Discussion on evaluation methodology of hydrothermal geothermal reservoir

Geothermal reservoir are the vehicle of geothermal resources and their occurrence as well as the storage mass. Precise description and evaluation of geothermal reservoir serves to be the cornerstone of geothermal resource exploration and exploitation. Based on the principles and basic train of geothermal reservoir evaluation, in this work, the content of geothermal reservoir evaluation was determined and the value range of geothermal reservoir evaluation parameters was discussed in combination with the actual production data of two types of geothermal reservoir in North China: The Neogene Guantao Formation sandstone pore-type geothermal reservoir, and the Cambrian-Ordovician and Middle Proterozoic Jixian carbonate karst-fissure-type geothermal reservoir. An evaluation method for the sandstone pore-type and the carbonate karstfissure-type geothermal reservoir is finally established based on the analysis of the production data, i.e. the values of geothermal reservoir temperature, geothermal fluid production, reinjection, physical properties and other parameters are assigned, and the geometric average value of the assigned values for the above-mentioned parameters is taken as the overall evaluation index of geothermal reservoir. From large to small, this index categorizes geothermal reservoir into three grades: I, II and III, which corresponds to advantageous, moderate advantageous and disadvantageous geothermal reservoir respectively. The geothermal reservoir of the same grade are further classified in light of the index value, thus realizing the comprehensive evaluation of geothermal reservoir.