Research and Application for the Fine Identification Method of Lost Circulation Characteristics During Drilling

Lost circulation is a common downhole complex problem in drilling engineering, which severely affects the safety of drilling operation and drilling cycle. Fine identification of lost circulation characteristics is the key to effectively control lost circulation. Firstly, a new method of lost circulation zone identification based on the “comprehensive lost circulation index” was established by integrating logging, drilling, and geological data, analyzing the mechanical properties and physical mechanisms of the lost circulation zone, and using the weighting coefficient method. Then, the quantitative analysis method of the lost circulation characteristic parameters, such as the type and size of the lost circulation channel, leakage pressure difference, and lost circulation velocity were studied, and the calculation models were given, forming a new technology of lost circulation characteristic identification with multi-information fusion. The example analysis results showed that the processing results of actual well data in block X were basically consistent with the lost circulation characteristics of the actual lost circulation formation, such as the lost circulation zone, lost circulation type, and lost circulation velocity. The fine identification method of lost circulation characteristics comprehensively considers the main influencing factors of lost circulation, and can accurately identify the characteristics of the leakage layer, providing scientific guidance for the optimization and operation of leakage prevention and plugging technologies.