石油与天然气地质 ›› 2022, Vol. 43 ›› Issue (2): 277-285.doi: 10.11743/ogg20220203

• 油气地质 • 上一篇    下一篇

深部煤层气资源开发潜力

何发岐1(), 董昭雄2()   

  1. 1.中国石化 华北油气分公司,河南 郑州 450006
    2.中国石化 华北油气分公司 勘探开发研究院,河南 郑州 450006
  • 收稿日期:2020-11-16 修回日期:2022-01-17 出版日期:2022-04-01 发布日期:2022-03-11
  • 通讯作者: 董昭雄 E-mail:Hefq.hbsj@sinopec.com;Dongzx.hbsj@sinopec.com
  • 作者简介:何发岐(1967—),男,博士、教授级高级工程师,石油与天然气勘探与开发。E?mail:Hefq.hbsj@sinopec.com

Development potential of deep coalbed methane: A case study in the Daniudi gas field, Ordos Basin

Faqi He1(), Zhaoxiong Dong2()   

  1. 1.North China Oil and Gas Company, SINOPEC, Zhengzhou, Henan 450006, China
    2.Research Institute of E&P, North China Oil and Gas Company, SINOPEC, Zhengzhou, Henan 450006, China
  • Received:2020-11-16 Revised:2022-01-17 Online:2022-04-01 Published:2022-03-11
  • Contact: Zhaoxiong Dong E-mail:Hefq.hbsj@sinopec.com;Dongzx.hbsj@sinopec.com

摘要:

煤成气理论指导下煤系“源外型”大气田的陆续发现有效促进了中国天然气工业的发展,而“源内型”煤层气却发展缓慢。研究认为“源内型”深部(2 000 m以深)煤层气同样具有巨大的勘探潜力。以鄂尔多斯盆地大牛地气田为例,通过石炭系-二叠系含煤地层取心系统开展实验研究,结果表明煤系岩石普遍含气,其中煤层中存在原地游离气且煤层气资源丰度最高为3.86×108 m3/km2;结合地层埋藏和热演化史,认为层状非均质地层中泥岩和灰岩的喉道半径较小,毛管阻力封堵形成了以砂岩和煤岩为主的煤系岩性圈闭,煤岩(性)圈闭是其中游离气形成的主控因素;煤岩心含水饱和度介于6.5 %~30.1 %,较低的含水饱和度使常规煤层气开采过程中的“排水减压”变成了“排气降压”,有利于深部煤层气的动用;原生-碎裂型煤体结构也是储层压裂改造的有利特征。研究认为深部煤层气是煤系“甜点”资源,辅以科学合理的技术和经济手段可实现有效开发。

关键词: 烃源岩, 游离气, 岩性圈闭, 深部煤层气, 非常规天然气, 上古生界, 大牛地气田, 鄂尔多斯盆地

Abstract:

Guided by coal-derived gas theories, a batch of coalbed methane fields with external sources have been discovered in China. However, “internal-sourced” coalbed methane fields are barely found in the country despite many studies indicating great potential of internal-sourced coalbed methane from deep layers (more than 2 000 m deep). This study carries out experiments on the core samples taken from deep Carboniferous-Permian coal-bearing strata in the Daniudi gas field, Ordos Basin, and finds that all coal measures in the field generally contain gas and sometimes free gas and that the coalbed methane abundance can be as high as 3.86 bcm/km2. Combined with stratigraphic burial history and thermal evolution, it is suggested that these layered heterogeneous strata like mudstone and limestone contain mostly small-sized pore throats and thus form the lithological traps dominated by sandstone and coal rocks due to capillary resistance sealing. The coalbed lithological traps control the accumulation of free gas within. Low water saturation values (6.5 %-30 %) of the cores may explain the phenomenon that the depressurization via dewatering in conventional coalbed methane extraction often ends with depressurization via de-gassing, which is conducive to the producing of deep coalbed methane. The primary-cataclastic coal structure is also a favorable feature for fracturing stimulation. The study concludes that deep coalbed methane can be commercially extracted with suitable techniques and thus is worthy of attention.

Key words: source rock, free gas, lithological trap, deep coalbed methane, unconventional gas, Upper Paleozoic, Daniudi gas field, Ordos Basin

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