陆相断陷盆地陡坡带早期大型斜向扇三角洲的发现及其勘探潜力  

The discovery of large-scale oblique fan delta and potential for its exploration during the early stage in the steep slope zone of the continental rift basin

作　　者：刘震[1] 李晋[1] 刘惠民[2] 王晓文[3] 卢朝进 任梦怡 钱亮亮 王春颖 LIU Zhen;LI Jin;LIU Huimin;WANG Xiaowen;LU Chaojin;REN Mengyi;QIAN Liangliang;WANG Chunying(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Manage Center of Oil and Gas Exploration,Shengli Oil field Company,SINOPEC,Dongying,Shandong 257017,China;Exploration Department ofjidong Oilfield Company,PetroChina,Tangshan,Hebei 063004,China)

机构地区：[1]中国石油大学(北京),北京102249 [2]中国石化胜利油田分公司油气勘探管理中心,山东东营257017 [3]中国石油冀东油田公司勘探部,河北唐山063004

出　　处：《地质学报》2022年第1期265-283,共19页Acta Geologica Sinica

基　　金：国家重大科技专项“岩性油气藏成藏动力、临界条件与分布模式”(编号2011ZX05001-001-004)资助成果。

摘　　要：现今我国东部断陷盆地油气勘探已达到较高的程度,目的层系逐渐向深部转移,是东部断陷盆地下一步主要勘探方向之一。断陷湖盆陡坡带早期发育短轴物源形成的垂直于边界断层的近岸水下扇、扇三角洲和湖底扇,但对于陡坡带其他方向的沉积相类型及其勘探潜力研究较少。本文依据断陷湖盆沉积学原理,采用地震地层学方法,对我国东部典型断陷湖盆陡坡带进行解剖,提出断陷盆地非边缘地区陡坡带早期可发育大型长轴物源沉积体的新观点,并讨论了其勘探意义。本次研究取得以下成果:(1)基于地震相组合在南堡凹陷柳赞洼陷、东营凹陷盐18地区和车镇凹陷车西地区均发现大型前积-充填相(透镜相),指出存在三角洲沉积,并进一步利用地震均方根属性认识到存在斜交三角洲的可能性;利用岩芯资料证明了同时存在牵引流和重力流两类流体性质;通过岩性组合、测井和录井数据证实厚层富砾沉积物(斜交于边界断层的三角洲)为扇三角洲,因此综合得出断陷湖盆陡坡带早期发育斜交于边界断层的斜向扇三角洲。(2)斜向扇三角洲与前人发现的短轴的近岸水下扇和扇三角洲之间存在着巨大的差别,主要受盆地在陡坡带断陷早期构造格局和古地貌的控制,并且与垂直边界断层的近岸水下扇或扇三角洲在空间上形成了一种复合沉积模式,这种模式在断陷湖盆早期具有普遍代表性。(3)大型斜向扇三角洲多发育于现今断陷湖盆陡坡带和深洼槽内,并且现今部分探井已经证明斜向扇三角洲砂体具有相对较高的含油性,认为该套含油砂体并不属于近岸水下扇的亚相;此外,斜向扇三角洲具有非常有利的成藏条件,具有巨大的勘探潜力。(4)本次研究成果不仅可以作为断陷湖盆沉积学以及油气成藏模式一个新的进展或者补充,而且丰富了盆内陡坡带储集相类型,指出断陷湖盆陡坡�At present the exploration of the rift basin in eastern China and the exploration of the target layer in the deep strata, one of the main exploration directions of the next eastern rift basin, is in focus. The current understanding generally indicates that nearshore subaqueous fans, fan deltas and sublacustrine fans, which are formed by short-axis provenance, were developed in early stage of rifting in steep slope zone. However, less attention has been paid to the types of sedimentary facies and its exploration potential in other directions of the steep slope zone. Based on sedimentological principle of rift lacustrine basin and the seismic stratigraphic method, the typical rift basins in the steep slopes in eastern China are dissected, a new viewpoint that the early intrabasinal axial provenances development is proposed, and its exploration potential is discussed in the steep slopes of the rift basins in this paper. The results of this study are as follows:(1) Based on the combination of seismic facies in the Liuzan area of the Nanpu sag, Yanjia area of the Dongying sag and Chexi area of the northern of the Chezhen sag, large-scale progradating-channel-filled(or lenticular) seismic facies are found, indicating the existence of delta deposits, and the possibility of oblique delta has been further recognized by using the seismic RMS attribute. By using the core data, it is proved that there are two kinds of flow properties, namely traction current and gravity flow. It is also proved that the gravel-rich sediments(oblique delta) with thick layers is a fan delta using the data from lithologic association, wirelines and logging data. Therefore, it is concluded that the oblique fan delta develops in early stage of rifting at the steep slope belt of the rifting lacustrine basin, which is inclined to the border fault.(2) There is a great difference between the oblique fan delta and the short-axis nearshore subaqueous fan or fan delta. The oblique fan delta is mainly controlled by the tectonic pattern and paleogeomorphic

关 键 词：断陷湖盆陡坡带 前积地震相 斜向扇三角洲 勘探潜力 

分 类 号：P618.13[天文地球—矿床学]