Thermal Analysis of the Wellbore System During Drilling Operations Using an Improved Drilling Simulator

Abstract

Abstract Prediction of the wellbore fluids and formation temperatures during well construction is an essential step for efficient drilling operation. This work presents the applications of an improved comprehensive drilling simulator for predicting the wellbore system temperature during the drilling process. A fully transient numerical model of the wellbore temperature is developed for drilling and geothermal production applications. The model describes the dynamic behaviour of the thermal state of the wellbore during circulation, drilling and static conditions. The developed model is successfully implemented with the commercial virtual drilling simulator through an application programming interface (API) provided by the simulator. The model is capable to predict the temperature of the wellbore fluids, drill string, casing, cement, and rock formation with variable properties in real-time. This implementation allows the coupling of the thermal model with other physical models, which leads to more advanced and realistic simulations. The model is assessed and validated through a direct comparison with field data. The data is acquired during the drilling of a geothermal well located in the Hanover area in Germany. The results showed a good agreement between the predicted outlet fluid temperature and the measured one. Furthermore, an analysis of the effect of various parameters on the wellbore system temperature is performed. These parameters include drilling parameters such as weight on bit, bit and drill string rpm, circulation rate and drilling rate, in addition to the wellbore geometry parameters such as wellbore radius, casing and drill string sizes. This analysis showed the impact of these parameters on the wellbore temperature profile including the critical areas such as the casing setting point and bottom hole assembly. This information may lead to enhancing the wellbore stability by monitoring the thermal stresses, especially in high-temperature wells. Moreover, predicting the drill bit temperature can result in increasing the lifetime of the bit by adjusting the operating conditions to keep the bit temperature within the specified range. Based on these results, the enhanced drilling simulator with the transient temperature model showed to be a suitable tool for effective well planning.