| 摘要 |
A first set of measurements is made when the apparatus is rotating, a second set of measurements is made when the apparatus is not rotating, the first and second sets are combined to obtain the directional measurements. The system 10 comprises at least one transmitter-receiver pair 14,12 wherein the transmitter has a magnetic dipole moment parallel to a longitudinal axis of the apparatus and the receiver has a magnetic dipole moment that is tilted relative to the longitudinal axis of the apparatus. The system also comprises an electronics module to excite the transmitter and detect a receiver signal to make a first set of measurements when the apparatus is rotating and a second set of measurements when the apparatus is not rotating, and a processor to combine the first and second sets of measurements to obtain the directional measurements. The method of combining measurements may contain the steps of computing harmonic coefficients, their ratios, and orientation angles. The processor may be positioned close to the drill bottomhole assembly (BHA) or may be at the surface 20, with a means also provided for transferring measurements to the surface. |
