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[Ally0138]

Hello,

 

Please would someone be able to offer advice/assistance with the following? :-

 

I am a reasonably experienced HYSYS user, however I have never before now used the 'Oil Manager' or dealt with crude assay data, TBP curves, etc.

 

I have been asked by the client to characterise a crude oil / reservoir fluid for a contractor using HYSYS.

 

I have been provided with a PVT Report and a Crude Assay Report, which contain the following information:

• Fluid Composition
• Calculated pseudocomponent data (Molecular Weight & Density) for C7+, C11+, C20+ and C36+.
• GOR and oil & gas densities @ 0 psig & 15.6 °C
• Whole crude density @ 15 °C
• UOP K factor
• Crude Assay True Boiling Point (TBP) curve

 

As far as I understand there are at least 3 approaches that can be taken here:

1. Create a new material stream.  Enter the composition as given in the PVT report up to, say C10, then add a C11+ pseudocomponent defined as per the PVT report MW & density values.  Flash this through a separator and then manually adjust the MW in order to match the reported GOR.
2. Create a new material stream, then use the 'Oil & Gas Feed' tab to specify oil density & K factor, gas composition and GOR.  HYSYS will then automatically adjust the composition of the feed stream to match.
3. Use the 'Oil Manager' tab in the 'Properties' view to enter the TBP curve and density curve (also MW and viscosity curves, but in this case I don't have this data) and a series of blend cuts and allow HYSYS to generate a series of pseudocomponents to fit this data.

 

What are the main advantages/disadvantages of each method?

 

Are there any other methods which I may have missed?

 

The main problem I have with method 2 is that whilst the resulting GOR and oil density match the lab data perfectly (not surprising given that's what HYSYS is matching by adjusting other variables), the resulting gas density and bubble point pressure don't match the lab data very well at all (the simpler method 1 gives a better match at the cost of only a slight deviation in the oil density value compared to the lab data).

 

With method 3 I can't get the GOR to match up to the lab data at all.  After a week or so of back-and-forth with AspenTech they haven't been able to resolve this yet either.  I don't know why and I don't know what else I should be trying in order to get a better match to the measured GOR.  I think the source of the discrepancy has something to do with the fact that the distillation and density curves produced by HYSYS for the 'Blend' do not match up very well with the curves I've input, but none of the calculation options appear to give a better match - in fact, they don't seem to make any difference at all.

 

I really appreciate any advice that anyone could offer here.  Thanking you in advance for your assistance.