Answer
The chances of that scoop from the pacific containing even one molecule of the ancient water are very high.
Work Step by Step
Given that one mole of water is $6X10^{23}$ molecules and the volume of all the oceans converted to cubic centimeters is $1.5X10^{24} cm^3$, there would be 0.4 average that there would be an ancient water molecule in that scoop of the pacific. More specifically, the average would be 0.4 per $cm^3$, which would be 7.2 molecules in 18 g of the Pacific. This can be determined by the equation $6X10^{23}/1.5X10^{24}$.
