Application of Chemical Engineering Methods to Integrated Production Modelling

The main objective was to apply advanced methods, first developed for the solution of chemical engineering processes, to petroleum engineering problems; specifically the modelling of hydrocarbon flows from underground reservoirs, through wells, flowlines, risers and processing equipment. This is, essentially, a pressure bounded problem where the reservoir pressure and the reception facilities pressure are fixed, at a given instant in time, and the production rate adjusts accordingly. The equation oriented approach was used as the basis of the numerical algorithms. The entire process, from reservoir to end-user, can be viewed as a digraph where the physical equipment items form the nodes and edges, collectively referred to as objects. Each object is described by a set of equations - founded on the conservation principles - with variables shared between object equations depending on the connectivity of the digraph. The algorithms assemble the entire set of equations into a large sparse matrix which is then reduced to block triangular form for solution. The paper gives an overview of this methodology. The results of two integrated production modelling (IPM) case studies are summarised, highlighting the important predictions and describing how these are used to resolve key techno-economic decisions in oil and gas design. It is concluded that the application of these methods, first developed for the solution of chemical processes, provides an efficient approach for the solution of petroleum engineering problems, in this case IPM, resulting in highly accurate and physically representative predictions generated in practical engineering timeframes.