Water/Brine Imbibition Experiments in Mudrocks Immersed in scCO2


Publications

  1. Water/Brine Imbibition Experiments in Mudrocks Immersed in scCO2>
    . Mudrock Wettability at Pressure and Temperature Conditions for CO2 Geological Storage. SSRN. .
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    Abstract — Structural trapping provided by seals is one of the key components of CO2 geological storage systems. Clay-rich caprocks and fault gouge are commonly assumed to be water-wet at supercritical CO2 conditions and provide a capillary pressure MPa for trapping buoyant CO2 through capillary forces. This paper explores wettability through experiments of water and brine imbibition in resedimented clay mudrocks immersed in wet supercritical CO2 at temperature from 60 to 90°C and pressure from 27.6 to 41.4 MPa. The tested samples include kaolinite clay and Anahuac shale from the Gulf of Mexico Coast. Additional control tests include Berea sandstone and silane-treated Berea sandstone. Direct experimental observations exhibit spontaneous and rapid imbibition of water/brine droplets into resedimented clay-rich and rock samples initially saturated with wet supercritical CO2 for all trials except for control test with silane-treated sandstone. These observations indicate that typical siliciclastic minerals found in caprocks are water-wet to CO2 at deep pressure and temperature conditions. The results and analysis extend –to high pressure and temperature– previous confirmation of siliciclastic caprock and fault gouge to provide a positive capillary entry and breakthrough pressure. These results validate structural trapping expectations of buoyant CO2 at target storage conditions and observations from natural and deep CO2accumulations.