Mitigate Risk When Drilling Mature Offshore Fields
Directional casing while drilling (DCwD) uses a retrievable BHA to steer the wellbore in casing-while-drilling operations. This provides a unique solution to the lost circulation and wellbore stability problems commonly encountered during mature field well construction offshore. The steerable, retrievable BHA makes DCwD a viable alternative to conventional directional drilling in these fields.
The DCwD techniques—developed through close collaboration between Schlumberger and TESCO under the sponsorship of ConocoPhillips—may reduce the number of casing strings needed because they improve wellbore quality. In addition, DCwD rotation actually strengthens the borehole wall because of the plastering effect, also referred to as smear or stress cage, that occurs in the narrow annulus.The techniques were developed for hole sizes between 6 and 17 1/2 in.
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