河流相沉积的河型转换特征与控制因素及其油气地质意义——以南苏丹Melut盆地Ruman地区坳陷期Jimidi组为例  

Features and Controlling Factors of River Pattern Transition in Fluvial Deposition and its Significance for Petroleum Geology:An insight from the Jimidi Formation in the Ruman area,Melut Basin,South Sudan

作　　者：陈彬滔[1] 于兴河[2] 王磊[1] 史忠生[1] 马轮[1] 薛罗[1] 史江龙 白洁[1] 赵艳军 CHEN BinTao;YU XingHe;WANG Lei;SHI ZhongSheng;MA Lun;XUE Luo;SHI JiangLong;BAI Jie;ZHAO YanJun(Research Institute of Petroleum Exploration&Development-Northwest(NWGI),PetroChina,Lanzhou 730020,China;China University of Geosciences(Beijing),Beijing 100086,China;CNPC International Nile Limited,Khartoum 10687,Sudan)

机构地区：[1]中国石油勘探开发研究院西北分院,兰州730020 [2]中国地质大学(北京),北京100086 [3]中油国际尼罗河公司,苏丹喀土穆10687

出　　处：《沉积学报》2021年第2期424-433,共10页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(41472091,41872116)。

摘　　要：河流相砂体是陆相含油气盆地的重要储层类型,其河型的时空转换不仅是研究盆地演化的直接证据,更是精准评价与预测油气储层的核心内容,已成为近年来国内外沉积研究的热点之一。以Melut盆地Ruman地区坳陷期Jimidi组为例,通过开展层序划分、岩相类型与岩相组合分析、高分辨率储层反演、以及砂体平面展布分析,结果表明:1)坳陷期Jimidi组河流相研究层段发育3个中期基准面旋回,可识别出垂向加积型、侧向加积型、充填型、充填—废弃型、漫溢型等5类典型岩相组合。2)揭示出Jimidi组由下至上具有"曲—辫—曲"河型转换规律,明确了构造作用所造就的古地貌背景和长期基准面上升的总体趋势是控制河型转换的主要因素。3)河型转换的新认识有效指导了研究区曲流河型层段内连续分布的相对低孔封隔带的发现,推动了Jimidi组首口岩性油藏风险探井的部署与勘探突破。Fluvial sandstone is an important type of reservoir in continental petroliferous basins.The time-space transition of river type is direct evidence of basin evolution studies and also the core content for accurate evaluation and prediction of oil and gas reservoirs.It has become one focus of sedimentation research in recent years.Taking the Jimidi Formation in the Ruman depression of the Melut Basin as an example,sequence division,lithofacies type and lithofacies association analysis,high-resolution reservoir inversion,and plane sandbody distribution analysis were carried out.The results show that(1)Three medium-term base-level cycles developed in the fluvial interval of the Jimidi Formation in the depression period,and five types of lithofacies assemblage were identified:vertical accretion,lateral accretion,filling,abandoned-filling,and overflow type.(2)The study revealed that the Jimidi Formation has a meandering-braided-meandering-river transition feature from bottom to top,and the main controlling factors for this were the paleogeomorphologic background created by tectonic activity and a general trend of long-term base level rise.(3)The new understanding of river-type transition has effectively guided the discovery of isolated,relatively low-porosity zones continuously distributed in the meandering-river type in the study area,and promoted the deployment and exploration breakthrough of a first-risk exploration well for a lithological reservoir in the Jimidi Formation,Melut Basin.

关 键 词：曲流河 辫状河 河型转换 控制因素 岩性油气藏 Melut盆地 Jimidi组 

分 类 号：P618.13[天文地球—矿床学]