Improved Predictive Model for Surge/Swab Pressure Estimation using a New Simplified (NS) Model

Drilling operations are a high-cost, technology-dependent industry, and even minor cost-cutting measures can save millions of dollars. Non-productive time (NPT), which accounts for a significant portion of total drilling time, is primarily accounted for in drilling engineering by tripping operations. The surge and swab pressure during tripping operations can cause fluid loss, fluid influx, and blowout. As a result, accurate differential pressure estimation is critical to avoiding unexpected drilling difficulties and ensuring desired well stability and control. Existing models for predicting pressure imbalances caused by tripping operations did not incorporate the mud-clinging effect, and only a few automatic predictive models are available in the literature. Furthermore, available models do not accurately predict boreholes with low diameter ratios. This study proposes a newly developed model for predicting surge and swab pressure during drilling operations that take mud-clinging into account. The proposed model is a mathematical and analytical combination of momentum equations, fluid rheological equations, mud clinging properties, and frictional pressure losses equation. The dimensionless parameters obtained from the dimensional analysis are then used to develop a regression-based predictive model. With an R-squared value of 0.9889, an MAEP of 3.8%, and an RMSE of 298.8 Pa/m, the newly developed model is found to be accurate and reliable.