Petroleum Measurement
Convert crude-oil or condensate API gravity and specific gravity using the conventional 60°F/60°F petroleum reference basis.
Defined reference
API gravity is not a generic operating-density conversion. The standard relationship uses petroleum specific gravity referenced to 60°F relative to water at 60°F.
Higher API gravity corresponds to lower specific gravity on this reference basis.
No observed-density temperature correction is performed here. If the available density/relative-density measurement is at another temperature, use the applicable petroleum measurement procedure before treating it as SG 60°F/60°F.
Interpretation
On the conventional petroleum basis, increasing °API corresponds to decreasing specific gravity. The result is useful for reporting and comparison only when the specific-gravity value is on the stated 60°F/60°F reference basis.
Worked example
Using SG = 141.5 ÷ (°API + 131.5), a 35 °API fluid corresponds to approximately 0.8488 specific gravity at the 60°F/60°F reference basis. This is a reference conversion, not a flowing-temperature density correction.
Field boundary
A density or relative-density measurement taken at another temperature should first be corrected using the applicable petroleum measurement method. Temperature, pressure and product basis must be defined before using the value as reference SG.