Methods and systems for automated sonic imaging

Abstract

A method is provided for identifying and characterizing structures of interest in a formation traversed by a wellbore, which involves obtaining waveform data associated with received acoustic signals as a function of measured depth in the wellbore. A set of arrival events and corresponding time picks is identified by automatic and/or manual methods that analyze the waveform data. A ray tracing inversion is carried out for each arrival event (and corresponding time pick) over a number of possible raypath types to determine i) two-dimensional reflector positions corresponding to the arrival event for the number of possible raypath types and ii) predicted inclination angles of the reflected wavefield for the number of possible raypath types. The waveform data associated with each time pick (and corresponding arrival event) is processed to determine a three-dimensional slowness-time coherence representations of the waveform data for the number of possible raypath types, which is evaluated to determine azimuth position and orientation of a corresponding reflector, and determine the ray path type of the reflected wavefield. The method outputs a three-dimensional position and/or orientation for at least one reflector, wherein the three-dimensional position of the reflector is based on the two-dimensional position of the reflector determined from the ray tracing inversion and the azimuth position of the reflector determined from the three-dimensional slowness-time coherence representation. The information derived from the method can be conveyed in various displays and plots and structured formats for reservoir understanding and also output for use in reservoir analysis and other applications.