This is what was reported on Upstream last October prior to...

This is what was reported on Upstream last October prior to drilling:

"Knowledge Katti, chief executive of Custos and a Sintana director, said the partners estimated that Mopane could hold a mean, oil-in-place resource of “up to 10 billion barrels”, representing “one of the most significant and attractive known opportunities in the basin today.” “The significant prospectivity of Petroleum Exploration Licence 83 (which covers the two blocks) together with its relatively shallower water depth, position it to be one of the most significant and profitable developments in the Orange basin,” he added."

They must have been very confident to state that sort of number (which now appears likely to be surpassed). Hence, I believe multi-billion barrel estimates will be provided this year prior to drilling.