Stokes Bay 1 has two well defined zones of interest. The first zone of interest is in the Anderson Formation sandstones where there is a probable five metres net oil reservoir. Although this interval appears to be relatively poor quality reservoir, it needs to be tested because it has the potential to be a significant oil reserve. The second zone of interest is the Nullara Formation reefal interval. In contrast to the Anderson, where the issue is reservoir quality, this zone is an excellent reservoir where we lost over 10,000 barrels of drilling mud while we were drilling the well. Although we had no drilling fluid returns and hence don’t know what is in the reservoir, pressure data indicates potential for a significant hydrocarbon column. We plan to test this reservoir again in the dry season when the weather allows us to return to the site.
It is possible that the best way of evaluating the Nullara is by redrilling this interval under-balanced using a coiled tubing unit like we did for Beharra 4 with spectacular results. This would get around the problems of the massive losses in such a porous and permeable interval and give us a definitive result.
Valhalla
The data we obtained during drilling indicates there is an approximate five meter oil column at a depth of 1770 metres in the Anderson sandstones based on oil shows, mud gas and electric logs. In the Upper Laurel Formation clastic section, high mud gas and cut and fluorescence over the interval 2130 metres to 2180 metres suggests the presence of gas charged sandstones, and there is similar evidence associated with the Lower Laurel Formation clastics over a gross interval of about 200 metres below 2700 metres well depth.
