Determination of azimuthal offset and radius of curvature in a deviated borehole using periodic drill string torque measurements

摘要

Methods and apparatus for determining the direction of borehole azimuthal offset and the borehole radius of curvature. Rotation rate of a borehole assembly is measured and mathematically converted into azimuthal torque imparted to the borehole assembly. Relative azimuthal offset is determined from variations in azimuthal torque over a rotation cycle of the borehole assembly. Relative radius of curvature is obtained from the magnitude of azimuthal torque over a rotation cycle. Relative azimuthal offset is converted to true azimuthal offset using an independent reference angle measurement. Relative borehole curvature is converted to true radius of curvature using a calibration constant determined in known borehole conditions.