支撑砾岩的成因类型及其沉积特征  

Origin and depositional characteristics of supported conglomerates

作　　者：张昌民[1] 宋新民[2] 王小军[3] 王绪龙[3] 赵康 双棋 李少华[1] ZHANG Changmin;SONG Xinmin;WANG Xiaojun;WANG Xulong;ZHAO Kang;SHUANG Qi;LI Shaohua(School of Geosciences,Yangtze University,Wuhan 430100,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;PetroChina Xinjiang Oilfield Company,Karamay 834000,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]中国石油勘探开发研究院,北京100083 [3]中国石油新疆油田公司,新疆克拉玛依834000

出　　处：《石油勘探与开发》2020年第2期272-285,共14页Petroleum Exploration and Development

基　　金：国家自然科学基金“中国西部主要盆地周缘及邻区分支河流体系分布与沉积模式”(41772094);国家科技重大专项“深层优势储集层沉积成因机制及地质预测技术”(2016ZX05027-002-007)。

摘　　要：以准噶尔盆地玛湖凹陷砾岩为重点,研究支撑砾岩的成因类型及其沉积特征。通过对相关术语的比较分析、现代沉积考察和岩心描述,研究了支撑砾岩的这一概念的初始内涵与其他相似概念的异同,分析发育支撑砾石的现代沉积环境,描述了准噶尔盆地玛湖砾岩油田钻井岩心揭示的不同沉积环境中形成的支撑砾岩的沉积学特征。认为支撑砾岩与颗粒支撑砾岩、开放结构砾岩具有相似的结构但也存在一定的差异,倡议使用'支撑砾岩'这一术语,但需要重新认识支撑砾岩的形成机理。通过对新疆白杨河冲积扇、黄羊泉冲积扇、乌伦古湖等地区的现代沉积考察,发现支撑砾石并非仅仅由洪水形成,也可以发育在山间河流、山麓塌积扇、冲积扇砾质河床、冲积扇表面戈壁滩、砾质湖滩、砾质三角洲前缘、泥石流和水下颗粒流等沉积环境中。支撑砾石被埋藏后有可能形成支撑砾岩。在新疆准噶尔盆地玛湖凹陷三叠系和二叠系钻井岩心中,识别出砾质河床沉积支撑砾岩、风对干河床沉积改造形成的支撑砾岩、砾质滩坝沉积的支撑砾岩、三角洲前缘受波浪改造形成的支撑砾岩、河口坝沉积的支撑砾岩、颗粒流沉积的支撑砾岩和泥石流沉积的支撑砾岩等7种不同成因的支撑砾岩。研究认为支撑砾石结构既可能是一次沉积形成的,也可能经过多次沉积甚至经成岩改造形成。通过水槽实验、数值解析、经验模型和现代沉积调查,可以重建砾质河床的渗滤过程,预测支撑砾石的孔隙结构特征。对新疆玛湖油田三叠系百口泉组各类储集层物性统计发现,细砾岩和小中砾岩具有较高的孔隙度和渗透率,粗砾岩和大中砾岩的渗透率较低,说明支撑砾石结构容易遭受沉积后渗滤和成岩作用改造,导致孔隙度和渗透率变小。The origin and depositional characteristics of supported conglomerates in the Mahu Sag,Junggar Basin,Xinjiang,China,are examined.Based on the terminological comparison,modern sedimentary survey and core description,the initial connotation and similarities and differences in definition between supported conglomerates and other similar concepts are discussed,the modern sedimentary environment in which supported conglomerates develop is analyzed,and the sedimentological characteristics of supported conglomerates formed in different depositional environments revealed by the cores description of Mahu conglomerate oil field in the Junggar Basin are described.The supported conglomerate is similar in texture to grain supported conglomerate and openwork conglomerate but has differences from them,so it is suggested to keep the term'supported conglomerate',but the formation mechanism of supported conglomerate needs to be re-examined.Through field survey of modern sediments in Baiyanghe alluvial fan,Huangyangquan alluvial fan,and Wulungu Lake in Xinjiang,it is found that supported gravels not only formed by flooding events but also by sieving,avalanching,fluvial sorting as well as wind and wave reworking in the depositional environments such as inter-mountain creek,colluvium fan,gravel channel on gobi and the fan surface,lake beach,delta front,subaerial debris flow and subwater grain-flow etc.Supported gravels could form supported conglomerate after being buried.Supported conglomerates of seven different origins have been recognized in the cores of the Triassic and Permian stratum of Mahu Depression,Junggar Basin,namely,supported conglomerates in gravel channel deposits,in wind reworked channel deposits,in gravel beach bar deposits,in wave reworked delta front deposits,in mouth bar deposits and in debris flow deposits respectly.The study shows the supported conglomerates may be formed by a single depositional event or by multi-events during the post-depositional sedimentary reworking and even in diagenesis stage.Through flum

关 键 词：支撑砾岩 开放结构砾岩 颗粒支撑砾岩 岩石结构 沉积环境和相 储集岩 砾岩油气藏 玛湖凹陷 

分 类 号：TE122[石油与天然气工程—油气勘探]