巴布亚盆地侏罗系陆架边缘三角洲沉积特征及其油气勘探方向  

Sedimentary characteristics of the Jurassic shelf-edge delta and oil and gas exploration in the Papuan Basin

作　　者：张义娜 蔡文杰 杨松岭 张科 陈景阳 ZHANG Yina;CAI Wenjie;YANG Songling;ZHANG Ke;CHEN Jingyang(CNOOC International Ltd.,Beijing 100027,China)

机构地区：[1]中国海洋石油国际有限公司,北京100027

出　　处：《地学前缘》2021年第1期167-176,共10页Earth Science Frontiers

基　　金：“十三五”国家油气重大专项“海外重点区勘探开发关键技术(2017ZX05032)”。

摘　　要：为明确巴布亚盆地主要的含油气系统发育层段——侏罗系的沉积特征及其与油气勘探的关系,在分析前人研究成果、沉积背景与古物源的基础上,通过地震相、测井相、岩心相“三相”联合分析及与周边的布劳斯盆地的类比,识别了沉积微相类型,刻画了沉积体系的纵横向展布特征;通过不同沉积相带生烃指标、储层物性参数对比,明确了有利的烃源岩与储层发育区,以指导油气勘探。研究结果如下:(1)巴布亚盆地在中生代侏罗纪具有宽缓的古地貌,盆地西南高,东北部低。侏罗系发育稳定被动大陆边缘三角洲沉积,主要物源来自澳大利亚西部古陆,周缘凸起提供局部物源。盆地内以三角洲平原分流河道、三角洲前缘水下分支河道、河口坝、分支河道间等沉积为主。该层段的沉积特征与同处于澳大利亚北缘的布劳斯盆地侏罗系Plover组的特征相似。(2)三角洲主体来自盆地西南部,纵向上四期叠置继承性发育,经历了两期主要的海退和海侵沉积旋回,并且以上升半旋回为主。中下侏罗统的Magobu组地层主要为进积叠加序列,该时期物源充足,水动力强,而上侏罗统的Imburu组则主要为退积序列,晚期沉积了一套稳定的泥岩。三角洲平面上分布范围广,巴布亚褶皱带处于三角洲前缘带,其砂体被潮汐作用改造成指状或点状形态。(3)侏罗系Magobu和Koi Iange组前三角洲浅海相带烃源岩品质相对较好,三角洲前缘河口砂坝砂体被簸选和改造为优质的储层,该区带内发育的逆冲挤压圈闭为盆地的潜在有利勘探目标。In order to ascertain the sedimentary characteristics of the Jurassic and their relationships with oil and gas exploration in the Papuan basin,on the basis of previous studies of the sedimentary background and paleosource in the basin,we performed joint analyses of seismic,logging and core facies in comparisons with the surrounding Browse basin,from which we identified microfacies and described the vertical and horizontal spreads of the basin's sedimentary systems.Then by comparing the hydrocarbon indices and reservoir physical properties of different sedimentary deposition zones,we defined the favorable source rock and reservoir developmental areas to guide oil and gas exploration.The results show that(1)the Papuan basin featured broad and gentle paleogeomorphology during the Jurassic of the Mesozoic era sloping downward from SW to NE.The main provenance was from the Australia paleocontinents and the peripheral bulge provided local material sources.The Jurassic Formation deposited thick passive continental margin delta sediment,and the microfacies were distributary channels,underwater channels,mouth bars and inter-distributary channels.Its sedimentary characteristics were similar to that of the Plover group of the Jurassic Browse basin also in the northern edge of Australia.(2)The dominant components of the delta came from the southwest,with four delta phases developing vertically in succession through two major regressive and transgressive cycles dominated by an ascending half cycle.The Magobu formation of the middle-lower Jurassic was dominated by a progradational stacking sequence and had sufficient provenance and strong hydrodynamic force,while the Imburu formation of the upper Jurassic mainly consisted of retrogradational sequence with stable mudstone deposition on the top.On the plane,the sedimentary sequence was delta plain-delta front-semi deep water-deep water,with the delta distributing widely.The Papuan fold belt was mainly in the delta front,and the front-end sandbodies were transformed into finger-o

关 键 词：油气勘探 沉积相特征 沉积演化 侏罗系 巴布亚盆地 

分 类 号：P618.13[天文地球—矿床学] P534.52[天文地球—地质学]