An investigation was performed on the suitability of abandoned wells in California for Enhanced Geothermal Systems (EGS). The study identified three counties characterized by high numbers of abandoned wells, medium to high crustal heat flows (75-100 mW/m~2), and suitable sedimentary geology: Santa Clara, Monterey, and Santa Barbara. Temperature gradients ranging between 4 and 7.3 °C/100 m access bottom hole temperatures between 40-73 °C for an average 1,000 m deep well. These rock temperatures are sufficient for the extraction of low-temperature geothermal energy for direct use such as district heating, greenhouse heating, and aquaculture. The mitigation of drilling costs and the documented lithology both reduce the risk associated with EGS. However, hydraulic fracturing of loosely to moderately consolidated sedimentary rock in transitional stress regimes remains one limitation to the EGS conversion of these abandoned wells.
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