What are two benefits of keeping gas dissolved in oil in the reservoir?

What are two benefits of keeping gas dissolved in oil in the reservoir?

• A. Gas increases density
• B. Gas raises oil interfacial tension
• C. Gas lowers the viscosity of oil and increases mobility
• D. Gas reduces compressibility

Answer: (C)

Keeping gas dissolved in oil under reservoir pressure lowers the oil’s viscosity. When viscosity drops, mobility (permeability divided by viscosity) goes up, so the oil can flow more easily through the rock under the same pressure gradient. That combination—reduced resistance to flow and higher mobility—improves the displacement efficiency and sweep, helping to move more oil toward the producers. The other ideas don’t reflect the typical effects: dissolved gas doesn’t raise interfacial tension in a way that helps sweep, and the gas–oil mixture is not characterized by reduced compressibility.

Keeping gas dissolved in oil under reservoir pressure lowers the oil’s viscosity. When viscosity drops, mobility (permeability divided by viscosity) goes up, so the oil can flow more easily through the rock under the same pressure gradient. That combination—reduced resistance to flow and higher mobility—improves the displacement efficiency and sweep, helping to move more oil toward the producers. The other ideas don’t reflect the typical effects: dissolved gas doesn’t raise interfacial tension in a way that helps sweep, and the gas–oil mixture is not characterized by reduced compressibility.