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Oil Characterization 1

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Oil Characterization

2003 AspenTech. All Rights Reserved.EA1031.31.0505 Oil Characterization.pdf


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2 Oil Characterization

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Workshop

The petroleum characterization method in HYSYS converts laboratory

analyses of condensates, crude oils, petroleum cuts, and coal-tar liquids

into a series of discrete hypothetical components. These petroleum

hypo components provide the basis for the property package to predict

the remaining thermodynamic and transport properties necessary for

fluid modeling.

HYSYS produces a complete set of physical and critical properties for

the petroleum hypocomponents with a minimal amount of

information. However, the more information you supply about the fluid,

the more accurate these properties will be, and the better HYSYS will

predict the fluids actual behaviour.

In this example, the Oil Characterization option in HYSYS is used to

model a reservoir fluid. The fluid is a combined gas and oil stream.

Learning Objectives

Once you have completed this section, you will be able to:

Understand the steps required for oil characterization.

Characterize an oil using chromatographic data.

Prerequisites

Before beginning this module you need to understand the basics of the

fluid package (Getting Started).


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Process Overview

ComponentMole

Fraction

Mass

Fraction

Volume

Fraction

N2 0.0048 0.0017 0.0014

CO2 0.0087 0.0048 0.0039

H2S 0.0000 0.0000 0.0000

C1 0.4183 0.0843 0.1871

C2 0.0887 0.0335 0.0626

C3 0.0711 0.0394 0.0517

i-C4 0.0147 0.0107 0.0127

n-C4 0.0375 0.0274 0.0312

i-C5 0.0125 0.0113 0.0121n-C5 0.0163 0.0148 0.0156

C6+ 0.3274 0.7721 0.6217

H2O 0.0000 0.0000 0.0000

TOTAL 1.0000 1.0000 1.0000

ResidueRelative Density

@ 15C

Relative

Molecular MassData Summary

OBS CALC OBS CALC MOLEFRACTION

MASSFRACTION

VOLUMEFRACTION

C6+ 0.8265 188 0.3274 0.7721 0.6217

TOTALSAMPLE

0.6659 79.6

Paraffinic Component Groups (Molar Fractions)

Component B.Pt. Temp (C) Mole

Hexane (C6) 68.9 0.0268

Heptane (C7) 98.3 0.0371

Octane (C8) 125.6 0.0348

Nonane (C9) 150.6 0.0231

Decane (C10) 173.9 0.0240

Undecane (C11) 196.1 0.0183

Dodecane (C12) 215.0 0.0142

Tridecane (C13) 235.0 0.0141

Tetradecane 252.2 0.0113

Pentadecane 270.6 0.0099

Hexadecane 287.8 0.0074

Heptadecane 302.8 0.0082


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Paraffinic Component Groups (Molar Fractions)

Component B.Pt. Temp (C) Mole

Octadecane 317.2 0.0062Nonadecane 330.0 0.0049

Eicosane (C20) 344.4 0.0046

Heneicosane 357.2 0.0039

Docosane (C22) 369.4 0.0036

Tricosane (C23) 380.0 0.0032

Tetracosane 391.1 0.0027

Pentacosane 401.7 0.0024

Hexacosane 412.2 0.0021

Heptacosane 422.2 0.0020

Octacosane 431.7 0.0018

Nonacosane 441.1 0.0016

Triconane Plus 450.0 0.0133

Aromatic Component Groups (Molar Fractions)

Benzene (C6H6) 80.0 0.0004

Toluene (C7H8) 110.6 0.0015

EBZ, p+m-Xylene 136.1 0.0070

o-Xylene (C8H10) 144.4 0.0028

1,2,4 168.9 0.0028

Naphthenic Component Groups (Molar Fractions)

Cyclopentane 48.9 0.0002

MethylCycloPenta 72.2 0.0106

Cyclohexane 81.1 0.0050

MethylCycloHexa 101.1 0.0156

TOTALS 0.3274


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5

Building the Simulation

Before you start the characterization process, you must:

Select a property package.

Add any non-oil components, specifically the light ends that are tobe used in the characterization process.

Defining the Simulation Basis

For this module, you will be building on the case you started in the

Getting Started Module.

1. Open the case you saved at the end of the Getting Started module.

2. Click the Enter Basis Environment icon to return to the BasisEnvironment.

3. Go to the Oil Managertab and click the Enter Oil Environmentbutton. You could also press the Oil Environmentbutton on the toolBar. The Oil Characterization view appears.

Figure 1

Enter Basis Environment icon

Oil Environment icon


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Oil Characterization

The petroleum characterization in HYSYS accepts different types ofinformation about the oil. The more information you can supply about

your sample, the more accurate the representation.

There are three steps involved in characterizing any oil in HYSYS:

1. Characterize the assay.

2. Generate hypocomponents.

3. Install the oil in the flowsheet.

Characterize the Assay

The assay contains all of the petroleum laboratory data, boiling point

curves, light ends, property curves, and bulk properties. HYSYS uses the

supplied assay data to generate internal TBP, molecular weight, and

density and viscosity curves (referred to as Working Curves).

Assay Types

Accurate volatility characteristics are vital when representing a

petroleum fluid in your process simulation. HYSYS accepts the followingstandard laboratory analytical assay procedures:

True Boiling Point (TBP). Performed using a multi-stage batchfractionation apparatus operated at relatively high reflux ratios.TBP distillations conducted at atmospheric or vacuum conditionsare accepted by the characterization.

ASTM D86. Distillation employing batch fractionation butconducted using non-refluxed Engler flasks. Generally used forlight to medium petroleum fluids. HYSYS can correct forbarometric pressure or cracking effects. You must provide thedata on a liquid volume basis.

D1160 distillation. Distillation employing batch fractionation but

conducted using non-refluxed Engler flasks. Generally used forheavier petroleum fluids. Curves can be given at atmosphericpressure or corrected for vacuum conditions. You must providethe data on a liquid volume basis.

The Minimum amount ofinformation that HYSYSrequires to characterize anoil:

a laboratory distillationcurve

or

two of the followingbulk properties:Molecular Weight,Density, or Watson KFactor.

For all Distillation Curves,you are required to enter atleast five data points.


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D86_D1160. This is a combination of the D86/D1160 distillationdata types. You can correct for thermal cracking and enablevacuum distillation for sub-atmospheric conditions. You must

provide data on a liquid volume basis. ASTM D2887. Simulated distillation analysis from

chromatographic data. Reported only on a weight percent basisat atmospheric conditions.

Equilibrium Flash Vaporization (EFV). Involves a series ofexperiments at constant atmospheric pressure, where the totalvapour is in equilibrium with the unvapourized liquid.

Chromatographic Analysis. A gas chromatograph analysis of asmall sample of completely vapourized oil, analyzed for paraffin,aromatic and naphthenic hydrocarbon groups from C6 to C30.Chromatographic analyses may be entered on a mole, mass orliquid volume basis.

Light Ends

Light Ends are defined as pure components with low boiling points.

Components in the boiling range of C2 to n-C5 are most commonly of

interest.

HYSYS provides three options to account for Light Ends:

Ignore. HYSYS characterizes the Light Ends portion of yoursample as hypocomponents. This is the least accurate methodand as such, is not recommended.

Auto Calculate. Select this when you do not have a separateLight Ends analysis but you want the low boiling portion of yourassay represented by pure components. HYSYS will only use thepure components you have selected in the fluid package.

Input Composition. Select this when you have a separate LightEnds assay and your petroleum assay was prepared with theLight Ends in the sample. HYSYS will provide a form listing thepure components you selected in the fluid package. This is themost accurate method of representation.

Bulk Properties

Bulk Properties for the sample may also be supplied. The bulk

properties are optional if a distillation curve or chromatograph have

been supplied.

Molecular Weight. This is the Molecular Weight of the bulksample. It must be greater than 16.


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Mass Density. The mass density must be between 250 and 2000kg/m3.

Watson (UOP) K Factor. This must be between 8 and 15.

Bulk Viscosities. Given at two reference temperatures, typically37.78C and 98.89C (100F and 210F).

Physical Property Curves

HYSYS accepts different types of physical property curves:

Molecular weight curve

Density curve

Viscosity curve

Physical property analyses are normally reported from the laboratoryusing one of the following two conventions:

IndependentAssay Basis. A common set of assay fractions isnotused for both the distillation curve and the physical propertycurve.

DependentAssay Basis. A common set of assay fractions isused for both the distillation curve and the physical propertycurve.

As you supply more information to HYSYS, the accuracy of the

petroleum characterization increases. Supplying any or all of the bulk

molecular weight, bulk density, or bulk Watson K factor will increase the

accuracy of your hypocomponent properties. You can also supply

laboratory curves for molecular weight, density, and/or viscosity which

will increase the accuracy further.

Adding Assay Data

On the Oil Characterizations view:

1. SelectAssaytab.

2. Click theAddbutton.

3. The Input Datatab of the Assay view appears.

4. In the Name cell, change the assay name to Res-Fluid.

5. For the Bulk Props cell, use the drop-down list to select Used.

6. From theAssay Data Type drop-down list, select Chromatograph.

The units for densitycan be mass density,API or specific gravity,chosen from the dropdown list in the EditBar

The Watson K Factoris an approximateindex of paraffinicity. K= (Mean Avg BP)1/3/(sp gr 60F/60F)


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7. Once the correct Data Type is chosen, a third cell should appear.This is the Light Ends cell; use the drop-down list to select InputComposition as shown below.

8. Select the Light Endsradio button in the Input Datagroup.

9. Specify the Light Ends Basisas Mole %.

10. Enter the following data. Note that the default basis for Light Ends isLiquid Volume %; this must be changed before the data is entered.

Figure 2

For this Component... Enter this Mole Fraction...

N2 0.48

H2S 0.00

CO2 0.87

C1 41.83

C2 8.87

C3 7.11

i-C4 1.47

n-C4 3.75

i-C5 1.25

n-C5 1.63

C6 0.00

H2O 0.00

You need to enter the lightcomponents in the fluidpackage for them to beavailable to the Oil Manager.


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11. Select the Paraffinicradio button and specify the Basis as Mole.Enter the following data.:

12. Select theAromaticradio button, and enter the following molefractions:

For this component... Enter this Mole Fraction...

Hexane (C6) 0.0268

Heptane (C7) 0.0371

Octane (C8) 0.0348

Nonane (C9) 0.0231

Decane (C10) 0.0240

Undecane (C11) 0.0183

Dodecane (C12) 0.0142

Tridecane (C13) 0.0141

Tetradecane (C14) 0.0113

Pentadecane (C15) 0.0099

Hexadecane (C16) 0.0074

Heptadecane (C17) 0.0082

Octadecane (C18) 0.0062

Nonadecane (c19) 0.0049

Eicosane (C20) 0.0046

Heneicosane (C21) 0.0039

Docosane (C22) 0.0036

Tricosane (C23) 0.0032

Tetracosane (C24) 0.0027

Pentacosane (C25) 0.0024

Hexacosane (C26) 0.0021

Heptacosane (C27) 0.0020

Octacosane (C28) 0.0018

Nonacosane (C29) 0.0016

Triconane Plus 0.0133

For this Component... Enter this Mole Fraction...

Benzene (C6H6) 0.0004

Toluene (C7H8) 0.0015

EBZ, p+m-Xylene (C8H10) 0.0070

o-Xylene (C8H10) 0.0028

1,2,4 TriMethylBenzene (C9H12) 0.0028


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13. Enter the following data for the Naphthenic components:

14. Select the BulkProps radio button to enter the Bulk information.

15. The Molecular Weight is 79.6and the Standard Densityis 0.6659SG_60/60api.

16. Once you have entered all of the data, click the Calculatebutton.The status message at the bottom of the Assay view will display

Assay Was Calculated. HYSYS indicates that the sum of all fractionsdoes not equal to 1.

Once the Assay is calculated, the working curves are displayed on the

WorkingCurvestab. The working curves are regressed from the Assay

input. The calculation of the Blend is based on these working curves.

17. Close this view to return to the Oil Characterizationview. Youshould still be on theAssaytab of the view.

Notice that all of the buttons on the view are now accessible.

Hypocomponent Generation/Blending the Oil

The Cut/Blend characterization in HYSYS splits the internal working

curves for one or more assays into hypocomponents. The Blendtab of

the Oil Characterization view provides two functions, Cutting the Oil

into Hypocomponents and Blending two or more Assays into one set of

hypocomponents.

For this component... Enter this Mole Fraction...

Cyclopentane (C5H10) 0.0002

MethylCycloPentane (C6H12) 0.0106

Cyclohexane (C6H12) 0.0050

MethylCycloHexane (C7H14) 0.0156

Just as with fluid packages,assays can be imported andexported to be used indifferent cases.


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Cut Ranges

You have three choices for the Cut Option Selection:

Auto Cut - HYSYS cuts the assay based on internal values

User Points- You specify the number of hypocomponentsrequired. HYSYS proportions the cuts according to an internalweighting scheme.

User Ranges. You specify the boiling point ranges and thenumber of cuts per range.

Cutting the Assay

Once the Assay has been calculated, you can cut the Assay intoindividual hypocomponents.

1. Move to the Cut/Blendtab of the Oil Characterization view. Click theAddbutton to create a new Blend.

2. In the Name cell, change the name from the default, Blend-1 to Res-Fluid.

3. From the list of Available Assays (there should only be one), selectRes-Fluidand click theAddbutton. This adds the Assay to the OilFlow Information table and a blend (cut) will automatically becalculated. The Blend is calculated using the default Cut Option,

Auto Cut.4. Instead of using the default Auto Cut option, change the Cut Option

Selection to User Pointsand change the Number of Cuts to 5.

The results of the calculation can be viewed on the Tablestab of the

Blend view.

Range Cuts

37.78 - 425C (100 - 800F) 28 (4 per 37.78C/100F)

425 - 650C (800 - 1200F) 8 (2 per 37.78C/100F)

650 - 870C (1200 - 1600F) 4 (1 per 37.78C/100F)

Cutpoint Range Internal Weighting

IBP - 425C (IBP - 800F) 4 per 37.78C/100F

425 - 650C (800 - 1200F) 2 per 37.78C/100F

650C - FBP (1200F - FBP) 1 per 37.78C/100F

Note that reducing theNumber of Cuts will

increase simulation speed,but it may have a negativeeffect on simulationaccuracy.


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Installing the Oil in the Flowsheet

The final step of the characterization is to transfer the hypocomponentinformation into the flowsheet.

1. Move to the Install Oiltab of the Oil Characterization view. Theblend, Res-Fluid appears in the Oil Install Informationgroup.

2. In the Stream Name column, enter the name, GasWell 4, to whichthe oil composition will be transferred.

HYSYS will assign the composition of your calculated Oil and Light Ends

into this stream, completing the characterization process.

Return to the Basis Environment by clicking the Return to BasisEnvironmentbutton.

When you return to the Basis Environment, the hypocomponents that

you have generated in the Oil Characterization are placed in the current

fluid package. You can view the fluid package and examine the

individual hypothetical components which make up your oil.

Save your case!


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Analyzing the Results

Once you have calculated a blend, you can examine various property

and flow summaries for the generated hypocomponents that represent

a calculated oil.

Return to the Oil Environment and open the view for the blend, Res-

Fluid.

Tables Tab

The Tablestab of the blend contains various information, representing

the oil and the components. From the Table Typedrop down, you can

select different information to display.

Component Properties. When this is selected, choose eitherMain Propertiesor Other Propertiesfrom the Table Control.

Main Properties. Provides the normal boiling point,molecular weight, density, and viscosity information for eachcomponent in the oil.

Other Properties. Provides the critical temperature, criticalpressure, acentric factor, and Watson K Factor for eachindividual hypocomponent.

Component Breakdown. For the input light ends and each

hypocomponent, this provides individual liquid volume %,cumulative liquid volume %, volume, mass, and mole flows.

Molar Compositions. Provides the molar fractions of each lightends component and each hypocomponent in the oil.

Oil Properties. Choose the Basis (Mole, Mass, Liquid Volume)and then the property you want to display.

Boiling Points. Provides TBP, D86, D86 Corr, D1160 Vac, andD1160 Atm temperature ranges for the oil.

Other Properties. Provides critical temperature, critical pressure,acentric factor, molecular weight, density, and viscosity ranges forthe oil.

User Properties. Provides all user property ranges for the oil.

Oil Distributions. Provides tabular information of how your assaywould be distributed in a fractionation column. You can usestandard fractionation cuts or user defined cuts.


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Property Plot Tab

HYSYS can plot various properties versus liquid volume, mole, or masspercent distilled.

From the Basis drop-down list, choose Mass, Mole, or Liquid Volume for

the X-Axis.

From the Property drop-down list, choose the property to be plotted on

the Y-axis.

Distillation. You can plot one or more of the following: TBP, D86,D86 (Crack Reduced), D1160 (Vac), D1160 (Atm), or D2887.

Molecular Weight

Density

Viscosity

Critical Temperature

Critical Pressure

Acentric Factor

User Properties

Figure 3


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Composite Plot Tab

The Composite Plottab allows you to visually check the match betweenthe input assay data and the calculated property curves. The choice for

the graphical comparison is made from the Property drop-down list.

TBP or ASTM Distillation Curve

Molecular Weight Curves

Mass Density Curves

Viscosity Curves

Any User Property Curve

Viewing the Stream in the Simulation1. Leave the Oil Environment to return to the Basis Environment.

2. Enter the Simulation Environment.

3. Move to the Workbook to view the stream that you created, GasWell4. You can view the stream composition on the Compositionstab.

If you determine that some of the hypocomponents parameters need to

be recalculated, you can return to the Oil Environment at any time to

make changes.

The following parameters need to be added to the stream GasWell 4:

In this cell... Enter...

Temperature 35C (95F)

Flowrate 545 kgmole/h (1200 lbmole/hr)

Input assay data is onlydisplayed for distillationassay input and not forchromatographic input.

Save your case!

sr - caracterización de crudos - assay complejo.desbloqueado

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