Technical and Economic Uncertainties Assessment to Derive a High Enthalpy Geothermal Project Optimal Development Scheme

Abstract

Like in the oil and gas business or gas storage industry, getting reliable production and temperature forecasts is a key aspect of any geothermal project. The field assessment phase prior to investment sanction is characterized by relatively large uncertainties at the time important decisions have to be made. It is, for instance, crucial to select an appropriate development strategy (e.g. number of producers, well architecture or re-injection pattern) to obtain optimal cumulative energy production whilst ensuring good profitability of the project. Reservoir evaluation as well as economic uncertainties and quantification of their impact on the project reserves and economics are needed before the field development concept selection. The proposed application case is about high enthalpy geothermal projects for electricity generation through ORC cycle, like the ones which might be found in Germany, Italy, Turkey or the United States for instance. A fully integrated numerical modeling of the (well+pump+ORC) system was developed including technical as well as economic inputs, ending up with a business model delivering typical economic figures for management decision making. Capitalizing on existing workflows from the oil and gas business to assess those subsurface and economic uncertainties, an optimal development scheme is then derived through an optimization process, while taking correctly into account both types of uncertainties. In more details, extensive use of : - advanced Design of Experiments techniques for optimal uncertainty space sampling (of both technical and economic parameters), - reliable proxy-models computations of technical and/or economic modeling outputs, - global sensitivity analysis to rank the most impacting parameters, - optimization techniques under uncertainty to find the optimal values of controllable parameters (e.g. well architecture), ending up with an optimal development scheme. allows - througha single study - to assess boththetechnical and economic uncertainparameters for uncertainty quantification and risk analysis for optimal decision making.

AAPG Datapages/Search and Discovery Article #90346 ©2019 AAPG European Region, 3rd Hydrocarbon Geothermal Cross Over Technology Workshop, Geneva, Switzerland, April 9-10, 2019