Strike AWE Mitsui Comparison, page-87

DP,

FYI.....gas has density, therefore exerts a hydrostatic head from surface on the reported reservoir pressure of 9700 psi at or around 4294m TVD.

Dry methane gas has gradient of approximately 0.08 psi/ft therefore the maximum shut in pressure at the wellhead is more likely to be in the vicinity of 8,500 psi on a fully mud evacuated wellbore.

So the buffer is higher than 300 psi and in most situations, full evacuation to only gas in the wellbore is also unlikely.

Also, FYI, there are no 13 5/8" 15K drilling BOPs in Australia and even if there was, I would expect them to be too large to fit within the available space in the substructure area of an ADR 1500 (Ensign 970).