NonLinear Earth Sciences
Permeable Fracture Imaging maps the fracture networks that carry fluid and heat underground, before drilling and injection decisions are made.
NonLinear Earth Sciences (NLES) is a subsurface imaging company. Its core service is Permeable Fracture Imaging (PFI™), a passive seismic method that maps the permeable fracture networks controlling where fluids and heat move underground.
A high temperature gradient alone does not make a productive geothermal reservoir. Rock conducts heat poorly, and wells produce where connected natural fractures carry fluid. A well drilled unknowingly into a major fault can also bring fluid losses or induced seismicity. Conventional surveys map geologic structure; PFI maps where flow is possible, so drilling targets can be ranked before the rig arrives.
PFI can also follow the subsurface as it responds to injection: activity builds around the injection interval, spreads along fracture pathways, then fades.
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Technology
A passive seismic method that produces three-dimensional images of permeable fracture networks, used to rank drilling targets and plan wells.
Learn more →Projects
PFI has been developed and demonstrated at the Newberry Volcano Enhanced Geothermal System in Oregon through two field campaigns under DOE ARPA-E grants.
Learn more →Contact
From choosing a first drilling target to tracking an active injection, NLES designs and runs PFI surveys end to end: field deployment, processing, and interpretation tailored to your project.
Discuss a survey →Recognition
Permeable Fracture Imaging received the Geothermal Rising 2026 Technology Award.
The award was presented at the Geothermal Rising Conference in Houston, Texas, September 20–23, 2026.
About
NonLinear Earth Sciences (NLES) is a geoscience company focused on imaging the subsurface permeability field: the connected fractures, joints, faults, and fault zones that govern where fluid moves in rock. Its core service, Permeable Fracture Imaging (PFI), is a passive seismic method that maps these pathways directly rather than inferring them from thermal, electrical, or structural proxies.
Permeability decides whether a well produces, yet it is rarely measured before drilling. NLES applies PFI to geothermal and enhanced geothermal development, subsurface fluid injection, and the characterization of flow pathways for storage and resource development.
Technology
A passive seismic method for mapping the subsurface permeability field.
PFI (Permeable Fracture Imaging) maps the subsurface permeability field directly: the fractures, joints, faults, and fault zones that form the connected pathways for fluid flow. Field results from the FORGE project indicate that heat extraction in enhanced geothermal systems is dominated by fluid flow through fractures rather than conduction, which makes these pathways the property that matters most.1
A dense array of seismic sensors records the natural seismic signals these structures emit. Processing converts the recordings into three-dimensional images of where flow is possible. Where conventional seismic surveys image geologic structure, PFI images the pathways that carry fluid. The method is passive and requires no controlled source.
PFI is not microseismic monitoring. Microseismic methods locate discrete failure events and depend on induced earthquakes during stimulation. PFI images the fracture and fault architecture itself, and can be applied before any well is drilled or any fluid is injected.
Because it is passive, PFI can also be repeated during an injection. The sequence shown here follows activity building around the injection interval, spreading outward along fracture pathways, and fading over about two and a half hours.
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1 Leary and Malin, 2025. ↩
PFI images inform decisions at each stage of a subsurface project.
Where PFI fits in a project
PFI has been developed and demonstrated through two field campaigns at the Newberry Volcano Enhanced Geothermal System in Oregon, in 2023 and 2025, under DOE ARPA-E grants with industry support.
Projects
PFI has been developed and demonstrated at the Newberry Volcano Enhanced Geothermal System in Oregon, under DOE ARPA-E funding with industry support.
Newberry Volcano, Oregon
The survey imaged the permeable fracture network around the project well. It resolved NNW-trending normal faults, correlated them with well-log density and lithology, and identified a low-permeability clay cap that was validated against magnetotelluric resistivity data. Its results were reproduced by the 2025 survey.
Eppink et al., 2025, SGP-TR-229. Publications →
Newberry Volcano, Oregon
The second campaign mapped the fracture system around an existing geothermal well doublet, with fracture orientations matching the regional NW–SE tectonic trend. Using distributed acoustic sensing and vibroseis velocity control, it imaged to about 4 km depth and located near-wellbore fluids during a live injection test between the two wells.
Eppink et al., 2026, SGP-TR-230. Publications →
Planning a geothermal or subsurface project?
Discuss a PFI survey →Team
The scientists and engineers behind Permeable Fracture Imaging.
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Publications
Peer-reviewed proceedings documenting the development and field demonstration of PFI.
Eppink et al. Proceedings, 51st Workshop on Geothermal Reservoir Engineering, Stanford University, SGP-TR-230.
Eppink et al. Proceedings, 50th Workshop on Geothermal Reservoir Engineering, Stanford University, SGP-TR-229.
Contact
Discuss a PFI survey for your project, or a research collaboration.
