Other Planning LL with INEOS

Fat Canyon (6306/3-1 S) – Top hole

What happened:

Hit shallow gas on drilling pilot hole.

What was planned:

After running conductor, drill 9 7/8″ pilot hole to +/- 1050m. Open hole to 17 1/2″. Run 13 3/8″ x 20″ casing to pilot hole depth.

What was learned:

The contingencies of kill mud volumes, slimhole 9 7/8″ BHA, rig procedures and drills, 20″ casing were all well prepared for.
However the logistics of “what to do next” i.e. managing the mud volumes required to safely attempt to drill ahead with the rig’s resources are hard to manage. Whether 17 1/2″ or 26″ hole, the mud volumes required to drill ahead with “mud caps” are huge.

What actions are required:

When planning the well, irrespective of geological uncertainty of shallow gas, have contingencies for drilling ahead if shallow gas encountered with either RMR or a “mud boat” alongside fully loaded with cheap weighted PAD (Pump And Dump) mud explored, costed and screened as either viable or non-viable.
This is the second time in less than 18 months where I have been on board for an exploration well offshore Norway where shallow gas was prognosed as a “low probability”.