Four curves designated as I, II, III, and IV are shown in the figure. \( P_b \) is the bubble point pressure of a crude oil at the given temperature.Which ONE of the following options correctly depicts the solubility of asphaltene (\( q_a \)) in the crude oil with pressure (\( P \)) at a given temperature?
Show Hint
The solubility of asphaltenes in crude oil typically decreases as the pressure increases beyond the bubble point pressure. This is important for understanding the stability of crude oil emulsions and the potential for asphaltene precipitation.
The solubility of asphaltene (\( q_a \)) in crude oil generally decreases with an increase in pressure after reaching the bubble point pressure \( P_b \). The behavior of the curves in the figure corresponds to the solubility trend.
- Curve I shows an unusual increase in solubility as pressure increases beyond the bubble point, which is not typically observed in crude oil asphaltene behavior.
- Curve II shows a typical decrease in solubility of asphaltene with increasing pressure after reaching the bubble point pressure \( P_b \), which is the expected behavior in crude oil.
- Curve III shows a more complex relationship, but it does not match the typical solubility trend as expected for asphaltenes.
- Curve IV also does not exhibit the expected behavior, as it suggests an increase in solubility beyond the bubble point.
Therefore, the correct option is II, which accurately represents the solubility of asphaltenes with increasing pressure.
