In order to evaluate the efficiency of the catalytic aquathermolysis process, physical modeling was carried out on bituminous sediments of Paleocene–Miocene carbonate rocks, characterized by the presence of open and closed fractures. In this context, three filtration experiments were performed on an unextracted reservoir model with extra-viscous oil (EVO). Prior to the experiments, the mineral composition of the rock was determined by X-ray diffraction analysis (XRD) and the content of organic matter and coking products was determined before and after the experiment by thermogravimetric analysis (TGA) as well as the group composition of oil (SARA) before and after the experiment by nuclear magnetic resonance (NMR), gas composition at the fluid separation line, and oil displacement coefficient (ODC). The results of the conducted experiments show that the efficiency of displacement of extraviscous oil could be significantly increased by the use of a solvent and the combined use of a solvent and a catalyst (+9.3% and +17.1% of the oil displacement coefficient, respectively), which is associated with the processes of oil refining.

Thermally enhanced oil recovery methods, such as in situ combustion and steam injection, are generating considerable interest in terms of improving oil reserve exploitation and satisfying oil demand and economic growth. However, the early breakthrough of the in situ combustion front and the significant amount of heat loss associated with steam injection for deeper reservoir applications are the main challenges that require urgent solutions. Further data collection related to the effects of a reservoir’s physical and chemical properties, temperature, and pressure on in situ combustion front propagation and steam injection heat transfer inefficiency would be needed to achieve better reservoir oil recovery. Most studies have focused on the application of catalytic systems and the investigation of minerals’ effects on combustion front stabilization; however, the effect of clay interlayers’ minerals on the performance of in situ combustion is still poorly understood. This paper takes a new look at the role played by the interlayers’ minerals in stabilizing the combustion front using X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC) combined with nuclear magnetic resonance (NMR), and combustion tube experiments. The studied samples’ compositions were analyzed by XRD, TG/DSC, and NMR techniques. Meanwhile, the effects of interlayers’ minerals on oil production were screened by combustion tube experiments. The data obtained from this study suggest that clay dispersion within a reservoir would improve oil recovery via in situ combustion, and our study led us to obtain an 80.5% recovery factor. However, the experiments of models with clay interlayers showed less recovery factors, and the model with interlayers led to a 0% recovery factor in the presence of air injection. Meanwhile, the same model in hydrothermal and air injection conditions led to a 13.9% recovery factor. This was due to the hydrothermal effect improving permeability and pore enlargement, which allowed the transfer of heat and matter. Moreover, our study found that clay minerals exhibit excellent catalytic effects on the formation of fuel deposition and the coke oxidation process. This effect was reflected in the significant role played by clay minerals in decreasing the number of heteroatoms by breaking down the C-S, C-N, and C-O bonds and by stimulating the processes of hydrocarbon polymerization during the in situ combustion. Our results add to a growing body of literature related to in situ combustion challenges and underline the importance of a reservoir’s physical parameters in the successful application of in situ combustion.

Currently, most explored oil fields in Russia are at a late stage of development, and in order to maintain high levels of oil production, it is rational to put into operation fields with hard-to-recover reserves. For complicated oil fields, in particular fields with high-viscosity oil, the known traditional methods of development are ineffective. Therefore, the search for new technologies for the development and operation of such fields to significantly increase oil recovery and intensify production is of fundamental importance. One such method of heat treatment of the bottomhole formation zone is the use of heat and gas generating systems on site. In this work, new results were obtained on physical modeling of thermochemical reaction initiation with delayed-action catalyst (2,2-bis(hydroxymethyl)butanoic acid) filtration tests on composite core models of sandstone and carbonate with foam heat generation and initiating additives of binary type. Using hydrodynamic modelling, the results of laboratory studies were reproduced, and the preliminary efficiency of the developed technology for thermochemical treatment of deposits in the Samara region (Russia) was evaluated.

Гидравлический разрыв пласта (ГРП) является ключевым методом разработки трудноизвлекаемых запасов углеводородов. Его эффективность в низкотемпературных коллекторах лимитируется замедленной и неполной деструкцией полимерного геля жидкостей разрыва на основе гидроксипропилгуара, что приводит к значительному остаточному повреждению проводимости трещин и прискважинной зоны пласта. В представленной работе исследуется подход к модификации традиционных гуаро-боратных систем путём введения бинарных термохимических реагентов, обеспечивающих контролируемую активацию экзотермической реакции непосредственно в пластовых условиях. Ключевым аспектом является индуцирование in situ процесса, сочетающего термическое разложение полимерной матрицы, генерацию давления и газодинамический эффект, направленных на полную деструкцию геля до ньютоновской жидкости с вязкостью ~1,1 мПа•с. Лабораторные исследования подтвердили, что разработанная композиция сохраняет стабильные реологические свойства на этапе закачки (вязкость сшитого геля >500 cP при 100 с⁻¹), а последующая активация кислотным агентом обеспечивает быстрый рост температуры до 73–83 °C и полную деградацию геля. Установлено, что использование поверхностно-активных веществ в составе активатора позволяет генерировать стабильные пенные системы с кратностью до 25, способствующие механическому вытеснению продуктов деструкции из порового пространства. Показано, что вторичными, но значимыми эффектами технологии являются очистка породы от кольматантов и создание термических условий для закрепления проппанта со смоляным покрытием (RCP). Результаты работы демонстрируют потенциал применения термохимических композиций для решения фундаментальной проблемы остаточного повреждения низкотемпературных пластов неразрушенными полимерными остатками. Hydraulic fracturing (HF) is a key method for developing hard-to-recover hydrocarbon reserves. Its effectiveness in low-temperature reservoirs is limited by the delayed and incomplete degradation of the polymer gel in hydroxypropylguar (HPG)-based fracturing fluids, leading to significant residual damage to fracture and near-wellbore zone conductivity. This paper investigates an approach to modifying conventional guar-borate systems by introducing binary thermochemical reagents that provide controlled activation of an exothermic reaction directly under reservoir conditions. A key aspect is the induction of an in situ process that combines thermal decomposition of the polymer matrix, pressure generation, and a gas-drive effect, aimed at the complete degradation of the gel into a Newtonian fluid with a viscosity of ~1.1 mPa·s. Laboratory studies confirmed that the developed composition maintains stable rheological properties during the injection stage (crosslinked gel viscosity >500 cP at 100 s⁻¹), while subsequent activation by an acid agent ensures a rapid temperature increase to 73–83 °C and complete gel degradation. It was established that using surfactants within the activator composition enables the generation of stable foam systems with a quality of up to 25, which facilitates the mechanical displacement of degradation products from the pore space. It is shown that secondary, yet significant, effects of the technology include the cleanup of formation damage (clays, mud) and the creation of thermal conditions for the consolidation of resin-coated proppant (RCP). The results demonstrate the potential of using thermochemical compositions to address the fundamental problem of residual damage in low-temperature reservoirs caused by undegraded polymer residues.