| Title | Assessment of Reinjection Trials in Kizildere Geothermal Field |
|---|---|
| Authors | Abdurrahman Satman, Umran Serpen and Ibrahim Metin Mihcakan |
| Year | 2000 |
| Conference | World Geothermal Congress |
| Keywords | geothermal, Kizildere Field, reinjection tests, heat model, environmental protection |
| Abstract | Kizildere Geothermal Field discovered in 1968 produces hot water and saturated steam from two hydraulically connected reservoirs. During fourteen years of operation of the power plant in the field, the production of about 80 million tons of water caused approximately 1 MPa drop in reservoir pressure. The estimated recharge rate of the field is about 550 tons of water per hour and is insufficient for maintaining the reservoir pressure and desired power generation. Produced hot water has been discharged as waste into nearby Buyuk Menderes River from where the water is used for agricultural irrigation. The adverse effects of high boron content of geothermal water on agricultural activity has put a limitation on both the discharge and the production rates, and thus on power generation capacity. Reinjection of wastewater back into the reservoir seems to be the only viable method for both disposal and reservoir pressure maintenance. Two reinjection pilot tests have been conducted to study the effects of reinjection on reservoir performance and to measure the injectivity index. The first test lasted for 29 weeks in 1976. The cooling effect of reinjection was felt at the bottom of the observation well. A heat flow model describing the non-isothermal fluid flow in naturally fractured reservoirs is applied and the temperature behavior in the observation well is predicted successfully. A sudden increase in injectivity after an initial decline in injectivity and a similar trend observed in pressure is attributed to the possible fracturing of the formation. The second test lasted for 40 days in 1995. Decline in injectivity is related to the possible plugging by scale deposition in the injector. Some change in the chloride content but no change in the temperature of the produced water is observed. The rise in water levels in observation wells gave good clues about the flow mechanism of the reservoir. |