Page 39: of Offshore Engineer Magazine (Nov/Dec 2014)

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Drilling

Close collaboration: drilling with liner

By Mark van-Aerssen, Wintershall

Weatherford discusses how a collaborative approach

Noordzee B.V., Steven M. Rosenberg,

Ronald Wever, Ming Zo Tan, Alexandro helped in the planning and execution of a North Sea

Salinas, Moji Karimi, and Rex L. Winchell, drilling with liner operation.

Weatherford istorically, it has been stan- dard practice to use conven-

H tional drilling techniques as the go-to method of choice for drilling challenging wells. However, in some cases, this can lead to major dif? culties, such as catastrophic mud losses with resultant high-expense, non-productive time and even complete loss of the hole. Such a situation was facing an operator when drilling a new well in a mature ? eld in the southern sector of the North Sea.

The target of this new well is the virgin pressured Carboniferous reservoir in 3300mTVDSS with a pore pressure of 14ppg EMW (equivalent mud weight).

The Volcanics, a heterogeneous forma- tion consisting of around 15 lava ? ow sequences, separates the Carboniferous from the by production depleted shallower fan carbonate reservoir in 2500mTVDSS with a pore pressure of only 1.7ppg EMW. Above the fan car- bonates are overpressured shale forma- tions requiring mud weights of around 14.5ppg to avoid well bore stability issues. Figure