate that transgression might take place during the formation of hydrocarbon source rocks in some continental basins. The influence of transgression on the formation of the source rock is reflected in the abundance and type of organic matter, with the abundance higher and type better. In addition, it promotes the development of larger scale source rocks. In the future, we should continue to strengthen the study of finding macro and micro evidence supporting the transgression. In addition, the case study in southeastern China can provide a good complementary, where the depositional environment has a transitional change from marine, lacustrine influenced by transgression, to lacustrine. Thus a sophisticated temporal and spatial comparison can be obtained. The results will help to comprehensively and precisely understand the forming mechanism of hydrocarbon source rocks and provide information for hydrocarbon exploration