Azimuth ambiguity elimination for borehole imaging using 3D borehole RTM scheme

Junxiao Li, Kristopher A. Innanen, Guo Tao, Laurence R. Lines, Kuo Zhang

The azimuth ambiguity has been an issue ever since the beginning of borehole acoustic reflection imaging. The reason of this imaging authenticity indistinguishability occurring not only in the borehole reflection imaging but also in seismic imaging is due to the intrinsic defect of the 2D data processing that treats recorded real data as a 2D data set, which inevitably leads us to take for granted that the data (which actually may be from every possible direction of underneath formations) is only from one direction. The 4-C dipole acoustic well logging technique is then applied to solve the azimuth ambiguity problem by analyzing the azimuthal information contained in the recorded shear wave signals. Thereafter, the migration procedure is carried out to get the imaging result. In this paper, the 3D reverse time migration in the borehole environment is proposed and applied in the simulated data set with a similar source and receiver system as sonic scanner tool developed by Schlumberger. The result shows the directional information of the structures outside the borehole can be directly obtained.