Linking reservoir and surface simulators: how to improve the coupled solutions

Abstract

Abstract A full analysis of the problem of coupling two independent industrial simulators, a reservoir simulator and a steady-state network simulator, has been performed. A classification of the industrial needs has been obtained from the examination of several actual cases studies (fields at development, or production stage, requiring performance optimization through short to long term forecasts). Several coupling configurations and specific requirements, for both reservoir and surface software, have been identified to satisfy the industrial needs. Various commercial solutions have been screened to evaluate the adequacy between the software functional capacities and the identified configurations and requirements. Limitations have been brought to evidence. The paper, issued from the work of a multidisciplinary team, presents the details of each step described briefly here above. Practical solutions for improving coupled solutions, i.e. to go beyond the identified limitations and to reduce the elapsed times of the coupled simulations, are provided. An improved mutual understanding of the needs of each discipline concerned by the integration of reservoir and surface has been experienced as essential for a successful integrated approach of field optimization. It is intended in the paper to contribute to a better communication between the various upstream petroleum skills: reservoir, production, surface and process engineers. Introduction It has been well recognized that coupling surface network and reservoir simulations is a critical technology for field development/optimization studies, particularly in the deep offshore area, or when many wells share the same surface network. Various methods have been proposed to solve in a coupled way the reservoir model and the surface model, for enabling time savings (by avoiding multiple information returns between reservoir and surface engineers), and for an improved reliability of the global solution. Since the pioneer work of Dempsey1 in 1971, the development of a coupled resolution of reservoir and surface models, firstly for application in gas field development and production optimization, has been extended some years after by Chevron for oil field developments2–4 in offshore area. Since then, several other major companies have developed their proprietary integrated reservoir/surface solution5–8, and/or have integrated their proprietary reservoir simulator with a commercial network software9,10. To our knowledge, the only reported experience of a compositional integration is from Litvak11–13. In these integrated solutions, the two programs are merged in a unique one (solution named ‘fully integrated solution’ in what follows) ; such a procedure has also been used by Trick14 for integrating two commercial software Forgas and Imex. Another integration method, enabled by the emergence of message passing libraries as PVM (Parallel Virtual Machine), is to couple independent programs through an interface. In the coupling development of two commercial simulators, Eclipse as reservoir simulator, with Netopt (Hepguler15) or with Forgas (Trick16), the interface which controls the software communication has been implemented in the surface simulator, the reservoir simulator being a slave process. The coupling location, retained for linking two independent simulators, is either at the bottom hole (Trick), or at the reservoir level with an Inflow Performance Relationship (IPR) represented in both reservoir and surface models (Hepguler).