Zachary Frone

Heat flow and thermal modeling of the Appalachian Basin, West Virginia

Recent heat flow studies indicate that the Appalachian Basin in West Virginia may represent an important location for high heat flow and future geothermal energy development. Currently, however, only limited one-dimensional (1-D) heat flow studies exist in this region, making it difficult to assess the potential for geothermal development. Here, we develop the first high resolution 2-D basin model for a portion of West Virginia. The model uses 2-D finite difference heat conduction, basin cross sections, equilibrium temperature, and oil and gas bottom-hole temperature data to quantify heat flow at the surface and at the base of the sedimentary basin. The temperature data show elevated temperature gradients in the eastern portion of the basin. A 2-D advection-diffusion model, created using available lithologic and structural data, was designed to test whether variations in crustal properties, structure, erosion, or fluid advection can account for the observed temperatures in the basin. Thermal properties were populated using measured values as well as published averages. A linear heat flow vs. heat production relationship was used to determine heat flow at the base of the model. The model constrains the heat flow at the base of the sedimentary basin to 49–55 mW/m 2 . Analysis of modeling results suggests that heat flow at the base of the sedimentary basin is nearly uniform. Variations in basin temperatures are most likely due to variations in sediment thermal properties, complex structures, and/or localized fluid advection.

Geothermal energy characterization in the Appalachian Basin of New York and Pennsylvania

Analysis of geothermal energy resources in the Appalachian Basin of the eastern United States is of interest, given the region’s population- and climate-driven demand for thermal energy. This study provides a fuller picture of geothermal resources across New York and Pennsylvania than previous studies by providing a rigorous statistical analysis of temperature-depth data using records from nearly 8000 locations. The compilation of thousands of temperature-depth data enables a significant increase in the spatial resolution of geothermal resource assessment maps for this region. In addition, this project has contributed to the compilation of geothermal data at a national level through the National Geothermal Data System. These temperature-depth measurements are byproducts of historical and recent drilling for petroleum and natural gas in the sedimentary basin. Bottom hole temperatures (BHTs) were recorded before the wells reached thermal equilibrium and at a wide range of depths. To extract a comprehensive description of the thermal state of the Appalachian Basin strata required application of both a BHT correction scheme and a simple thermal model. The model results for individual wells were combined with geostatistical interpolation employing kriging to produce maps that reveal significant variations in subsurface thermal gradient and surface heat flow with markedly improved spatial resolution. An area in south-central New York State displays favorable geothermal resource potential, with heat flow estimates of 50–60 mW/m 2 . There are 2 elongate, 200–300 km long, northeast-trending bands of favorable geothermal resource potential in central and western Pennsylvania, with heat flow of 55–90 mW/m 2 .