What Is Gas/Oil Ratio?

The original gas-oil ratio, also known as the original dissolved gas-oil ratio, refers to the ratio of the standard volume of the separated gas to the surface degassed oil volume when the formation oil is degassed once at the surface.

Natural gas is dissolved in the formation crude oil, and the amount of dissolved natural gas in the formation crude oil of different types of reservoirs varies greatly. The original gas-oil ratio is a physical parameter that measures dissolved natural gas in formation crude oil. The formation oil is usually degassed once at the surface, and the ratio of the volume of the separated gas standard (20 ° C, 0.101 MPa) to the volume of the surface degassed oil is called the original gas-oil ratio.

Where

Original gas-oil ratio, (standard) m ³ / m ³ ;

The volume of natural gas separated by one degassing, (standard) m ³ ;

Volume of ground degassed oil, m ³ . ^[1]

When the formation pressure is higher than the saturation pressure, the dissolved gas-oil ratio is the original dissolved gas-oil ratio R _si . After the formation pressure drops below the saturation pressure, as the pressure decreases, a part of the gas has escaped from the formation crude oil, and the amount of dissolved gas in the crude oil decreases, so the dissolved gas-oil ratio R _s decreases.

If oil and gas are dissolved under pressure, the dissolved gas-to-oil ratio becomes larger and larger as the pressure increases. When P = P _b (saturation pressure), the dissolved gas-to-oil ratio is R _si . Continue to increase until the original formation pressure, the dissolved gas-oil ratio no longer changes. ^[1]