Which reservoir-drive mechanism occurs when there is no gas cap and production quickly drives below bubble point pressure?

Which reservoir-drive mechanism occurs when there is no gas cap and production quickly drives below bubble point pressure?

• A. Gas cap drive
• B. Solution gas drive
• C. Water drive
• D. Viscous drive

Answer: (B)

In oil reservoirs, the energy that pushes oil toward the well when pressure drops below the bubble point, without a gas cap, comes from dissolved gas coming out of solution and expanding. As production lowers the pressure, gas that was dissolved in the oil emerges as free gas and expands, helping to push the oil toward the well. This mechanism is called solution gas drive. If there were a gas cap, its expansion would also contribute energy (gas cap drive), and water drive would rely on water from an aquifer maintaining pressure, while viscous drive depends on viscosity differences or injected polymers and isn’t tied to bubble-point behavior.

In oil reservoirs, the energy that pushes oil toward the well when pressure drops below the bubble point, without a gas cap, comes from dissolved gas coming out of solution and expanding. As production lowers the pressure, gas that was dissolved in the oil emerges as free gas and expands, helping to push the oil toward the well. This mechanism is called solution gas drive. If there were a gas cap, its expansion would also contribute energy (gas cap drive), and water drive would rely on water from an aquifer maintaining pressure, while viscous drive depends on viscosity differences or injected polymers and isn’t tied to bubble-point behavior.