Methodology to Estimate Low Grade Enhanced Geothermal System (EGS) Reserves Using Heat Extracted from Depleted Wells in High Temperature Shale Gas Formations

Eventually there will be low-production gas wells in the Haynesville and Eagle Ford shale formations that are no longer monetized. The objective of this study is to assess the potential for repurposing multiple transverse fracture horizontal wells (MTFHWs) in these formations as low-grade enhanced /engineered geothermal systems. We use DrillingInfo and other available data, including formation temperature, to categorize existing gas wells as active, depleted, and still on production or abandoned, and to estimate an abandonment time for those still on production. Once the categorization is done, further study applies machine learning to quantify the current and future EGS potential of these wells. Finally, the results from the preceding studies are used to evaluate how best to distribute power plants for effective use of these resources, and to estimate how much power generation is possible. The result of this research is a methodology for forecast of EGS power generation potential of low-grade EGS reserves in the Eagle Ford and Haynesville shale gas formations. This forecast addresses both technical and economic aspects. In effect, this work also provides a methodology for assessing the economic potential of EGS from existing MTFHWs in other formations having sufficiently high temperature for low-grade geothermal heat extraction. This research provides input to support potential EGS development in Texas that could provide clean and affordable continuous (unfluctuating) power for small municipalities or industrial applications and/or as a contribution to the regional grid power supply.