The Exploration Workflow

Exploration works from the general to the specific, spending progressively more money on progressively smaller areas as confidence grows.

Stages

1. Basin evaluation — regional geology, existing wells and seismic, published data and analogues, to establish whether a working petroleum system is likely to exist at all.
2. Play definition — a play is a family of prospects sharing the same source, reservoir, seal and trapping style. Thinking in plays rather than individual structures is what allows a company to see a portfolio rather than a set of unrelated bets.
3. Lead identification — features that may be prospects, identified on regional or sparse seismic, not yet well enough defined to drill.
4. Prospect definition — a lead matured with dense, well-processed seismic into a mapped structure with estimated volumes and assessed risk.
5. Drilling — the only way to know.
6. Appraisal — if successful, establishing extent, deliverability and commerciality.

Other exploration data

Seismic dominates, but it is not alone:

• Gravity and magnetic surveys — cheap, wide coverage, used early to map basin shape, basement depth and salt bodies.
• Surface geology and geochemistry — outcrop studies, seep detection, soil gas surveys.
• Satellite and remote sensing — surface structure, and offshore slick detection indicating natural seepage.
• Electromagnetic surveys — controlled source electromagnetics can indicate resistive bodies, which may be hydrocarbons, as a complement to seismic.
• Existing wells — the most valuable data of all where it exists, calibrating everything else.

The economics of exploration

Most exploration wells do not find commercial hydrocarbons. Success rates vary widely by basin and play, and are lower in frontier areas than in mature ones. The business therefore only works as a portfolio: a company drilling one well is gambling, while a company drilling many wells across well-chosen plays is running a statistical business.

This has a practical consequence that is often missed. A dry hole in a well-chosen prospect, drilled for good reasons, is not a failure of process — it is an expected outcome that the risking predicted. What matters is whether the risking was honest, whether the well tested what it was meant to test, and whether the result improved the understanding of the play.