石油学报 ›› 2019, Vol. 40 ›› Issue (6): 646-659.DOI: 10.7623/syxb201906002

• 地质勘探 • 上一篇    下一篇

准噶尔盆地玛湖凹陷下二叠统风城组致密油充注特征——碱性矿物中的流体包裹体证据

田孝茹1, 张元元1, 卓勤功2, 于志超2, 郭召杰1   

  1. 1. 北京大学地球与空间科学学院 造山带与地壳演化教育部重点实验室 北京 100871;
    2. 中国石油勘探开发研究院 北京 100083
  • 收稿日期:2019-01-31 修回日期:2019-09-28 出版日期:2019-06-25 发布日期:2019-07-02
  • 通讯作者: 张元元,女,1987年2月生,2006年获南京大学地质学专业学士学位,2012年获北京大学构造地质学专业博士学位,现为北京大学地球与空间科学学院研究员,主要从事盆地与造山带构造、油气盆地分析与成藏方面的研究。Email:yy-zhang@pku.edu.cn
  • 作者简介:田孝茹,女,1993年12月生,2013年获中国地质大学(武汉)资源勘查工程专业学士学位,现为北京大学地球与空间科学学院博士研究生,主要从事准噶尔盆地油气成藏方面的研究。Email:tianxr@pku.edu.cn
  • 基金资助:

    国家科技重大专项(2017ZX05008,2016ZX05003-002)和中国石油天然气股份有限公司科技重大专项(2016B-0502)资助。

Tight oil charging characteristics of the Lower Permian Fengcheng Formation in Mahu sag, Junggar Basin: evidence from fluid inclusions in alkaline minerals

Tian Xiaoru1, Zhang Yuanyuan1, Zhuo Qingong2, Yu Zhichao2, Guo Zhaojie1   

  1. 1. School of Earth and Space Science, Peking University;Key Laboratory of Orogenic Belts and Crustal Evolution of the Ministry of Education, Beijing 100871, China;
    2. PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, China
  • Received:2019-01-31 Revised:2019-09-28 Online:2019-06-25 Published:2019-07-02

摘要:

准噶尔盆地玛湖凹陷致密油的生油层及储集层均为下二叠统风城组。以风城组中发育的特征性碱性矿物为研究对象,探讨了致密油的成藏演化过程以及碱性矿物对致密油富集的作用。通过岩相学观察以及扫描电镜、X射线衍射、激光拉曼光谱和流体包裹体分析,在风城组的4种碱性矿物(碳酸氢钠石、碳钠钙石、碳钠镁石和硅硼钠石)以及菱镁矿中识别出3类流体包裹体。第1类为碱性矿物中的原生流体包裹体(包括原生重质油包裹体、沥青包裹体及原生盐水包裹体),其中,原生盐水包裹体的均一温度为70~110℃;第2类为碱性矿物中的次生流体包裹体(包括次生中质油包裹体及次生盐水包裹体),其中,次生盐水包裹体的均一温度为100~110℃;第3类为菱镁矿中的原生轻质油包裹体。结合埋藏史、热演化史及生烃史,认为玛湖凹陷致密油的聚集是在碱性矿物形成及断裂活动的共同促进作用下完成的,其充注过程可分为3期。受早期地层快速埋藏及较高古地温的影响,晚二叠世为重质油充注期,风城组有机质已进入生烃门限,生成的重质油伴随着碱性矿物形成过程中流体交换的促进作用,发生小规模富集;早三叠世为中质油充注期,有机质处于成熟阶段,生成的大量中质油沿活动断裂和裂隙进入邻近的储层中发生大规模富集;早侏罗世为轻质油充注期,由于局部地区受热液流体影响,烃源岩温度持续升高,有机质进入高成熟阶段,生成的少量轻质油在断裂活动以及菱镁矿形成过程中流体交换作用下富集。

关键词: 致密油, 碱性矿物, 流体包裹体, 油气充注期, 玛湖凹陷, 准噶尔盆地

Abstract:

The oil-bearing strata and reservoirs of tight oil in Mahu sag, Junggar Basin are the Lower Permian Fengcheng Formation. Aiming at the special alkaline minerals developed in Fengcheng Formation, this study explores the accumulation evolutionary process of tight oil and the effect of alkaline minerals on the enrichment of tight oil. Through the petrographic observation, scanning electron microscopy, X-ray diffraction, laser Raman spectroscopy and fluid inclusion analysis, three types of fluid inclusions have been identified in four alkaline minerals (wegscheiderite, shortite, eitelite and reedmergnerite) and magnesites in Fengcheng Formation. The first type is the primary fluid inclusions in alkaline minerals (including primary heavy oil inclusions, bitumen inclusions and primary aqueous inclusions), wherein the primary aqueous inclusions have a homogenization temperature of 70-110℃. The second type is the secondary fluid inclusion in alkaline minerals (including secondary medium oil inclusions and secondary aqueous inclusions), wherein the secondary aqueous inclusions have a homogenization temperature of 100-110℃. The third type is the primary light oil inclusions in the magnesite. In combination with the burial history, thermal evolution history and hydrocarbon generation history, it is believed that the accumulation of tight oil in Mahu sag is completed as promoted by both alkaline mineral formation and fracture activity, and the oil charging process can be divided into three stages. Influenced by rapid burial of early strata and high paleogeotherm, the Late Permian is the heavy oil charging stage. The organic matters of Fengcheng Formation have entered into the hydrocarbon generation threshold. The resulting heavy oil is accompanied by the promotion of fluid exchange during the formation of alkaline minerals, thus forming the small-scale enrichment. The Early Triassic is the medium oil charging stage. Organic matters at this time are in the mature stage, and a large amount of medium-sized oil is generated along active faults and fissures into adjacent reservoirs. The Early Jurassic is a light oil charging stage. Due to the influence of hydrothermal fluids in some areas, the temperature of source rocks continues to rise, organic matters enter the high mature stage, and a small amount of light oil is enriched under fault activity and fluid exchange during the formation of magnesite.

Key words: tight oil, alkaline mineral, fluid inclusion, oil charging stage, Mahu sag, Junggar Basin

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