A MATLAB code is generated to estimate some properties of gases. With the given specific gravity, mole fractions of non-hydrocarbon components, wellhead and bottom-hole temperatures and pressures, and the depth of interest, the properties below are calculated.
- Density (lbm/ft^3),
- Viscosity (cp),
- Formation volume factor (rcf/scf),
- Compressibility (1/psia),
- Pseudo-Pressure (psi^2/cp).
During the implementation of the code, critical temperature and critical pressure are evaluated with two methods. Depending on the user's request, the program can use Standing's (1977) correlation or Sutton's (1985) correlation for miscellaneous gases. Other correlations can also be implemented; however, for this stage, I haven't coded any other method for critical properties. The correction of non-hydrocarbon components can be calculated using either Wichert Aziz (1972) or Carr-Kobayashi-Burrows (1954) corrections. It is again chosen upon the decision of the user.
Viscosity is calculated using Lee-Gonzales and Eakin Correlation (1966), and Z-factor is calculated with the Redlich Kwong Equation of State. Gas compressibility, in other words, isothermal gas compressibility is evaluated using the numerical method proposed by Meehan and Lyons (1979). Finally, the pseudo-pressure is calculated with numeric methods.
The resulting plots are as follows:
- Depth vs Density,
- Depth vs Viscosity,
- Depth vs Formation Volume Factor,
- Depth vs Compressibility,
- Depth vs Pseudo-Pressure,
A user interface is developed for ease in calculations. It is created with MATLAB App Designer. Although the UI uses the same code used for the project, it can be developed for further correlations to offer a variety of options for the user. The sample figures from the UI can be seen below.
 |
| Figure 1. Input Section |
 |
| Figure 2. Input Section 2 |
 |
| Figure 3. Results Section - Depth vs Density |
 |
| Figure 4. Results Section - Depth vs Formation Volume Factor |
Thank you.