Professionally I work at BPT and focus on creating value adding App for Process Simulation. You can find more info on those on the BPT website. Below are posts that should help HYSYS, PetroSIM and UNISIM users alike in their day to day challenges to produce accurate yet fast models efficiently.

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Saturday, 31 January 2015

Is your modelling as efficient as it could be?

I am pretty sure the answer is: "No", but, that doesn't mean you can't something about it!

When looking at modelling efficiency, there are three areas to consider:

  • The building of the model
  • The execution of the model
  • Getting the data you need out of the model

Being properly trained in the use of HYSYS is of course an important factor in all three areas. However, even a skilled HYSYS user will end up with a workflow that has many opportunities for improvement. I estimate that the total time required to build, run and extract data could be reduced by more than 75%.

In the area of building and executing a model, there are often instances where you need to create what you really need by putting together multiple existing blocks and one or more spreadsheets. This obviously makes the building less efficient. On top of that, these things make the quality assurance of the model a bit of a nightmare and the added complexity also makes the model prone to input errors.  All of the above will not only affect build time, but also execution time. If you have to spend time validating the model of a colleague, that counts as added execution time. If you have to rerun a calculation because of a typo, classify it where you want, but it will add a lot to overall modelling time.

In the area of data extraction, lots of possibilities already exist in HYSYS. But when it comes to extracting large amounts of data for multiple cases, there is no great solution just using the available HYSYS tools. So you end up doing a lot manual steps. That will probably a sequence of steps that include copying and pasting or exporting and opening and closing cases.  Even though a step may seem to be safe from error, it usually isn't. Copy/Paste is the prime example, you may have selected only part of the data or you may have pasted it one cell to high or too low. These things easily go unnoticed until later.

BPT have created a number of tools that address the above issues (and I had a serious hand in the making). If you want more info, have a look at I'll discuss three examples to illustrate the sort of things to expect.

Consider modelling a compressor with performance curves. How long will it take you to obtain the data from the compressor vendor? And when you get the data, there is 95% chance you'll get them as a graphic. With BPT-CODES, you'd get curves in minutes and they'd immediately be inside your HYSYS compressor. With a couple more minutes you would match that curve to the vendor curve. So, something that would otherwise take you 2 hours (assuming have the vendor data ready!) will only take 15 minutes.

A second example is more specific to the oil&gas industry. Consider you received several fluid compositions with the usual added information that you should be looking at obtaining a GOR of X, a water cut of Y and a stock tank oil flow rate of Z. Moreover, you need to model the plant over the life time of the field, so the X, Y, Z will vary for all cases. The traditional approach is to install a subflowsheet for each feed and replicate the GOR calculation process in each subflowsheet. To get the correct results, you'll most likely need a couple of adjust operations per subflowsheet and at least one spreadsheet. Then, to make things manageable, you will need another spreadsheet in the min flowsheet to bring everything together. BPT-MWF reduces all of that to a single unit operation, it even includes the manifolding to send combinations of fluids to multiple trains if needed. Once the unit is set up, there is just one view in the unit op that needs changing as you change the values of GOR, water cur and oil flow. As everything is in a single unit op, the downstream flowsheet will only be kicked off once all feed preparation calculations are done. With the traditional approach, it will take a serious effort to make sure this doesn't happen. The gain in build time is massive and unless you put a real effort in sequencing the calculations, the solution time with MWF easily be below 20% of the traditional case.

As a third example, consider that your are finished building your model and you have checked that it will properly model the various cases that need to be studied. How do you extract the HYSYS results for all cases such that you can determine the design conditions for all your equipment? BPT developed BPT-EXT, an Excel add-on with two important features:
  • The case study tool will save a separate HYSYS file for each case. So, if during the data extraction you need some extra data, there is no need to rerun the simulations, only the data extraction.
  • The data extraction tool extracts a wide range of data to Excel. You can get stream data, equipment data, line sizing data, ... The data is extracted in a format that makes it easy to select the proper design conditions for each piece of equipment amongst the result from all cases.
At the time of this posting, the oil price is low. So competition for jobs is fierce, being able to do the job cheaper will increase your chances of getting the job. To be in the best position, spend a little and gain by winning the jobs you would otherwise have lost! And if you were to read this later, when the oil price is high again, it might be easier to spend a little on a toolkit than to quickly find additional engineers to do the jobs.

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