地学前缘 ›› 2018, Vol. 25 ›› Issue (2): 99-111.DOI: 10.13745/j.esf.2018.02.011

• 沉积相与储层 • 上一篇    下一篇

尼日尔Termit盆地低阻油层成因机理及综合识别技术

李早红，程小岛，姜虹，郑凤云，袁圣强，刘邦，刘计国，王玉华   

  1. 中国石油勘探开发研究院, 北京 100083
  • 收稿日期:2017-09-10 修回日期:2017-10-20 出版日期:2018-03-15 发布日期:2018-03-15
  • 作者简介:李早红(1969—)，女，高级工程师，主要从事测井资料综合处理解释、方法研究及地质应用工作。E-mail:lizaohong@petrochina.com.cn
  • 基金资助:
    国家专项29课题“海外重点探区目标评价与未来领域选区选带研究”(2016ZX05029005)

Genetic mechanism of lowresistivity oil zones and comprehensive identification technology for well logging in the Termit Basin, Niger.

LI Zaohong,CHENG Xiaodao,JIANG Hong,ZHENG Fengyun,YUAN Shengqiang,LIU Bang,LIU Jiguo,WANG Yuhua   

  1. PetroChina Research Institute of Petroleum Exploration & Development, Beijing 100083, China
  • Received:2017-09-10 Revised:2017-10-20 Online:2018-03-15 Published:2018-03-15

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摘要： 尼日尔Termit盆地地层水矿化度低(矿化度为200×10-6~1 500×10-6)，油气水系统和流体类型非常复杂，不仅发育多套油气水系统，而且正常油气层、低阻油层均存在。实践证明，应用单一的资料和相同的方法很难评价如此复杂的流体类型，尤其是低阻油层的识别。通过已钻井证实，该盆地古近系Sokor1组和白垩系Yogou组普遍存在低阻油层，其电阻率特征主要表现为两类，一是同一沉积时期内油层电阻率与相邻水层电阻率相近，二是油层的电阻率与邻近泥岩的电阻率相近。根据薄片、扫描电镜、黏土X衍射、压汞等资料，考虑岩石粒度、孔隙结构、黏土矿物含量及类型、油层厚度、导电矿物等，分析研究了该盆地低阻油层成因的微观机理和宏观影响因素。研究结果表明，岩石颗粒细、黏土含量高及微孔隙发育导致束缚水含量高是目标盆地低阻油层形成的主要微观机理。宏观影响因素主要是油层薄和咸水泥浆侵入。根据低阻油层成因及其测、录井资料的响应特征分析研究认为，综合利用电阻率和自然伽马、电阻率和自然电位相对值交会图，将录井油气显示定量化得到的录井油气显示级别的综合指数GEOFI与气测总烃TG交会图，RFT压力资料计算的流体密度可以有效识别该盆地低阻油层。研究还揭示了低阻油层在Termit盆地平面和纵向上的分布规律，平面上分布在Dinga地堑、Fana低凸起和Yogou斜坡的各油田中，纵向上主要集中在第三系Sokor1组的E1、E2小层河流相沉积及白垩系三角洲和湖相沉积的砂泥岩互层中。

关键词: 尼日尔, Termit盆地, 低阻油层, 成因机理, 综合识别技术

Abstract: The Termit Basin of Niger, covered with low salinity stratum water (salinity 200×10-61500×10-6 ), developed a highly complex oilgaswater system of complex fluid type, with several oilgaswater systems present including normal and lowresistivity oil zones. Previous studies demonstrated that it is very difficult to identify the complex fluid type by single data analysis, especially in lowresistivity oil zones. It has also been proven by drilling that, in the Termit Basin, low resistivity oil zones were commonly developed in the Sokor 1 and Yogou formations in the Paleogene and Cretaceous, respectively. The lowresistivity oil zones have two main resistivity features: similar resistivity for the reservoir and adjacent water zone within the same sedimentary period, and similar resistivity for the reservoir and adjacent mudstone. Here, we studied the microscopic mechanism and factors influencing low resistivity oil zones, by using thin section, scanning electron microscopy, Xray diffraction and clay mineral analysis techniques, combining with capillary pressure data and knowledges of rock size, pore structure, clay mineral content type and thickness of oil layer. The results showed that high saturation of bound water due to rocks fine grain size, high clay content and development of micro pores, was the main microscopic cause for the low resistivity oil zone in the basin; while thin reservoir and invasion of saltwater mud filtrate were largely macro impact factors. According to their dominant characteristics and cause, the low resistivity oil zones can be effectively identified by cross plotting resistivity vs. natural gamma, resistivity vs. relative value of spontaneous potential, GEOFI vs. TG, and using fluid density calculated by RFT pressure data. Furthermore, our research revealed that the lowresistivity oil zones are laterally distributed in the oil field of Dinga fault terrace, Fana low uplift and Yogou slope, and vertically distributed in the fluvial sediments of E1 and E2 sand in the Sokor1 Formation and delta, and lacustrine sediments of the Cretaceous.

Key words: Niger, Termit Basin, low resistivity oil zone, genetic mechanism, logging comprehensive identification technology

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