GIS Based Geothermal Resource Potential Assessment

For a long time, Fujian Province has lacked fossil resource, and the total reserve of coal resource is small. No oil resource or natural gas resource has been found on land. The utilization of hydropower resource is becoming increasingly saturated. But there are abundant geothermal resource reserved in Fujian province. The total area of geothermal anomalous region is about 77km2, therefore geothermal resources have broad development prospects. Distribution of hot springs present the trend of increasing from north to south, from west to east and from mountain area to littoral area. The proved reserves of geothermal energy in Fujian province is only a fraction of its reserves. Geothermal resource potential still needs further evaluation. To identify the areas of high potential of geothermal resource.This thesis aims to predict the probable undiscovered geothermal systems through investigation of spatial relation between geothermal occurrences and the factors of geology and geophysics. Selecting four different public data, which are epicenter map, lineament map, Bouger gravity anomaly and magnetic anomaly maps, as evidence factors by analyzing the geology and geophysics datasets. In order to extract the necessary information for each map layer, the initial public data is converted to a synthetic data which are directly used in the spatial analysis. Epicenter, lineament, Bouger gravity anomaly and magnetic anomaly datasets are utilized to extract four evidence maps; Gutenberg-Richter b-value, distance to lineaments, distance to major grabens and magnetic anomaly respectively. The weighted information model is built by combining weights of evidence and information method. Weighted information model can determine the weight of each evidence factor objectively and it is simple in theory, easy in operation.Using weighted information and fuzzy logic model to calculate the information value and fuzzy membership of four evidence maps respectively. Geothermal potential favorability maps are produced by overlaying the four evidence maps. Evaluation of differences and accuracy of the two models has been made to select the model which has the best effect. This research found that weighted information model has better effect than fuzzy logic model. The findings show that geothermal high potential areas locate in Fuzhou city, Zhangzhou city, Longyan city, western Xiamen city and southern Gutian county. Since the 1980 s, Fuzhou and Zhangzhou began to exploit and utilize geothermal energy. While geothermal energy in Gutian county has never been explored and it belongs to high potential region. This thesis is able to provide the guide of early stage of geothermal exploration and it will help to optimize geothermal drilling location and to reduce the risk of geothermal development.The assessment of geothermal resource potential in China was made by using weighted information model which achieved good results in evaluation of geothermal resources in Fujian province. Selecting six different public data, which are epicenter map, lineament map, Bouger gravity anomaly, magnetic anomaly maps, heat flux and geothermal gradient, as evidence factors and convert them into the corresponding evidence layers. Weight of evidence method is used to establish spatial association between the known hot springs and evidence layers, and the weight of each evidence factor was calculated. Using information model to calculate the information value of each evidence layer. Information of evidence layer multiplied by corresponding weight, and the geothermal resource potential map of China was produced. The result shows that Xian city, southern Yuncheng city, Zhongning county, Suzhou city, Yingkou city, Harbin and other areas have high geothermal potential. It is meaningful to do exploration and determine its development and utilization value.