ejemplos de gases #8
TRANSCRIPT
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EJEMPLOS DE GASES #8
1. A sour natural gas has a specific gravity of 0,7. The compositional analysis
of the gas shows that it contains 5 percent CO2 and 10 percent H2S.Calculate the density of the gas at 3.500 psia and 160°F.
SOLUTION
Step 1. Calculate the uncorrected pseudo-critical properties of the gasfrom Equations ( ) and ( ):
Step 2. Calculate the pseudo-critical temperature adjustment factor from
Equation ( ):
Step 3. Calculate the corrected pseudo-critical temperature by applyingEquation ( ):
Step 4. Adjust the pseudo-critical pressure Ppc by applying Equation ( ):
Step 5. Calculate Ppr and Tpr :
Step 6. Determine the z-factor from Figure:
z = 0,89
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Step 7. Calculate the apparent molecular weight of the gas from Equation ( ): Step 8. Solve for gas density:
2. Using the data in Example 1, calculate the density by employing the abovecorrection procedure.
Step 1. Determine the corrected pseudo-critical properties from Equations( ) and ( ):
Step 2. Calculate Ppr and Tpr :
Step 3. Determine the gas compressibility factor from Figure:
z = 0,820
Step 4. Calculate the gas density:
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3. A hydrocarbon gas system has the following composition:
Component yi
C1 0,83
C2 0,06
C3 0,03
n-C4 0,02
n-C5 0,02
C6 0,01
C7+ 0,03
The heptanes-plus fraction is characterized by a molecular weight and specificgravity of 161 and 0,81, respectively.
a. Using Sutton’s methodology, calculate the density of the gas 2.000 psi and150°F.
b. Recalculate the gas density without adjusting the pseudo-critical properties.
SOLUTION
PART A.
Step 1. Calculate the critical properties of the heptanes-plus fraction by the Riazi-
Daubert correlation ( ):
Step 2. Construct the following table:
Component yi Mi Tci Pci yiMi yi(Tci /Pci) yiz(̅ )i yi(Tc /̅ )i C1 0,83 16,0 343,33 666,4 13,31 0,427 0,596 11,039
C2 0,06 30,1 549,92 706,5 1,81 0,047 0,053 1,241
C3 0,03 44,1 666,06 616,4 1,32 0,032 0,031 0,805
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Step 7. Calculate the pseudo-reduced properties of the gas by applying Equations
(
) and (
), to give:
Step 8. Calculate the z-factor from Figure, to give:
z = 0,745
Step 9. From Equation ( ), calculate the density of the gas: PART B.
Step 1. Calculate the specific gravity of the gas
Step 2. Solve for the pseudo-critical properties by applying Equations ( ) and ( ):
Step 3. Calculate and :
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Step 4. Calculate the z-factor from Figure, to give:
Step 5. From Equation , calculate the density of the gas:
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4. A hydrocarbon gas mixture has a specific gravity of 0,72. Calculate the
isothermal gas compressibility coefficient at 2.000 psia and 140°F by
assuming:
a. An ideal gas behavior
b. A real gas behavior
SOLUTION
a. Assuming an ideal gas behavior, determine by applying Equation
b. Assuming a real gas behavior
Step 1. Calculate and by applying Equations and
Step 2. Compute and from Equations and .
Step 3. Determine the z-factor from Figure:
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Step 4. Calculate the slope *+ :
Step 5. Solve for by applying Equation
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Step 6. Calculate from Equation
5. Using Trube’s generalized charts, rework Example 4.
SOLUTION
Step 1. From Figure, find :
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Step 2. Solve for by applying Equation
:
6. A gas well is producing at a rate of from a gas reservoir atan average pressure of 2.000 psia and a temperature of 120°F. The specific
gravity is 0,72. Calculate the gas flow rate in scf/day.
SOLUTION
Step 1. Calculate the pseudo-critical properties from Equations and
, to give:
Step 2. Calculate the
and
:
Step 3. Determine the z-factor from Figure:
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Step 4.
Calculate the gas expansion factor from Equation :
Step 5. Calculate the gas flow rate in scf/day by multiplying the gas flow rate (in
ft3/day) by the gas expansion factor as expressed in scf/ft3:
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7. Using the data given in Example 6, calculate the viscosity of the gas.
SOLUTION
Step 1.
Calculate the apparent molecular weight of the gas:
Step 2.
Determine the viscosity of the gas at 1 atm and 140°F from Figure:
Step 3. Calculate
and
:
Step 4. Determine the viscosity rates from Figure:
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Step 5. Solve for the viscosity of the natural gas: