Amoco Australia Petroleum Company, as a prelude to considering farming-in to PEL 53 over the Stansbury Basin, applied to SADME to conduct a near bottom water geochemical exploration survey of Gulf Saint Vincent. This survey was intended to detect dissolved light hydrocarbons (primarily methane, ethane/ethene, propane/propene, and butane/butene; longer chain molecules(C5 and higher) are only occasionally encountered in this type of survey) in sea water, that may have leaked or seeped to the surface of the sea floor from a subsurface source. Most subsurface petroleum accumulations are known to have microseeps that allow hydrocarbon molecules (generally, light ends, C1 to C4) to migrate to the surface. The bottom water survey technique utilises continuous shipboard degassing of samples pumped from a submersible sensor unit, towed about 10 metres above the sea floor at a speed of around 6 knots. Depending on conditions, minimum analytical detection limits for dissolved gaseous hydrocarbons stripped from the water samples can be as low as 10 parts per billion. Such a survey is a broad-brush basin analysis tool intended to provide an indication of whether or not migrating hydrocarbons are present in a particular basin. In February 1989 Amoco employed geochemical prospecting contractor Transglobal Exploration and Geoscience Inc., using proprietary methods aboard the BMR research vessel Rig Seismic, to collect a total of 521 Gulf Saint Vincent bottom water samples for light hydrocarbon analysis, while traversing approximately 200 kms of reconnaisance survey track. No anomalous hydrocarbons were detected in the water column in any portion of the survey area. The measured hydrocarbon levels were extremely low and consistent with levels created by natural marine processes.