A Stochastic Evaluation of Geothermal Reservoir Potential for the Tuscarora Sandstone in Morgantown, West Virginia, USA

摘要

The Tuscarora Sandstone is a target for use as a geothermal reservoir for direct-use heating of the West Virginia University campus in Morgantown. Currently, the nearest wells drilled to the Tuscarora are located about 15 km from Morgantown, and the nearest well with permeability data is about 60 km from Morgantown. As a result, there are relatively large uncertainties in geologic properties and flow geometries for the Tuscarora below Morgantown, which is common in the exploration phase of geothermal projects. This paper presents a stochastic estimation of the geothermal reservoir productivity for the Tuscarora Sandstone that accounts for these uncertainties. Statistical analyses of available geologic datasets are used to characterize probability distributions for reservoir properties, including porosity, permeability, reservoir thickness and depth. A Monte Carlo analysis of these reservoir properties and fluid properties is used to estimate the Tuscarora reservoir flow productivity. Results are compared for fracture-dominated and matrix flow productivity to estimate bounds of the favorability. A sensitivity analysis of flow productivity results explores the impact of uncertainties in engineering-controlled variables and variables whose probability distributions are not well-characterized by the available data. Transforming the reservoir productivity predictions into favorability values allows for probabilistic interpretations of the Tuscarora achieving certain favorability thresholds. The methods presented in this paper may be applied before site-specific data are collected to inform project decision making and data collection.