Digital Solutions Using Advanced Computational Techniques to Simulate Hole Cleaning

Cuttings transport and hole-cleaning is a challenging issue associated with the efficiency of wellbore hydraulics and drilling operation. Traditional methods used to understand hole cleaning problems are based on field observations and extensive flow loop testing to formulate empirical correlations and mechanistic models. The focus of this study is to create digital twin utilizing advanced simulation techniques that provides better insight for cuttings transport and hole-cleaning. This study explores the use of Eulerian-Lagrangian based numerical techniques to estimate critical flow rate needed for efficient hole cleaning. Digital twin for the cuttings transport is formulated utilizing three dimensional Navier stokes equations employing combination of Eulerian and lagrangian approaches to model the drilling mud flow and cuttings interaction with the drilling mud, wellbore walls and between cuttings themselves. One of the important model to estimate the drag force on cuttings is modified for non-spherical cuttings shape coupled with non-newtonian Herschel Bulkley behavior of the drilling mud in this work. The influence of important parameters, such as fluid rheology, rotation of drill-string, and inclination of wellbore on the hole-cleaning process is investigated. Digital solutions are compared against the published data for Newtonian and non-Newtonian drilling fluids under different wellbore configurations. The advanced computational simulation involving novel drag force correlation and unique combination of numerical methods allowed to create digital twin for cuttings transport process accurately. The numerical strategy utilizing modified drag law showed a very good match with experimental results for straight vertical wellbore, the cuttings transport velocity estimated by digital solutions was within 5% difference of experimental results. Further upon validation, numerical results are successfully computed for drill -string rotation effects which clearly showed physics of cuttings transported efficiently with added energy due to rotation. The phenomenon of cuttings bed sliding in inclined and horizontal wellbores is also correctly simulated with the proposed drag law and numerical methods. The proposed methodology works without any issues with high concentration of cuttings and provides detailed insight into cuttings flow path and effect of various operational parameters on hole cleaning. Advanced computational simulations and modification of drag force law assisted in formulating digital twin that provided excellent insights in understanding effects of operational parameters for efficient hole cleaning.