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Energy Transition International Inc.
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  • Glossary of Terms

ETI's Glossary of Terms

AMT/MT (Audio-Magnetotellurics / Magnetotellurics)

Passive EM methods that use natural variations of the Earth’s electromagnetic field to estimate subsurface resistivity. AMT targets shallower depths than MT; MT is commonly used for deeper crustal imaging, geothermal exploration, and regional structure mapping.

Anisotropy

Directional dependence of subsurface electrical resistivity. Critical for interpreting EM data because vertical and horizontal resistivity influence fluid movement differently. Full anisotropy  not only includes horizontal and vertical directions but also in arbitratry direction to account for dipping beds.

Asset Participation

A structured commercial mechanism where ETI takes a small equity or royalty position in a CCUS, EOR, or geothermal project in exchange for monitoring and technical support.

Baseline Survey

The initial EM/CSEM measurements taken before injection or production activity begins, thus establishing a reference for time-lapse comparisons. If the injection has already started, Baseline can be established at any stage thereafter.

Borehole EM

Electromagnetic measurements acquired inside a wellbore. Borehole data provide high-fidelity resistivity and anisotropy information used to calibrate larger 3D EM models.

CSEM (Controlled-Source Electromagnetics)

A geophysical method using an active EM transmitter and multiple receivers to image subsurface resistivity variations, enabling detection of fluids like CO₂, hydrocarbons, or geothermal and lithium  brines.

Cap Rock

A low-permeability sealing layer (often shale, anhydrite, or salt) that overlies a reservoir and helps prevent upward migration of injected CO₂ or hydrocarbons. Cap-rock integrity is a key requirement for safe CO₂ storage and effective containment.

CCS (Carbon Capture and Storage)

Capturing CO₂ from industrial sources and storing it underground in a secure geological formation.

CCUS (Carbon Capture, Utilization, and Storage)

Same as CCS, but includes utilization of CO₂, such as using the CO₂ to drive the reservoir fluids towards the producer well in enhanced oil recovery (EOR) operations.

Class VI (EPA)

U.S. Environmental Protection Agency well classification for CO₂ geologic storage. Requires robust MMV (Monitoring, Modeling, and Verification).

CO2Watch

Baker Hughes’ monitoring and reporting platform for CO₂ storage, integrating EM, seismic, and borehole data into a unified MRV-ready dashboard.

Conformance (EOR)

The degree to which injected fluids move through the reservoir as intended. Poor conformance leads to bypassed oil and wasted CO₂. It is a crucial aspect of enhanced oil recovery that involves controlling the flow of fluids to improve the oil production recovery factor. 

Containment Verification

Demonstration that injected CO₂ remains within the permitted storage reservoir and does not migrate into unintended zones.

Direct Lithium Extraction (DLE)

A process that uses brines to extract lithium. EM imaging identifies brine structure and conductivity.

EM (Electromagnetics)

A geophysical technique that uses electromagnetic waves to measure subsurface resistivity to detect fluids and map reservoir behavior.

EMGS

ElectroMagnetic Geo Services ASA. A marine acquisition contractor (global leadrer) that collects CSEM, and magnetotellurics (MT). ETI collaborates with EMGS to extend its EM solutions offshore and also to derive mutal benefit in our activities.

Energy Transition

The global shift toward low-carbon energy systems, including CCUS, geothermal, hydrogen, and renewable energy technologies.

EOR (Enhanced Oil Recovery)

Techniques that increase oil extraction from mature fields. CO₂-EOR injects CO₂ to improve sweep and recovery.

ERT (Electrical Resistivity Tomography)

A resistivity imaging method that uses electrodes to inject current and measure voltages, producing 2D/3D resistivity models. Common for near-surface to intermediate-depth applications such as environmental studies, shallow CO₂ monitoring, and groundwater mapping.

Fluid Imaging

The process of visualizing subsurface fluid movement—CO₂, oil, water, or brine—through EM and borehole-calibrated inversion.

Full Tensor

A measurement approach that captures multiple directional components of a field (e.g., multiple components of the EM field or the gravity gradient). Full-tensor measurements can improve sensitivity to complex structures and reduce ambiguity compared to single-component measurements.

Geothermal Reservoir

A naturally occurring underground system containing hot water, steam or hot dry rock, that can be used for electricity generation or heating.

Gravity

A geophysical method that measures spatial variations in the Earth’s gravitational field caused by density contrasts in subsurface rocks. Used for basin structure, salt mapping, geothermal systems, and integration with EM/seismic to reduce uncertainty.

Inversion (Geophysics)

Mathematical reconstruction of subsurface resistivity from measured EM data to the geologic model. ETI uses 3D anisotropic inversion calibrated to borehole logs.

Joint Inversion

Combining multiple data types—EM, borehole logs, seismic—into a single subsurface model for reducing model ambiguity.

Lithium Brine

Subsurface saltwater enriched with lithium. EM imaging helps map brine structure and potential extraction zones.

Marine CSEM

Offshore EM surveying performed using vessels, electromegnetic transmitters, and seafloor receivers. Allows imaging of deepwater reservoirs or offshore CO₂ storage sites.

MMV (Monitoring, Modeling, and Verification)

Documentation process for regulatory compliance and carbon credit validation, often including third-party verification.

Permeability Corridor

Subsurface pathways where fluids move more easily. Identified through EM and used to optimize geothermal or EOR well placement.

Plume Mapping

Visualization of injected CO₂ distribution and movement over time using EM imaging and time-lapse comparisons.

Reservoir Intelligence

Data-driven understanding of fluid behavior, reservoir heterogeneity, and conformance, enabling operators to optimize performance.

Saturation Mapping

Quantifying the amount of CO₂, oil, water, or brine in a reservoir using the fractional fluid content that is derived from the resistivity interpretation (from EM data). Usually, a saturation equation is used such as Archie's Law or anisotropic saturation equations.

Seismic (3D / 4D)

Geophysical imaging using acoustic waves. 4D seismic tracks changes over time. Integrated with EM to create an enhanced picture of the reservoir.

SOUNDINGS

A class of geophysical surveys (commonly resistivity/EM) that estimate how properties vary with depth at a location. Soundings are used to build layered-earth models and guide more detailed 2D/3D surveys.

Strata

Distinct layers of rock or sediment formed over time. Understanding strata is essential for identifying reservoirs, seals (cap rock), and migration pathways.

Surface-to-Borehole Calibration

ETI’s worflow for tying high-fidelity borehole resistivity logs to broad-area EM data, dramatically improving interpretation accuracy.

Sweep Efficiency (EOR)

Measurement of how effectively injected fluids push hydrocarbons toward production wells. Usually measured as pore volume fraction of hydrocarbons being swept.

TAM (Total Addressable Market)

The revenue opportunity available to ETI across CCUS, EOR, geothermal, and mineral imaging markets.

TEM (Transient Electromagnetics)

An active EM method that transmits a time-varying magnetic field and measures the decay response to infer subsurface resistivity with depth. Used for groundwater, mineral exploration, near-surface to intermediate-depth mapping, and some geothermal reconnaissance.

Thief Zones (EOR)

High-permeability intervals or pathways that preferentially take injected fluids, causing poor sweep and early breakthrough. Identifying thief zones supports conformance control and improved recovery.

Time-Lapse EM (4D EM)

Repeated EM surveys comparing baseline and subsequent measurements to detect reservoir changes over time.

Well Logs

Measurements recorded in a borehole (e.g., resistivity, porosity, density, sonic) used to characterize rock and fluids. Logs provide ground truth for calibration of EM and seismic interpretations.

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