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Characterising an offshore block without drilling: Sierra Leone

Eleven thousand square kilometres, sixteen prospects in five clusters and an independent third-party report — all delivered in three months, before the next meter of seismic.

Case study · 5 min read

A frontier with pedigree

Block 2020a, offshore Sierra Leone, sits in a conjugate twin of the Guyana basin — one of the most prolific oil frontiers discovered this century. The opportunity was clear; the challenge was characterising a vast offshore area without an expensive, open-ended drilling and seismic campaign.

Three remote stages

We ran an ERS workflow in three phases: multisensor satellite imaging to map hydrocarbon anomalies across the full block, followed by targeted NMR and point electromagnetic acquisition over the most promising areas. Coverage was narrowed from 4,000 km of candidate 2D lines down to roughly 1,000 km of focused acquisition.

11,000 km²
Block area characterised
16
Prospects across 5 clusters
~-2,700 m
Average target depth (TVDSS)

Validated by a third party

The findings were independent of us where it mattered most: the Competent Person's Report was issued by Ryder Scott, not by Inside Earth. It assessed a P50 of 8.4 TCF plus 234 million barrels. Subsequent DHI studies revealed an additional 693 million barrels across two lead clusters.

Characterise it fully before the next meter of seismic.

The takeaway

Compared with a seismic-only program, the remote-first approach turned an open exploration problem into a ranked, drill-ready portfolio in a fraction of the time — and put independent numbers behind it.

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