GRIDWELL Atlas: a self-updating screen to find the abandoned oil and gas wells best placed to add Enhanced Geothermal System electricity to the U.S. grid

Ashraf Mohammed 

Drilling is the largest single cost of geothermal electricity, and the United States already has about 4.1 million abandoned oil and gas wells. However, the potential of these wells for Enhanced Geothermal Systems (EGS) has been screened at each well's own depth only for documented orphaned wells. Earlier screens treated orphaned wells as a separate population, although an orphaned well is an abandoned well that no operator can be required to plug. This paper presents GRIDWELL Atlas, a self-updating screen that places orphaned wells and all other abandoned wells in one inventory.

GRIDWELL Atlas assembles 948,992 abandoned wells from six state registries (Oklahoma, Kansas, California, New York, Colorado and North Dakota) and the U.S. Geological Survey (USGS) list of documented orphaned wells for 26 states. Each well is assigned one of four abandonment types: 1) inactive and unplugged with an operator of record (57,765 wells); 2) orphaned and unplugged (130,813); 3) plugged and abandoned (518,750); and 4) dry and abandoned (241,664). Formation temperature is then estimated at the 382,424 wells that report a usable vertical depth, using a depth-matched bottom-hole temperature field. On 20,000 held-out measurements deeper than 8,202 ft (2,500 m), the median error of the depth-matched field is 14 °F (7.8 °C), compared to 16 °F (9.1 °C) for the all-depth interpolation it replaces.

The results show that only 1,869 graded wells (0.49%) reach 302 °F (150 °C) at total depth. Inactive, unplugged wells are the most accessible type and also the type most often hot, with 1.3% of the graded wells of this type reaching EGS temperature. The 300 inactive, unplugged wells that reach EGS temperature are the best-fit wells. They are located in the Piceance Basin of Colorado and the Williston Basin of North Dakota, at a median depth of 12,108 ft (3,690 m) and a median temperature of 319 °F (160 °C). Only 7 of these wells are within 6.2 mi (10 km) of a grid interconnection at 69 kV or higher, and none is in a county that is a 2026 energy community. This paper also documents the wellbore, thermal, seismic and legal barriers that apply to each abandonment type, with the evidence for each barrier. The atlas downloads the state registries again every month, so wells are added as agencies record them as abandoned.