| Title | Sustainability of a Geothermal Reservoir |
|---|---|
| Authors | Abdurrahman Satman |
| Year | 2010 |
| Conference | World Geothermal Congress |
| Keywords | Sustainability, geothermal field, analytical approach |
| Abstract | Most geothermal fields are exploited at a rate faster than the energy is replaced by the pre-production flow. Thus fields cannot be produced at a rate corresponding to the installed capacity of their heating facilities or power plants on a continuous basis, forever. In this sense they are not sustainable. However if after a time the field is shut-in the natural energy flow will slowly replenish the geothermal system and it will again be available for production. Therefore when operated on a periodic basis, with production followed by recovery, geothermal systems are renewable and sustainable. The difference between renewability and sustainability is a matter of time scale. This paper addresses renewability and sustainability concept by considering a lumped parameter model with simple analytical solutions. An analytical approach is presented to analyze the parameters involved to estimate the time that a geothermal field takes to fully recover to its original state after shut-down at some production time. A simplified lumped-parameter type of an approach to model the temperature behavior of a relatively low-temperature single liquid-phase geothermal reservoir is discussed here. New analytical equations and correlations are presented to investigate the pressure and temperature behavior of geothermal systems. Emphasis is given to understand the characteristics of temperature recovery following some production period. The time to reach a recovery depends on many factors as discussed in the paper. Primarily it depends on the production period. However, the natural recharge and reinjection conditions considerably affect the recovery. |