| Title | A Field-Wide Numerical Simulation Model of the Geysers Geothermal Field, California, USA |
|---|---|
| Authors | Anthony J. Menzies and Minh Pham |
| Year | 1995 |
| Conference | World Geothermal Congress |
| Keywords | The Geysers, case histories, simulation, TETRAD, forecast |
| Abstract | The Geysers geothermal field is the largest developed geothermal system in the world. The total installed capacity is presently 2,056 MW although actual production in early 1994 was estimated to be only 1.200 The inability to produce at higher generation levels is due to the significant pressure decline that occurred within the reservoir, particularly since the 1980's. In 1992, a comprehensive field-wide numerical simulation model of The Geysers field was completed, based on drilling, well-test and production data provided by four of the five major field operators. The numerical simulation model was originally developed by based primarily on data from the (U-N-T) lease areas, and was extended in this study to incorporate data fiom the other operators. The expanded model was successfully calibrated by matching the responses of individual observation wells and changes in fieldwide isobaric maps to 30 years of production history. Forecast runs were conducted using the calibrated model to calculate the reservoir response for two possible production scenarios: maintaining wellhead pressures constant at their 1991 levels and reducing wellhead pressure by up to 40 psi (0.28 over next five years. With the reduction in wellhead pressure, an additional 1 million (453 tonshour) of steam can be produced over the next ten years; equivalent to 55 additional power production. However, overall field production will continue to decline from the present level of approximately 20 million (9,100 tonshour) to 8.5 million (3,850 by the year 2014; equivalent to a reduction in overall power production from the present level of 1,200 to 47.5 |