ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ КИСЛОТНОЙ ОБРАБОТКИ ПРИЗАБОЙНОЙ ЗОНЫ ПЛАСТА, ИСПЫТАВШЕЙ МНОГОКРАТНОЕ ВОЗДЕЙСТВИЕ

Salt-acid treatment (SAT) remains one of the key methods of stimulation of carbonate reservoirs, including in the conditions of the bottomhole zone of the formation (BHZ), which was subjected to repeated acid exposure. This paper presents a comprehensive analysis of the technological efficiency of RMS in the Tournaisian carbonate reservoirs of the Volga-Ural oil and gas province (VUOGP). The purpose of the study is to systematize the impact of key process parameters — the volume and concentration of hydrochloric acid solution (HCl), the use of moderators and deflectors, the rate of injection of reagents — on the depth of acid penetration and the final increase in oil production. Within the framework of the work, the physical processes characteristic of repeatedly processed PPP were reproduced on a three-phase three-dimensional hydrodynamic model. Particular attention is paid to the phenomenon of abnormally high injectivity observed during well workover, which is explained by the presence of free gas in the BHZ, which has high compressibility and can significantly change the hydrodynamic behavior of the formation. Numerical experiments were performed using the RN-STIM software package and include 11 scenarios for injecting RSK with various parameters (speed of 0.2 and 1.0 m ³/min, concentrations of 6 and 15 %, 10-fold deceleration, resale deep into the formation). The results showed that using a delayed 6 % RSK in the amount of 37.5 m ³ and an injection rate of 1.0 m ³/min with subsequent resale of 30 m³ of process fluid, the maximum acid penetration depth is 6.27 m, which is 250 % higher than in traditional modes. The increase in oil production in this scenario is 208 % higher than the base case. The most important conclusion is that in conditions of repeatedly processed PPP with high injectivity and gas saturation, an increase in injection rate and the use of moderators ensure deep acid penetration. The work demonstrates the transition from the traditional strategy of «surface dissolution» to the modern concept of «deep targeted stimulation», where the key role is played not only by the chemical composition, but also by the dynamics of the interaction of acid with the rock. The proposed methodological approaches can be used to optimize RMS in similar geological conditions of VOGP and other carbonate provinces with a high degree of depletion.