RECENT CONTRIBUTIONS TO PALAEOZOIC GEOLOGY IN THE SOUTH CANNING BASIN, WESTERN AUSTRALIA
The APPEA Journal
6(1) 105 - 109
Published: 1966
Abstract
Regional aeromagnetic surveys of the interior Canning Basin, completed in 1964, showed a distinct pattern of deep sub-basins separated by relatively shallow platforms south of the Broome Platform. Seismic work on the margins of two of these basins-the Parda and Kidson Sub-basins--resulted in three drill sites. In 1965 WAPET drilled Sahara No. 1 in the Kidson Basin (suspended T.D. 6,956 feet in salt); Parda No. I near the southern margin of the Broome Platform (T.D. 6,256 feet in Basement); and Willara No. 1 in the Parda Basin (T.D. 12,806 feet in Ordovician). This paper is a preliminary report of the section encountered in these three wells.No commercial quantities of oil or gas were encountered in the recent wells but they have added significantly to our knowledge of the South Canning. The three major contributions to our stratigraphic knowledge are:
The Ordovician thickens from about 2,000 feet to over 6,500 feet basinward from the Broome Platform (Parda No. 1) southward to the Parda Basin (Willara No. 1). This demonstrates that the Parda Basin was a depositional basin (mainly shale) during the Ordovician. An oil show was noted in the Goldwyer shale unit in Parda No. 1.
A Redbed-Evaporite sequence with major amounts of rock salt occurs between the Middle Ordovician and the 1liddie Devonian. This sequence has not been previously encountered in the Canning Basin.
The Sakmarian Grant Formation of the Lower Permian which is typically glacial and fluvioglacial includes an upper marine shaly member in two of the recent wells (Sahara No. 1 and Willara No. 1). It is suggested that an arm of the sea extended across large portions of the South Canning while adjacent areas were subjected to continental glaciation. A small hydrocarbon show was recorded in the Upper Grant in Willara No. 1.
The significance of these drilling results to oil and gas exploration can be summarised as:
A major Ordovician marine basin with rapid thickening and carbonate-shale facies changes in the South Canning presents attractive hydrocarbon prospects.
The presence of widespread evaporites as an indicator of restricted marine conditions and as a seal to prevent the escape of hydrocarbons is a favourable factor.
The presence of a marine shaly unit with porous sandstone beds in the Permian Grant Formation presents an additional shallow drilling target in the South Canning, especially in the light of the show encountered in Willara No. 1.
https://doi.org/10.1071/AJ65017
© CSIRO 1966
