Estimation of temperature-dependent parameters using an integrated thermal and hydraulics simulator for drilling applications

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Fallah, AmirHossein

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Today, wells are being drilled under complex conditions with complex well geometries, under High-Pressure High-Temperature (HPHT) conditions, with risk of riser gas unloading in deepwater operations, while using Managed Pressure Drilling (MPD) techniques, etc., resulting in a clear need for comprehensive multi-phase hydraulics software to simulate these conditions. To address this need, a thermal model is developed and added to a previously developed multi-phase software package. The de-coupled thermal model is able to estimate the temperature in the drillstring and the annulus fluids, as well as the formation temperature adjacent to the well, using an advanced explicit finite volume approach integrated with a semi-implicit scheme used in the hydraulics model. The model solves the energy equation for the wellbore fluids, assuming that the gas and liquid phases are at the same temperature. Comprehensive thermal resistance networks are used to calculate the heat transfer between the annulus and drillstring fluids, the annulus fluid and the formation, and in the formation. For better accuracy, axial heat conduction in the drilling fluid and heat generation at the bit are accounted for. Results of the model are compared against the well-known Hasan and Kabir model and commercial software, showing a very good match for both steady-state and transient cases. To show the importance of accurate temperature estimations, offshore and onshore kick scenarios are simulated for different drilling fluids and kick control methods. Using a comprehensive heat transfer model, a user-friendly Graphical User Interface (GUI) and advanced numerical schemes makes this model a robust tool for estimation of the drilling fluid and the formation during complex well control applications. The developed model is able to estimate crucial parameters during complex conditions, such as the pressure and temperature profiles, increased pit gain and outflow during kicks, gas solubility and unloading at low pressures, and even temperature-dependent formation strength. The addition of the energy equation comes without loss of previous modeling capabilities of the hydraulics simulator, such as accounting for area discontinuity in the well and drillstring, non-Newtonian fluid rheology, MPD techniques, and arbitrary 3-D well trajectories


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