古近系文昌组湖盆古环境及其对烃源岩的控制作用OACSTPCD

The lacustrine mudstone of Wenchang Formation is the main source rock section of Lufeng 15 depression in the Pearl River Mouth Basin.In order to restore the paleoenvironment of Wenchang Lake Basin and further explore the development model of high-quality hydrocarbon source rocks,a comprehensive analysis of paleontology,organic geochemistry,organic petrology and element geochemistry characteristics of Wenchang Formation mudstone in well L15-1 in the depression was carried out.The research results indicate that there are significant differences in the paleoenvironment of each layer of the Wenchang Formation,with relatively shallow water bodies during the sedimentary periods of the Wen-1 to Wen-3 and Wen-5 sections,mainly the shore-shallow lake environment with oxygenated distant sources,and average levels of paleoproductivity;during the sedimentary period of Wen-4 section,the water body was relatively deep,with a semi-deep lake to deep lake environment and the highest level of paleoproductivity.The quality of hydrocarbon source rocks in the Wenchang period paleo-basin of Lufeng 15 depression is positively correlated with paleowater depth,paleoproductivity,and paleo-xygenation facies under the condition of freshwater and brackish water medium.The difference in paleoclimate during the sedimentation period of Wenchang Formation is not significant,and a warm and humid climate is favorable for the development of high-quality hydrocarbon source rocks.Paleoproductivity and paleo-xygenation facies are the main controlling factors for the enrichment of organic matter in Wenchang Formation of Lufeng 15 Depression.In fact,paleoproductivity and preservation condition are well matched,which jointly control the development of effective source rocks.