POTENTIAL ASSESSMENT OF THE URBAN GEOTHERMAL FIELD, BEIJING, CHINA

Abstract

The Urban Geothermal Field in the City of Beijing, located in the central part of the city, has had more than 30 years of production history. Long-term production has caused remarkable drawdown of reservoir pressure in the southern part of the geothermal field where most of the geothermal wells and geothermal production are concentrated. Volumetric method was used to calculate the geothermal storage, and the result shows that the heat and water storage is 202.50?1018J and 2,079.55 million m3 respectively. Through lumped fit modeling, a two-tank open model was found out to be able to well-simulate the production history of the south part of Urban Geothermal Field. The model was used to predict the water level change of the geothermal reservoir, and the result shows that if the annual production could be controlled within 2 million m3/a, the water level would not go further down. This may indicate that the annual recharge of the geothermal reservoir is about 2 million m3/a at the present situation of water level. If the production increases, the water level will go further down, and the recharge of the reservoir will increase accordingly till a balance between the production and recharge has been reached. According to the lumped parameter model, if the production in the south part of the geothermal field is controlled to be around 6 million m3/a, the water level lowering will be acceptable for the coming 20 years. This should be the upper limit of the annual production for the south part of the geothermal field. For the whole geothermal field, the production should not be more than 8 million m3/a.