CFD Modelling of Observed Cuttings Transport in Oil-Based and Water-Based Drilling Fluids

Abstract

Abstract Cuttings transport has been a topic of research for many years. It has been observed that drilling fluids with similar properties according to the API standard can have significantly different behaviour with respect to the efficiency of cuttings transport. Oil based drilling fluids have been considered to be superior to water based drilling fluids when it comes to the hole cleaning, even if the fluid properties are equal as measured in accordance with API specifications. Despite this well-known fact, very limited studies are available in the literature to address this issue. Experimental studies with various oil-based drilling fluids and water-based drilling fluids were conducted in a 10m long flow loop under identical and controlled conditions. Further to understand the physics behind the observed differences in the cuttings transport efficiency, we have developed an Eulerian-Eulerian multiphase computational fluid dynamics (CFD) model using commercial software ANSYS FLUENT. Experimental values from the flow loop experiments are compared with the CFD model results. CFD model helps to fill the gap in the results, which could not be obtained using experiments. The experimental results confirm that the annular frictional pressure loss in a fully eccentric annulus are significantly lesser than the values predicted by using models available in the literature for concentric annulus. CFD model includes realistic conditions like eccentric annulus and flow velocities. CFD model is used to conduct simulations for a wide range of parameters and the obtained results will be used to develop improved correlations for the prediction of cuttings transport.