EXAMPLE OF CALCULATION OF FLOW OF GAS PRESSURE AVERAGE
Tarek Ahmed Translation – Chapter 3
Example. PVT properties of a gas sample taken from a dry gas reservoir
The reservoir is produced under the condition pseudosteady-state. The following additional information is available:
Calculate the ratio of gas flow under the following conditions:
SOLUTION
(a) Calculation of Qg = 4000 pr = 3200 psi and PWF:
Step 1. Select the method of approach. Because PR and PWF are both larger than 3000, the method of approximation of the pressure is used, Equation 3.1.9.
Step 2. Calculate the average pressure and determine the corresponding properties of gas.
Step 3. Qg recalculated using the equation pseudopressure Equation 3.1, to:
Comparing the results of the method of approximation of the pressure with pseudotime approach indicates that the ratio of gas flow can be approximated using the “pressure” with an absolute percentage error of 2.25%
(b) calculation of Qg to pr = 2000 and PWF = 1200:
Step 1. Select the appropriate method of approach.
Since pr and PWF <= 2000, use the square root-pressure approach. Step 2. Calculate the average pressure and the corresponding ug and Z:
