Jeff Pepin, PhD
Jeff Pepin is a Hydrologist at the USGS Central Energy Resources Science Center.
Jeff’s research focuses on geothermal resource characterization and resource assessment methodology development. His research often utilizes hydrothermal modeling, geostatistics, electromagnetic geophysics, and machine learning. He is also experienced collecting thermal and hydrogeologic data in the field to support these research efforts. Jeff currently leads the national thermal energy storage assessment program as part of the USGS Geothermal Resources Investigations Project (GRIP). He began his career with the USGS in 2016.
Professional Experience
2024 to present: Hydrologist, U.S. Geological Survey, Central Energy Resources Science Center, Denver, Colorado
2022 to 2024: Hydrologist, U.S. Geological Survey, Colorado Water Science Center, Denver, Colorado
2019 to 2022: Hydrologist, U.S. Geological Survey, New Mexico Water Science Center, Albuquerque, New Mexico
2016 to 2019: Student Trainee Hydrology, U.S. Geological Survey, New Mexico Water Science Center, Albuquerque, New Mexico
2012 to 2019: Research & Teaching Assistant, New Mexico Institute of Mining & Technology, Socorro, New Mexico
2012 to 2012: Well-Logging Specialist, New Mexico Bureau of Geology and Mineral Resources, Socorro, New Mexico
Education and Certifications
Ph.D. in Earth & Environmental Science with specialization in Hydrology, New Mexico Institute of Mining & Technology, 2019
M.S. in Hydrology, New Mexico Institute of Mining & Technology, 2015
B.S. in Geology, California State Polytechnic University Pomona, 2011
Science and Products
Salinity contributions from geothermal waters to the Rio Grande and shallow aquifer system in the transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin Salinity contributions from geothermal waters to the Rio Grande and shallow aquifer system in the transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin
Freshwater scarcity has raised concerns about the long-term availability of the water supplies within the transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin in Texas, New Mexico, and Chihuahua. Analysis of legacy temperature data and groundwater flux estimates indicates that the region’s known geothermal systems may contribute more than 45,000 tons of dissolved solids...
Authors
Jeff Pepin, Andrew Robertson, Shari Kelley
Machine learning to identify geologic factors associated with production in geothermal fields: A case-study using 3D geologic data, Brady geothermal field, Nevada Machine learning to identify geologic factors associated with production in geothermal fields: A case-study using 3D geologic data, Brady geothermal field, Nevada
In this paper, we present an analysis using unsupervised machine learning (ML) to identify the key geologic factors that contribute to the geothermal production in Brady geothermal field. Brady is a hydrothermal system in northwestern Nevada that supports both electricity production and direct use of hydrothermal fluids. Transmissive fluid-flow pathways are relatively rare in the...
Authors
Drew Siler, Jeff Pepin, Velimir Vesselinov, Maruti Mudunuru, Bulbul Ahmmed
3-D geologic controls of hydrothermal fluid flow at Brady geothermal field, Nevada, USA 3-D geologic controls of hydrothermal fluid flow at Brady geothermal field, Nevada, USA
In many hydrothermal systems, fracture permeability along faults provides pathways for groundwater to transport heat from depth. Faulting generates a range of deformation styles that cross-cut heterogeneous geology, resulting in complex patterns of permeability, porosity, and hydraulic conductivity. Vertical connectivity (a throughgoing network of permeable areas that allows advection of...
Authors
Drew Siler, Jeff Pepin
National-scale reservoir thermal energy storage pre-assessment for the United States National-scale reservoir thermal energy storage pre-assessment for the United States
The U.S. Geological Survey is performing a pre-assessment of the cooling potential for reservoir thermal energy storage (RTES) in five generalized geologic regions (Basin and Range, Coastal Plains, Illinois Basin, Michigan Basin, Pacific Northwest) across the United States. Reservoir models are developed for the metropolitan areas of eight cities (Albuquerque, New Mexico; Charleston...
Authors
Jeff Pepin, Erick R. Burns, Jesse Dickinson, Leslie Duncan, Eve Kuniansky, Howard Reeves
Optimization assessment of a groundwater-level observation network in the Middle Rio Grande Basin, New Mexico Optimization assessment of a groundwater-level observation network in the Middle Rio Grande Basin, New Mexico
The U.S. Geological Survey, in cooperation with the Albuquerque Bernalillo County Water Utility Authority (ABCWUA), measures groundwater levels continuously (hourly) and discretely (semiannually and annually) at a network of wells and piezometers (hereafter called the observation network) within the Middle Rio Grande Basin in central New Mexico. Groundwater levels that are measured in...
Authors
Andre Ritchie, Jeff Pepin
Non-USGS Publications**
Pepin J (2018) New Approaches to Geothermal Resource Exploration and Characterization. PhD Dissertation, New Mexico Institute of Mining & Technology, 186 p.
Pepin J, Person M, Phillips F, Kelley S, Timmons S, Owens L, Witcher J, Gable C (2017) Deep Fluid Circulation within Crystalline Basement Rocks and the Role of Hydrologic Windows in the Formation of the Truth or Consequences, New Mexico Low-Temperature Geothermal System. In Crustal Permeability, John Wiley & Sons, Ltd., United Kingdom, 560 p.
Zhang Y, Edel S, Pepin J, Person M, Broadhead R, Ortiz JP, Bilek S, Mozley P, Evans J (2016) Exploring the Potential Linkages Between Oil-Field Brine Reinjection, Crystalline Basement Permeability, and Triggered Seismicity for the Dagger Draw Oil Field, Southeastern New Mexico, USA Using Hydrologic Modeling. Geofluids, 16, 971-987.
Kelley S, Person M, Kelley R, Pepin J (2016) Low-temperature geothermal resources in the Acoma Basin and Lucero Uplift, eastern Cibola and western Valencia counties, New Mexico. In The Geology of the Belen Area, New Mexico Geological Society, Guidebook, 67th Field Conference, Socorro, New Mexico, 263-274.
Pepin J (2015) Sustainability Assessment of the Truth or Consequences, New Mexico Geothermal Resource. M.S. Thesis, New Mexico Institute of Mining & Technology, 87 p.
Bielicki J, Blackwell D, Harp D, Karra S, Kelley R, Kelley S, Middleton R, Pepin J, Person M, Sutula G, Witcher J (2015) Hydrogeologic Windows: Regional Signature Detection for Blind and Traditional Geothermal Play Fairways. Los Alamos National Laboratory Final Report LA-UR-15-28360, 94 p
Person M, Kelley S, Kelley R, Karra S, Harp D, Witcher J, Bielicki J, Sutula G, Middleton R, Pepin J (2015) Hydrogeologic Windows: Detection of Blind and Traditional Geothermal Play Fairways in Southwester New Mexico Using Conservative Element Concentrations and Advective-Diffusive Solute Transport. Geothermal Resource Council Transactions, 39, 751-759.
Pepin J, Person M, Phillips F, Kelley S, Timmons S, Owens L, Witcher J, Gable C (2015) Deep Fluid Circulation within Crystalline Basement Rocks and the Role of Hydrologic Windows in the Formation of the Truth or Consequences, New Mexico Low-Temperature Geothermal System. Geofluids, 15, 139-160.
Person M, Phillips F, Kelley S, Timmons S, Pepin J, Blom L, Haar K, Murphy M (2013) Assessment of the Sustainability of Geothermal Development Within the Truth or Consequences Hot Springs District, New Mexico. New Mexico Bureau of Geology and Mineral Resources Open-File Report 551, 65 p.
Pepin J (2011) Geology of Hawk Canyon, Anza-Borrego Desert State Park, California. B.S. Thesis, California State Polytechnic University Pomona, 59 p.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Salinity contributions from geothermal waters to the Rio Grande and shallow aquifer system in the transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin Salinity contributions from geothermal waters to the Rio Grande and shallow aquifer system in the transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin
Freshwater scarcity has raised concerns about the long-term availability of the water supplies within the transboundary Mesilla (United States)/Conejos-Médanos (Mexico) Basin in Texas, New Mexico, and Chihuahua. Analysis of legacy temperature data and groundwater flux estimates indicates that the region’s known geothermal systems may contribute more than 45,000 tons of dissolved solids...
Authors
Jeff Pepin, Andrew Robertson, Shari Kelley
Machine learning to identify geologic factors associated with production in geothermal fields: A case-study using 3D geologic data, Brady geothermal field, Nevada Machine learning to identify geologic factors associated with production in geothermal fields: A case-study using 3D geologic data, Brady geothermal field, Nevada
In this paper, we present an analysis using unsupervised machine learning (ML) to identify the key geologic factors that contribute to the geothermal production in Brady geothermal field. Brady is a hydrothermal system in northwestern Nevada that supports both electricity production and direct use of hydrothermal fluids. Transmissive fluid-flow pathways are relatively rare in the...
Authors
Drew Siler, Jeff Pepin, Velimir Vesselinov, Maruti Mudunuru, Bulbul Ahmmed
3-D geologic controls of hydrothermal fluid flow at Brady geothermal field, Nevada, USA 3-D geologic controls of hydrothermal fluid flow at Brady geothermal field, Nevada, USA
In many hydrothermal systems, fracture permeability along faults provides pathways for groundwater to transport heat from depth. Faulting generates a range of deformation styles that cross-cut heterogeneous geology, resulting in complex patterns of permeability, porosity, and hydraulic conductivity. Vertical connectivity (a throughgoing network of permeable areas that allows advection of...
Authors
Drew Siler, Jeff Pepin
National-scale reservoir thermal energy storage pre-assessment for the United States National-scale reservoir thermal energy storage pre-assessment for the United States
The U.S. Geological Survey is performing a pre-assessment of the cooling potential for reservoir thermal energy storage (RTES) in five generalized geologic regions (Basin and Range, Coastal Plains, Illinois Basin, Michigan Basin, Pacific Northwest) across the United States. Reservoir models are developed for the metropolitan areas of eight cities (Albuquerque, New Mexico; Charleston...
Authors
Jeff Pepin, Erick R. Burns, Jesse Dickinson, Leslie Duncan, Eve Kuniansky, Howard Reeves
Optimization assessment of a groundwater-level observation network in the Middle Rio Grande Basin, New Mexico Optimization assessment of a groundwater-level observation network in the Middle Rio Grande Basin, New Mexico
The U.S. Geological Survey, in cooperation with the Albuquerque Bernalillo County Water Utility Authority (ABCWUA), measures groundwater levels continuously (hourly) and discretely (semiannually and annually) at a network of wells and piezometers (hereafter called the observation network) within the Middle Rio Grande Basin in central New Mexico. Groundwater levels that are measured in...
Authors
Andre Ritchie, Jeff Pepin
Non-USGS Publications**
Pepin J (2018) New Approaches to Geothermal Resource Exploration and Characterization. PhD Dissertation, New Mexico Institute of Mining & Technology, 186 p.
Pepin J, Person M, Phillips F, Kelley S, Timmons S, Owens L, Witcher J, Gable C (2017) Deep Fluid Circulation within Crystalline Basement Rocks and the Role of Hydrologic Windows in the Formation of the Truth or Consequences, New Mexico Low-Temperature Geothermal System. In Crustal Permeability, John Wiley & Sons, Ltd., United Kingdom, 560 p.
Zhang Y, Edel S, Pepin J, Person M, Broadhead R, Ortiz JP, Bilek S, Mozley P, Evans J (2016) Exploring the Potential Linkages Between Oil-Field Brine Reinjection, Crystalline Basement Permeability, and Triggered Seismicity for the Dagger Draw Oil Field, Southeastern New Mexico, USA Using Hydrologic Modeling. Geofluids, 16, 971-987.
Kelley S, Person M, Kelley R, Pepin J (2016) Low-temperature geothermal resources in the Acoma Basin and Lucero Uplift, eastern Cibola and western Valencia counties, New Mexico. In The Geology of the Belen Area, New Mexico Geological Society, Guidebook, 67th Field Conference, Socorro, New Mexico, 263-274.
Pepin J (2015) Sustainability Assessment of the Truth or Consequences, New Mexico Geothermal Resource. M.S. Thesis, New Mexico Institute of Mining & Technology, 87 p.
Bielicki J, Blackwell D, Harp D, Karra S, Kelley R, Kelley S, Middleton R, Pepin J, Person M, Sutula G, Witcher J (2015) Hydrogeologic Windows: Regional Signature Detection for Blind and Traditional Geothermal Play Fairways. Los Alamos National Laboratory Final Report LA-UR-15-28360, 94 p
Person M, Kelley S, Kelley R, Karra S, Harp D, Witcher J, Bielicki J, Sutula G, Middleton R, Pepin J (2015) Hydrogeologic Windows: Detection of Blind and Traditional Geothermal Play Fairways in Southwester New Mexico Using Conservative Element Concentrations and Advective-Diffusive Solute Transport. Geothermal Resource Council Transactions, 39, 751-759.
Pepin J, Person M, Phillips F, Kelley S, Timmons S, Owens L, Witcher J, Gable C (2015) Deep Fluid Circulation within Crystalline Basement Rocks and the Role of Hydrologic Windows in the Formation of the Truth or Consequences, New Mexico Low-Temperature Geothermal System. Geofluids, 15, 139-160.
Person M, Phillips F, Kelley S, Timmons S, Pepin J, Blom L, Haar K, Murphy M (2013) Assessment of the Sustainability of Geothermal Development Within the Truth or Consequences Hot Springs District, New Mexico. New Mexico Bureau of Geology and Mineral Resources Open-File Report 551, 65 p.
Pepin J (2011) Geology of Hawk Canyon, Anza-Borrego Desert State Park, California. B.S. Thesis, California State Polytechnic University Pomona, 59 p.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.