石油学报 ›› 2019, Vol. 40 ›› Issue (8): 900-913.DOI: 10.7623/syxb201908002

• 地质勘探 • 上一篇    下一篇

鄂尔多斯盆地奥陶系中组合内幕气源特征及勘探方向

徐旺林1, 胡素云1, 李宁熙1, 魏新善2, 高建荣1, 赵振宇1, 李相博3, 刘俊榜1, 张月巧1, 宋微1   

  1. 1. 中国石油勘探开发研究院 北京 100083;
    2. 中国石油长庆油田公司勘探开发研究院 陕西西安 710018;
    3. 中国石油勘探开发研究院西北分院 甘肃兰州 730020
  • 收稿日期:2019-01-06 修回日期:2019-04-17 出版日期:2019-08-25 发布日期:2019-08-28
  • 通讯作者: 徐旺林,男,1970年6月生,1994年获石油大学(华东)学士学位,2006年获中国石油大学(北京)地质资源与地质工程专业博士学位,现为中国石油勘探开发研究院一级工程师,主要从事综合地质研究及地震解释工作。Email:wlxu@petrochina.com.cn
  • 作者简介:徐旺林,男,1970年6月生,1994年获石油大学(华东)学士学位,2006年获中国石油大学(北京)地质资源与地质工程专业博士学位,现为中国石油勘探开发研究院一级工程师,主要从事综合地质研究及地震解释工作。Email:wlxu@petrochina.com.cn
  • 基金资助:

    国家科技重大专项"下古生界—前寒武系碳酸盐岩油气成藏规律、关键技术及目标评价"(2016ZX05004)和中国石油天然气股份有限公司重大科技专项"低/特低渗透油藏有效开发技术研究——长庆油田油气当量上产5000万吨关键技术研究"(2011E-1301)资助。

Characteristics and exploration directions of inner gas source from the middle assemblage of Ordovician in Ordos Basin

Xu Wanglin1, Hu Suyun1, Li Ningxi1, Wei Xinshan2, Gao Jianrong1, Zhao Zhenyu1, Li Xiangbo3, Liu Junbang1, Zhang Yueqiao1, Song Wei1   

  1. 1. PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China;
    2. Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Shaanxi Xi'an 710018, China;
    3. PetroChina Research Institute of Petroleum Exploration & Development-Northwest, Gansu Lanzhou 730020, China
  • Received:2019-01-06 Revised:2019-04-17 Online:2019-08-25 Published:2019-08-28

摘要:

鄂尔多斯盆地下古生界马家沟组按照勘探程度划分为上、中、下3个组合,分别为马家沟组五段1-4小层(上组合)、马家沟组五段5-10小层(中组合)和马家沟组四段-马家沟组一段(下组合)。为探索中组合内幕天然气气源特征,开展了天然气组分、同位素、流体包裹体、天然气成因识别及烃源岩评价等研究工作,并与研究区上古生界及奥陶系风化壳的天然气开展比较分析。研究结果表明:①奥陶系中组合内幕天然气在组分特征、同位素特征等方面与上古生界石炭系-二叠系及风化壳天然气存在差异;利用天然气组分数据,结合前人实验图版判识,认为奥陶系中组合内幕天然气中存在原油裂解气。②奥陶系中组合内幕发育沥青,是内幕烃源岩生成液态烃热裂解产物。③受潮坪环境沉积体系控制,中组合典型烃源岩层段(马家沟组五段6小层)可以划分为泥云坪环带、含膏盐缓坡、膏盐岩洼地3个相带。④马家沟组五段6小层烃源岩主要分布在泥云坪环带,累积厚度可达8~20 m,有机碳含量最高达1.75%,Ro为1.9%~2.7%,处于热裂解生气阶段,具备规模供烃潜力。⑤泥云坪环带和含膏盐缓坡是有利勘探方向,乌审旗东部、靖边西北部和吴起-志丹地区是3个有利勘探区带。

关键词: 鄂尔多斯盆地, 奥陶系, 膏盐岩, 烃源岩, 天然气同位素, 原油裂解气

Abstract:

Majiagou Formation of the Lower Paleozoic in Ordos Basin is divided into three assemblages by the degree of exploration:the upper, middle and lower assemblage, respectively corresponding to the 1-4 sub-members of the 5th Member of Majiagou Formation(the upper assemblage), the 5-10 sub-members of the 5th Member of Majiagou Formation(the middle assemblage) and the 4th to the 1st Member of Majiagou Formation(the bottom assemblage). To explore the characteristics of natural gas source in the middle assemblage, this study carries out natural gas genetic identification, source rock evaluation and researches on the natural gas components, isotopes and fluid inclusions, as well as a comparative analysis with natural gas in the Upper Paleozoic and Ordovician weathering crust. The results show that:(1) In terms of composition characteristics and isotopic characteristics, the inner-type natural gas in the middle assemblage of Ordovician is different from the natural gas in the Upper Paleozoic Carboniferous-Permian and weathering crust. Through identifying based on the natural gas component data and previous experimental plates, it is believed that crude oil cracking gas exists in the internally-developed natural gas from the Ordovician middle assemblage. (2) The bitumen internally developed in the Ordovician is the thermal cracking product of liquid hydrocarbons formed in the inner source rocks. (3) Controlled by the tidal flat sedimentary system, the typical source rock stratum of the middle assemblage (the 6th sub-member of the 5th Member of Majiagou Formation) can be divided into three facies belts:argillaceous dolomitic flat belt, gypsum-containing slope, and gypsum-salt depression. (4) Source rocks in the 6th sub-member of the 5th Member of Majiagou Formation are mainly distributed in the argillaceous dolomitic flat belt, with a cumulative thickness of 8-20 m; the organic matter abundance is up to 1.75%, and Ro is 1.9% -2.7%. In the stage of thermal cracking and generation, there is a potential for hydrocarbon supply in a large scale. (5) The argillaceous dolomitic flat belt and gypsum-containing slope indicate the favorable exploration direction, and the eastern part of Wushenqi, northwest of Jingbian and Wuqi-Zhitan area are three favorable exploration zones.

Key words: Ordos Basin, Ordovician, gypsum-salt rock, hydrocarbon source rock, natural gas isotope, crude oil cracking gas

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