石油与天然气地质 ›› 2006, Vol. 27 ›› Issue (5): 644-651,659.doi: 10.11743/ogg20060509

• 油气地质与成藏 • 上一篇    下一篇

川东石炭系气藏的岩性封堵与高压流体封堵

徐国盛, 李建林, 彭大钧, 李仲东   

  1. 成都理工大学"油气藏地质及开发工程"国家重点实验室,四川,成都,610059
  • 收稿日期:2006-03-13 出版日期:2006-10-25 发布日期:2012-01-16
  • 基金资助:

    国家重点基础研究发展规划(973)项目(2005CB422106)

Sealing ability of lithology and high pressure fluid in carboniferous gas pools in eastern Sichuan

Xu Guosheng, Li Jianlin, Peng Dajun, Li Zhongdong   

  1. State Key Laboratory of Oil and Gas reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059
  • Received:2006-03-13 Online:2006-10-25 Published:2012-01-16

摘要:

川东地区是四川盆地稳定地块中的相对构造活动区,发育10排高陡构造带。20世纪90年代以来,高陡构造带石炭系成组气田勘探获得巨大突破。石炭系气藏的直接盖层是下二叠统梁山组泥岩层。从梁山组的渗透率、孔喉中值半径值分析可知,其属于较差盖层,封盖能力较低;而从孔隙度和突破压力看,梁山组具较强的封闭能力,但这种单一因素的封闭能力还不能完全封盖住研究区具有较高含气高度的石炭系丰富的天然气藏。从压力封闭的机理来考察,上覆层系对下伏层系天然气聚集产生的封闭条件必须是上部地层的原始地层压力大于下伏层系,上部地层的原始地层压力系数大于下伏层系。石炭系上覆二叠系阳新统具有异常高的孔隙流体压力,形成了阻挡烃类逸散的高质量封闭层,从而对下伏石炭系天然气聚集产生高压流体封堵。部分高陡构造带上“通天”破裂逆断层出现压力释放和油气大量散失的现象。研究与勘探实践表明,可将二叠系阳新统现今流体压力系数1.30作为压力封闭的临界值,超过此值即能对下伏石炭系气藏起压力屏蔽作用。

关键词: 岩性封堵, 高压流体封堵, 石炭系, 川东地区

Abstract:

Eastern Sichuan region,the relatively active belt between the stable massifs in Sichuan basin,harbors ten rows of high and steep structural zones where a great breakthrough has been made in the exploration of Carboniferous gas pools since the 1990s.The Liangshang Formation mudstone is the direct cap rock of the Carboniferous gas pools.Judging from the permeability and median pore throat radius,its sealing ability is poor,while in terms of porosity and breakthrough pressure,its sealing ability is relatively good.This single sealing ability,however,is insufficient to hold the abundant Carboniferous gas pools with high gas saturation in the study area according to the mechanism of pressure sealing,the premise for an overlying layer to seal gas accumulation in an underlying layer is the original pressure and pressure coefficient of the former is higher than that of the later.The overlying Permian Yangxin Series with abnormal high porefluid pressure serve as a high quality seal for the underlying Carboniferous gas pools.The reverse faults that extend to the surface in some high and steep structural zones can cause pressure release and hydrocarbon emission.The research results and exploration data show that the pressure coefficient of 1.30 for Permian Yangxin Series can be used as the critical value of pressure seal.When the pressure coefficient surpasses the value,the Carboniferous gas pools would be safely sealed.

Key words: lithology sealing, high pressure fluid sealing, Carboniferous, eastern Sichuan basin

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