Co-current and Counter-current Imbibition Analysis for Tight Fractured Carbonate Gas Reservoirs

ABSTRACT

The problem of low productivity natural gas reservoirs that are positioned over active aquifers is addressed. The principles of co-current and counter-current imbibition as used in fractured oil reservoirs are adopted for application in natural gas formations. Experiments were performed on core samplesfrom Western Canada and on Berea sandstone. The tests involved both co-current and counter-current primary and spontaneous imbibition. The production of gas was measured through weight increases in the core samples. Long term effects of the imbibition process were also observed. Furthermore, visualization experiments using glass micromodels were performed.

The results to date indicate that the imbibition process in natural gas reservoirs is also direction oriented. Large amounts ofothenvise producible gas will be trapped because of the elimination of accessible pathways from the fast advancing water. The potential of gas migration through these pathways is addressed. Moreover, the productivity increase of such wells is discussed. It is concluded that alternative methods for the recovery of these reservoirs must be sought.

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