南海白云凹陷深水区渐新世-中新世陆架边缘三角洲形成及演化  

Generation and Evolution of the Shelf-Edge Delta in Oligocene and Miocene of Baiyun Sag in the South China Sea

作　　者：吴景富[1] 徐强 祝彦贺 

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [2]中海石油研究中心,北京100027

出　　处：《地球科学（中国地质大学学报）》2010年第4期681-690,共10页Earth Science-Journal of China University of Geosciences

基　　金：国家重点基础研究发展计划“973”项目(No.2009CB219400)

摘　　要：南海白云凹陷深水区渐新世-中新世沉积特征对深水油气勘探具有非常重要的意义,中新世发育的陆架边缘三角洲与南海陆坡深水沉积体系有特殊的三级"源-汇"响应关系.研究基于近期新钻井、精细三维地震资料解释,进一步揭示了陆架边缘三角洲的形成、演化,及其对陆坡深水重力流沉积形成的"源"控作用.渐新世该陆架边缘三角洲主要形成于层序低位期晚期,以三角洲前缘沉积为主,在陆架断阶坡折控制下呈"S"型向陆坡生长.中新世自外陆架到上陆坡的延伸空间内,沉积机理发生改变,由牵引流向重力流发生变化,在白云凹陷内形成陆坡复合水道、重力流沉积,并有东沙隆起的碳酸盐岩短轴物源耦合,形成双(多)物源控制的混合沉积.这种沉积演化特征受控于陆架边缘三角洲发育和陆架断阶坡折带的演化,形成陆架边缘三角洲和深水储集体特殊分布.因此,白云凹陷深水区油气勘探要注重陆架边缘三角洲形成、演化、分布及其与深水沉积体三级"源-汇"响应.Sedimentary characteristics of Baiyun sag in Oligocene and Miocene play an important role in deep-water Oil and gas exploration in South China Sea, among which there is a special three-order ＂source to sink＂ relationship between shelf-edge delta and slope sedimentary systems. Based on recent cores and exact 3D seismic interpretation, we find out how shelf-edge delta formed and how it evolved, and we also find out that the ＂source＂ of the shelf-edge delta controled deep-water gravity flow. The shelf-edge delta generated in late of LST in Oligocene, and delta front is the main component, shelf-edge fault controled its development and delta progressed as ＂S＂. On the other hand, between outer shelf and upper slope the sedimentation mechanism changed from tractive current to gravity flow in Miocene. Slope complex channels and gravity flow settings accumulated in Baiyun sag, meanwhile, proximal carbonate rocks from Dortgsha uplift blended, so clastic rocks and carbonate rocks mixed. This kind of sedimentary characteristic is controlled by the development of shelf-edge delta and shelf-edge fault, which dominates the distribution of shelf-edge delta and deep-water reservoirs. Therefore, we should pay more attention to formation, evolution and distribution of shelf-edge delta, and its three-order ＂source to sink＂ response to deep-water sediment in oil and gas exploration of Baiyun sag.

关 键 词：白云凹陷 渐新世-中新世 陆架边缘三角洲 双物源 陆架断阶坡折. 

分 类 号：P539.2[天文地球—古生物学与地层学] P618.130.2[天文地球—地质学]