some feedback needed on the below.
The situation is the following: after casing off the well with 20" casing, we need to drill a pilot hole for FE purposes and then open up the hole to 17" with a separate run. The well is vertical at this point.
We are looking at 2 options to avoid a dedicated run:
I personally dont like much the first scenario, as cement would be falling down on the BHA- which should be ok for drilling, considering the clearances, but could cause issues for the wireline run thereafter.
The second option could be achievable, but we are still confirming availability of the tools in country.
In a previous life, I was part of a group that did something highly similar to what it appears you have planned: On a fairly high-cost jack-up, using staged fixed-cutter reamers, the hole was opened from 8-1/2" hole to 16", from ~3,500' BRT to ~4,740' BRT, at ROPs ranging from 10 fph to 50 fph (this was a cored and logged section).
The 'only' issue of significance was a jar twisting off, which was successfully fished on the first try.
From memory, the failure was not attributed directly to the increased torque, though that was obviously a contributing factor. What the failure and subsequent RCFA highlighted was the jar vendor's lack of a predictive component replacement program. The vendor only, as pretty much all rental tool vendors do, replaced components detected as failing during the service interval. Unfortunately, the window of detection for components which are subject to fatigue failure is rarely in sync with the service interval (see attached presentation).
And yes, despite the high cost of the reamers and the fishing trip, the opening operation was considered a success.
Hope that helps,