Geothermal resource assessment of the NW-Sabalan field, Iran, through well testing

Abstract

The assessment of the properties and capacity of geothermal resources involves various kinds of logging tests, data interpretation, monitoring and modelling. This ranges from the analysis of data collected during the warm-up and testing of single wells to the simulation of the response of the geothermal reservoir to utilization over years or even decades. This work presents a comprehensive review of the theoretical background and methodology used in analysing well-test, temperatureand pressure logging data from the Sabalan geothermal wells as well as a review of the methods generally used for geothermal reservoir pressure response modelling. These methods are then applied to data from the Sabalan geothermal field in northwest Iran. The purpose of the well test analysis is to identify the type of reservoir involved and to determine the parameters of the reservoir quantitatively. Data from three Sabalan wells, NWS-5D, NWS-6D and NWS-7D, was analyzed by the application of the computer software Well Tester developed by ÍSOR - Iceland GeoSurvey. This incorporates modern well-test analysis techniques such as derivative analysis and computer software simulation. Lumped parameter models have been used extensively to simulate data on pressure changes in geothermal systems in Iceland. The lump fit model analysis of injection test data from well RN-23 in Reykjanes, Iceland was used to estimate the permeability of the Sabalan field, and those results were then compared with the results from the Well Tester analysis. The volumetric method using the Monte Carlo simulation was applied to estimate the geothermal power potential of the Sabalan geothermal field given three scenarios of 25, 50 and 100 years duration.