Reservoir simulation is traditionally one of the main tools used for reservoir management plan definition. The situation gets more complex when the surface network plays an important role in the production profiles definition and behaviours, at least for part of the field life, as a bottleneck. New products have just been commercialised (PipeSim™, GAP™, Resolve™, R2SL™) but coupling complex surface network representation with reservoir simulators still remains at its beginnings. This paper describes a multi stage approach to model the impact of the multiphase pumps constraints of a Northern North Sea Field on the production profiles. From the simplest representation (GAP™ model plus look-up tables) to the most integrated, the implications of this model on the field development plan will be presented and the key issues of such a coupling discussed.
Understanding behaviours of reservoirs, wells and surface networks, and forecasting the production profile over the entire field life have always been challenging tasks for the petroleum industry. They are usually addressed using separate simulators for every node of the production chain.
In this situation, interactions and influence of upstream or downstream events on the results of each model are only approximately accounted for. Reservoir simulators model the production from sandface to the wellhead only through the use of Vertical Lift Performance (VLP) tables and have a limited modelling of the surface piping. So production network effects on the behaviour of the overall system are not fully acknowledged. This may have a direct impact on the evaluation of the production targets that will actually be achieved. On the other hand, production network simulators typically use surface network model analysis that fully accounts for those effects but can only model the reservoir with a simple «inflow» model: material balance, decline curves or even fixed productivity index.
However, for the last few years, significant developments have been implemented to allow the construction of fully integrated models. Various types of controller for coupling reservoir simulation and surface facility network have been introduced in the literature. Since end 2004, the research tools have been finally proposed on the market, launching a new era for the simulation of the production chain from reservoir to surface.