Fetters, R.T., Esso Australia Ltd. Australia
Exploration activity in Australia has increased steadily since the mid-1970's following the downturn seen at the beginning of the decade. Almost four million square kilometres is now held under permit, and competition is strong for the available acreage.
Seismic activity has reflected this upturn in interest, with 63,000 kilometres of data acquired in 1980 and almost as much again in 1981. It is intended that the number of seismic crews operating in Australia, both on-and offshore, will be substantially increased by the end of 1981, allowing further enlargement of the industry's seismic data acquisition capabilities.
Drilling has increased similarly since the mid-1970's following the unsuccessful activities of the previous few years. Approximately 140 wells previous few years. Approximately 140 wells are to be completed in 1981. and with the arrival of several new rigs in the country it is anticipated that the number of wells drilled in the coming years will steadily increase.
Up until the present, virtually all exploration wells have been drilled in areas of known hydrocarbon occurrence, such as the Cooper, Surat and Gippsland Basins. Few wells have been truly wildcat despite the fact that many of Australia's sedimentary basins have not yet been explored by modern methods. The scope for exploration in new areas is extremely wide, and the chances of an economically significant discovery must therefore be quite high.
Expenditure on exploration has increased at an even greater rate than activity, and this trend is expected to continue in the coming years. This overall increase in industry activity points to a very optimistic future for both oil exploration in Australia and for the country's self-sufficiency in energy.
Exploration activity in Australia has increased steadily since the mid-1970s. Acreage held for exploration now totals almost four million square kilometres or a billion acres. The downturn seen in acreage held during the early seventies was due to a combination of factors which include lack of success, low price, government policy and a negative philosophy on the part of explorers.
A map of current acreage (Fig.1) shows that virtually all prospective acreage is now held under permit. This had led to stronger competition for the available land and an increase in the number of farm-ins occurring. Other trends include the formation of relatively large consortiums and a willingness of companies to accept a lower equity position. A comparison of today's acreage with that of mid 1979 shows that most of the areas picked up recently represent high risk ventures.
Seismic activity also reflects the upturn in interest since the mid 1970s (Fig. 2). In 1980, 63,000 kilometres of data was acquired with 22,000 kilometres of that onshore and 41,000 kilometres offshore. In 1981, the total has increased to around 93,000 kilometres offshore. Currently there are two offshore seismic crews working in Australia with twenty-five onshore crews. By year end we expect three high sea marine crews and one shallow water marine crew and up to thirty onshore crews.
Drilling in the early 1970s corresponds to a low level of onshore seismic activity. This infers that many wells were drilled without adequate seismic control and hence many were probably drilled on valid structures. This may well explain the lack of success in the early seventies which led to the downturn in activity in the mid seventies. Following improvements in price and government policy, drilling activity has steadily increased policy, drilling activity has steadily increased (Fig. 3). In 1979, 52 exploration wells were drilled. In 1980 this increased to 82 with 68 onshore and fourteen offshore. In 1981 we expect 158 exploration wells to be drilled with 140 onshore and eighteen offshore. Development drilling has also increased from 27 wells in 1980 to an expected 86 this year. Currently we have only two offshore rigs operating with twenty onshore rigs. By year end we expect between five and eight offshore rigs and between 25 and 35 onshore rigs.
Although this seismic and drilling represents an exciting increase for Australia, it is still very low compared with worldwide activity. In the lower 48 states of the USA, for example, thousands of exploration wells are drilled each year.
Expenditure levels have increased at an even greater rate than activity. In 1978 industry spent around $150 million. This year it will exceed $450 million.
It is interesting to study a map of Australia showing the sedimentary basins, which represent the hunting area for petroleum exploration. Virtually all exploration well have been drilled in the areas of known hydrocarbon occurrences, such as the Surat, Cooper, Gippsland and Perth Basins. NW Shelf/Exmouth and Bonaparte Gulf. There are only a handful of truly wildcat wells, and many basins are yet to be explored at all by modern methods. No basin in Australia has yet been fully explored.
Within these basins, we expect there to be around 3.6 billion barrels of oil with an upside of fourteen billion barrels, and an average of 40.6 trillion cubic feet of gas with an upside of 120 trillion cubic feet yet to be found. Exploration over the last twelve months has been successful. In 1980 discoveries included the non-commercial gas wells of Lesseur, Brewster, Phoenix, Sirius and Eendracht, and the commercial gas discoveries at Gorgon. Woodada and Wareena. A small oil pool was found at Cutapirrie in 1981 already pool was found at Cutapirrie in 1981 already several exciting discoveries have been made including the Blina oil discovery and the small gas discoveries at Marrabooka, Mudera, Kerna and Yapeni.