Nodal Analysis, IPR and TPR Curve

 The project is a computer coding assignment given in our Natural Gas Engineering course. The aim of the assignment is to prepare the IPR and the TPR curves and perform nodal analysis for a given well. It is the same implementation as the bottom hole nodal gas excels file that calculates gas well deliverability with the bottom hole node pressure squared method. I assumed an average pressure of the wellbore and reservoir pressure. Calculated parameters are the compressibility factor and the friction factor from Jain's correlation (1976) which depends on the viscosity at the pressure of interest for the Reynold number calculation. Also, by applying my Z-factor and viscosity functions written in my code, I calculated the viscosity at the same average pressure and temperature used for Z-calculation.


The bottom hole pressure equation

Friction Factor from Jain's Correlation (1976)

I created an input field in which we can insert relevant parameters, such as specific gas gravity, nitrogen mole fraction, carbon dioxide mole fraction, hydrogen sulphide, wellhead pressure, and perforation depth.



Figure 1: Input Field


The bottom hole pressure versus gas production rate graphs known as IPR and TPR curves are drawn. Some values were taken from the BottomHoleNodalGas.xlsm shared with the question. Then, critical pressure and temperature values of the natural gas were found. Also, the Standing correlation was used and assumed as dry gas. Kay's mixing rule was applied to include non-hydrocarbon and Wichert and Aziz correlation was used to correlate critical temperature and pressure, so average pressure and temperature were determined and assumed that pressure and temperature linearly changing from wellbore to bottom hole. After that, average Z-Factor and average viscosity were found. C and n constant were also taken from the excel file and AOF was calculated. Initially, the operation flow rate was chosen and manually changed to make the residual of the objective function as close as to 0.

IPR and TPR curves are determined in Matlab. For loop is working million times to get better resolution and results and to find operation point, if statement is made. The output and figure are shown below.

Figure 2: Result of IPR TPR Curves


I checked our results from the PIPESIM, and detect a 5 psi pressure difference and a 9 Mscf/D flow rate difference. This difference might occur from small constant number differences or loop cycle numbers. As a result, I can say that our program works well and is usable.



Figure 3: Pipesim Result





REFERENCES

Bottom Hole Nodal Gas. (2021). [Slides]. Bottom Hole Nodal Gas. https://odtuclass2021f.metu.edu.tr/pluginfile.php/482527/mod_folder/content/0/BottomHoleNodalGas.xlsm?forcedownload=1

Wellbore Flow Performance and Recovery. (2021). [Slides]. Wellbore Flow Performance and Recovery. https://odtuclass2021f.metu.edu.tr/pluginfile.php/460269/mod_resource/content/0/PETE461Chapter06_WellPerformanceRecovery.pdf

Workflow for building single well model in Pipesim. (2021). [Slides]. Workflow for Building Single Well Model in Pipesim. https://odtuclass2021f.metu.edu.tr/pluginfile.php/481641/mod_resource/content/0/Workflow%20for%20building%20single%20well%20model%20in%20Pipesim_2021.pdf










Location: Üniversiteler, Dumlupınar Blv. 1/6 D:133, 06800 Çankaya/Ankara, Türkiye

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