| Abstract |
Geothermal reservoir analysis and the prediction of geothermal production behavior are important considerations for reservoir management. It is necessary to combine surface exploration results and well data obtained from various surveys in order to form an integrated three-dimensional model of a geothermal reservoir. Exploration data has been collected by many researchers in the fields of geology, geophysics, chemistry, drilling, logging, reservoir engineering, etc. over a long period of time. Specialists in geology and reservoir engineering must make a great effort to find essential information for geothermal reservoir modeling from the tremendous amount of data presented in various formats. The geothermal database system GEOBASE (Sato et al., 1995) was developed to assist in reservoir management. GEOBASE includes well data (drilling, logging etc.), and geological, geophysical, topographic, production/injection, and image data etc. GEOBASE works on many platforms including PCís (Windows95/98/NT), UNIX (HP, SUN workstation) and client server systems. Based on ORACLE7.3, client server systems are easily constructed using LAN/WAN networks on PC and UNIX machines. The system also has a functional post-processor for numerical reservoir simulations. This system operates by clicking on a data keyword and then immediately drawing the selected data by using X-Y line graph options or two / three-dimensional mapping options. Although geochemistry is one of the important factors in understanding a reservoir, GEOBASE previously did not have functions to access geochemical data. Recently, such function as the geochemistry table and display functions were added to GEOBASE. This paper describes a summary of GEOBASE, the addition of the geochemical functionality, and the application of GEOBASE to the Yanaizu-Nishiyama geothermal field in northern Japan. The efficiency of handling geochemical data was improved by upgrading the software. Newly developed graphic routines include 1) Ternary diagrams, 2) Hexadiagrams, 3) X-Y plots, 4) Time series displays, and 5) Shoeller plots. Furthermore, a geochemical thermometer computing facility was added to estimate reservoir temperatures. The database functions were applied to the Yanaizu- Nishiyama geothermal field. Comparison and correlation of chemical elements from different wells was accomplished by using the graphing functions. These indicated the distribution of the chemical elements in each well. The reservoir temperature was calculated by appropriate use of a silica geochemistry thermometer . |