The after-drilling single-well imaging technique (SWI) has been successfully accepted by industry operators, especially the dipole SWI, it is becoming a valuable and challenging task to extend this technology into acoustic logging-while-drilling (LWD) measurement. A combined quadrupole-dipole measurement mode (CQD) is proposed to be applied in acoustic LWD for single-well imaging (SWI), which allows for the treatment of acoustical isolation, and might be easy to be made in quadrupole LWD practice. Starting from the SH and SV-wave radiations from an LWD quadrupole source and the dispersion and excitation properties of LWD quadrupole and dipole sources, we theoretically demonstrate the feasibility of the CQD in LWD SWI. Our results demonstrate that (1) the azimuth ambiguity can be eliminated by the amplitude difference of the hybrid datum, (2) a greater swing angle corresponds to high reflected wave amplitude, and (3) wave modes are characterized by the quadrupole cutoff frequency in LWD SWI.
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