珠江口盆地白云凹陷西区始新世张裂-拆离作用下沉积转换及源-汇响应  

Sedimentary transformation and source-to-sink response to the Eocene rifting-detachment in the western Baiyun Sag,Pearl River Mouth Basin

作　　者：刘军 彭光荣 郑金云 蔡嵩 朱定伟 王梓颐 LIU Jun;PENG Guangrong;ZHENG Jinyun;CAI Song;ZHU Dingwei;WANG Ziyi(Shenzhen Branch of CNOOC,Shenzhen,Guangdong 518000,China;Deepwater Development Ltd.,CNOOC,Shenzhen,Guangdong 518000,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518000 [2]中海石油深海开发有限公司,广东深圳518000

出　　处：《石油与天然气地质》2023年第3期600-612,共13页Oil & Gas Geology

摘　　要：珠江口盆地始新世裂陷期盆地呈隆-坳相间格局,陆缘深水区脆性张裂作用向韧性拆离作用的转变多表现为洼陷由深变浅和沉积中心的迁移。目前针对张裂-拆离裂陷转换过程中洼陷内沉积响应的研究还比较少,制约了沉积体分布的预测。基于珠江口盆地白云凹陷西区钻井与全覆盖三维地震数据,恢复始新世张裂期与拆离期沉积古地貌。研究结果表明:①张裂期窄深湖盆发育多沉积中心,拆离期宽缓湖盆水体连片、向拆离中心区汇聚;②联合井-震格架与地震构型标定,认为白云凹陷西区张裂期受先存断块的调控作用而出现了短轴物源供给,发育了扇三角洲-半深湖-辫状河三角洲(扇辫)沉积体系,而拆离期地壳韧性隆升导致整体地形坡度减缓(<10°),水深变浅、高能水体范围扩大,出现隆升带长轴供源体系,沿低隆带广泛发育辫状河三角洲-滩坝(滩扇)沉积体系;③番禺低隆源区流域分区参数耦合揭示张裂-拆离转换过程中滩扇沉积体系供给效率提高、砂质含量增加,与韧性隆升对应的长轴区所发育的沉积体系可形成有利的源-储配置关系。During the Eocene rifting period,the Pearl River Mouth Basin(PRMB)was in an alternating pattern of uplift and depression.The transition of tectonic activity from brittle rifting to ductile detachment in the deep water area of the continental margin is mostly manifested as the change of sag from deep to shallow and the migration of depositional center.However,the lack of discussion on the sedimentary responses in the depression has restricted the prediction of the distribution of sedimentary bodies formed in the process of transition.The study serves to restore the sedimentary palaeogeomorphology during the Eocene rifting and detachment periods based on the drilling and 3D seismic data of full coverage in the western Baiyun Sag,PRMB.The results are shown as follows.First,during the rifting period,the lacustrine basins were narrow and deep,generally with multiple depositional centers developed,while during the detachment period,the lacustrine basins were wide and gentle,with water converging toward the detachment center.Second,combined with well-tied seismic interpretation of depositional framework and seismic calibration of depositional configuration,it is believed that minor-axis provenances existed in the western Baiyun Sag due to the control of preexisting fault blocks,leading to the development of fan delta,semi-deep lake and braided river delta(fan/braid)depositional systems during the rifting period;while during the detachment period,as a result of ductile uplifting,the overall terrain slope got lowered(<10°),the water body got shallowed and the range of high-energy water body expanded.Major-axis provenances appeared in the uplifted zone,and braided river delta-beach bar(beach/fan)depositional systems were widely developed within the structural lows.Third,the coupling of drainage zoning parameters in Panyu low uplift area reveals that the sediment supply efficiency of beach/fan sedimentary systems was high,with an increasing proportion of sand in the sediments,and the sedimentary system developed in the maj

关 键 词：张裂-拆离转换 沉积地貌恢复 源-汇系统 始新世 白云凹陷 珠江口盆地 

分 类 号：TE121.2[石油与天然气工程—油气勘探]