28 July 2005
Another question regarding a well to be drilled offshore Wales later
this year. For 30" structural casing, we will be using squnch joint
connectors with an OD of 33.75" and 34.38". In the past, we have had
some trouble getting these connectors in a 36" hole due to
insufficient clearance in ledgy formations. Does anyone have
experience with modifying either 36" or 42" hole openers to 37" or
38" to provide more clearance? If so, who provided the hole openers?
In "ledgy?" Northern Europe top hole formations, perhaps one of the
greatest risks are instantaneous doglegs resulting from the non-
useable wellbore drilled that often results directly from inadequate
BHA design. e.g. That's why a 34.38" OD does not fit into a straight
vertical 36" wellbore ID.
Therefore running a BHA that is stiffer and properly stabilised will
alleviate this (Ref Heidrum platform where 60 conductors were batch
set in a very difficult top hole (glacial drift (boulder/cobble
beds!) ) stratigraphical sequence.
Finally Drillco produced a document in the 70's entitled 'how to
drill a useable hole'. This supports statement made above. I
produced an electronic copy of this in 2004 for SPE TIG distribution-