| Title | Fracture Network Characterization and Permeability for Direct-Use Geothermal Energy – Cornell University Borehole Observatory ESH No. 1 |
|---|---|
| Authors | Sean A. FULCHER, Daniela PINILLA, Teresa E. JORDAN, Patrick M. FULTON, Pedro Henrique Vieira DE LUCA |
| Year | 2023 |
| Conference | Stanford Geothermal Workshop |
| Keywords | geothermal energy, direct-use, fracture analysis, borehole imaging, gas chromatography, district heating |
| Abstract | Space heating demand of the Cornell University campus in Ithaca, New York, reaches approximately 240,000 MWth-hrs/yr and is supplied by a natural-gas-fed district heating system, accounting for 50% of the annual Ithaca campus energy consumption. Cornell University plans to have a carbon neutral Ithaca campus by 2035 and is exploring the feasibility of providing the campus space heating demand with a deep direct-use (DDU) geothermal district heating system. Initial studies predicted development of a campus DDU district heating system would depend on the formation temperature and fracture permeability within Ordovician to Precambrian rock ranging from depths of 2.3 to 3.2 km beneath the Cornell University Ithaca campus. Understanding the nature and extent of natural fracture zones is paramount for thermal hydraulic reservoir modeling and economic geothermal energy extraction. Cornell University recently completed drilling, construction, and testing of the 3-km deep exploratory Earth Source Heat Well No. 1 to aid feasibility assessment of potential DDU geothermal energy for campus wide district space heating. Here we present data and initial analysis of fracture networks within Ordovician to Precambrian rock underlying the Cornell University campus, based on newly acquired micro-resistivity and acoustic borehole image (BHI) surveys coupled with sidewall core data obtained from ESH No. 1. Preliminary fracture analysis of BHI surveys identifies five depth intervals with increased fracture intensity spanning from sedimentary Ordovician formations into the Precambrian basement complex. Most identified fractures present low electrical resistivity values; however, high resistivity fractures are also observed in some depth intervals. Additionally, well drilling parameters and gas chromatography data are examined to further define and bracket permeable fracture zones within intercepted borehole rock. Last, stratigraphic relationships are further defined with additional offset well data to provide lithological facies and spatial extents of potential DDU geothermal reservoir zones. |