The figure displays the visual evolution of scCO2 ganglion, the average geometric contact angle along different grain surfaces, and the change in strain between two drainage-imbibition (D-I) cycles for three separate ganglion trapped in different pore spaces. These plots show the scCO2 trapped in a Bentheimer sandstone core (A) advanced along the pore network, decreased in volume, and initially was in contact with six surfaces which reduced to four surfaces after the second D-I cycle. The average contact angle increased along two grain surfaces of contact and slightly decreased along the other two surfaces appearing to reach a new state of equilibrium where the strain slightly decreased after the second D-I cycle. With the scCO2 migration, the immediate surrounding pore geometry changed and thus a change in contact angle along the advancing and receding ends occurred. The ganglion trapped in a Nugget sandstone pore (B) increased in volume after the second D-I cycle. Five surfaces of contact were present between cycles with contact angles remaining constant along two surfaces and increasing along the remaining three surfaces. The pore-filling occurrence increased the local strain while the ganglion trapped in a dead-end pore in the Nugget sandstone (C) remained consistent in volume, number of contact surfaces, and the average contact angle along each surface remained unchanged. These observations show how changes in the trapped scCO2 curvature can influence continued migration or promote more permanent residual trapping.
Laura Dalton (Leidos Research Support Group, National Energy Technology Laboratory)
Feb. 15, 2021
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