A report in BP’s Frontiers magazine* provides insights from BP chemicals units that might interest the digital oilfield community. The report by Michelle Brown describes how optimization in a chemical plant happens at different granularities and time scales. BP deploys the AspenPlus process simulator from AspenTech to simulate its processes, leveraging ‘equation-oriented modeling’ to simulate the entire plant. The model-based optimization is performed several times a day.
The technique was first tried in 2000 at BP’s Decatur chemicals plant in Alabama and is now in use worldwide. ‘Significant’ commercial gains from the technique are described as ‘too commercially sensitive to report!’ A layered approach to optimization has been used. The foundation is the distributed control system (DCS) operating at a high granularity with control of individual equipment set points. The second tier concerns ‘multi-variable control,’ using AspenTech’s DMCplus. Here dynamic, non steady state optimization works on equipment groups at a time scale of minutes. The top tier optimizes steady state operations at a timescale of hours. Once a solution has been obtained, DMCplus moves the key variables throughout the plant towards their new targets. The approach has enabled BP to push process units to ‘safe operating conditions that previously were thought to be technically impossible.’
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