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Friday Haggler

A reminder of last Friday’s Haggler

The 12-1/4” hole section has just been drilled to TD (4429m MD) after the top of the sandstone reservoir was picked using LWD resistivity. The driller picked up off bottom and shut down rotation and circulation to do a flow check, while picking up to 310 klbs and slacking off to 150 klbs to keep the string moving. After the flow check the pipe is stuck, although full unrestricted circulation is possible and the bit is one single off bottom.
What happened and what should the driller do next (see options below)?

a) Pull to the maximum allowable overpull
b) Torque and slump
c) Handover the brake to the AD and pretend nothing is wrong
d) Shut down circulation and pull to the maximum allowable overpull

The Answer

Short Answer: Differential sticking and option d. However, most folk wanted a bash at torque and slump first (option b)

Long Answer: After penetrating the reservoir the pipe was reciprocated but it was not breaking over (picking up to previous PU weight and slacking off to previous SO weight – stretching the pipe). The BHA was therefore stationary across the permeable interval.

First response by the driller is normally torque and slump, which assumes the last movement was pulling into a restriction and that weight can be effectively transferred down to the stuck point. However, on a high angle well (the FF spread on the drag plot indicates it is a high angle well as do the SO curves that show buckling occurs at higher FFs) where SO in hole is not possible without rotation (as shown by the lack of SO weights on the drag chart) then your best bet is overpull with torque (within combined loading limits) and trying to fire the jars up. Shutting down the pumps or at least reducing circulation will reduce the ECD and therefore overbalance. Preparing a PRA pill would also be wise.

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