白云凹陷东南部晚渐新世陆架边缘三角洲沉积特征及沉积地貌演化

发布时间：2018-08-27 05:46

【摘要】：综合利用岩心、测井及三维地震资料,应用地震沉积学和地震地貌学方法,建立白云深水区晚渐新世三级层序地层格架,揭示白云凹陷东南部晚渐新世大型陆架边缘三角洲的沉积结构和沉积地貌特征。结果表明:珠海组至珠江组下段可划分7个层序,中上部ZHSQ5、ZHSQ6和ZHJSQ1时期发育三期陆架边缘三角洲沉积,其中ZHSQ5时期陆架边缘三角洲发育范围较小且相对富泥,前三角洲在地震剖面上呈约300m厚的斜交前积反射;ZHSQ6时期陆架边缘三角洲展布最广,前缘水下分流河道微相呈网状交织,横向展布达5km,三角洲前缘在地震剖面上为S型前积反射,前积体的高度向盆地方向逐渐减薄,前三角洲斜坡远端发育多个小型滑塌浊积体;ZHJSQ1时期继承早期陆架边缘三角洲的沉积特点,同时前缘下斜坡伴生较大规模的滑塌浊积扇。估算三角洲沉积古水深为600m,三角洲前缘斜坡倾角为4°~7°,反映三角洲形成于深水陆架边缘环境。晚渐新世相对海平面变化和沉积物供给共同作用控制研究区陆架边缘三角洲的形成期次和展布规模,而同沉积断裂活动对陆架边缘三角洲的发育位置及沉积形态具有制约作用。陆架边缘三角洲前缘砂坝、分流河道砂体及前三角洲浊积砂体可构成重要的油气储层。
[Abstract]:The third order sequence stratigraphic framework of late Oligocene in the Baiyun deep water area was established by using the core, logging and 3D seismic data, using seismic sedimentology and seismic geomorphology. The sedimentary structure and sedimentary geomorphology of the deltas of the large continental shelf of late Oligocene in the southeast of Baiyun depression are revealed. The results show that the lower member of the Zhuhai formation to the Pearl River formation can be divided into 7 sequences. In the middle and upper parts of the ZHSQ5,ZHSQ6 and ZHJSQ1 periods, the three stages of continental shelf margin delta deposits are developed, and the ZHSQ5 period has a relatively small range of continental shelf margin deltas and is relatively rich in mud. The front delta is about 300 m thick oblique forward product reflection. In ZHSQ6 period, the continental shelf margin delta spread most widely, and the front underwater distributary channel microfacies interweaved in the shape of network, and the transverse distribution reached 5 km. The delta front was S-type proaccumulative reflection on the seismic profile. The height of the protects is gradually thinning towards the basin, and several small sloughed turbidite bodies developed at the far end of the front delta slope in ZHJSQ1 period inherited the sedimentary characteristics of the early continental shelf margin delta, and accompanied by a large scale sloughing turbidite fan on the lower slope of the front edge. It is estimated that the paleo-water depth of the delta is 600 m, and the slope inclination of the delta front is 4 掳/ 7 掳, which indicates that the delta was formed in the edge environment of the deep-water shelf. The late Oligocene relative sea level change and sediment supply control the formation stage and distribution of marginal deltas in the study area, while synsedimentary fault activity restricts the development position and sedimentary morphology of continental shelf marginal deltas. The delta front bar, distributary channel sand body and pre delta turbidite sand body on continental shelf edge can form important oil and gas reservoir.
【作者单位】：中国地质大学(北京)能源学院;中国海洋石油(中国)有限公司深圳分公司;中国地质大学(北京)海洋学院;
【基金】：国家自然科学基金项目(91328201;91528301)
【分类号】：P618.13

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