Sniffing out that offshore oil

摘要

The concept of a seismic survey vessel towing a high-powered acoustic source and receivers designed to detect oil in rocks beneath the seabed is long-established and well understood, but in the last couple of years a new oil exploration concept has emerged which its proponents claim can complement conventional seismic operations. To date, these operations, known as electromagnetic survey (or EM imaging or 'seabed logging') have been carried out by vessels that have been modified to enable them to deploy seabed logging equipment. In recent months, the world's first purpose-built seabed logging vessel has been delivered to owner Boa Offshore and has entered service under a long-term charter with seabed logging specialist EMGS. EM imaging uses electromagnetic energy to detect 'resistive bodies,' including hydrocarbon reservoirs, beneath the seabed. If conventional seismic techniques indicate the presence of potential oil-bearing strata, EM data can dramatically improve confidence in ranking the prospect; it also has the potential to find hydrocarbon 'traps' that cannot be detected using seismic methods and that would otherwise be overlooked.