石油与天然气地质 ›› 2022, Vol. 43 ›› Issue (5): 1141-1154.doi: 10.11743/ogg20220511

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地南部三叠系长73亚段凝灰岩沉积成因及储层特征

李庆1,2(), 卢浩1,2, 吴胜和1,2, 夏东领3, 李江山1,2, 齐奉强1,2, 付育璞3, 伍岳3   

  1. 1.中国石油大学(北京) 油气资源与探测国家重点实验室,北京 102249
    2.中国石油大学(北京) 地球科学学院,北京 102249
    3.中国石化 石油勘探开发研究院,北京 102206
  • 收稿日期:2022-01-27 修回日期:2022-07-18 出版日期:2022-10-01 发布日期:2022-09-02
  • 第一作者简介:李庆(1985—),男,副教授、博士生导师,沉积学及非常规油气地质学。E?mail: liqing@cup.edu.cn
  • 基金项目:
    国家自然科学基金项目(41602137);中国石油天然气集团有限公司-中国石油大学(北京)战略合作科技专项(ZLZX2020-02);中国石油大学(北京)科研基金项目(2462020YXZZ022)

Sedimentary origins and reservoir characteristics of the Triassic Chang 73 tuffs in the southern Ordos Basin

Qing Li1,2(), Hao Lu1,2, Shenghe Wu1,2, Dongling Xia3, Jiangshan Li1,2, Fengqiang Qi1,2, Yupu Fu3, Yue Wu3   

  1. 1.State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum (Beijing),Beijing 102249,China
    2.College of Geosciences,China University of Petroleum (Beijing),Beijing 102249,China
    3.Research Institute of Petroleum Exploration and Production,SINOPEC,Beijing 102206,China
  • Received:2022-01-27 Revised:2022-07-18 Online:2022-10-01 Published:2022-09-02

摘要:

鄂尔多斯盆地延长组7段3亚段(长73 亚段)发育较多的凝灰岩,且有较好的油气显示,可作为下一步非常规油气勘探的目标,但该区凝灰岩类型多样、成因复杂,储集性能差异较大,且缺乏系统研究。以鄂尔多斯盆地南部长73 亚段富凝灰质岩石为研究对象,厘定研究区富凝灰质岩石的岩相类型,明确不同类型凝灰岩的沉积成因,并揭示凝灰岩储层的储集空间特征。结果表明:长73 亚段富凝灰质岩石主要发育5种岩相类型,即玻屑凝灰岩、晶屑质玻屑凝灰岩、晶屑凝灰岩、沉凝灰岩和凝灰质砂岩。凝灰岩存在火山灰沉降和重力流2种成因类型,沉降型凝灰岩主要以纹层形式分布在“张家滩页岩”内,重力流成因凝灰岩主要分布在长73 亚段下部,发育沟道体系的碎屑流、浊流沉积以及小型滑塌沉积,厚度较大,含油性好。凝灰岩储集空间类型包括粒间孔缝(含脱玻化孔)、粒内孔缝、晶间孔隙、有机质边缘孔隙以及裂缝等。岩相对凝灰岩储集空间类型和发育程度等有明显的控制作用,其中玻屑凝灰岩的孔渗条件最好。

关键词: 沉积模式, 细粒沉积学, 重力流, 凝灰岩, 页岩油, 延长组, 鄂尔多斯盆地

Abstract:

A large number of tuff layers with plenty of oil and gas shows in the third sub-member of the seventh member of the Yanchang Formation (Chang 73), Ordos Basin, are deemed as targets for further exploration of unconventional oil and gas. The tuffs in this area are characterized by diverse types, complex origins, great differences in reservoir property, and a lack of systematic study. The study determines the lithofacies types of the highly tuffaceous rocks, clarify the sedimentary origins of different types of tuffs, and disclose the reservoir space characteristics of the tuff reservoirs in the Chang 73, Ordos Basin. The results show that there are five lithofacies types dominating the highly tuffaceous rocks, including vitric tuff, crystal-vitric tuff, crystal tuff, tuffite, and tuffaceous sandstone. In terms of origin, there are two types of tuffs in the study area, that is, the volcanic ash deposition type and the gravity flow deposition type. The tuffs of volcanic ash deposition origin are mainly distributed in the Zhangjiatan shale in the form of laminae, while tuffs of the gravity flow origin are mainly in the lower part of Chang 73. The latter consists of debris flow, turbidite and small-scale slumping deposits accumulated in channel systems, featuring large thickness and higher oil content. The reservoir spaces in tuffs can be divided into several types including intergranular pores/seams (including devitrification pores), intragranular pores/cracks, intercrystalline pores, marginal pores/seams of organic grains, and fractures, etc. Lithofacies plays a marked role in controlling the types and development of the reservoir spaces in tuffs, and the vitric tuffs, among others, are the best in terms of physical properties.

Key words: sedimentary pattern, fine-grained sedimentology, gravity flow, tuff, shale oil, Yanchang Formation, Ordos Basin

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