Estudo numérico do escoamento bifásico líquido-sólido em poços de petróleo horizontais

Abstract

During the drilling of wellbores, cuttings originated from the fracture of rocks must be carried away from the annular space formed by the bore walls and the drill pipe. Recently, the extraction of oil in extended reach drilling wells (ERD) has become common in the Brazilian pre-salt. The horizontal orientation, however, induces the formation of an agglomerate of particles in the bottom of the annular space, known as particle bed. The bed is hazardous to the system, because it results in undesired effects such as a higher power demand to clean up the well, early bit wear and stuck pipe.. In order to have a more efficient wellbore cleaning, it is necessary to understand how the operational and geometric parameters affect the outcome. Aiming to understand the relative importance of the parameters, numerical simulations of solid-liquid flows are made.The fluid phase is treated via an eulerian framework and the solid phase through a lagrangian framework, with the aid of a DDPM-DEM coupling. Validation tests for a single particle were performed and compared with experimental data available in the literature. Simulations of flows in horizontal annular spaces are carried out for several values of mud flow rate and cuttings diameter. Results show that an increase in the flow rate is of great importance in order to obtain a better cleaning of horizontal wellbores. On the other hand, when the cuttings diameter changes, the efficiency of the cleaning process remains unchanged. Correlations for development length and pressure drop are given for the whole range investigated.