Algorithm for Optimal Well Placement in Geothermal Systems Based on TOUGH2 Models
Author: Dagur Helgason
Year: 2017
Supervisors: Ágúst Valfells & Egill Júlíusson
Abstract
In a world of ever increasing use of renewables geothermal has lagged behind and has seen little growth compared to other renewables due in part to its high capital cost. Geothermal wells account for about a third of the capital cost and it is therefore important to ensure the highest possible success rate and value creation from these wells. In order to address this, an algorithm has been developed that utilizes a numerical TOUGH2 model of a geothermal system to evaluate the optimal well placement based on a net present value estimation. The algorithm was tested using a hypothetical model and found the optimal wells to be in the hottest parts of the model at depth, for deliverability wells, and in the upper heat zone, for wellbore file wells. The algorithm was also subjected to a sensitivity and processing time analysis with the hypothetical model as an input model. The sensitivity analysis showed that the models results were most sensitive to changes in reinjection enthalpy, discount rate and the power plants thermal efficiency. The processing time analysis showed that the algorithm can potentially be run in a reasonable enough time to serve as a tool for decision making.