Study on the Applicability of Downhole Sonic Gas Invasion Monitoring Acoustic Models

In deepwater drilling gas invasion monitoring, existing conventional platform monitoring methods face issues such as delayed warning times and low monitoring accuracy. Downhole drilling-with-while-logging acoustic gas invasion monitoring, characterized by its non-intrusiveness, timeliness, and stability, has emerged as one of the directions for improving gas invasion monitoring during drilling operations. To explore the mechanism of downhole sonic gas invasion monitoring, this paper conducts a study on the applicability of acoustic propagation models in multiphase media. We compared five mathematical models: the EACH model, McClements model, Urick model, HT model, and BLBL model. Each model’s computational form and parameter selection range were described, and we investigated the propagation velocity and attenuation of sound waves in multiphase flowing media within the wellbore. An analysis of the suitability of each model under downhole conditions was provided. We propose a method that combines the HT model with the BLBL model for downhole acoustic propagation calculations. The research findings provide a theoretical foundation for further exploration of sonic gas invasion monitoring during drilling operations and offer valuable insights for subsequent engineering applications.