A borehole compensated 3D reverse time migration method for monopole source acoustic reflection imaging logging

Three-dimensional borehole reverse time migration (3DBRTM) offers superior theoretical imaging fidelity and enables detailed delineation of geological structures adjacent to the borehole. However, when applied to remote detection acoustic reflection imaging logging, 3DBRTM using a monopole source suffers from substantial computational inefficiency. Furthermore, the imaging results are significantly contaminated by strong borehole-guided waves. These limitations have substantially hindered the broader application of 3DBRTM. To address these challenges, a heterogeneous CPU–GPU parallel computing algorithm is developed that substantially accelerates 3DBRTM computations. Leveraging GPU-based parallelism in conjunction with Hybrid-PML absorbing boundaries, the algorithm achieves several-fold speedup in 3D elastic wave propagation compared to conventional OpenMP implementations. To mitigate borehole-related imaging artifacts, the borehole compensation method based on theoretical waveform inversion is proposed. This technique preserves reflected signals while effectively suppressing borehole-guided wave interference in 3DBRTM. Compared to conventional RTM and reflected-wave RTM, the proposed borehole-compensated 3DBRTM delivers enhanced imaging clarity, superior noise suppression, and higher spatial resolution. Numerical examples demonstrate that the method enables high-fidelity imaging of inclined, intersecting, and complex fracture networks, accurately revealing fracture morphology and orientation. This study provides a computationally efficient and accurate framework for 3DBRTM in remote acoustic reflection imaging, laying a foundation for its application to complex fracture network characterization and offering valuable recommendations for fractured reservoir evaluation.