Effect of solid particle size on the filtration properties of suspension viscosified with carboxymethylcellulose and xantham gum

The invasion of drilling fluids into reservoir rocks can cause irreversible damage to the oil well, reducing the initial permeability of the rock reservoir. Evaluated different sizes of materials of circulation loss (LCMs) on the mud cake parameters. The methodology was based on a model for predicting of the fluid invasion in the reservoir taking in account the properties of the mud cake, such as permeability and porosity. Static filtration tests were carried out on high temperature and high pressure (HTHP). The Newtonian fluids were composed of a solution of glycerin in water and the non-Newtonian fluid was composed of water solution of linear polymer carboxymethylcellulose (CMC) or crosslinked polymer xanthan gum (XG). In both solutions added LCMs, calcium carbonate (CaCO3) or glass sphere. The glass spheres were chosen because they did not show the typical properties of the LCMs, thus making it possible to evaluate the effect of the different solids in the filtration process. From the non-Newtonian drilling fluid filtration tests, it was possible to conclude that the proposed model and the methodology in the evaluation of the mud cake's parameters provided information necessary to characterize the efficiency of the LCMs and polymers in the filtration. The results indicated that when using glass sphere a high volume of filtrate invaded the porous medium. The interaction of the CMC polymer with the LCM particles in the range of 0 up to 150 mu m of calcium carbonate formed a rigid structure and was efficient in the filtrate invasion control. However, it was necessary to apply higher shear stress to its flow, preventing the rapid formation of the mud cake over the porous medium. The XG suspension composed of LCM particles in the range 0 < Dp < 150 mu m proven to form a thinner, less porous and less permeable mud cake.