Compensation of magnetic influence in a mwd system

摘要

The present disclosure provides a downhole tool that includes a magnetometer and a nuclear magnetic resonance (NMR) sensor. One more compensating magents are provided on the tool to cancel or offset the effect of the magnetic field of the magnets of the NMR sensor on the magnetometer measurements made during drilling of a wellbore. The compensating magnets may have the same magnetic field characteristics as the sensor magnets and may be made of the same material.