Three-dimensional expansion processing method and system for borehole transient electromagnetic method

The invention discloses a borehole transient electromagnetic method three-dimensional expansion processing method and system, and the method comprises the steps: collecting the measurement information of each measurement point in a to-be-measured borehole, and the measurement information comprises secondary field induced electromotive force and a roll angle; aiming at each measuring point, taking a roll angle as an abscissa and a secondary field induced electromotive force as an ordinate to establish an expansion graph; when the electromotive force signal in the expanded drawing is negative response, the electromotive force signal is converted into positive response according to a roll angle conversion formula, and measurement conversion information of each measuring point is obtained; according to the method, the processing problem of detecting the negative induced electromotive force response through the borehole transient electromagnetic method is fundamentally solved, the obtained measurement transformati