Gas-Oil-Water Apps

Home  -  AGA-3  -  ISO-5167  -  Gas-Leak  -  Restriction Orifice  -  GOWProp  -  WatGas  -  GOSep  -  Contact

Easy to use engineering apps for the oil and gas industry - designed for practical field applications.
Apps have been tested and proven both on offshore and onshore oil and gas installations.
Written as Excel macros, requiring Microsoft Excel with 'Macro' enabled (Excel 2007 and newer).
Download free apps, demo apps or purchase full version apps from $4.99 to $9.99 each.
Available Apps
AGA-3 Calculations
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AGA-3 calculates size, flowrate or pressure drop for gas and liquid flow orifice meters based on ANSI/API-2530-1991, Part 3 (AGA-3).
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ISO-5167 Calculations
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ISO-5167 calculates size, flowrate or pressure drop for gas and liquid flow orifice meters based on International Standard ISO-5167-2:2003.
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Gas-Leak Calculations
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Gas-Leak estimates gas-leak rates from piping based on restriction orifice calculations as per R.W. Miller's "Flow Measurement Handbook", assuming critical flow across the leak point.
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Restriction Orifice Calculations
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Restrict_Ori calculates size and flowrates for gas and liquid restriction orifice meters based on R.W. Miller's "Flow Measurement Handbook".
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Gas-Oil-Water PVT Calculations
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GOW-Prop calculates physical properties (PVT) of Gases (Natural Gas, Air and Nitrogen) and Liquids (Oil, Water, MeOH, MEG, DEG and TEG) based on published correlations.
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Water-Gas Interaction Calculations
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WatGas performs calculations for:
- Hydrate Formation Conditions
- Water Content of Natural Gases
- MeOH/Glycol Inhibition Requirements
- Solid CO2 Formation Conditions
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Gas-Oil Separation Calculations
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GOSep performs flash calculations through two Oil/Gas separator stages optimize liquid recovery depending on pressure/temperature at each separator stage.  Free App.
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Free App
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ReadMe GOWDoc is the free documentation for the listed programs with correlations included (PDF-file).
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Free Documentation
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For more information, please e-mail questions/queries to:

oilgasapp@gmail.com

or

norcraft@lycos.com


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AGA-3 Orifice Calculations
 
Program AGA3  will size orifice plates for given design conditions, find pressure drop for a given flow, or flow for a given pressure drop. The standard (AGA-3 ( API-2530: 1991) is originally designed for gas orifices. In this program the standard is also used for liquid orifices.

Gas calculations are performed for Natural Gas, Nitrogen and Air.  For liquid orifice calculations, the options are Crude Oil, Water, Methanol, Mono-ethylene glycol (MEG), Diethylene glycol (DEG) and Triethylene glycol (TEG).

Input requirements are specific gas gravity, temperature and pressure for gas calculations. You can also give mole-fractions of N2, CO2 and H2S for sour gas calculations.  The AGA-8 equation is used for calculating Z-factor (compressibility factor) for natural gases, and the Redlich-Kwong equation of state for Nitrogen and Air.

For oil-calculations you have to enter specific oil gravity, temperature and pressure. It is also recommended to give molecular weight of oil. For water-calculations the input requirements are salinity, temperature, and pressure.  It is assumed that all dissolved solids for water are expressed as equivalent sodium chloride concentration.

The result will be an orifice specification sheet giving the necessary data for design of an orifice or evaluating an existing orifice.  The results will contain a few factors that you should know:

The velocity of approach factor is defined as:

Ev = 1/(Sqrt(1-Beta^4))

The flow coefficient, Alpha, is defined as:

Alpha = Ev * Cd

and orifice to pipe diameter ratio is given as:

Beta = OD/PID

The basic flow equation is:

Qm = C*E*Eps*Pi/4*OD^2*Sqrt(2*dP*Roh)

where

Qm = Mass flow rate (kg/s)

C = Discharge coefficient = Alpha/E

E = Velocity of approach factor = 1/(Sqrt(1-Beta^4))

Eps = Expansion factor due to pressure drop

Pi = 3.14159

OD = Orifice diameter at actual flowing conditions

dP = Differential pressure across orifice

Roh = Density of flowing fluid measured at upstream tap


API/ ANSI-2530 - 1991 (AGA Report No. 3) (AGA)

The basic flow equation is:

Qv = Fn*(Fc+Fsl)*Y1*Fpb*Ftb*Ftf*Fgr*Fpv*Sqrt(Pf1*hw)
 
where

Fn = Numeric conversion factor

Cd = Discharge coefficient = (Fc + Fsl)

Fc = Orifice calculation factor

Fsl= Slope factor

Y1 = Expansion factor based on upstream tap

Fpb= Pressure base factor, set to 1.0 (14.73 psia)

Ftb= Temperature base factor, set to 1.0 (60 deg F)

Ftf= Flowing temperature factor

The velocity of approach factor is defined as:

Ev = 1/(Sqrt(1-Beta^4))

The flow coefficient, Alpha, is defined as:

Alpha = Ev * Cd

and orifice to pipe diameter ratio is given as:

Beta = OD/PID

Fgr= Specific gravity factor

Fpv= Super-compressibility factor

Pf1= Absolute flowing pressure based on upstream tap

hw = Orifice differential pressure, in H2O at 60 deg F

The above equation is often simplified to:

Qv = C' * Sqrt(Pf1*hw)

where C' is called the Composite orifice flow factor.

For other factors and the factors for pipe taps you are advised to consult the standard API-2530-1991, Part 3.


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ISO-5167 Orifice Calculations
 
ISO-5167 will size orifice plates for given design conditions, find pressure drop for a given flow, or flow for a given pressure drop. The standard (ISO-5167:2003) is originally designed for gas orifices. In this program the standard is also used for liquid orifices.

Gas calculations are performed for Natural Gas, Nitrogen and Air.  For liquid orifice calculations, the options are Crude Oil, Water, Methanol, Mono-ethylene glycol (MEG), Diethylene glycol (DEG) and Triethylene glycol (TEG).

Input requirements are specific gas gravity, temperature and pressure for gas calculations. You can also give mole-fractions of N2, CO2 and H2S for sour gas calculations.  The AGA-8 equation is used for calculating Z-factor (compressibility factor) for natural gases, and the Redlich-Kwong equation of state for Nitrogen and Air.

For oil-calculations you have to enter specific oil gravity, temperature and pressure. It is also recommended to give molecular weight of oil. For water-calculations the input requirements are salinity, temperature, and pressure.  It is assumed that all dissolved solids for water are expressed as equivalent sodium chloride concentration.

The result will be an orifice specification sheet giving the necessary data for design of an orifice or evaluating an existing orifice.  The results will contain a few factors that you should know:

The velocity of approach factor is defined as:

Ev = 1/(Sqrt(1-Beta^4))

The flow coefficient, Alpha, is defined as:

Alpha = Ev * Cd

and orifice to pipe diameter ratio is given as:

Beta = OD/PID


ISO-5167-2: 2003 ( ISO-5167)

The basic flow equation is:

Qm = C*E*Eps*Pi/4*OD^2*Sqrt(2*dP*Roh)

where

Qm = Mass flow rate (kg/s)

C = Discharge coefficient = Alpha/E

E = Velocity of approach factor = 1/(Sqrt(1-Beta^4))

Eps = Expansion factor due to pressure drop

Pi = 3.14159

OD = Orifice diameter at actual flowing conditions

dP = Differential pressure across orifice

Roh = Density of flowing fluid measured at upstream tap


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Gas-Leak Calculations

Gas leak rate calculations are based on the assumption that the pressure difference across the leak-point (hole) is large enough to cause critical flow across the hole/crack.  The calculated flowrates are based on restriction orifice correlations.  This means that sonic velocity exists at the orifice throat, and further decrease in the downstream pressure will not increase the mass flow rate.  The flow-rate calculated is only correct if the upstream and downstream pressures remain constant.  If a blow-down situation occurs, the flowrate drops significantly due to the reduction in the upstream pressure and will be zero when pressures are equalized across the leak-point.  In this case, the program only calculates the initial flowrate.
 
Restriction orifice calculations in this program are performed according to R. W. Miller's "Flow Measurement Engineering Handbook". 

The basic mass flow rate equation is: 

Qm = 1335.485*C*d^2*Ycr*Sqrt(Z*Roh*Ftp*P)

where 

 Qm  = mass flow rate, lbm /h
 
 C  = critical discharge coefficient
 
 d  = orifice diameter at flowing conditions, in
 
 Yrc = critical flow function
 
 Ftp = total pressure correction factor to adjust for difference between static pressure read at the pipe wall (Manometer) and total pressure of the fluid 
 
 and  Z, Roh and P are measured at flowing upstream conditions
 
For Beta-ratios less than 0.5 the total pressure correction factors are approximated by:
 
     Ftp = {1 - k/2*[2/(k+1)]^[(k+1)/(k-1)] * Beta^4}^(-1)    
 
     Ycr = {k/Z*[2/(k+1)]^[(k+1)/(k-1)]}^0.5    
 
where  k = isentropic coefficient at flowing conditions
 
Assuming steady isentropic flow, critical flow (choked flow) occurs when:
 
     P2/P1/Ftp < [2/(k+1)]^[k/(k-1)]      
 
where  P1 = pressure upstream orifice and P2 = pressure downstream orifice
 
By assuming sharp-edged orifices with plate thickness to bore diameter between 1 and 6 the discharge coefficient is a constant given in the program as:
 
               C = 0.83932
 
Program Gas_Leak will check if flow is critical. If flow is found to be sub-critical, the program will simply perform normal orifice calculations based on ISO-5167-2: 2003, assuming a flange-tapped orifice, and basic flow equation given above as for the ISO-5167 calculation.


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Restriction Orifice Calculations

Restriction orifice calculations in this program are performed according to R. W. Miller's "Flow Measurement Engineering Handbook".

Gas restriction orifices are calculated based on critical flow in the orifice.  This means that sonic velocity exists at the orifice throat, and further decrease in the downstream pressure will not increase the mass flow rate.  For critical flow the basic mass flow rate equation is:

Qm = 1335.485*C*d^2*Ycr*Sqrt(Z*Roh*Ftp*P)

where 

 Qm  = mass flow rate, lbm /h
 
 C  = critical discharge coefficient
 
 d  = orifice diameter at flowing conditions, in
 
 Yrc = critical flow function
 
 Ftp = total pressure correction factor to adjust for difference between static pressure read at the pipe wall (Manometer) and total pressure of the fluid 
 
 and  Z, Roh and P are measured at flowing upstream conditions
 
For Beta-ratios less than 0.5 the total pressure correction factors are approximated by:
 
     Ftp = {1 - k/2*[2/(k+1)]^[(k+1)/(k-1)] * Beta^4}^(-1)    
 
     Ycr = {k/Z*[2/(k+1)]^[(k+1)/(k-1)]}^0.5    
 
where  k = isentropic coefficient at flowing conditions
 
Assuming steady isentropic flow, critical flow (choked flow) occurs when:
 
     P2/P1/Ftp < [2/(k+1)]^[k/(k-1)]      
 
where  P1 = pressure upstream orifice and P2 = pressure downstream orifice
 
By assuming sharp-edged orifices with plate thickness to bore diameter between 1 and 6 the discharge coefficient is a constant given in the program as:
 
               C = 0.83932
 
Liquid choked flow occurs if a cavitation barrier exists within an orifice.  Only upstream pressure increases can increase flowrates.  Thick square-edged orifices are used as they are inexpensive.

The sizing and flowrate equation used for liquids is:

Qm = C*E*PI/4*d^2*Sqrt(2*DeltaP*Roh1)

where   
   
  DeltaP  =     P - Pv     = upstream pressure minus vapor pressure of liquid, Pa

    Roh1  =      1.0          = expansion factor for liquids

Other factors are defined above as part of the Gas Restriction Orifice calculations.

Assuming square-edged orifices with plate thickness to bore diameter less than 6 with a minimum of 0.125 in (3 mm), the liquid restriction orifice constant is :

                                       C = 0.6


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Gas-Oil-Water Properties

Program GOWProp is a Physical Properties program that calculates PVT properties of gas, oil, and water - with your choice of calculation methods. Pick from a selection of standard equations for calculating certain properties. More than 12 properties are calculated and the results include a pressure depletion table of the various properties and will plot the output on screen. U.S. and SI Units.

Oil properties are calculated based on a black-oil model. In fluid-property terms the black-oil model employs 2 pseudo-components:

1) "OIL" defined as produced oil at stock tank conditions

2) "GAS" defined as produced separator gas

The basic assumption is that gas may dissolve in the oil phase, but oil will not dissolve in the gas phase. For mixtures of heavy oil and light components this is a reasonable assumption, but is a misleading assumption for mixtures of light and intermediate components.

 The following fluids are included:

 Gases:

    -Natural gas

    -Nitrogen

    -Air

 Liquids:

    -Oil

    -Water

    -Methanol/Water mixtures (MeOH)

    -Monoethylene glycol/Water mixtures (MEG)

    -Diethylene glycol/Water mixtures (DEG)

    -Triethylene glycol/Water mixtures (TEG)

 GOWProp will let you choose between SI-units (metric) or Customary units (US).

The gas property routine calculates:

- Molecular weight

- Density

- Compressibility

- Gas formation volume factor

- Z-factor (gas deviation factor)

- Viscosity

- Thermal conductivity

- Specific heat

- Ideal isentropic coefficient, Cp/Cv

- Real isentropic coefficient, k

- Pseudo Critical properties

- Pseudo Reduced properties

 The liquid property routine calculates:

- API gravity (for oil only)

- Density

- Compressibility

- Formation volume factor (oil and water only)

- Solution gas-liquid ratio (oil and water only)

- Bubble point pressure (oil only)

- Viscosity

- Thermal conductivity

- Surface tension

- Specific heat

- Pseudo Critical properties

- Pseudo Reduced properties

A pressure liberation table of properties (at constant temperature) will also presented from given pressure down to atmospheric conditions (14.696 psia [1.01325 Bara]).


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Water-Gas Physical Properties

WatGas calculates Water-Natural Gas interaction properties, including the following PVT-properties:

- Hydrate formation calculations

- Water content predictions of natural gases

- Inhibitor quantities (methanol/glycols) to avoid hydrate problems in pipelines

- Solid CO2 formation predictions

The program handles gases with known compositions and non-compositional gases (only gas gravity is needed). Note that the compositional model is more reliable than the non-compositional model, although they give similar results.

Almost all gases contain some water vapor. When leaving the producing formation, gas is saturated with water vapor, which is in equilibrium with reservoir liquid water at temperatures and pressures prevailing there.

Knowing the water content of natural gases is essential to the design and operation of production, dehydration and transmission systems. Water may condense in production and gathering systems. This may result in hydrate formation and plugging of flow systems and damage to internals of production equipment.

Condensed water may form water slugs, which will tend to decrease flow efficiency and increase pressure drop in a line.  Presence of free water in pipeline systems may also cause corrosion.  If carbon dioxide and/or hydrogen sulfide are present, the gases may form carbonic acid and sulphuric acid respectively if dissolved in water.

 

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Gas-Oil Separator Flash Calculations

Program GOSep performs flash calculations for gas/oil separators to optimize liquid recovery.  The program performs vapor-liquid equilibrium calculations for two stages of separation and Stock Tank conditions (Standard Conditions), defined in the program as 14.73 psia and 60 °F.

Equilibrium ratios (K-values) are used for calculating compositions of gas and liquid phases at given temperatures and pressures at each stage.  Normally an equation of state (EOS) is used for predicting equilibrium ratios, and is a function of composition, pressure and temperature.  Based on the fact that compositional effects on equilibrium ratios are small below about 1000 psia, Standing developed a correlation for calculating equilibrium ratios based on data reported by Katz and Hachmuth.  The correlation gives the following equation for each component:

                    K = (1/P) x 10 (a + c x F)                                                                             

where

               F          = b x (1/Tb - 1/T)  

              K          = equilibrium ratio    

               a, b, c  = correlating parameter  

              P          = pressure, psia 

              T         = temperature, deg R    

             Tb        = boiling point, deg R

             X         = mole fraction in liquid phase      

              y         = mole fraction in vapor phase

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Updated Dec 1, 2016 - Copyright © Norcraft - 2016