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What is the potential size of a fractured carbonate reservoir at Matuku?

If the Tikorangi limestone is fractured then the most obvious cause of fracture is possibly associated with movement on the local fault system that surrounds Matuku. The area enclosed by this fault system is some 200km2, however this area will not necessarily represent the limits of fracture and therefore the potential field size.

The problem then is to identify the limits of the fracture area as this will describe the stratigraphical extent of any potential hydrocarbon accumulation and yet at the same time show that the fractures do not extend into any features that will allow the hydrocarbon to escape. For example, if fracture extended to the Whitiki fault in the east it is possible that this fault would not provide an adequate seal and hydrocarbon would merely be migrating along the Tikorangi fracture field and passing out into the upper sands of Maui.

Nevertheless it is clear that we could be looking at a quite sizable hydrocarbon accumulation within a fractured carbonate reservoir - if in fact such a reservoir does exist somewhere within the locality of Matuku. At Matuku the limestone is perhaps about half the depth of the limestone interval at Waihapa/Ngaere and ultimate recovery of oil from this field was about 1mmbbl/km2. Therefore on a prorata basis the 200km2 enclosed area at Matuku as above is suggesting 100mmbbl. Of course, the actual area of fractured carbonate that is contained within some potential stratigraphic feature remains entirely uncertain.