EORstrategier

EORstrategier are techniques used to increase the amount of crude oil recoverable from a reservoir beyond primary and secondary methods. They aim to modify the petroleum system, improving flow paths, increasing reservoir energy, or altering oil properties to boost cumulative production.

The main categories are thermal, gas-injection, chemical, and microbial approaches. Thermal methods inject heat or develop in-situ combustion to lower oil viscosity. Gas-injection methods introduce CO2, natural gas, or nitrogen to maintain pressure and improve sweep efficiency. Chemical EOR uses polymers or surfactants to change interfacial tension and mobility. Microbial EOR employs microorganisms or their metabolic byproducts to influence rock properties or oil viscosity. In practice, combinations of methods are used across different field developments.

Selection depends on reservoir temperature and pressure, oil viscosity, porosity and permeability, availability of agents (steam, CO2, chemicals), energy costs, and economic risk. Environmental and regulatory considerations, such as emissions, water use, and long-term storage of CO2, also shape decisions.

Examples include steam-assisted gravity drainage in heavy-oil sands, especially in Canada; CO2-EOR projects in various basins; polymer flooding in mature onshore fields; and surfactant-polymer schemes in offshore or complex reservoirs.

EORstrategier involve substantial capital expenditure and technical risk, with long project lifetimes. Advances focus on improved materials, better reservoir characterization, and integration with carbon management and digital monitoring to optimize performance and reduce environmental impact.