TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOptimization of natural gas production systems is a challenging problem because of nonlinear pressure-flowrate relationships in wells, facilities and trunklines, a multicommodity network and complex production-sharing contracts. A short-term production-planning model can aid in formulating an operational policy that satisfies contractual rules and customer requirements while simultaneously meeting specified production levels. Such an operational planning model with two components, an infrastructure model and a contractual model, is presented in this work. The infrastructure model is a representation of the physical system that incorporates nonlinear pressure-flowrate relationships for wells and pipelines, multiple qualities of gas in the trunkline network and models of facilities. The contractual model is a mathematical representation of the complex productionsharing contracts, associated operational rules and customer requirements. The model features and requirements are inspired by the Sarawak Gas Production System (SGPS) in East Malaysia. The final formulation is a nonconvex mixedinteger nonlinear program and is solved with GAMS/BARON to global optimality. A hierarchical multi-objective case study is also presented.