| 摘要 |
A method for determining the direction of a borehole during drilling comprises determination of inclination angle .theta. and highside angle .PHI. from gravity acceleration ~ measurements and determination of azimuth angle .PSI. from magnetic field ~ measurements, the determinations being carried out in conventional XYZ-and-NEV coordinate systems coupled by Euler-angle coordinate transformations. In particular ~ and ~ are measured at least at two borehole depths such that ~i .noteq. ~i+1, .PSI.i and .PSI.i+1 being calculated from ~ i = [~i]T [.theta.i]T{[.PSI.i]T ~ e} + ~ P and sin2.PSI.i + cos2.PSI. i= sin2.PSI.i+1 + cos2 .PSI.i+1, with i as number of measurement, ~ e as local earth magnetic field, and B p as perturbating magnetic field. As a result perturbation magnetic fields, for example caused by hot spots or nearby magnetic steel components in the drilling or logging string nearby the B-measuring device, are determined accurately.
|
