Filter cake formation process by involving the influence of solid particle size distribution in drilling fluids

Abstract

In the filter cake formation process (FCFP), existing models have assumed that the particles in drilling fluids are monosized, which is completely inconsistent with actual drilling fluids. Therefore, a novel FCFP prediction model was proposed by considering the solid particle size distribution (SPSD) and was verified using Hashemzadeh's model. The influences of SPSD, formation properties, drilling fluid properties, and engineering parameters on the FCFP were investigated. The results indicated that when the influence of SPSD is involved, the filter cake thickness is 2 times thicker than that of mean particle size; this means that the influence of SPSD on the FCFP cannot be ignored. The solid particle distribution type and mode in drilling fluids directly influence the FCFP. Adding the appropriate content of small-sized particles in drilling fluids will help form a high-quality filter cake. The filter cake growth rate increased with increasing in formation permeability, drilling fluid consistency coefficient, drilling fluid mobility index, pressure difference between the wellbore and formation; while it decreased with rising filtrate viscosity and drill-string rotational speed. The order of importance of influencing factors is mobility index > particle mean size > filtrate viscosity > particle size standard deviation > pressure difference > consistency coefficient > formation permeability > drill-string rotational speed. The present model can provide theoretical guidance for drilling fluid optimization, reservoir protection and well construction safety, thereby to facilitate safe, high-quality, efficient and economical drilling.