This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 188377, “Coupled Multireservoir, Multinetwork Production Optimization of an Onshore Middle Eastern Reservoir With Sour-Gas Reinjection for Miscible EOR,” by Varun Pathak, SPE, Chelsea Palaschak, Anjani Kumar, SPE, and Rob Eastick, Computer Modelling Group, and Ralf Schulz, SPE, and Abdullah Al-Hadhrami, Petroleum Development Oman, prepared for the 2017 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 13–16 November. The paper has not been peer reviewed. Integrated reservoir and production modeling can be beneficial in conducting production forecasting for complex systems consisting of multiple reservoirs, fluid mixing, and complex production networks. In the complete paper, a new, fully coupled implicit tool was used to model an onshore Omani asset with multiple reservoirs, each featuring different fluids and multiple networks. A multifidelity approach was used throughout the modeling work flow, incorporating reservoir- and production-related uncertainty in the forecast and optimization processes. Introduction Petroleum Development Oman operates, in the south of the country, the Southern Sour cluster of high-pressure, highly sour oil fields. These fields are currently produced by what is known as the H Station. A second such facility, R Station, is under construction and will be onstream by 2019. These two facilities will be interlinked and will allow large-scale miscible gasfloods in more than 10 fields. The integrated nature of the production and injection systems is extremely complex and will be unique in terms of its scale and the technology deployed. The project involves tying together multiple reservoirs and separating the reservoir fluids in the surface network, including the handling and separation of sour gas [the asset has a high hydrogen sulfide (H2S) content in reservoir fluids]. The separated acid and sour gases will be compressed at a high pressure and reinjected into the various reservoirs to create miscibility in the oil, thereby increasing its mobility and preventing a rapid decline in reservoir pressures. Because the development is a critical one that requires correct modeling of fluid flow throughout the reservoirs, wells, and facility, the process of integrated production systems modeling (IPSM) becomes important. In the past, for such a project, implementation has been achieved by coupling several specialized tools for different aspects of the IPSM process in an explicit manner. The complete paper discusses the use of a new fully coupled, implicit solver to overcome the challenges faced during conventional IPSM work. Work Flow The work flow for developing the integrated model for the asset can be divided into the following broad but interdependent areas: Reservoir simulation Fluid modeling Well modeling Facilities modeling IPSM solution