Ejemplos de Gases #8

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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 .



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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

:



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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:

Ejemplos de Gases #8

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