石油与天然气地质 ›› 2021, Vol. 42 ›› Issue (5): 1089-1097.doi: 10.11743/ogg20210507

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地中部地区三叠系延长组7段暗色泥岩烃源岩特征

张亚雄()   

  1. 中国石化 石油勘探开发研究院, 北京 100083
  • 收稿日期:2021-03-25 出版日期:2021-10-28 发布日期:2021-10-26
  • 作者简介:张亚雄(1983-), 男, 博士、高级工程师, 石油地质。E-mail: zhangyx.syky@sinopec.com

Source rock characterization: The dark mudstone in Chang 7 Member of Triassic, central Ordos Basin

Yaxiong Zhang()   

  1. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China
  • Received:2021-03-25 Online:2021-10-28 Published:2021-10-26

摘要:

鄂尔多斯盆地延长组7段(长7段)为典型的湖相沉积。在鄂尔多斯盆地中部地区,由于靠近湖泊的边缘,长7段泥页岩厚度偏薄,针对该地区的烃源岩研究尤其是泥岩的研究薄弱。基于15口探井开展了暗色泥岩的甄别工作并进行了采样,然后运用岩心观察、有机碳测定、岩石热解、色谱-质谱等分析手段,全面获得了暗色泥岩的烃源岩特征参数。研究表明,长7段暗色泥岩发育于弱还原-弱氧化的沉积环境。暗色泥岩的有机质丰度高,TOC平均值2.39%;有机质以Ⅱ2型和Ⅲ型为主;生烃潜力好,S1+S2平均值7.65 mg/g;热演化适中,Ro平均值0.98%。暗色泥岩的生烃量总计7.93×108 t,排烃量总计3.37×108 t,残留烃量总计4.56×108 t,综合排烃效率42.50%。暗色泥岩与页岩对研究区油气资源的贡献比为1:1.8。长7段暗色泥岩的生烃有机质包括陆源性输入来源和水体有机质来源。

关键词: 暗色泥岩, 页岩, 烃源岩, 延长组, 鄂尔多斯盆地

Abstract:

The seventh member of Yanchang Formation (Chang 7 Member) in Ordos Basin is typical lacustrine dark mudstone, which slims down while approaching lake rim at the central part of the basin.The study of source rocks, especially the dark mudstone as source rock in that part, has been very limited due to its thinness.Dark mudstone samples from 15 exploration wells in the area are collected and analyzed through core observation, TOC determination, rock pyrolysis, GC-MS and organic carbon isotope analysis.The results indicate a sedimentary environment of weak reduction and oxidation with mixed inputs of plankton and terrestrial plants for the dark mudstone and provide parameters that define the dark mudstone as a good source rock: high TOC (averaged at 2.39%), type Ⅱ2 and type Ⅲ dominated organic matter with an average S1+S2 at 7.65 mg/g, and moderate thermal evolution with Ro averaged at 0.98%.The total hydrocarbon generation amount, hydrocarbon expulsion amount and residual hydrocarbon amount of the dark mudstone are respectively measured to be 793, 337 and 456 million tons.And the comprehensive hydrocarbon expulsion efficiency is 42.50%.The contribution ratio of dark mudstone and shale to the oil and gas resources in the area is 1:1.8.All indicate great source rock potential of the stone.

Key words: dark mudstone, shale, source rock, Yanchang Formation, Ordos Basin

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