Solution Gas

Definition - What does Solution Gas mean?

Solution Gas is natural gas which is dissolved in the reservoir along with crude oil, condensates and water. It is also known as dissolved gas as it remains dissolved in the solution until it experiences a pressure and temperature change during the production. Once the gas is at atmospheric temperature and pressure, it becomes free gas which can be utilized for wellhead platform operations or flared in atmosphere.

Petropedia explains Solution Gas

Since Solution Gas remains dissolved in the reservoir along with oil, condensates and water, in order to calculate the amount of the gas present in the reservoir, it is necessary to find out the amount of original oil in place (OOIP). The unit of measurement for Solution Gas in original oil is either standard cubic feet (scf) or million standard cubic feet (mmscf).

OOIP can be determined by the following equation:

OOIP = [7758 A x H x phi x (1-Swi)]/Boi


OOIP = Original oil in place (stb or MMstb)

A = Area of the Reservoir (acres)

H = Thickness of the reservoir (ft)

Phi = Porosity of the reservoir

Swi = Connate water saturation

Boi = Volume factor of the initial formation (rb/stb)

Once OOIP is determined, Solution Gas in the original oil can be estimated by the following equation:

Gsi = OOIP x Rsi


Gsi = Solution Gas in the original oil (scf or MMscf)

Rsi = Solution Gas to oil ratio (scf/stb)

The above calculations need to be performed with the assumption that there is no gas cap on the oil reservoir.

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