Transgas Weald Basin | ADR & Oxford Seismic Comparison | VEXRAD
VEXRAD • Energy • Weald Basin Case Study

Two independent subsurface methods. One target depth.

At Transgas Target 1, an ADR Virtual Borehole placed the top of a conventional oil target at approximately 1,040 m — the same level reported for the contour depth from 2019 reprocessed and reinterpreted seismic work undertaken by Transgas in conjunction with the Shell Geoscience Laboratory at Oxford University.

Weald Basin, UKTransgas LimitedADR Virtual BoreholeSeismic cross-check
The exploration question

Could a surface ADR survey independently locate a known subsurface target?

The value of the Transgas project was not simply that ADR produced a subsurface interpretation. A separate seismic interpretation already existed, creating an unusually useful comparison between two very different sensing approaches.

The objective was to use a rapid, non-invasive Virtual Borehole to add another evidence layer to Transgas’s conventional exploration workflow and test whether the interpreted target depth was consistent with the seismic earth model.

Independent comparison

Different physics. Convergent target depth.

ADR Virtual Borehole

~1,040 m

Surface ADR acquisition and interpretation indicated the top of Transgas Target 1 at approximately 1,040 m.

Non-invasive electromagnetic / dielectric subsurface measurement.
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2019 seismic interpretation

~1,040 m

Transgas stated this was the same level as the contour depth of its reprocessed and reinterpreted seismic.

Work undertaken by Transgas in conjunction with the Shell Geoscience Laboratory at Oxford University.
Why this matters: agreement between independent methods is more informative than a stand-alone anomaly. The comparison provides an evidence point for using ADR alongside established subsurface datasets rather than treating it as a replacement for them.
Field value

A low-disturbance evidence layer before drilling

1

Acquire

Transgas reported that ADR testing required only one day on site and no drilling rig, with no ground disturbance and a low operational profile.

2

Compare

The Virtual Borehole interpretation was compared with the pre-existing seismic target model rather than being judged in isolation.

3

De-risk

Transgas said the experience gave it sufficient confidence to commission further testing on other targets and explore combining ADR with seismic ahead of drilling decisions.

Client evidence

What Transgas said

Transgas described the Target 1 ADR result as tying closely to its Oxford-associated seismic work and identified practical advantages including rapid site work, low disturbance, quiet operation and avoiding a drilling rig for the survey itself.

The client’s published statement explicitly says it does not constitute a formal recommendation of the technology; it records Transgas’s experience of using ADR at that time.

“At ‘Target 1’ … the ADR testing results tied closely to work Transgas Limited has carried out in conjunction with the Shell Geoscience Laboratory at Oxford University.”Transgas Limited client feedback — excerpt reproduced here in shortened form for case-study context.
VEXRAD interpretation

Why this case remains strategically relevant

The Transgas project demonstrates a model that extends beyond hydrocarbons: acquire a Virtual Borehole, compare it with an independent earth model, identify agreement and disagreement, and use the combined evidence to make the next subsurface decision.

That workflow is directly relevant to VEXRAD’s current work in geothermal exploration, critical minerals, water and CCUS, where independent geological and geophysical validation is central to confidence.

Important: This case study does not imply that Oxford University or the Shell Geoscience Laboratory independently validated or endorsed ADR. The published Transgas statement says that Transgas’s ADR result tied closely to seismic work that Transgas had carried out in conjunction with the laboratory. ADR remains a decision-support method and should be integrated with appropriate geological ground truth.

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