中国湖底扇研究现状与建议

Current research status and suggestions on the sublacustrine fans in China

湖底扇是中国国内重要的油气勘探领域之一。基于国内外文献分析,了解了中国国内湖底扇的研究历程,梳理了湖底扇概念、成因分类、相带划分等不同观点,总结了湖底扇层序发育位置、主控因素和储层物性等方面的整体认识。综合分析基础上认为,湖底扇是指沉积物以重力流方式堆积在湖盆浪基面之下的地质体;可划分为滑动/滑塌型、碎屑流型、浊流型、洪水型(或异重流型)和混合型(重力流-牵引流型)5种成因类型;4个亚相和10种微相的相划分方案相对合理;按断陷、拗陷和前陆三种盆地类型总结了湖底扇发育的主控因素;指出不同地区湖底扇储集物性的影响因素具有较大差异性;并就湖底扇形成机理、有利砂体和有利储层综合预测方面提出了后续研究建议。对未来湖底扇深入研究及指导勘探实践具有一定的理论和实践参考价值。

Sublacustrine fans are among the significant domains for oil and gas exploration in China.Through the analysis of both domestic and international literature,the research history of China's sublacustrine fans has been recognized.The varying perspectives on concepts,genesis classification,and facies division are reviewed.The overall understanding of sequence stratigraphic positions,main controlling factors,and reservoir properties of sublacustrine fans is summarized.The comprehensive analysis suggests that sublacustrine fans are geological bodies where sediments accumulate beneath the lake's wave base level through gravity flows.They can be genetically classified into five types:slide/slump,debris flow,turbidity current,flood(or hyperpycnal flow),and mixed(gravity flow-traction flow).The facies division scheme of 4 subfacies and 10 microfacies is relatively reasonable.The main controlling factors for sublacustrine fan development have been summarized for three basin types:fault-depression,depression,and foreland.It is noted that factors influencing the reservoir properties of sublacustrine fans vary greatly across different regions.Suggestions for further research on the formation mechanism of sublacustrine fans,and the comprehensive prediction of favorable sand bodies and prospective reservoirs are put forward.These insights offer certain theoretical and practical references for future in-depth studies and exploration practices of sublacustrine fans.