The Composite Oil calculation finds the densitometer, turbine meter, prover and standard conditions for a typical crude oil metering system.

Values for temperature and pressure can be entered for three different locations, densitometer, turbine meter and prover.

The density can be entered at densitometer, turbine meter and prover. The flow rate or volume can be entered at either the turbine meter, prover or to standard conditions.

Density and flow rate or volume are calculated for each location using information on the fluid type with the prover constants and either the API or Downer Compressibility standard. Quantities can therefore be converted in the forwards direction (from a location on the metering skid to standard conditions) or backwards (from standard conditions to a location on the metering skid) or between locations on the metering skid.

References
API2540 First Edition Aug 1980 MPMS Ch. 11.1, Volume correction factors.
Institute of Petroleum 200, September 1984
ANSI/ASTM D1250, 1993