Name the five reservoir fluids.

Name the five reservoir fluids.

• A. Black oil, volatile oil, retrograde gas, dry gas, and methane
• B. Black oil, volatile oil, retrograde gas, wet gas, and dry gas
• C. Black oil, volatile oil, wet gas, condensate gas, and dry gas
• D. Black oil, volatile oil, retrograde gas, gas, and dry gas

Answer: (B)

In reservoir engineering, fluids are categorized by how gas and liquids coexist under reservoir conditions and how they behave as pressure changes. The five reservoir fluids are black oil, volatile oil, retrograde gas, wet gas, and dry gas. Black oil consists of oil with relatively little gas in solution, so surface behavior is dominated by oil with modest amounts of dissolved gas. Volatile oil has more dissolved gas, so as pressure drops more gas exsolves and the gas–oil ratio increases, giving the oil a more “volatile” character. Retrograde gas occurs in gas-condensate systems: when reservoir pressure falls below the dew point, some gas condenses into liquid within the reservoir, reducing the gas phase and forming condensate in place. Wet gas contains enough heavier hydrocarbons (C2+) to be condensable into liquids, so produced gas carries natural gas liquids that can be separated at surface. Dry gas is essentially methane-dominated with little to no heavier hydrocarbons, so there are few or no liquids that condense out. This set uses the standard naming that reflects how each fluid behaves with pressure and temperature changes, making it the correct five-fluid classification.

In reservoir engineering, fluids are categorized by how gas and liquids coexist under reservoir conditions and how they behave as pressure changes. The five reservoir fluids are black oil, volatile oil, retrograde gas, wet gas, and dry gas. Black oil consists of oil with relatively little gas in solution, so surface behavior is dominated by oil with modest amounts of dissolved gas. Volatile oil has more dissolved gas, so as pressure drops more gas exsolves and the gas–oil ratio increases, giving the oil a more “volatile” character. Retrograde gas occurs in gas-condensate systems: when reservoir pressure falls below the dew point, some gas condenses into liquid within the reservoir, reducing the gas phase and forming condensate in place. Wet gas contains enough heavier hydrocarbons (C2+) to be condensable into liquids, so produced gas carries natural gas liquids that can be separated at surface. Dry gas is essentially methane-dominated with little to no heavier hydrocarbons, so there are few or no liquids that condense out.

This set uses the standard naming that reflects how each fluid behaves with pressure and temperature changes, making it the correct five-fluid classification.