Actually, even with new finds, total North Sea output is in decline. Even under a peak oil scenario, with total oil production falling, new supplies must be found to replace fields that are depleted. The question is not whether we discover new oil. We must. The question is whether the capacity of newly found reserves is replacing the capacity of depleted reserves.
How can you make this claim in light of the fact the article clearly states the size of the find is not yet known?