断陷湖盆陡坡带扇三角洲—滑塌扇复合扇体的沉积演化及油气地质意义——以中非地区Melut盆地A凹陷白垩系为例  

Sedimentary Evolution and Controlling Factors of Fan Delta and Slump Fan Complex Deposition in a Steep Slope Belt of a Faulted Basin:A case study from the Cretaceous deposits of the A Sag in Melut Basin,Central Africa

作　　者：陈彬滔[1,2] 马轮[1] 洪亮[1] 史忠生[1,2] 庞文珠 薛罗[1] 王磊[1] 代寒松[1] 赵艳军 CHEN BinTao;MA Lun;HONG Liang;SHI ZhongSheng;PANG WenZhu;XUE Luo;WANGLei;DAI HanSong;ZHAO YanJun(PetroChina Research Institute of Petroleum Exploration&Development-Northwest(NWGI),Lanzhou 730020,China;Key Laboratory of Reservoir Description,CNPC,Lanzhou 730020,China;China National Oil and Gas Exploration&Development Corporation(CNODC),Beijing 100034,China)

机构地区：[1]中国石油勘探开发研究院西北分院,兰州730020 [2]中国石油天然气集团公司油藏描述重点实验室,兰州730020 [3]中国石油国际勘探开发公司,北京100034

出　　处：《沉积学报》2024年第3期1058-1072,共15页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41472091,41872116)。

摘　　要：【目的】扇三角洲—深水滑塌扇组成的复合扇体作为断陷盆地陡坡带重要的粗粒沉积体系和油气储层,其展布范围、演化期次、成藏模式等一直是湖盆沉积和成藏研究的热点。【方法】以中非地区Melut盆地A凹陷高精度三维地震和钻测井资料为基础,采用岩心观察、层序划分、地震反射特征与地震属性分析等方法,对扇三角洲—滑塌扇复合扇体的沉积特征与演化规律进行了研究。【结果与结论】发现研究区复合扇体的沉积相类型包括扇三角洲和重力流成因的滑塌扇,滑塌扇具有两类形貌特征,第一类为受坡折控制的线状供源滑塌扇,第二类为受较陡地形坡度控制的单点供源多级滑塌扇。白垩系研究层段刻画出五期扇体,单期复合扇体内部具有退积特征,多期复合扇体具有“先进积、后退积”的垂向演化特征,其中下白垩统Renk组沉积末期复合扇体规模最大,达到148 km^(2)。复合扇体演化主要受幕式构造活动、古地貌和物源供给,以及相对湖平面变化的影响,构造活动强烈、物源供给充足、短轴构造隆升幅度大的时期,复合扇体规模更大,相对湖平面下降初期和上升初期滑塌扇最为发育。提出A凹陷早白垩世和晚白垩世发生沉积格局转换的新认识,明确了断陷期陡坡带扇三角洲-滑塌扇复合扇体的勘探潜力,指导了勘探部署。[Objective]As an important type of coarse-grained sedimentary system and oil and gas reservoir in faulted basins,fan delta and slump fan complex deposition has been the hot topic of research on lacustrine sedimentary and reservoir formation,such as distribution area,evolution period and accumulation model.[Methods]Based on high resolution 3D seismic and drilling and logging data in the A Sag of Melut Basin in central Africa region,the sedimentary characteristics and evolution of fan delta-slump fan complex are studied by using core observation,sequence division,seismic reflection characteristics and seismic attribute analysis.[Results and Conclusions]The results showed that the types of sedimentary facies of fan in the study area included fan delta and slump fan caused by gravity flow,slump fan had two types of morphology characteristic,the first one was line source slump fan controlled by slope break,the second one was multistage slump fan with single point source controlled by steep topographic slope.Combined with seismic profiles and well logging features,five periods of fans were recognized in the Cretaceous study section.The single-stage fan all had the characteristics of retrogradation,the vertical evolution of multiple periods of fans was characterized by“first progradation and later retrogradation”.The fan distribution was the largest at the end of Renk Formation deposition in the Lower Cretaceous,reaching 148 km2.However,the fan evolution was mainly influenced by tectonic activity,palaeogeomorphology,provenance supply,and base-level cycle.The fan distribution was larger in the period of strong tectonic activity,abundant provenance supply and large short-axis tectonic uplift,and the slump fan was most developed in the early period of relative base-level rising cycle and decreasing cycle.A new understanding of the sedimentary pattern transformation occurred in the Early Cretaceous and Late Cretaceous in the A Sag was put forward.The exploration potential of the fan delta and slump fan complex depositio

关 键 词：Melut盆地 白垩系 复合扇体沉积 扇三角洲 滑塌扇 沉积演化 成藏模式 

分 类 号：P618.13[天文地球—矿床学]