近源砂砾岩体沉积特征研究——以涠西南凹陷X油田为例  

Study on Sedimentary Characteristics of Near-source Glutenite Bodies——A Case Study of Oilfield X in Weixinan Sag

作　　者：沈聪敏 谭诗锦 胡崇 白洁 Shen Congmin;Tan Shijin;Hu Chong;Bai Jie(School of Earth Science and Engineering,Xi′an Shiyou University,Xi′an Shaanxi 710065;Shaanxi Province Key Laboratory of Oil and Gas Formation Geology,Xi′an Shaanxi 710065)

机构地区：[1]西安石油大学地球科学与工程学院,陕西西安710065 [2]陕西省油气成藏地质学重点实验室,陕西西安710065

出　　处：《中外能源》2023年第11期53-60,共8页Sino-Global Energy

摘　　要：以涠西南凹陷X油田作为研究对象,通过沉积微相研究和测井精细解释综合分析,研究X油田古近系始新统流沙港组三段近源砂砾岩体的沉积特征。研究结果表明,流三段沉积期,古地貌整体呈现东南高西北低的特征,且南东—北西向粒度变细,稳定重矿组分增多,结合地震反射资料,初步判定其物源来源于东南方的企西隆起。研究区岩石类型主要以长石石英砂岩为主,其次为岩屑,岩性主要为含砾中砂岩、含砾粗砂岩和砂砾岩。粒度总体上表现为牵引流作用与重力作用相结合的特征。岩心上见冲刷面、正粒序、平行层理、板状交错层理和槽状交错层理等沉积构造。在研究区扇三角洲平原亚相中识别出水上分流河道、水上河道间2种沉积微相,在前缘亚相中共识别出水下分流河道、河口坝、席状砂、水下河道间4种沉积微相。研究区发育了多期次扇三角洲,多期河道交错叠加,砂体规模较大,连片分布。平面上由于断层的分隔作用,形成彼此相互独立的断块,有利于形成油气藏。Oilfield X in Weixinan Sag is studied as an object.Based on the comprehensive analysis of sedimentary microfacies research and fine logging interpretation,the sedimentary characteristics of the near-source glutenite bodies in the third member of Paleogene Eocene Liushagang Formation in Oilfield X are discussed.The results show that palaeogeomorphology has the characteristics of being higher in the southeast and lower in the northwest in general,and the grain size became finer and stable heavy mineral components increased in the southeast-northwest direction during the depositional period of the Liu3 Member.Combined with seismic reflection data,it is preliminarily determined that its provenance came from Qixi Uplift in the southeast.The main rock types in the study area are feldspar quartz sandstones,followed by cuttings.The main lithology is gravelly medium sandstones,gravelly coarse sandstone,and glutenite.The particle size is generally characterized by both traction flow and gravity.Sedimentary structures such as scour surface,positive grain sequence,parallel bedding,plate cross-bedding,and trough cross-bedding are observed on the cores.Two kinds of sedimentary microfacies,upper river distributary channels,and upper river inter-channels,are identified in the subfacies of the fan delta plain in the study area,and four kinds of sedimentary microfacies are identified in the front subfacies,including underwater distributary channel,mouth bar,sheet sand,and underwater inter-channel.In the study area,multi-stage fan deltas are developed,multi-stage channels are staggered and superimposed,and sand bodies are large in scale and distributed in contiguous slices.Due to the separation of faults,independent fault blocks are formed on the plane,which is conducive to the formation of oil and gas reservoirs.

关 键 词：沉积特征 近源砂砾岩体 粒度特征 扇三角洲沉积 沉积微相 涠西南凹陷 

分 类 号：P618.13[天文地球—矿床学]