Value added by Xodus

Xodus has a history of repeated work with clients and facilities. Our in-depth understanding of how particular clients or facilities operate, combined with our technology enabled solutions, meant we were able to provide our client with realistic and achievable solutions. Our novel PYTHON based optimisation techniques, in combination with our operation expertise, resulted in a production increase and reduced carbon intensity for our client. 

Background

Xodus has developed optimisation techniques whereby PYTHON code will run a range of scenarios and case studies to understand the operational design space and home in on an optimum. Our techniques can call on a number of different simulation packages (such as HYSYS) and integrate them with bespoke calculations or spreadsheet data.  

We were able to use this technique to assess the full compressor train and cooling system operation for our Clients’ platform. The compressor motors and cooling system were “maxed out” and we were tasked with finding a better operating point to reduce overall energy consumption and free up capacity for additional gas lift flowrate.  

Inbuilt HYSYS Optimiser Issues 

Aspen HYSYS in-built Optimiser is quite rigid in its set-up and in our experience has proven difficult to use on larger models due to their complex nature. If solution errors occur, the inbuilt optimisation stops and you are left with no results.  

Our Solution 

The process model is treated like a “Black-Box” function as the form of the target function is unknown.  

Use external software to enter operating parameters temperatures, pressures, etc. into HYSYS.  

HYSYS generates an answer e.g. Compressor Duty (kW).  The optimiser then uses these answers that come back to home in on an optimum operating solution.   

We are able to “trap” errors so that if a simulation case fails, the results from that case are rejected and the optimiser continues onto the next case. This allows the full design space to be investigated even when, in some cases, the Process model fails to converge.  

Scope 

Optimise the current compressor operation, reduce energy usage and free up capacity.  

Certain operational constrains exist such as 

• Inlet pressure 
• Export pressure 
• Total Cooling Water flowrate 
• Cooling water supply temperature 

Benchmark the existing HYSYS process model for the Gas Processing topsides, complete with compressor curves, recycle / anti-surge, adjust functions, condensate return etc..   

Simulation optimisation performance  

Initialisation points = 20 (Design Space Exploration, optimiser educates itself on the design space)  

Total Iterations = 60 to home in on an optimum   

Benefit 

• Capacity/production increase 
• No major Plant modifications required 
• 8% reduction in energy consumption for same throughput 
• Same energy input = lower carbon intensity 
• Achieved 5% greater throughput for the same energy