Estimation of Sustainable Production Limit by Using Lumped Parameter and USGS Hydrotherm Simulation

Author: Yagiz Bostanci
Year: 2018
Supervisor: Einar Jón Ásbjörnsson

Abstract

Sustainable development studies have become a subject that has been frequently addressed in recent decades. It is obvious that this term will continue to be popular over the next following decades in a number of studies. Many modeling methods have been developed to maintain the production and investigate the nature of geothermal reservoir. Objective of this thesis can be summarized as define sustainable production limits by using time and cost-effective models for given geothermal reservoirs. Lumpfit V3 software which based on nonlinear iterative least squares technique and developed by ISOR has been used to simulate reservoir conditions. USGS Hydrotherm simulations were created using Lumpfit V3 results. The purpose of using software of USGS Hydrotherm is to create the reservoir geometry which is ignored in the first step and to analyze the response of the reservoir according to the parameters to be applied. This two software were used to investigate the sustainable limit of Munadarnes low temperature geothermal reservoir. Water level changes, production rates and pressure data for the MN-08 well between 2007 and 2017 were provided for this thesis by Reykjavik Energy. All the lumped tank models have been simulated. Best fitting model and properties of reservoir were found in two tank open model. However, fit that obtained 3 tank closed and 3 tank open models were quite similar the fit that obtained from 2 tanks open model. For this reason, 56 different scenarios were simulated to estimate sustainable production limit of Munadarnes reservoir. Based on Lumpfit V3 result estimated the total area that covered by confined reservoir is 16.1 km2 with average permeability of 1.6 mDarcy. Reservoir modeling of the Munadernes geothermal resource was carried out using software of USGS Hydrotherm and 4 different production limits were simulated for a total of 32 years with injection and without injection. Based on ground-water flow and heat transport results which simulated by USGS Hydrotherm, there is no significant temperature change was observed in production well at the end of the simulation period. Overall results showed that changes in water levels have a significant impact on the determination of the sustainable limit of the Munadarnes low temperature geothermal reservoir.