Discovery in Bass Strait

On 27 December 1964 the floating rig Glomar III began exploration drilling in what became the Barracouta field. It was one of the first specialised self-propelled floating rigs and was a sister ship to Cuss I which had been used in the research Project 'Mohole' in the Pacific in 1961. Its novelty lay in its 'moonpool' which is a hole or well which extends through the ship from deck to keel, with the drilling tower above. The drill is lowered through the moonpool into the sea and stays relatively still, while the ship pitches and rolls around it with the waves. Its 70 day voyage from Houston to Port Welshpool under its own power was the longest ever undertaken by such a vessel.

After two months drilling a small blowout announced that it had struck gas. This was rapidly controlled and drilling continued. By mid April tests confirmed that the field was capable of commercial production and by the end of June it was clear that ESSO/BHP had discovered a large natural gas field with their first well.

While this was enormously encouraging to the partners, the real prize was oil and in March 1966 in only the fourth well the first oil was found. This was in the Marlin field, which proved to be a major gas field. Early in 1968, after the discovery of the Halibut and Kingfish oil fields, it became clear that Australia had major oil fields with reserves of 1500 million barrels and that production from the Bass Strait fields could be 300,000 barrels per day. Of the first ten structures drilled by ESSO/BHP only one was dry, and it is now believed that the dry hole was not drilled on a valid structure. This represents a remarkable success rate by industry standards.

Australian Academy of Technological Sciences and Engineering