The Controls of Laminae on Lacustrine Shale Oil Content in China: A Review from Generation, Retention, and Storage

Abstract

The successful development of shale oil in China has claimed that laminated shale is a favorable lithofacies for the effective extraction of petroleum. Clarifying the role of laminae in shale oil generation, migration, storage, and enrichment is urgent and important. Starting from the describing and classifying of the lamina, the common methods and terms used to delineate lamina types are briefly summarized. The results of different schemes are often mutually inclusive, which prompted scholars to work towards a unified division scheme. The influencing factors of oil retention in shale systems, including organic matter (OM) type, total organic carbon (TOC) content, OM maturity, mineral composition, pore structure, and preservation conditions, are systematically discussed. Subsequently, comparative work on source rock quality, reservoir properties, and hydrocarbon expulsion efficiency of shales with different laminar structures is carried out. The comparison results of shale with different rock structures reveal that the laminated shale has a high expulsion efficiency. However, the strong oil generation capacity and superior storage space of laminated shale synergistically control the considerable amount of retained oil in the shale system. Especially the oil mobility of laminated shale is also considered because of great pore size and pore connectivity. The fine evaluation of laminar structure and prediction of laminar distribution has great significance for the selection of shale oil “sweet spot area” or “sweet spot interval”.