Cuttings Removal in Eccentric Geometries: A Comprehensive Review of Hole Cleaning Mechanism, Affecting Parameters, and Assessment

DOI: 10.14800/IOGR.1317

Abstract

Horizontal and deviated wells offer higher drainage areas through reservoirs than vertical wells do. Such drilling techniques are globally employed to keep up with the growing demand for energy and provide extra fuel resources. However, inadequate hole cleaning (HC) has grown to be a challenge that may pose technical issues such as lower rate of penetration, excessive torque and drag or even stuck pipe. Furthermore, deviated annulus might be typically eccentric because of the weight of the drill string accompanied by intense drilling oscillations during directional drilling. Hence, this makes the task of HC more challenging. Numerous HC models and down hole technologies are employed for better cutting transport from down deviated and horizontal wellbores up to the surface. This paper investigates most of innovative equipment and down hole assemblies used in deviated and horizontal wells as well as the mechanism of cutting transport through each wellbore trajectory. Additionally, it provides a comprehensive review of the most influencing aspects including; rheological, geometrical, drilling operational parameters, cuttings characteristics and sweeps. Modeling and geometrical definition of eccentric annulus are assessed and graphically evaluated.  Further, the potential of experimental, intelligent, computational fluid dynamics (CFD) real time applications is addressed and their recent achievements are discussed. Finally, general conclusions and further recommendations are suggested to overcome HC issues, aid in assemblies/drilling fluid selection, and optimize the whole drilling operation for more efficient HC in directional and eccentric wells.