Hydrocarbon Generation by the Rocks of the Bremer Formation in Adjacent Areas of the Nonvolcanic Passive Margins of Australia and Antarctica

Resumo

This paper analyzes differences in the history of hydrocarbon (HC) generation by the rocks of the Bremer 1–6 formations in adjacent areas of the nonvolcanic passive continental margins of Australia and Antarctica. The problem is examined by the example of the numerical reconstruction of the burial and thermal history of two sedimentary sequences of approximately equal thicknesses: the section of well 19–2012 in the Bremer sub-basin of the southwestern margin of Australia and the section of pseudowell 2 in the adjacent area of the passive margin of Antarctica on seismic profile 5909 across the Mawson Sea. The asymmetry of Gondwana rifting in the region of interest resulted in asymmetry in the tectonic structure and development of adjacent areas of passive margins and, as a consequence, significantly different histories of HC generation by the rocks of the Bremer 1–6 formations in these areas. Modeling indicates that the rocks of the Bremer 1 and 2 formations are mainly gas-prone in the Bremer basin and can become oil-prone in the Mawson Sea region of the Antarctic margin. In contrast, according to modeling, the rocks of the Bremer 4 and 5 formations generate a minor amount of HC in the well 19–2012 area of the Bremer sub-basin and considerable amounts of heavy and light oil in the adjacent Antarctic margin area at pseudowell 2 in the Mawson Sea.