Modelling and numerical calculation of multiphase transport in deep drilling technology

The aim of the present project is to investigate the transport of particles in viscoplastic fluids using numerical methods and to aggregate derived findings in technical models. The background of the project is the transport of drill cuttings in deep drilling technology. Deep drilling technology is of great importance for securing the future energy supply. This concerns the use of fossil fuels as well as the extraction of geothermal energy. In both cases, the drilling process is the most important cost parameter, so that efficient, time-optimised process control is required. For ecological reasons, the integrity of the borehole is of particular importance in order to avoid undesired leakage of drilling fluids into the geological subsurface. The above objectives can only be achieved through model-based, systematic optimisation and automation of the drilling process. From a fluid mechanics perspective, the transport of cuttings out of the borehole is important. This must be quantified in suitable models for the conditions typical of deep drilling, i.e. high pressures and temperatures, the use of drilling fluids with complex rheology and over distances of several kilometres in variable environmental conditions.The present approach is based on state-of-the-art computational techniques for the analysis of particle transport in fluids. These methods will be extended as needed and validated against experimental data. This will make it possible to quantify previously unrecorded effects of secondary flows or the rheology of the fluid on particle transport. In the project, the work of the last few years in the applicant's group and at Clausthal University of Technology will be continued and expanded.The present project will contribute to clarifying and better quantifying the hydrodynamic processes for the deep drilling process. There are numerous parallels to other fields of technology where similar questions arise. Examples are fluidisation, filtration, paper processing, wastewater treatment or food technology.