Large areas of the North Sea contain Cretaceous sediments, which form a massive hard layer of chalk that historically has presented a major drilling risk and expense to operators in the area. To mitigate such problems, a Norwegian operator gathered an integrated team to thoroughly analyze drilling records and lessons learned from previous offset wells and to re-engineer the drilling process. The positive results of this effort are described in the paper.
Introduction
In 2011, an operator initiated preparations for drilling a series of deep, high-pressure/high-temperature exploration wells in the Norwegian part of the central North Sea. Given the depth of the exploration objectives, the first three wells in the program had to penetrate a massive body of hard Cretaceous chalk belonging to the Shetland geological group.
