Assessment of Severity Degree of Lost Circulation During Well Drilling Based on Integrated Geological and Technological Information Using Fuzzy Cluster Analysis

The paper concerns the study of the main factors that play an important role in the occurrence of such complications as lost circulation and loss prediction using fuzzy cluster analysis. The paper presents the results of studies of the distributions of the petrophysical characteristics of the reservoirs and their influence on the occurrence of lost circulation, which made it possible to substantiate the tasks, ways to solve them and the nature of the initial information necessary for this; based on the methods of mathematical statistics and fuzzy cluster analysis, an assessment was made of the mutual correspondence of geological conditions and the severity of lost circulation, which made it possible to justify the interval, the severity of lost circulation and the choice of a way to deal with them. A classification scheme allowing early prediction of lost circulation using linguistic rules based on the “if…, then…” principle, compiled based on the results of fuzzy cluster analysis has been proposed. In general, the results of the studies to which the article concerns make it possible to assess the influence of geological conditions on the nature of lost circulation in conditions of lack of information, to establish a mutual correspondence between the indicators of the petrophysical properties of rocks and the intensity of lost circulation based on fuzzy cluster analysis. It is very important for early diagnosis of lost circulation and accident risk assessment.