Evaluation of Near-Wellbore Formation Treatment by Gel Particles Using Dimensional Analysis

Abstract

Analysis and interpretation of experimental data of laboratory tests of porous formation treatment by gel particles conducted at different gel particles suspension and application conditions are presented based on the dimensional analysis method. The measured permeability reduction caused by gel particles suspension injection into sand packs is correlated successfully by using the dimensionless groups developed from the relevant variables of sand packs, gel particles suspensions, and application operation conditions. The dimensionless correlations are shown to assist in quantifying the effect of the particlediameter to pore-throat size ratio on permeability reduction, evaluating the treatment of highly permeable and weak near well-bore formations by gel particles, and extrapolating from laboratory to field conditions. The present dimensionless correlations can predict the evolving permeability reduction under the varying conditions of gel particles suspension injection processes. The proposed dimensionless correlations can assist in effective design and mitigation of treatment of highpermeability near-wellbore formations by gel particles for avoiding drilling-fluids lost circulation, remediating reservoir permeability heterogeneity, and reducing water production in waterflooded mature oil fields. Review of Experimental StudiesZhang and Bai (2011) examined the effect of brine concentration, fracture width, and injection rate of the preformed particle gel (PPG) injectivity and plugging efficiency. They used brine concentrations 0.05% for 0.903% PPG concentration, and 0.25% for 1.597% PPG concentration, 1% for 2.731% PPG concentration, and 10% for 2.961% PPG concentration. The flow rates used are 5, 10, 15, 20, 25, and 30 mL/min and the fracture widths are 0.55 mm, 1.0 mm, and 1.5 mm. They used visual fracture models for the experiments to observe the PPG propagation through fracture and water flow through packed gel in the fracture. The fracture model of 55 cm length and 10 cm height consist from two acrylic plates with inlet and outlet and there is a rubber O-ring between the plates. The brine was injected first into the fracture model and then the PPG was injected by using an Isco pump. By means of twelve experiments, they showed that the injection pressure increased by the brine concentration because the swollen PPG particles are more soft and deformable at the low concentration than at the high concentration. The experiments showed that the injection pressure increased by the flow rate but the increase was not as much as the flow rate, and the injection pressure decreased by the fracture width because the conductivity increased by the