They must be sitting right on top of the F Sand:
[NZO] The Matuku-1 well in PEP 51906 offshore Taranaki has been drilled to 3913 meters as of 6.00AM Sunday, 12 January 2014.
A 9 5/8 inch casing string has been set to 3409 meters.
The next operation is drilling ahead to a planned total depth of 4754 metres.