In recent years, methods of classifying and clustering objects have begun to be widely used when solving problems in oil and gas field theory and practice. The mentioned methods are usually used when working with information arrays both in enterprises (large and medium-sized) and in various fields of scientific activity. It should be noted that when carrying out cluster analysis, the quality of the results needs to be assessed. This paper presents the results of studies that analyze and evaluate the severity of such a complication in well drilling as mud loss. As is known, its main result is the lost circulation. In this work, cluster analysis based on the petrophysical characteristics of the section was used to identify lost circulation zones and classify them by severity (intensity). The entropy value was calculated to determine the quality of cluster analysis, which should tend to a minimum. As a result of assessing the quality of clustering, a value of 0.23 was obtained, which allows us to judge the fairly high quality of the cluster solution.