The high temperatures existing within a geothermal well preclude the use of most logging instrumentation which is necessary to study the wellbore and surrounding rock matrix. Possible solutions to this problem include cooling the wellbore and the surrounding rock by circulating fluid in the wellbore and by injecting fluid directly into the rock matrix. The latter method, however, is not preferred since it contdnates the formotion a considerable distance from the wellbore. The potential cooling effects of both these methods are investigated using the collprter code, GBOTEW2. which simulates heat transfer from the wellbore to the surrounding rock formation. Rro different wells from the Salton Sea Known Geothermnl Resource Area (KGIW are simulated. The first is a shallow, not well having a depth of 1400 m and 8 bottom-hole temperature of 330oC. The second is a deep well of depth greater than 3000 m and a bottom hole temperature of 380OC. Circulation of several different fluids for one day at flow rates of 16. 32, 47, and 63 11s. followed by a shut-in period, is simulated to study the effect of different fluid properties and flow rates. Also, the temperatures obtained by using two different flow rates, each for one day, are compared to the temperatures found when using only the lower flow rates. Finally, the temperature recovery in the wellbore is investigated when fluid injection occurs at the bottom of the hole. Heat conduction is the only heat transfer mechanism considered to warm the wellbore. Following steady-rate circulation. the wellbore temperatures were found to warm quickly after shut-in, approaching the undisturbed formation temperature within one day. Temperature recovery had a half-life on the order of six hours. Furthermore. the use of a higher initial flow rate did not significantly reduce the temperatures below those for the lower flow rate alone. Injecting fluid a relatively short distance into the formation was found to substantially decrease the rate of warming in the wellbore following injection.

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