Coiled tubing conveyed drilling and milling operations have over the last years been improved by several new inventions. One such invention is the Anti Stall Tool (AST). The Anti Stall Tool controls the force applied to the bit relative to torsion and prevents the bit from stalling under load. This way the AST technology provides improved operational flexibility and tolerance for abrupt weight transfer typical for operations in extended reach and high angle wells.

Statoil has conducted a qualification program involving the new invention and has found it to meet the objective of significantly reduced stall-outs. Additional advantages are improved bit and motor life and fast penetration. The AST is now in the early commercial stage with 8 field operations on the record and toolsizes ranging from 3" up to 4 ¾" OD. This document summarises the findings from the qualification program and the first field operations.

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