Slimhole in Deepwater

I'm looking into drilling a deepwater well offshore Ghana with known borehole stability and formation pressure issues. I'm looking at the option of drilling 14 3/4" hole through a zone of instability then setting 11 3/4" casing across this zone immediately above a high pressure zone; then drilling out in a suitable hole size for running
8 5/8" liner (or similar size) over the pressure zone. The subsequent section to TD would be 7 7/8" or 7 5/8" hole and as contingency in event of more pressure issues we'd have 6" liner with 5 3/8" or 5 1/8" hole drill-out.

Does anyone have experience with the following regime or could recommend a proven alternative:
14 3/4" hole/11 3/4" casing
10 1/2" hole/8 5/8" liner
7 5/8" hole/6" liner
5 1/8" hole

Graham Ross
Drilling Manager
Afren plc

2 Answer(s)

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