Experimental investigation of particle suspension injection and permeability impairment in porous media
Résumé
Damage and clogging of the granular structure of reservoirs are commonly observed during the re-injection of produced water containing solid particles and oil droplets. These phenomena can lead to a significant decrease of the reservoir permeability around the injectors and affect the injectivity of these wells. In this paper an experimental study on the transport and deposition of silica particles in a porous medium subjected to flow is presented. The study is performed on two different devices; the first one is an injection column 1 m long in which a sand pack with controlled density using the pluviation technique has been placed and the second one is an injection cell in which a cylindrical sand specimen (height 80 mm, diameter 80 mm) is put under isotropic stress. Water containing a low concentration of fine particles (diameter of few microns) is injected at a constant flow rate. The evolutions of the sample mass and of the injection pressure are recorded. The experimental results show an increase of particles mass retained inside the sample during the injection and an increase of the injection pressure attributed to a decrease of the permeability of the sample. They also show that despite the low concentration of particles of the injected fluid, a clogged area of a few centimetres forms at the column inlet. The analysis of this area by mercury porosimetry showed a significant decrease of the porosity and of the pore size and the formation of a new family of pores by the agglomerated particles. This study focuses on the impact of various parameters (diameter of the injected particles, pore size distribution of the porous medium, concentration of particles in the injected water, injection flow rate and surface roughness of the grains) on the reduction of the permeability.