# Oil Formation Volume Factor at saturation conditions

1. May 31, 2012

### PetEng

\check{}1. The problem statement, all variables and given/known data

Given the following data I need to find the oil formation volume factor at the saturation conditions;

A single flash separation of Angolan reservoir oil gave a stabilised (for stock tank) oil gravity of 37.19’ API and a gas gravity of 1.015. The GOR (gas oil ratio) of the separation measured as 1899 scf/stb. From a separation experiment (constant mass study) the density of reservoir oil at saturation pressure 3790psia and reservoir temperature 250F was determined to be 559.4kg/m3.
What is the oil formation volume factor at the saturation conditions?

oil gravity = 37.19API
gas gravity = 1.015
GOR = 1899 scf/stb
saturated reservoir oil density = 559.4 kg/m3

2. Relevant equations

3. The attempt at a solution

I used this method;

Bo = [ ρ(oil) + ρ(gas)*GOR(stb/stb)] / ρ(reservoir)
= [838.8 + 1.243*338] / 559.4

BO = 2.25 rb/stb

ρ(oil) = density of oil at surface (from 37.91 API)
ρ(gas) = density of gas at surface (using SGgas=1.015 to find MWgas and ideal gas equation PV=nRT to find density)
GOR (STB/STB) = 1899/5.615 = 338
ρ(reservoir) = density of reservoir oil at saturation = 559.4 kg/m3

Have I done this correctly?