Methods for characterizing and evaluating well integrity using unsupervised machine learning of acoustic data

Abstract

Methods and systems are provided that characterize and evaluate well integrity of a cased well using unsupervised machine learning of acoustic data. Sonic waveform data for acoustic signals received by the receiver array of a sonic logging tool is collected and processed to determine a high-dimensional representation of the sonic waveform data. The high-dimensional representation is input to an unsupervised machine learning system to determine a low-dimensional representation of the sonic waveform data. A clustering method is applied to the low-dimensional representation to identify a set of clusters therein. At least one well integrity property of the depth interval of the cased well is determined based on the set of clusters. In embodiments, the at least one well integrity property can characterize cement condition in an annulus of the cased well as a function of azimuth and depth and can be used to evaluate cement integrity in a depth interval of the cased well.