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Joshi provides several examples in Chapter 8 of his textbook "Horizontal Well Technology" that will be used to highlight various aspects of the calculations within these routines.
Critical Rate for Gas Coning
From Joshi's Example 8.7, the following data is provided and the Engineer is asked to calculate the critical rate for gas coning.
Input Data
Thickness of Oil Zone, ft |
80 |
Height - GOC and Well, ft |
72 |
Well Length [L], ft |
1640 |
Well Radius, ft |
0.328 |
Major Length [xe], ft |
2640 |
Minor Length [ye], ft |
2640 |
Radial Permeability, mD |
70 |
Vertical Permeability, mD |
70 |
Gas Density, gm/cc |
0.21 |
Oil Density, gm/cc |
0.69 |
Water Density, gm/cc |
1.01 |
Oil FVF, Bo rb/stb |
1.1 |
Oil Viscosity, cP |
0.42 |
Once the user has successfully input all the required data, as shown in the following two screen captures, they can press the calculate button to perform the coning calculations.
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Water Breakthrough Time
From Joshi's Example 8.8, the following data is provided, and the Engineer is asked to calculate the water breakthrough time for a bottom waterdrive oil reservoir.
Input Data
Thickness of Oil Zone, ft |
160 |
Well Length [L], ft |
2000 |
Well Radius, ft |
0.328 |
Porosity, fraction |
0.2 |
Radial Permeability, mD |
200 |
Vertical Permeability, mD |
20 |
Oil Density, gm/cc |
0.76 |
Water Density, gm/cc |
1.01 |
Oil FVF, Bo rb/stb |
1.1 |
Oil Viscosity, cP |
1.3 |
Swc, fraction |
0.27 |
Sor, fraction |
0.25 |
Oil Flow Rate, bbl/d |
5000 |
Gas and Water Breakthrough Time and Optimal Well Placement
From Joshi's Example 8.11, the following data is provided, and the Engineer is asked to calculate the breakthrough time and optimum well placement for simultaneous gas and oil breakthrough for a bottom water oil reservoir with a gas cap.
Input Data
Thickness of Oil Zone, ft |
92 |
Well Length [L], ft |
1500 |
Well Radius, ft |
0.328 |
Porosity, fraction |
0.31 |
Radial Permeability, mD |
5580 |
Vertical Permeability, mD |
1.8 |
Gas Density, gm/cc |
0.13 |
Oil Density, gm/cc |
0.79 |
Water Density, gm/cc |
1.01 |
Oil FVF, Bo rb/stb |
1.178 |
Oil Viscosity, cP |
1.6 |
Oil Flow Rate, bbl/d |
8000 |
Production above Critical Water rate
Extending Joshi's Example 8.8, the Engineer is asked to calculate the post water breakthrough performance for a bottom water oil reservoir, using the technique of Kuo and Desbrisay.
The following screenshots highlight the data input and resultant calculations
Similar to the vertical well calculations, with the following input panel, and a knowledge of production history (time in days and watercut), the user can iterate vertical permeability to achieve an acceptable match.
To toggle on and off individual series within the chart, just toggle the chart context menu item, as shown below.
Page url: http://www.YOURSERVER.com/help/index.html?example6.htm
