Study of physicochemical and geochemical aspects of enhanced oil recovery and CO₂ storage in oil reservoirs

Abstract

The object of research is the processes of multiphase filtration in porous media. These processes occur when carbon dioxide (CO₂) is injected into oil reservoirs to increase oil recovery. The object is also the interphase phenomena, geochemical interactions and technological operations for well control associated with these processes.

One of the most problematic areas is the lack of understanding of complex relationships. These relationships exist between physicochemical processes at the micro level (interfacial tension, wettability, solubility, adsorption, geochemical reactions) and macroscopic characteristics of the reservoir (permeability, porosity, heterogeneity). Technological parameters of CO₂ injection (pressure, temperature, speed, volume) are also important. This leads to suboptimal selection of technologies for increasing oil recovery technologies, premature CO₂ breakthroughs, low oil recovery ratios, and also complicates the prediction of the behavior of the “reservoir – fluid – CO₂” system in the long term, in particular, from the point of view of CO₂ storage safety. Another problematic area is the limitation of existing empirical models describing the impact of CO₂ injection on well productivity, which do not fully take into account the heterogeneity of the reservoir and the complexity of physicochemical processes.

A comprehensive overview of the mechanisms of CO₂ interaction with reservoir fluids and rock has been obtained. The impact of supercritical CO₂ on interfacial tension, wettability, swelling and viscosity of oil has been analyzed. Geochemical reactions and their impact on permeability have been considered. CO₂ mobility control has been investigated. Mathematical relations for the calculation of throttling devices have been developed. An analysis of industrial data has been conducted, which revealed a nonlinear response of wells and allowed to refine regression models.

This provides the possibility of obtaining increased oil recovery rates and long-term CO₂ binding. Compared with similar known methods, CO₂ provides a decrease in interfacial tension, a decrease in oil viscosity, dissolution of residual oil and a potential reduction in greenhouse gas emissions. Refined regression models allow for a more accurate prediction of well productivity. The developed mathematical relationships provide effective well management. The results obtained can be used in practice to optimize oil field development processes using CO₂ injection technologies, as well as to assess and ensure the safety of long-term CO₂ storage in geological formations.