Experimental Study on Renewal of the Reinjection Well

Abstract

In a water-dominated geothermal system, geothermal waste water is returned into the ground at a depth to maintain the reservoir pressure and also to avoid the environmental pollution caused by chemicals contained in the water. However, the decrement of injection capacity of wells occured in the reinjection system. For example, the injection capacity of wells in the Otake and the Hatchobaru fields decreases 20-30 % a year. Therefore, two to three additional wells have to be drilled annually to maintain the total injection capacity in Otake and Hatchobaru. Injectivity decrease of wells is probably caused by the silica scale deposition in a formation near wells. In this paper, a couple of techniques to recover the injectivity of wells were presented.