蓋層(英語:caprock)是指位於石油儲層之上能夠封隔油氣向上逸散的保護層。蓋層的好壞直接影響石油儲層中的聚集和保存[1]。常見的蓋層有泥岩頁岩、蒸發岩(石膏、鹽岩)和質密灰岩。蓋層之所以能封蓋油層,是因為蓋層具有較低滲透率和高的排替壓力(英語:displacement pressure[2]。蓋層空隙中多含水,油氣要通過其運移,必須首先排替其中的水;如果驅使石油運移的浮力未達到進入蓋層所需的排替壓力值,則石油就被封閉於蓋層之下,即所謂的毛細管封閉(英語:capillary seal[3]

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參考文獻

  1. ^ Talal M. Al Bazali;Jianguo Zhang; Martin E. Chenevert;Mukul Mani Sharma(2005). Measurement of the Sealing Capacity of Shale Caprocks.Paper presented at the SPE Annual Technical Conference and Exhibition, Dallas, Texas, October 2005.Paper Number: SPE-96100-MShttps://doi.org/10.2118/96100-MS
  2. ^ P.F.Boulin P.Bretonnier V.Vassil A.Samouillet M.Fleury J.M.Lombard(2013). Sealing efficiency of caprocks: Experimental investigation of entry pressure measurement methods.Marine and Petroleum Geology Volume 48
  3. ^ N.Shojai Kaveh A.Barnhoorn K.H.Wolf(2016)Wettability evaluation of silty shale caprocks for CO2 storage.International Journal of Greenhouse Gas ControlVolume 49