Gyrostab Project : The Missing Link Azimuth and inclination mastered with new principles for standard rotary BHAs.

摘要

Trajectory control in directional wells essentially requirescontrol of only two parameters: well inclination and wellazimuth. However, always tighter economic constraints andthe increasing complexity of well trajectories keep settinghigher challenges that demand purpose-designed and costefficientsolutions.The standard rotary drilling tools first used for directionaldrilling gave poor trajectory control. The subsequent additionof Variable Gauge Stabilizers (VGS) addressed only one sideof the problem: control of inclination. Both inclination andazimuth were then mastered with Steerable Motor technology,which rapidly gained supremacy. However, there has beendiscontent with Down Hole Motors (DHM) for a variety ofproblems ranging from Rate Of Penetration (ROP), slidingmode, friction and lost-in-hole incidents to well tortuosity andhole cleaning. Jumping to rapid conclusions, one might thusthink that that motors will soon be replaced by RotarySteerable Systems (RSS).This evolution of directional drilling techniques has led to thedevelopment of more and more sophisticated tools integratingelectric and/or hydraulic power systems and loads of“embarked” electronics. The related expenditures have drivenservice costs to levels that are very often prohibitive forstandard drilling programs and/or environments.This paper introduces an innovative technical solution thatmakes it possible to control both azimuth and inclination usingstandard rotary Bottom Hole Assemblies (BHAs). It is basedon a patented concept permitting command of Bit & BHAwalking tendencies through downhole friction management atthe level of a “strategic” string stabilizer.