A Study on Geological Boundary Imaging Ahead of Drill Bits During Logging While Drilling Based on Linear Phased Array Acoustic Transceivers

Anticipating geological formations prior to the advance of the drill bit is essential for optimizing drilling operations. This article introduces a novel design employing linear phased array acoustic transceivers to image subsurface structures ahead of the drill bit. The phased array, integrated into the drill collar as a transceiver device, scans the reservoir in a specific azimuth and utilizes echo signals to reconstruct the structure and properties of the underlying formation. To mitigate the impact of borehole model waves, we propose a semiblind source separation technique that isolates the predrilled boundary echo signal through residual error signal energy analysis. Numerical experiments demonstrate that the sector scan effectively visualizes the predrilled formation, with the reflected echo from geological boundaries enhanced by coherent accumulation using the receiving phased array. These results validate the feasibility of this method in identifying and alerting to predrilled formation boundaries.