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现代地质 ›› 2012, Vol. 26 ›› Issue (2): 384-392.

• 能源地质学 • 上一篇    下一篇

鄂尔多斯盆地姬塬地区长7段泥岩古孔隙度恢复方法研究

 王菁1,2, 刘震2, 朱文奇2 , 胡晓丹2   

  1. 1 中国石油勘探开发研究院 西北分院,甘肃 兰州730020;2 中国石油大学 油气资源与探测国家重点实验室,北京102249
  • 收稿日期:2011-10-09 修回日期:2011-12-27 出版日期:2012-04-20 发布日期:2018-09-19
  • 作者简介:王菁,女,助理工程师,1986年出生,沉积学专业,主要从事石油地质学和层序地层学的研究。 Email:wangjing2883@126.com。
  • 基金资助:

    国家油气重大专项项目“岩性地层油气藏成藏规律、关键技术及目标评价”(2008ZX05001)。

Restoration of PaleoPorosity of Shale within Chang 7 Member of Yanchang Formation, Jiyuan, Ordos Basin

 WANG  Jing-1,2, LIU  Shen-2, SHU  Wen-Qi-2, HU  Xiao-Dan-2   

  1. 1 Northwest Branch, Research Institute of Exploration and Development, PetroChina,Lanzhou, Gansu730020,China;2 State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing102249, China)
  • Received:2011-10-09 Revised:2011-12-27 Online:2012-04-20 Published:2018-09-19

摘要:

鄂尔多斯盆地上三叠统延长组长7段泥岩作为中生界油藏的重要烃源岩,其成藏期古压力是油气运移的主要动力,而泥岩古孔隙度的变化代表了古压力演化的特征,因此基于成藏期到最大埋深期烃类流体排出,地层超压释放的机理,提出了由孔隙度增量-最大埋深的关系逆推成藏期泥岩古孔隙度的新方法。通过分析最大埋深时期泥岩压实剖面的特征,利用长7段烃源岩欠压实孔隙度增量(△Φ)与最大埋深之间存在的指数关系,逆推出成藏期泥岩古孔隙度增量,并结合成藏期正常压实趋势下孔隙度值,恢复长7段泥岩成藏期总孔隙度。结果表明,姬塬地区长7段泥岩成藏期古孔隙度偏高,普遍在23%~35%之间,说明成藏期泥岩欠压实作用强烈,异常高压是源岩排烃的主要动力。

关键词: 孔隙度, 欠压实泥岩, 异常高压, 长7段泥岩, 延长组, 姬塬地区

Abstract:

The shale within Chang 7 Member of Yanchang Formation in Triassic is an important source rock of Mesozoic reservoirs in Ordos Basin. The paleopressure in the period of accumulation plays a vital role for the hydrocarbon migration, and the changes of paleoporosity represent the characteristics of the paleopressure evolution. So according to the mechanism of hydrocarbon fluid expulsion and overpressure release from the period of accumulation to the maximum burial depth,this article presents a new method that can extrapolate the paleoporosity of shale within Chang 7 Member in the period of accumulation on the basis of the relationship between porosity increment and the maximum depth. Through analyzing the characteristics of present shale compaction profiles, there is an exponent relationship between the porosity increment and the maximum depth of undercompacted shale within Chang 7 Member. Then by using this relationship, the increment of shale porosity in the period of accumulation can be extrapolated and by combining the porosity of normal compaction trend, the total porosity of undercompacted shale within Chang 7 Member in the period of accumulation can be restored effectively. The paleoporosity of shale within Chang 7 Member in the period of accumulation is generally high and the porosity ranges from 23% to 35%, indicating that the undercompaction of shale in the accumulation period is strong, and the abnormal high pressure is the main source rock expulsion power.

Key words: porosity, undercompacted shale, abnormal high pressure, the shale within Chang 7 Member, Yanchang Formation, Jiyuan area