石油与天然气地质 ›› 2017, Vol. 38 ›› Issue (4): 722-728.doi: 10.11743/ogg20170409

• 油气地质 • 上一篇    下一篇

白云岩的残余结构及其沉积相的意义——以塔中地区中-下奥陶统为例

张学丰1, 李晓锋2, 李宗杰3, 刘波1, 宋海强4   

  1. 1. 北京大学 地球与空间科学学院 石油与天然气研究中心, 北京 100871;
    2. 中国石油 海外勘探开发公司, 北京 100034;
    3. 中国石化 西北油田分公司, 新疆 乌鲁木齐 830000;
    4. 陕西延长石油国际勘探开发工程有限公司, 陕西 西安 710075
  • 收稿日期:2016-07-11 修回日期:2017-07-03 出版日期:2017-08-28 发布日期:2017-09-09
  • 作者简介:张学丰(1982-),男,博士、副研究员,碳酸盐岩沉积与储层学。E-mail:zhangxf@pku.edu.cn。
  • 基金资助:
    国家自然科学基金项目(41672123,41002029,41272137,41572117)。

Relict texture of dolostones and its significance to sedimentary facies:A case study from the Middle-Lower Ordovician in Tazhong area,Tarim Basin

Zhang Xuefeng1, Li Xiaofeng2, Li Zongjie3, Liu Bo1, Song Haiqiang4   

  1. 1. Institute of Oil & Gas, School of Earth and Space Sciences, Peking University, Beijing 100871, China;
    2. PetroChina International Exploration & Development Company, Beijing 100034, China;
    3. Northwest Oilfield Company, SINOPEC, Urumqi 830000, China;
    4. Shaanxi Yanchang Petroleum and Development Engineering Co., Ltd, Xi'an, Shaanxi 710075, China
  • Received:2016-07-11 Revised:2017-07-03 Online:2017-08-28 Published:2017-09-09

摘要: 白云岩虽然是一种沉积岩,原生、同生或准同生时期形成的泥晶-粉晶白云岩也常被视为局限-蒸发环境的指示标志,但埋藏条件下形成的交代白云岩或热液改造白云岩则不能直接作为沉积相标志,必须辨别白云岩的残余结构,并恢复原始灰岩的沉积环境。这对确定其沉积相及开展储层成因研究至关重要。以塔中地区中-下奥陶统白云岩发育段为例,这些白云岩就常被认为是局限-蒸发台地的标志。通过对取心段岩石类型的详细鉴定,以云质灰岩中的云化部分与未云化部分进行对比,建立了白云岩残余结构的识别标准。识别了白云岩的3种残余结构,发现白云岩以残余影像结构为主,残余粒屑结构和残余粒形结构很少,由此认为白云岩的原岩主要是一套颗粒滩相灰岩。中央隆起带早-中奥陶纪不属于前人所认为的局限-蒸发台地相,而是开阔台地相,且以发育台内滩亚相-高能砂屑滩微相为主。

关键词: 白云岩, 残余结构, 开阔台地相, 奥陶系, 塔里木盆地

Abstract: As a kind of sedimentary rock,primary,contemporaneous and penecontemporaneous dolostones with mud-or silt-sized crystalline structures are generally related to restricted-evaporative sedimentary setting.However,those formed by replacement or hydrothermal alteration during burial process could not be used as direct indicators of sedimentary facies,at least not until the relict texture of the dolostone is recognized and the original limestone depositional setting is restored.This is critical to sedimentary-and reservoir-related research on dolostone.The Middle-Lower Ordovician dolostone from the Central Uplift Zone,Tarim Basin,may serve as a good example.It is commonly regarded as signature of restric-ted-evaporative platform facies.However,an investigation of the dolostone in the study area proved otherwise.We identified the lithology of samples taken from the area through systematic core/thin section observation and established criteria for relict texture identification by comparing the dolomitized and the un-dolomitized parts of the same samples.The results show that dolostones in the area are characterized by three relict textures,among which the relict ghost texture dominates.The other two relict textures,i.e., the relict granular/biogenetic texture and the relict grain shape texture,are uncommon.We therefore suggest that the Ordovician dolostones originated mainly from a set of grained shoal limestone,and the sedimentary facies during the Early-Middle Ordovician was an open platform rather than a restricted platform.The predominant microfacies are intraplatform high-energy arenstritic shoal.

Key words: dolostone, relict texture, open platform facies, Ordovician, Tazhong area, Tarim Basin

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