With today's turmoil in the oil and gas industry, assessing the costs of replacing domestic reserves has become increasingly complex. The recent changes in drilling costs, oil and gas prices, and tax laws have created a premium for quick and clear analysis of this complex problem. This paper presents the methodology, design, and implementation of a microcomputer-based system for assessing oil and gas reserves replacement. The main components of this model are a supply analysis model, a capital formation model, a reserve additions and production forecasting model and an integrating model that relates each of the components to overall domestic oil and gas supply and demand. Finally, the paper discusses several possible scenarios for future oil and gas reserves replacement.