Drilling

Faster Rate of Penetration in Hard Chalk: Proving a New Hypothesis for Drilling Dynamics

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.

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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.

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