Increasing the efficiency of formation fluid extraction from highly clayey formations by affecting its structure with an electric field

Relevance. The need to evaluate the impact of a constant and alternating electric field on the physicochemical properties of various types of water, on the volumetric rate of filtration of liquids from highly clayey porous media and on the coefficient of oil displacement by water. Aim. To study the impact of a constant and alternating electric field on the hydrogen index and interfacial tension of aqueous electrolytes of various natures, as well as on porous medium permeability and the oil displacement coefficient under conditions simulating the above-mentioned formation of the Kirmakinsky formation. Objects. The experiments were carried out on a specially designed installation that allows measurements in both constant and alternating electric fields, taking into account the pressure drop. The body of the reservoir model was made of organic glass in the form of a tube with a variable length of 0.3–0.7 m and a diameter of 0.025 m with stainless steel electrodes mounted at the inlet and outlet. The research is devoted to the impact of constant and alternating electric fields on the hydrogen index and interfacial tension of aqueous electrolytes of various natures, as well as on the permeability of the porous medium and the oil displacement coefficient under conditions simulating the above-mentioned porous layer of the Kirmakinsky formation. Methods. The presence of an external electric field has a significant impact on the resulting value of the pH value and the value of the interfacial tension of aqueous electrolytes at the boundary with the hydrocarbon phase, which contributes, by analogy with the reagent treatment of oil reservoirs, to an increase in their permeability. When studying the processes of secondary oil migration in low-permeability water-saturated reservoirs, the practical absence of pressure filtration factors is noted and the dominance of diffusion-osmotic and electrokinetic factors during their occurrence is emphasized. The presence of electroosmotic movement of oil in various dispersed rocks (sand-silts and clays) under the effect of an external electric field was proven experimentally, and the possibility of displacing oil by the front of an aqueous solution of electrolytes through porous membranes of various capillary-porous nature was discussed in the work. Results. Based on the totality of the presented results, it is possible to come to an important conclusion from a practical point of view: by means of the directed action of an external electric field with regulated intensity parameters on the secondary process of oil extraction by aqueous electrolytes, it is possible to significantly increase the value of the displacement coefficient of difficult-to-permeate reservoirs, in particular high-clay reservoirs of the Kirmakinsky formation.