An integration study on a complex system of several sour oil and gas-condensate fields based in the south of Oman has been conducted. Sour components are removed from the sales gas stream with the resultant concentrated acid gas being reinjected into the reservoirs. Acid gas is highly miscible and improves ultimate recovery from the reservoir. Hence it is imperative to model the separation and injection of this acid gas accurately. The system is further complicated in that there are two surface plants with different reservoirs flowing into them leading to mixing of fluids. Tracking these fluids with time requires a completely integrated model. To this end subsurface reservoir simulation models, the pipeline production and injection networks and the surface facilities have been linked in a closed loop.
The objective of the model is for long term forecasting and development optimisation. It is also a useful diagnostic tool in debottlenecking the system and identifying areas of process improvement. Such large scale detailed complex integration studies can be very time consuming. Getting all the correct data from the respective stakeholders, overcoming software limitations, troubleshooting and optimizing various elements within the integrated model all make for an arduous task. The final result though is a model with all the working elements of the system that stakeholders can modify and interrogate on the whole to better plan and optimize the cluster development from both a sub-surface and surface perspective.