The objective of GSAM development is to create a comprehensive, non-proprietary, microcomputer model of the North American natural gas system. GSAM explicitly evaluates the key components of the system, including the resource base, exploration and development practices, extraction technology performance and costs, project economics, transportation costs and restrictions, storage, and end-use. The primary focus is the detailed characterization of the resource base at the reservoir and sub-reservoir level. This disaggregation allows direct evaluation of alternative extraction technologies based on discretely estimated, individual well productivity, required investments, and associated operating costs. GSAM`s design allows users to evaluate complex interactions of current and alternative future technology and policy initiatives as they directly impact the gas market. Key activities completed during the past year include: conducted a comparative analysis of commercial reservoir databases; licensed and screened NRG Associates Significant Oil and Gas Fields of the US reservoir database; developed and tested reduced form reservoir model production type curves; fully developed database structures for use in GSAM and linkage to other systems; developed a methodology for the exploration module; collected and updated upstream capital and operating cost parameters; completed initial integration of downstream/demand models; presented research results at METC Contractor Review Meeting; conducted other briefings for METC managers, including initiation of the GSAM Environmental Module; and delivered draft topical reports on technology review, model review, and GSAM methodology.