39 research outputs found

    SCA2003-22: TRAPPED VERSUS INITIAL GAS SATURATION TRENDS FROM A SINGLE CORE TEST

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    ABSTRACT When gas is displaced by liquid in porous media, the saturation at which gas becomes immobile is referred to as the trapped gas saturation. Trapped gas saturation magnitude is important in reservoir scenarios such as water invasion into a gas reservoir, WAG, or water flooding with pressure below the oil bubble point pressure

    EXPERIMENTAL INVESTIGATION OF THE EFFECTIVE STRESS COEFFICIENT FOR VARIOUS HIGH POROSITY OUTCROP CHALKS

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    ABSTRACT The contribution of the pore fluid pressure in reducing the effective stress during loading of fully saturated high porosity chalk (>40%) has often been assumed to be represented by an effective stress coefficient close to unity. This assumption entails the differential stress; the difference between the total stress and the pore fluid pressure, to equal the stress the rock matrix is exposed to. Laboratory experiments were conducted by simultaneously increasing the total stress and pore pressure. These tests resulted in substantial strains that should not occur if the assumption of an effective stress coefficient close to unity was true. Different explanations for these strains have been discussed, among these consolidation effects, partial saturation effects, micro damage and possible laboratory equipment effects. The strains that were observed during the above mentioned test phase, resulted in a focus on the effective stress coefficient for porous chalk material. The results presented in this study suggest that the effective stress coefficient for high porosity outcrop chalks depends on the applied stress and the pore fluid, and is not a constant nor close to unity as commonly presumed
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