Petroleum Engineering 324 — Well Performance
Homework 1 — Estimation of Reservoir Fluid Properties
2 February 2000 — Due: Wednesday 16 February 2000
Homework Assignment No. 1: due Wednesday 16 February 2000
In this homework you are to develop a computer program to generate fluid properties for
use in well testing and reservoir engineering. All of the pertinent fluid property correlations are included in the lesson—"Properties of Reservoir Fluids."
Given:

In the lesson "Properties of Reservoir Fluids" you are provided with the details of
the following correlations for natural gases, reservoir (black) oils, and reservoir
waters:
 Properties of Natural Gases
Sutton calculation for pseudoreduced temperature and pressure.
Wichert and Aziz corrections for pseudoreduced temperature and pressure, for
the presence of carbon dioxide (CO2) and/or hydrogen sulfide (H2S).
z-factor using the Dranchuk and Abou-Kassem equation of state (DAK-EOS).
Gas compressibility using the Dranchuk and Abou-Kassem equation of state.
Gas viscosity using the Lee, Gonzales, and Eakin correlation.
 Properties of Reservoir Oils
Oil formation volume factor (Standing correlation).
Solution gas-oil ratio (Standing correlation).
Oil compressibility (Villena-Lanzi and Vasquez-Beggs correlations).
Oil viscosity (Egbogah-Beggs-Robinson and Vasquez-Beggs correlations).
 Properties of Reservoir Waters
Water formation volume factor (McCain correlation).
Solution gas-water ratio (McCain correlation).
Water compressibility (Osif and McCain correlations).
Water viscosity (McCain correlation).
Required:
1. Create a computer program to generate the suite of PVT correlations given above—
you should create your program in Fortran or Visual Basic. You are required to
turn in a listing of your source code—collaboration is permitted, BUT each student
must develop his or her own program.
2. You are to provide validation of your computer program by completing the required
tasks given below. Where appropriate (i.e., where you calculate something as a
function of pressure), you are to plot the pressure-dependent property as a function
of pressure. The exception being oil compressibility (co), which should be plotted
as log(co) versus pressure for clarity. For the oil cases, you should clearly identify
the bubblepoint pressure (pb) using a vertical line and an appropriate label.
a. Using your program (based on the "Properties of Reservoir Fluids" materials)
solve the following: (use 14.7 <p< 10,000 psia)
 Properties of Natural Gases (g=0.65, T=200oF, 2% CO2, 4% H2S)
Sutton calculation for pseudoreduced temperature and pressure.
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Wichert and Aziz corrections for pseudoreduced temperature and pressure,
for the presence of carbon dioxide (CO2) and/or hydrogen sulfide (H2S).
z-factor versus pressure, using the Dranchuk and Abou-Kassem equation of
state (DAK-EOS).
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Petroleum Engineering 324 — Well Performance
Homework 1 — Estimation of Reservoir Fluid Properties
2 February 2000 — Due: Wednesday 16 February 2000
2. (Continued)
a. (Continued)
 (Cont) Properties of Natural Gases (g=0.65, T=200oF, 2% CO2, 4% H2S)
Gas compressibility (cg) versus pressure, using the Dranchuk and Abou-Kassem equation of state (DAK-EOS).
Gas viscosity (g) versus pressure, using the Lee, Gonzales, and Eakin correlation.
 Properties of Reservoir Oils (g=0.65, T=200oF, o=45oAPI, pb=5000 psia)
Oil formation volume factor (Bo) versus pressure, computed using the Standing correlation.
Solution gas-oil ratio (Rs) versus pressure, computed using the Standing correlation, as well as the Velarde, Blasingame, and McCain correlation.
Oil compressibility (co) versus pressure, computed using the Villena-Lanzi
and Vasquez-Beggs correlations. Plot log(co) versus pressure (for clarity).
Oil viscosity (o) versus pressure, computed using the Egbogah-BeggsRobin-son and Vasquez-Beggs correlations.
 Properties
of Reservoir Waters (T=200oF, salinity=50,000 ppm)
Water formation volume factor (Bw) versus pressure, computed using the McCain correlation.
Solution gas-oil ratio (Rsw) versus pressure, computed using the McCain correlation.
Water compressibility (cw) versus pressure, computed using the Osif and McCain correlations.
Water viscosity (w) versus pressure, using the McCain correlation.
b. Using your program you are to generate the following properties for the black oil
sample described in the Reservoir Fluid Study for Good Oil Co.—Oil Well No.
4, this report is attached.
 You
must plot BOTH the computed results and the laboratory data on the same
plot and clearly label each trend. I prefer that the lab data are plotted as
symbols (e.g., circles), and the computed results plotted as lines—do not use
the "smoothed" line function in MS Excel, as this can add error to your trends.
 For
this work you are to use the 100-psig separator condition.
Oil formation volume factor (Bo) versus pressure.
Solution gas-oil ratio (Rs) versus pressure.
Oil compressibility (co) versus pressure, co for p<pb can be computed from the
lab data using the following identity: (be sure to plot log(co) versus pressure)

co = – 1
Bo
 Bo
 p
– Bg
T
 Rs
p
T
Oil viscosity (o) versus pressure.
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