Modeling and Simulation of Gas Kick Behavior in Deviated and Horizontal Wellbores Under Variable Pressure Conditions

Abstract

Gas kicks represent one of the most critical transient events in well control during drilling operations, particularly in deviated and horizontal wellbores where complex hydrodynamic and transient multiphase effects arise. As modern field development increasingly targets extended-reach and unconventional reservoirs, the interplay of variable bottom-hole and surface pressure programs with gas migration and annular hydraulics requires detailed modeling and simulation. In such wells, non-vertical orientation modifies the effective hydrostatic head, enhances segregation and slip between gas and liquid phases, and alters the response of control systems such as chokes and managed pressure drilling equipment. This work presents a comprehensive modeling and simulation framework for gas kick behavior in deviated and horizontal wellbores under variable pressure conditions, combining transient multiphase flow modeling with numerical analysis and data-driven interpretation. The model incorporates depth-dependent inclination, realistic annular geometry, compressible gas behavior, and dynamic surface pressure control laws. Transient simulations are performed for a range of kick intensities, well inclinations, and pressure schedules in order to characterize gas migration, surface response, and operational envelopes. Additionally, synthetic simulation data are used to train machine-learning models for early detection and characterization of gas kicks based on surface measurements. The study emphasizes the interaction between physical modeling and data-based interpretation and explores the sensitivities of predicted kick behavior to flow, thermodynamic, and operational parameters in deviated and horizontal wells subject to variable pressure profiles.