Probabilistic Flow Modelling of Geothermal Wells in Sedimentary Aquifers

Abstract

Economic assessment of the development prospects for production of moderate temperature geothermal brine from a deep sedimentary aquifer is aided by a statistical analysis of information from existing petroleum or other wells. A statistical distribution of formation permeability, thickness, temperature and pressure is combined with a simplified wellbore model to produce an estimate of the flow from a submersible pump with a fixed maximum discharge head. Monte Carlo simulation of the pump discharge flow can then be used to produce a probability distribution of well output for economic analysis.
Estimates of the levelised electricity cost probability distribution can be obtained by using the output from the probabilistic flow model as one of the inputs to a Monte Carlo model of major cost. A preliminary financial model was created to investigate the potential economic viability of various options for low temperature geothermal developments in a sedimentary basin.
Using probabilistic modeling of the expected range of parameters affecting the flow from wells tapping low temperature sedimentary formations produces a model output of expected production well flow rate that can be used for economic assessment of project viability.
For low temperatures geothermal developments the production well flow rate and temperature are the major factors affecting the economic viability of projects.