Simulation of a strapdown inertial continuous wellbore survey algorithm

To achieve the fast and precise survey goal, a strapdown measuring algorithm based on an existing gyrocompass survey algorithm is studied. It offers two survey modes according to the inclination, including the gyrocompass survey mode (inclination &le 15°) and the continuous survey mode (inclination > 15°). During the gyrocompass survey procedure, wellbore headings are determined at predetermined stations. During the continuous survey procedure, wellbore headings are measured while the tool is continuously moving through the wellbore. The initial heading reference of the continuous mode is determined using gryocompass survey technique. Mathematical models of the two survey modes are built. Finally, simulation tests are carried out to demonstrate the validity of the continuous survey algorithm. Measurement error is obtained by comparing the designed trajectory and the simulated one. Result indicates that it can take measurements of inclination 0°-90° and azimuth 0°-360° continuously, and enhance the whole survey efficiency greatly.