Integration of MPD with Managed Temperature Drilling (MTD) for Geothermal and HPHT Drilling

Abstract Managed Pressure Drilling (MPD) enhances drilling efficiency and safety by enabling precise control of wellbore pressure. However, in the drilling of high-pressure-high-temperature (HPHT) and geothermal wells, downhole tool failure due to elevated temperatures necessitates active and efficient management of downhole temperature. To address this challenge, a physics-based pressure-temperature management framework integrating a Reduced Drift Flux Model (RDFM), thermodynamic equations, and proactive control algorithms is developed in this work to capture the transient behavior of both downhole pressure and temperature and achieve real-time control of these parameters. The Sparse Identification of Nonlinear Dynamics (SINDy) method is applied to synthetic datasets generated from a high-resolution RDFM, preserving the underlying pressure-temperature physics. Furthermore, a multivariable control framework based on Model Predictive Control (MPC) is developed using the reduced-order model to simultaneously regulate bottomhole pressure (BHP) and maintain the desired bottomhole circulating temperature (BHCT) by manipulating choke opening, mud flow rates, and inlet mud temperature. Simulation results demonstrate that the proposed control framework can effectively maintain the BHP within the narrow pressure window while satisfying the downhole temperature constraints.