re: Ann: Apache farms-in to coastal and easte... Hi LagaThe...

re: Ann: Apache farms-in to coastal and easte... Hi Laga

The potential hydrocarbon source for Acacia Sandstone is not well known yet even though it has been associated with significant hydrocarbon shows in some wells including Looma-1 (Oil bled from vugs in core; Nambeet gas shows. TD: 2,535m)

Acacia sandstone is a member Willara Formation. You can see it on the stratigraphic graphic below. (I have made this graphic for myslef before). It also shows how the sea levels changed during the formations ages (Level Zero is today's level). The original graphic is quite big. You can download it from here: Source: Canning Basin Biozonation and Stratigraphy, 2009

Willara formation is commonly dominated by limestone, with subordinate dolostone, mudstone, and sandstone, of shallow marine origin. In some central and eastern areas, the Willara formation contains a significant central sandstone body, which is named as ‘Acacia sandstone member’. It is not know well in Kidson sub-basin as you can see on the graphic however it is known that it should be present at the central Kidson sub-basin. Even the proportion of sandstone increases to the southeast, where locally the Nambeet and Willara Formations are replaced by the Wilson Cliffs Sandstone.

Regarding to the hc source for Acacia sandstone;

the only definite idea is this; the Acacia Sandstone play relies on northward migration of Ordovician oil charge from a kitchen in the Kidson Sub-basin.

There are two possible potential source rocks for Acacia sandstone;

1) Upper member of Nambeet formation underlying the Willara formation, and

2) Goldwyer Formation overlying the Willara formation. (Yes, I've checked; the oil can migrate to the underlying formations. It is possible)