Short-term modelling in refinery planning – and why ‘non-linear’ is not necessarily ‘more accurate’

The oil industry was one of the earliest users of linear programming. For many years, the linear approximations and transformations were enough to give adequate results. There were limitations, which were generally recognised, but it was not until the advent of much faster computers in the 1980s that these could be addressed. With ever greater pressures on profitability, and with better and more timely information, it has become possible to consider optimising and implementing solutions over a much shorter time frame than previously. These ‘short-term’ models need to be able to give answers in a short enough time to enable them to be explored and implemented effectively.