You normally get the oil/water ratio from a retort so you can use these numbers to determine density oil and water mixture by the following formula.
(V1)(D1) + (V2)(D2) = (V1 + V2)DF
Where;
V1 = percentage of oil
V2 = percentage of water
D1 = density of oil
D2 = density of water
DF = final density of mixed fluid between oil and water
Example: If the oil/water (o/w) ratio is 80/20 (80% oil and 20% water), please determine the density of mixed fluid between oil and water from the retort. Oil density = 7.0 ppg. Water density = 8.33 ppg.
V1 = 0.8
V2 = 0.2
D1 = 7.0
D2 = 8.33
(V1)(D1) + (V2)(D2) = (V1 + V2)DF
(0.8)(7.0) + (0.2)(8.33) = (0.8 + 0.2) DF
5.60 + 1.67= 1.0 DF
7.27 = DF
The density of the oil/water mixture = 7.27 ppg
Please the Excel sheet used to calculate the density of oil and water mixture.
Ref book: Formulas and Calculations for Drilling, Production and Workover, Second Edition