Comprehensive evaluation method for sealing ability of mudstone caprock to gas in each phase
Based on the study on sealing mechanisms of mudstone caprock to gas in each phase, the percolation and diffusion velocity of gas in free phase, water-dissolving phase and diffusive phase through mudstone caprock under the action of imposed pressure and gas-bearing concentration are applied to establish the evaluation parameters (Vs, Vw and Vd) for sealing ability of mudstone caprock to gas in free phase, in water-dissolving phase and in diffusive phase respectively. And then, a comprehensive evaluation method for sealing ability of mudstone caprock to gas in each phase is established by weighted average value. This method is applied to evaluate the sealing ability of mudstone caprock to gas in each phase of Qingshankou Formation in Binbei area. The result shows that the mudstone caprock of Qingshankou Formation is of middle sealing ability, and poor sealing ability in Nehe and eastern Suileng. Poor sealing ability is one of the main factors which caused the poor gas shows in this area.
Key words: sedimentary facies; depositional model; depositional system; Jiyuan area
SHI Xuefeng , DU Haifeng . Comprehensive evaluation method for sealing ability of mudstone caprock to gas in each phase[J]. Lithologic Reservoirs, 2008 , 20(1) : 21 -26 . DOI: 10.3969/j.issn.1673-8926.2008.01.004
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