珠江口盆地东部恩平12洼古近系文昌组古地貌演化及其对沉积充填的控制  

Paleogeomorphologic Reconstruction,Evolution,and Sedimentary System Control on Wenchang Formation in Enping 12 Sub-sag,Eastern Pearl River Estuary Basin

作　　者：罗泽 闫正和 谢明英 梁杰 吴静 LUO Ze;YAN Zhenghe;XIE Mingying;LIANG Jie;WU Jing(Shenzhen Branch of CNOOC Ltd.,Shenzhen,Guangdong 518054,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,广东深圳518054

出　　处：《现代地质》2020年第4期710-717,共8页Geoscience

基　　金：中海石油(中国)有限公司综合科研项目(YXKY-2019-SZ-01)。

摘　　要：珠江口盆地东部恩平12洼古近系文昌组湖盆沉积发育,但在构造活动及岩浆的相互作用下,湖盆沉积遭受强烈改造,严重制约着该区中深湖相烃源岩识别及油气勘探。在利用趋势外推法对恩平12洼文昌组进行古地貌恢复的基础上,分析了古地貌演化与沉积充填的匹配关系。结果表明:(1)中始新世恩平12洼文昌组为典型的箕状半地堑,受珠琼运动二幕构造作用影响,地层遭受强烈抬升剥蚀,其剥蚀地层主要为湖盆缓坡带辫状河三角洲沉积及滨浅湖相沉积;(2)恩平12洼残留地层主要为湖盆中心中深湖相和陡坡带扇体。基于以上认识推动该区A井的钻探并发现油层,证实了恩平12洼具有中深湖相烃源发育潜力,也证实并深化了古地貌恢复在改造型洼陷沉积充填研究的可靠性和重要性,为珠江口盆地东部强改造型洼陷的烃源潜力研究提供了思路。Lacustrine sedimentation of the Enping 12 sub-sag was developed in the Paleocene Wenchang Formation.The lacustrine-facies sediments were substantially modified by a combination of tectonism and magmatism,which severely hampers source rock identification and hydrocarbon exploration.Based on paleogeomorphologic reconstruction with trend extrapolation,the relation between paleogeomorphologic evolution and sedimentary depression of the Enping 12 sub-sag is revealed.The results indicate that:(1)The Enping 12 sub-sag is a typical half-graben in the Wenchang Formation that was intensely denudated.The main denudation occurred in the braided river delta deposits and shore-shallow lacustrine deposits in the lacustrine basin gentle slope zone.(2)The fan bodies are located in the steep slope zone.Based on this study,well A was drilled and oil-bearing sequence was discovered,which confirms that Enping 12 sub-sag is a potential deep lacustrine hydrocarbon source.It also demonstrates the reliability and importance of paleogeomorphic reconstruction in studying sedimentary infill of modified depressions,and provides insight on estimating hydrocarbon resource potential for strongly modified depressions in the eastern Pearl River Estuary basin.

关 键 词：珠江口盆地 文昌组 沉积充填 恩平12洼 

分 类 号：P534.6[天文地球—古生物学与地层学] P618.13[天文地球—地质学]