Drilling fluids consist of colloidal suspensions that are made up of solid particles suspended in liquid. The aqueous component of the drilling mud invades a permeable formation due to differential pressure, leaving solid deposits on the drilled formation walls, forming a filter cake.
Typical drilling fluids should create a thin, slick filter cake and fluid loss control to seal permeable zones as swiftly as possible. Tight holes, elevated levels of rotational resistance and friction, wellbore obstruction, fluid loss into formations, suboptimal well-log data, and reservoir formation impairment result from thick filter cakes and excessive filtration.
Controlling infiltration of fluids to establish a minimal, low-porosity filter cake is frequently required to avoid drilling and production issues. In this study, we used computational fluid dynamics (CFD) to model the development of filter cakes induced by pipe rotation in vertical and inclined wellbore walls under elevated temperature and pressure during deep drilling.
Multiple tests validate the basic model for application in both shallow and deep drilling operations. By use of a Eulerian-Eulerian approach to describe drilling fluids as a binary-phase system, including particles in suspension in the non-Newtonian fluid, our research investigates the power-law and Herschel-Bulkley rheological models. These models successfully predict the flow pattern of drilling fluid at the bottom region of deep drilling operations.
The study further explores filter-cake formation by examining the influence of overbalanced pressure on filter-cake thickness at various pressures. Drilling simulations, incorporating pipe rotation and eccentricity effects under realistic operating parameters, accurately project filter-cake thickness, aligning closely with experimental measurements and existing CFD literature in this domain.
This abstract is taken from paper SPE 219446 by A. M. Ramadan, A. Osman, A. Mehanna, A. I. Shehata, and M. Shehadeh, Arab Academy for Science, Technology and Maritime Transport. The paper has been peer reviewed and is available as Open Access in SPE Journal on OnePetro.