Investigation of the Effect of a Reagent Based on Ammonium Fluoride and Sulfosalicylic Acid on the Filtration Properties of Low-Permeability Terrigenous Sandstone for the Intensifi-Cation of Hydrocarbon Production

Ukraine’s subsurface holds significant natural gas reserves located in low-permeability siliciclastic reservoirs. Such deposits are promising but require specialized development strategies—specifically, stimulation methods that facilitate fluid extraction and substantially increase well flow rates. To enhance the recovery of unconventional gas, operations are conducted to create new fluid pathways or expand existing ones by increasing pore space volume, thereby improving the reservoir rock's filtration and storage properties. Depending on their composition and geological setting, low-permeability rocks are loosened through mechanical formation fracturing or chemical treatments, although a combination of these methods is sometimes appropriate. This study investigates the chemical impact of a new acid formulation on quartz grains and low-permeability siliciclastic sandstone. Quartz samples were treated at 80 °C to analyze how SiO2 dissolution rates depend on solution concentration and treatment duration. Core samples were treated under conditions similar to those used for the quartz grains, as well as under simulated reservoir conditions – 80 °C and 300 atm—using a high-pressure apparatus designed to replicate the temperature and pressure of the productive horizons. The results of these experiments confirm the interaction of the tested solution with siliceous minerals—specifically quartz, a constituent of the reservoir rock. The dissolution capacity of this acid formulation regarding sandstone samples is significantly higher than that observed for pure SiO2 grains, owing to the rock's polymineralic composition; its effectiveness stems from a synergistic effect among the mixture's components, driven by the release of HF, the primary solvent for siliceous minerals.Overall, the tested solution is effective for treating siliciclastic sandstones to enhance permeability and can be applied to intensify natural gas recovery from low-permeability si-liciclastic reservoirs.