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Always Question Your Dynamic Simulation

An Interview With Craig MacKay of the Xodus Group

I had a chance to sit down with Craig MacKay, a process dynamics team lead at Xodus Group. Craig has 16 years of experience in dynamic analysis and operator training. Dynamic modeling can be intimidating for new users, but it is an extremely powerful tool. In this interview, Craig discusses some of the tricks involved in getting it right, as well as the value and the future of dynamic modeling. 


Q: What do you say when people ask you what you do?

A: I suppose it depends upon their background. If they aren’t engineers, I say, “I’m an engineer within the oil and gas industry, and basically I make computer games for engineers.” If they have an engineering background, then I will tell them I work in process dynamics. This generally leads to further detailed discussions, as it tends to be quite a specialized field.

Q: How did you get started in dynamic modeling? What was your first project?

A: When I first started in the oil and gas industry it was for a company that developed training simulators for operators, utilizing Aspen HYSYS® Dynamics with a front-end GUI. The company shared an office with a consultancy, and I ended up working with them quite a bit, utilizing dynamics for process optimization and troubleshooting.

One of my first studies at Xodus was a de-bottlenecking and uptime enhancement study on a large offshore export compression facility. A desktop review was carried out, and it was discovered that one of the major issues was that the facilities were originally designed as two100-percent machines. However, they were operating as two 50-percent machines. This required a significant level of manual operation, so a two-phased approach was adopted.:

  • Phase 1 installed a custom-developed monitoring system that gave greater visibility to the operator on where the compressor was operating, which allowed better manual operation.
  • Phase 2 involved developing and testing a new load-sharing control scheme within Aspen HYSYS Dynamics. This scheme was then incorporated within the DCS offshore.

Within the first month of the new control scheme going online, the system was able to prevent two compression train trips, which in turn covered the full cost of the study. 

Q: What do you tell new engineers if they are just coming into dynamic modeling?

A: Luckily, when I first entered dynamic modeling, I had a great boss who taught me valuable tips that I use to this day.

  • Garbage in equals garbage out. Make sure that all the required data is collected, and only make assumptions where necessary. Always check the sensitivity and validity of these assumptions.
  • Don’t just trust the simulator. Before you run a case study, think about what you expect the system response to be. If the model prediction differs from this, then investigate to understand why.
  • Experience real-world troubleshooting. I was lucky enough to spend a lot of my earlier career on operating assets, which gave me a good understanding of real-world situations. Take opportunities to get real-world experience of transient operations to build a solid understanding.

Q: How does Xodus Group drive increased value for their clients?

A: Client satisfaction is key for us to retain clients and remain competitive. Increasing project efficiency and the accuracy of answers is one way to do that. Another is through continually challenging existing practices and looking for alternative solutions.

Xodus Group has an integrated approach to dynamic modeling. We make sure that we get the right people involved, both from the client and the experts on our side. We have created internal processes and templates at Xodus to reduce time frames and remove miscommunication. For example, we have implemented model acceptance test (MAT) reports so we can agree with the client on the model build before we start to assess any case studies.

With XPLORE, an online app which collects real time process data and makes accurate production predictions for the near future, we have helped clients use dynamic models in the background of process monitoring applications. For instance, if they want to track the fluid density within a pipeline to prepare the downstream facility, they can use XPLORE to model pipeline conditions in real-time.

Q: What excites you about dynamic modeling and the future of dynamic modeling?

A: Aspen HYSYS Dynamics is the perfect environment for dynamic modeling, and I like to push it to its limits.  What excites me is the important directions of improvement in Aspen HYSYS Dynamics, specifically the specialized tools for advanced analysis.

Much work has been done to increase the depth and customizability of analyses. I had the opportunity to test the new BLOWDOWN™ Technology when it was first released. I see this technology greatly expanding the work done in this area through the industry.

This advancement will help us expand our focus from safety, operability and controllability of systems. The tools allow us to be confident in our answers and less conservative with our analysis, and therefore more concerned about costs.


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  • one year ago

    Hello! The Xodus Group offers the app XPLORE for production monitoring. The Xodus Group is an AspenTech partner and they have presented the value of this solution through customer success stories at several of our OPTIMIZE user conferences. The solution uses Aspen HYSYS and Aspen HYSYS Dynamics. To learn more, please go here: http://www.xodusgroup.com/tools/xplore-production-monitoring

  • one year ago