Известия Томского политехнического университета: Инжиниринг георесурсов (Apr 2025)
Features of filtration of sediment-gelling compositions through porous media
Abstract
Relevance. The need to improve the efficiency of treatments of the bottomhole zones of wells by reducing the permeability of the washed zones of the bottomhole formation and its heterogeneity degree through the use of sediment-gelling compositions based on water-soluble polymers and alkalis. Aim. To develop and propose a method for using sediment-gelling compounds for treating the bottomhole zones of wells due to the reaction between polymers and alkalis, thereby avoiding repetitions of reactions. Objects. The studies were conducted on uncemented porous media. Quartz sand was used as a model of the porous medium. The permeability of the porous medium was 1.2 μm2. Technical polyacrylamide with a molecular weight of 1.35·106 and sodium hydroxide were used in the preparation of sediment-gelling compositions. The sediment-gelling compositions were prepared on distilled and fresh water with a total mineralization of 2.64 mg-eq. The concentrations of polyacrylamide and sodium hydroxide in the sediment-gelling compositions varied from 0.05 to 0.15% and from 0.1 to 0.75%, respectively. Methods. The nature of the filtration of sediment-gelling compositions in porous media is determined by conformational changes in the polymer macromolecules, depending on the concentration of alkali and polymer in the composition, on the mineralization of the solvent and waters saturating the porous medium, on filtration rate and on the interaction of sediment-gelling compositions with the porous medium. In addition, as noted in the works, the efficiency of using sediment-gelling compositions based on water-soluble polymers and alkalis is significantly increased due to the presence of a polymer that has flocculating properties and allows individual dispersed particles formed in the formation to be bound together and by the formation rock. Results. The behavior of sediment-gelling compositions in porous media is determined by conformational changes in polymer macromolecules, which depend on the alkali and polymer content in the composition, on the mineralization of the solvent and waters involved in the saturation of the porous medium, on filtration rate and interaction of sediment-gelling compositions with the porous medium (the results of the experiments are convincingly shown graphically, according to the experiments conducted). The decrease in the resistance factor for sediment-gelling compositions both on distilled and fresh water with an increase in alkali concentration in the solution can be explained by a decrease in the size of macromolecules and their associations.
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