Lithium from geothermal brine depends on granite-hosted, fractured rock — and a developer in NE England wanted to know how much a surface ADR interpretation could tell them before drilling, and how much sharper it got afterwards. Running the same two boreholes both before and after the drill, the answer was honest and useful: the temperature-proxy picks ADR made blind held up against the drill unchanged, while the finer lithology only sharpened once a calibration hole anchored it — pinning the top of the granite and resolving individual quartz veins. It’s the clearest illustration of why we now work calibrate-then-predict: one drilled hole turns a rough zonation into a sharp one.
Calibrate, then predict
How a single calibration against the drill turned a blind ADR log into a resolved lithology and temperature model — at a geothermal lithium-brine project in northeast England.
See before you drill.
VEXRAD interpreted deep ADR virtual boreholes at a geothermal lithium-brine project in northeast England twice over — once blind, before drilling, and once calibrated against the drill. The comparison is the clearest demonstration of why VEXRAD works calibrate-then-predict. Blind, ADR resolved the subsurface zonation and, critically, the temperature-proxy troughs — but could not cleanly separate sedimentary from igneous rock. Calibrated against the drill, ADR resolved the full lithology: the top of the granite, the sediment–igneous boundaries, and individual quartz veins. And the one thing calibration did not change — the temperature picks — matched the drilled temperature increases both times.
Interpret twice — blind, then calibrated
Two deep boreholes (coded LF03a and LF10) were each interpreted in two passes. The pre-drill pass used ADR alone, with no drilling to guide it. The post-drill pass calibrated the same ADR data against the completed drill log. Comparing the two shows precisely what ADR resolves on its own, and what a calibration step adds.
What the drill added
Findings are reported under VEXRAD’s four-tier standard — confirmed against the drill.
| Feature | Blind pre-drill ADR | After calibration to the drill | Read |
|---|---|---|---|
| Temperature increases | Troughs picked at 340–380 m & 520 m (LF03a); 220–240 m & 300–320 m (LF10) | Unchanged — and matched the drilled temperatures | Validated |
| Start of granite | Not clearly resolved | ~280 m (LF03a) / ~270 m (LF10) | Validated |
| Sediment vs igneous | Could not be separated | Cleanly differentiated | Validated |
| Quartz veins | Read as a broad fractured-granite zone | Three veins resolved, 425–650 m (LF10) | Validated |
The temperature model was right blind; the lithology model needed the drill. Calibrate once, and ADR predicts the rest — that is calibrate-then-predict.
What this doesn’t claim
- This was a focused two-borehole study, not a field-wide model.
- The lithological refinement depends on calibration; blind ADR here resolved structure and temperature, not rock names.
- Validation is against the operator’s drill logs; the correlations are strong but interpretive.
We report these plainly. A result is only worth as much as the honesty around it.
What it means for developers
This is the clearest picture of how VEXRAD delivers value on a live project. Calibrate ADR against one or two of your logged holes, and it will then predict lithology, temperature and structure into the un-drilled ground — at a fraction of the cost of drilling to find out. For a geothermal or lithium-brine developer, where temperature and permeability decide the project, that is a read worth having before the rig moves.
Talk to us about your project