In this study,we use a custom-designed visual cell to investigate nonequilibrium interactions between liquid propane(C_(3(1)))and a heavy oil sample(7.2°API)at 55°C.The heavy oil sample is taken from Clearwater Formation located in Western Canadian Sedimentary Basin(WCSB).We inject C_(3(1))into the visual cell containing the heavy oil sample(pressure buildup process)and allow the injected C_(3(1))to interact with the oil sample(soaking process).After the pressure buildup process,we observe three phases in the visual cell: 1)heavy oil(0.67 mol),2)liquid C3(C_(3(1)),0.60 mol),and gaseous C3(C_(3(g)),0.20 mol).We measure visualcell pressure and observe the C3-heavy oil interactions during the pressure buildup and soaking processes. Nonequilibrium interactions occurring at the interfaces of C_(3(1))-heavy oil and C_(3(1))-C_(3(g))are recorded over time. The results show that complete mixing of heavy oil with C_(3(1))occurs in two stages.First,upward extracting flow of hydrocarbon components from bulk heavy oil phase toward C_(3(1))phase form a distinguished layer(L1)during the soaking process.The extracted oil components become denser over time and move down(draining flows)towards the C_(3(1))-heavy oil interface due to gravity.The gradual color change of L1 from colorless to black suggests the mixing of hydrocarbon components from heavy oil.After L1 becomes homogenous,a second layer(L2)is formed at the upper part of the bulk C_(3(1))phase(above L1). Extracting and draining flows becomes active once again,leading to mixing of oil components from L1 into L2.At equilibrium condition,heavy oil and C_(3(1))are completely mixed and form a single homogenous phase.
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