Computer Optimization of Large Gas Reservoirs with Complex Gathering Systems

The modeling of large, shallow gas fields, which produce into complex gathering systems was once a difficult and uneconomical task to perform. The optimization of these systems has now become cost efficient through the use of electronic databases and efficient computer modeling software. This paper focuses on the study of a large Hatton shallow gas field in Southwest Saskatchewan, Canada. The field currently has 800 wells (1367 completions) and a complex surface network with substantial line looping and flow splitting. The reservoir is of low permeability and has three isolated productive zones. In 1998, 32 infills were drilled on the basis of adding incremental reserves. Encouraging results led to a desire to further improve the economic performance by infill drilling an additional 260 wells. A model of the surface network and reservoirs was constructed and used to plan facilities modifications upon the tie-in of the 1999 infill wells and to prepare long term forecasts, The study showed that numerical modeling of large, shallow gas properties can be cost effective.