Crude Oil Assay Characterization in Symmetry


A new option to characterize Crude Oil Assay reports has been added to the list of available analyses in the Oil Source unit operation of Symmetry. This new option, Cut Ranges, can be used to describe crude oils defined by property distribution curves similar to those provided in assay analyses like the one shown below.


In these laboratory analyses; physical properties, heteroatom and chemical family distributions are represented by curves that depend on cut temperature ranges. In the Oil Source unit operation, these data can be entered either in the specific curve tabs or as a whole in special forms similar to those provided by laboratories.

It is important to highlight that Yields, PIONA, Atomic Content and Density Distribution curves can be directly matched in the Oil Source unit operation without performing any parameter regression.

Cut Ranges Option in Oil Source

Entering the Data

The Cut Ranges option can be accessed in the Laboratory Analyses grid from the Summary tab, this option is only available when the Application type is Oil / Refinery.


Once the Cut Ranges option is selected, a new tab Yields (Cut Range) is brought up. This tab can be used to enter the cuts definition and yield distribution of the crude oil. Here, the number of cuts, names, boiling point ranges and yield basis can be customized. If light ends are part of the characterization, they can also be added in this tab.


The Cut Ranges IBP (Initial Boiling Point) can be set to an adequate boiling that describes the initial temperature of the first cut. The Cut Ranges EBP (End Boiling Point) is automatically set to the boiling point of the heaviest hydrocarbon in the current component slate.

The yields will be directly matched since their corresponding fractions are assigned to the slate components with boiling points belonging to the defined temperature range of the yield.


PIONA Distribution, Atomic Inclusion and Properties

The distributions that can be entered in the Cut Ranges characterization are: PIONA distribution, Atomic Inclusion and Physical properties.


The PIONA Distribution per Cut Range can be entered in the PIONA Distrib. (Cut Ranges) tab that is enabled by checking the PIONA Distribution box in the Summary Tab.

In this tab, along with the PIONA Distribution, the distribution basis and scale factors (for regression, if needed) for each family can be entered. In order to match the user-entered PIONA distribution, the PIONA Split regression factors (from the Settings Tab) are set to 1. The bulk PIONA contents can also be calculated in this tab.


The calculation procedure will do the best to honour the entered data and match the experimental values; however, situations like incomplete distributions or inconsistent data can be entered and matched through a regression pass.

The Atomic Inclusion curves can be entered in the Atomic Incl. (Cut Range) tab, the tab is enabled by checking the Atomic Inclusion box in the Summary Tab. The supported atoms are Sulfur, Nitrogen, Vanadium, Nickel, Iron and Hydrogen. For each atom, the distribution basis and factor (which defines the shape of the heteroatom distribution in each cut range) can be entered. The calculated Bulk contents per Atom are also showed in this tab.


The Physical Property curves can be entered in the Properties (Cut Range) tab, the tab is enabled by checking the Properties box in the Summary Tab. The supported properties are H/C Ratio, Molecular Weight, Density @ 60 F, Carbon Residue and Flash Point. For each property, the scale factors (for regression, if needed) and basis for some properties can be entered. The calculated Bulk properties are also showed in this tab.

If the property value for a specific range is not know, this can be left in blank and the value will be calculated based on the cut composition. The Oil Source unit operation can be regressed to match the entered properties distributions.


Being the Density @ 60 F a very important property to match, a direct calculation that allows the automatic match of the densities in each cut can be performed. The calculation can be triggered by checking the Direct Match box in the Density @ 60 F options.


The direct match is performed by adjusting the PIONA distribution in each Cut range to match the given density.

Input Templates

In order to facilitate data entering, an Inputs (Cut Range) tab was added. This tab contains templates similar to those used by laboratories; if users have their data in formats that are similar to one of these templates, they can easily copy and paste the data to Symmetry.

This tab can be enabled by checking the Inputs box from the Summary tab. The templates contain the same properties but in different order:


Template A


Template B


A great advantage of the PIONA characterization technique is that several crude oil assays can be represented with one single component slate, making the blending of these crudes consistent through an entire.

To learn more about the PIONA Characterization technique, please refer to our previous publications or contact your local support office.

Herbert Loria, Ph.D, P.Eng., VMG Calgary

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