Australian petroleum accumulations report. Bowen and Surat Basins, Clarence-Moreton Basin, Sydney Basin, Gunnedah Basin and other minor onshore basins, Qld, NSW and NT

As at January 1997, one hundred and eighty seven petroleum accumulations had been discovered in the Bowen and Surat Basins. Commercial petroleum production has taken place from ninety nine of these accumulations. Both oil and gas has been recovered from Jurassic, Triassic, Permian and Devonian reservoirs in the Bowen/Surat sequence. Gas production takes place from accumulations lying on the western flank of the Taroom Trough via a gas gathering system and pipeline to Brisbane and from the Denison Trough, where gas is transported by pipeline to Gladstone. The most prolific petroleum producing units in the Taroom Trough are the Showgrounds Sandstone (Triassic), Precipice Sandstone (Jurassic) and Evergreen Formation (Jurassic). In the Denison Trough to the north, the most significant reservoir is the Aldebaran Sandstone, where over fifty percent of the remaining gas reserves in the Denison Trough are found. Gas production from many of the gas accumulations on the western flank of the Taroom Trough is currently in decline. Total remaining gas reserves for the western flank of the Taroom Trough have been estimated at 2298 million cubic metres (as at 30/06/96, QDME), while in the Denison Trough, 2931 million cubic metres of recoverable gas is thought to remain in the identified accumulations in the Bowen Basin sequence. Moonie, the largest oil accumulation found in the Bowen and Surat Basins to date, was discovered early in the exploration history of the two basins (1961) and provided the initial stimulus for an expanded exploration effort in the area. The oil at Moonie is trapped in a large, anticlinal closure on the upthrown side of a major, north-south trending thrust fault on the eastern margin of the Taroom Trough. 'Look-alike' plays to Moonie, (associated with the thrust faulting on the eastern basin margin), have been drilled with only limited success. A number of small oil accumulations have been identified, both to the north of Moonie on the same structural trend and on the western flank of the Taroom Trough. However, the Moonie accumulation appears to be unique and it is likely that future oil discoveries in the Bowen and Surat Basins will be small (less than 50 megalitres). The oil from Moonie is produced directly into the Jackson-Moonie oil pipeline while the oil from many of the small producing oil accumulations on the western flank of the basin is trucked to the Moonie facility. The Moonie accumulation is nearing depletion, with only 173 megalitres of recoverable oil remaining from initial reserves of 3859 megalitres (as at 30/06/96, QDME). In spite of this, over sixty percent of the remaining, identified oil reserves in the Bowen and Surat Basins are reservoired at Moonie.