Optimization and transformation of water treatment technology for surface water reinjection into geothermal reservoir in Dongli Lake area of Tianjin

Abstract

Tianjin is one of the areas with higher geothermal resources development and utilization in China. In 2013, the first surface water reinjection test base in China was established in Dongli Lake area. However, some problems had occurred during the operation of surface water reinjection, which affected the effect of surface water reinjection. Aiming at the problems during operation, we optimized and transformed the water treatment process of surface water reinjection, so that the reinjection system could operate stably. This will supply the thermal reservoir effectively and alleviate the decline of thermal reservoir pressure, and then geothermal resources will be developed and utilized sustainably. After the transformation and upgrading of surface water treatment process, the maximum reinjection volume was 150 m3/h, it could increase the production of geothermal resources to 200000 m3/a, and increased the heating area of geothermal to 150000 m2/a. The surface water treatment process will reduce the emission of carbon dioxide, sulfur dioxide, nitrogen oxides, coal ash and other pollutants, saving 879100 yuan of environmental treatment fee (environmental protection tax) and 2.6 million yuan of resource tax every year. And the calculated operation cost was about 1.80 ∼ 2.26 yuan/m3. It will play an exemplary role in the stable operation of surface water reinjection, provide new ideas for surface water reinjection and the protection of geothermal resources, and provide technical support for the realization of the double carbon goal.