Adjacent Borehole Imaging Method Based on Acoustic Remote Detection in Shallow Unconsolidated Formations

In order to prevent drilling collision in significantly unconsolidated formations and describe borehole trajectories, a dipole P-wave imaging method for adjacent boreholes was developed based on acoustic remote detection logging technology. First, scattered full-wave fields of adjacent wells that were excited by dipole acoustic sources from wells were simulated based on the finite difference method, and the amplitude and azimuth characteristics of different scattered waves were analyzed. Then, the influence of non-coplanar wells on the amplitude and arrival time of scattered waves was studied. Finally, the reliability of dipole P-wave imaging for adjacent wells was verified by a model test of two wells and actual logging data measured in the field. The results indicated that the dipole P-wave was superior to S-wave in adjacent well imaging in significantly unconsolidated formations, and the clearest azimuth after four-component rotation was the azimuth of the target well. In addition, adjacent well imaging was not affected by non-coplanar wells. It was shown by the study results that the dipole P-wave imaging method for adjacent boreholes can provide a new technical tool to prevent drilling collision in shallow unconsolidated formations and describe borehole trajectories.