Fundamentals and Physical Principles for Drilled Cuttings Transport—Cuttings Bed Sedimentation and Erosion

Abstract

The increasing necessity of challenging wellbore structures and drilling optimization for improved hole cuttings cleaning has been growing along time. As a result, operator companies have been researching and applying different hole cleaning techniques. Some of these are applied as traditional rules of thumb but are not always suitable for the new and up-coming challenges. This may result in inefficient hole cleaning, non-productive times, pipe stocking and low rate of penetration (ROP), among other problems. Here are presented some results and improvements for hole cleaning optimization obtained by the different research groups. The different authors mainly focus on specific cuttings transport parameters and sometimes combination of some of them. For this reason, there has not been a study that takes into account all of the different factors at the same time to accurately predict the cuttings bed height, formation and erosion, critical fluid velocity and properties and other key parameters. Consequently, there is a lack of understanding about the relation between different factors, such as the cohesiveness of the drilled cuttings with the different interstitial drilling fluids within the cuttings-bed. This relation can be analyzed establishing a wet-granular approach to obtain more efficient cuttings transport mechanism in challenging conditions.

Wet Drilled Cuttings Bed Rheology

“…The behavior depends on the solid fraction (ϕ), the internal friction coefficient (µ*), by cohesive forces between particles, e.g., due to capillarity [9], and by the rheological properties of the interstitial fluid. As a result, the net shear strength of the bed might be different for different interstitial fluids, such as water-based or oil-based drilling fluids [10].…”

Indicators of cutting removal efficiency when drilling directional wells

“…В удалении продуктов разрушения отмечают ключевые факторы, такие как скорость оседания шлама, образование пласта шлама на нижней стенке наклонно направленной скважины и его эрозия [5].…”

Cuttings Transport With Oil- and Water-Based Drilling Fluids

“…Within this accuracy, it is reasonable to approximate the drilling fluids' yield stresses by a linear extrapolation using the two lowest shear rate measurements as described by Power and Zamora [14,15] if using measurements in accordance with API. The fluids are modelled as Herschel-Bulkley fluids using dimensionless shear rates to ensure parameter independent Herschel-Bulkley parameters [16][17][18] as shown in Equation 1. The flow curves are shown in Figure 4 and the Herschel-Bulkley parameters are tabulated in Table 1.…”