Question

The effect of pressure on various properties of black oil is shown in the figure. The bubble point pressure is \(P_b\). 

Which of the following option(s) is/are CORRECT?

• A. Curve 1 represents solution gas-oil ratio.
• B. Curve 2 represents oil viscosity.
• C. Curve 3 represents oil formation volume factor.
• D. Curve 3 represents oil density.

Hint:

At bubble point pressure \(P_b\), three important transitions occur: solution gas-oil ratio \(R_s\) becomes constant, viscosity shifts from decreasing to increasing trend, and formation volume factor \(B_o\) shifts from increasing to decreasing trend.

Answer 1

The Correct Option is A, B, C

Step 1: Identify Curve 1.
- The solution gas-oil ratio (\(R_s\)) increases with pressure until bubble point pressure \(P_b\). 

- Beyond \(P_b\), oil is saturated, and no more gas dissolves. Thus, \(R_s\) remains constant for \(P > P_b\). 

- This matches the behavior of Curve 1. 

Step 2: Identify Curve 2.
- The oil viscosity decreases with increasing pressure below \(P_b\) because gas goes into solution. 

- At \(P_b\), viscosity is minimum. Beyond \(P_b\), viscosity increases with pressure due to compression. 

- This behavior matches Curve 2. 

Step 3: Identify Curve 3.
- The oil formation volume factor (\(B_o\)) increases as more gas dissolves in oil, reaching a maximum near \(P_b\). 

- Beyond \(P_b\), oil becomes slightly compressible, so \(B_o\) decreases with pressure. 

- This matches Curve 3. 

Step 4: Oil density check.
- Oil density does not match Curve 3's behavior. Density generally increases monotonically with pressure. 

- Hence, option (D) is incorrect. 

Final Answer: \[ \boxed{\text{(A), (B), and (C)}} \]