石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (3): 852-865.doi: 10.11743/ogg20240319

• 方法技术 • 上一篇    下一篇

基于成像测井的深层陆相页岩油储层天然裂缝有效性评价

杜晓宇1(), 金之钧1,2(), 曾联波1,3, 刘国平1, 杨森4, 梁新平1, 陆国青3   

  1. 1.北京大学 能源研究院,北京 100871
    2.页岩油气富集机理与有效开发国家重点实验室,北京 100083
    3.中国石油大学(北京) 地球科学学院,北京 102249
    4.中国石油 新疆油田公司 勘探开发研究院,新疆 克拉玛依 834000
  • 收稿日期:2024-02-23 修回日期:2024-05-14 出版日期:2024-06-30 发布日期:2024-07-01
  • 通讯作者: 金之钧 E-mail:duxiaoyu2016@163.com;jinzj1957@pku.edu.cn
  • 第一作者简介:杜晓宇(1995—),男,博士研究生,页岩油储层天然裂缝。E-mail: duxiaoyu2016@163.com
  • 基金项目:
    国家自然科学基金项目(42090025);中国石油科技创新基金项目(2023DQ02-0103)

Evaluation of natural fracture effectiveness in deep lacustrine shale oil reservoirs based on formation microresistivity imaging logs

Xiaoyu DU1(), Zhijun JIN1,2(), Lianbo ZENG1,3, Guoping LIU1, Sen YANG4, Xinping LIANG1, Guoqing LU3   

  1. 1.Institute of Energy,Peking University,Beijing 100871,China
    2.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 100083,China
    3.College of Geosciences,China University of Petroleum (Beijing),Beijing 102249,China
    4.Research Institute of Exploration and Development,PetroChina Xinjiang Oilfield Company,Karamay,Xinjiang 834000,China
  • Received:2024-02-23 Revised:2024-05-14 Online:2024-06-30 Published:2024-07-01
  • Contact: Zhijun JIN E-mail:duxiaoyu2016@163.com;jinzj1957@pku.edu.cn

摘要:

准噶尔盆地玛湖凹陷二叠系风城组陆相页岩油储层埋深超过4 500 m,天然裂缝作为重要的储集空间和渗流通道,对页岩油的富集和高产至关重要。尽管前人对风城组裂缝进行了表征,但是在裂缝有效性评价方面缺少系统研究,严重制约了玛湖凹陷页岩油下一步的勘探开发。基于微电阻率成像测井资料,对研究区天然裂缝的发育规律和有效性进行了系统研究。研究表明:准噶尔盆地玛湖凹陷风城组陆相页岩油储层天然裂缝有穿层裂缝和层内裂缝两类。穿层裂缝规模较大,裂缝高度通常超过米级,受断层的控制;层内裂缝发育在脆性地层内,裂缝高度受岩层厚度的控制,多小于50 cm。垂向上单井裂缝发育程度与脆性矿物含量呈正相关关系;平面上随距断层距离的增加,裂缝发育程度逐渐降低。不同方位裂缝的充填情况差异较大,北西-南东向裂缝多数未被矿物充填,有效性好。随着埋深增加,裂缝开度整体呈现减小的趋势。评价认为北东东-南西西向裂缝的开度最大,有效性最好。

关键词: 有效性, 成像测井, 天然裂缝, 页岩油, 风城组, 玛湖凹陷, 准噶尔盆地

Abstract:

The lacustrine shale oil reservoirs of the Fengcheng Formation in the Mahu Sag, Junggar Basin have burial depths exceeding 4 500 m. Natural fractures in these reservoirs, serving as important storage spaces and seepage channels, are critical to the enrichment and high yield of shale oil. There is a lack of systematic study on their effectiveness evaluation despite existing characterization of these fractures in previous works, severely restricting the further exploration and exploitation of shale oil in the Mahu Sag. Given this, we conduct a systematic study on the distribution patterns and effectiveness evaluation of natural fractures in the study area using formation microresistivity imaging (FMI) logs. The results indicate that there exist two types of natural fractures in the lacustrine shale oil reservoirs in the study area: cross-layer fractures and intralayer fractures. The cross-layer fractures are characterized by a large scale, with heights generally reaching up to several meters or above, and their distribution is governed by faulting. The intralayer fractures are found within brittle beds, and their heights are limited by the thickness of rock layers, largely less than 50 cm. Vertically, the fracture density in a single well is positively correlated with the brittle mineral content. Laterally, the fracture density gradually decreases with increasing distance from faults. Fractures with different orientations exhibit greatly varying degrees of filling. The NW-SE-trending fractures, among others, are mostly not filled with minerals, thus boasting high effectiveness. As the burial depth increases, fracture apertures generally trend downward. The evaluation results reveal that the NEE-SWW-trending fractures exhibit the largest aperture and, accordingly, the highest effectiveness.

Key words: effectiveness, formation microresistivity imaging logging, natural fracture, shale oil, Fengcheng Formation, Mahu Sag, Junggar Basin

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