- Foam Stability
- Foam Stability is considered in two different processes: film thinning and film rupturing (coalesence).
- Lamella
- Liquid film
- Lammella is the thin liquid film that separates adjacent gas bubbles. It is the region that contains the thin film, two interfaces on either side of the thin film, and part of the junction to other lamella. (Image)
- Key aspects of lamella in foam stability are: - *Thickness*: thicker lamella results in more stable foam, while thinner lamella is more prone to rupture. - *Drainage*: the rate of liquid drainage from the lamella affects foam stability. Overtime, liquid drains from the lamella due to gravity and capillary forces. - *Coalescence* or *film rupturing*: the process of two lamella merging into one. This process is detrimental to foam stability. [links](http://large.stanford.edu/courses/2016/ph240/almajid2/)
- Anionic Surfactant
- Anionic surfactant is a surfactant that carries a negative charge in the water phase. <img src="/img/glossary/type_surfactant.png" style="background-color: white; opacity: 0.85; padding: 0.125rem; border-radius: 0.375rem" width="450" alt="Example image" />
- Nonaninonic Surfactant
- Nonaninonic surfactant is a surfactant that carries a neutral charge in the water phase.
- Hydrophobic
- Hydrophobic is a term used to describe a molecule that is repelled by water or "water-fearing".
- Hydrophilic
- Hydrophilic is a term used to describe a molecule that is attracted to water, or "water-loving". <img src="/img/glossary/hydrophobic.png" style="background-color: white; opacity: 0.85; padding: 0.125rem; border-radius: 0.375rem" width="450" alt="Example image" />
- Surfactant
- Surfactant or surface-active agent, is a compound that lowers the surface tension between two liquids, between a gas and a liquid, or between a liquid and a solid. * Surfactants have a unique structure with hydrophilic head (water-loving) and hydrophobic tail (water-fearing / oil-loving) parts. (draw) <img src="/img/glossary/surfactant.png" style="background-color: white; opacity: 0.85; padding: 0.125rem; border-radius: 0.375rem" width="450" alt="Example image" />
- In **CO₂-Foam Injection**: * Surfactants are used to stabilize the foam and reduce the surface tension between the CO₂ gas and the water phase. * Surfactants prevent the coalescence of bubbles, which increases the foam stability. * Surfactants improve sweep efficiency by increasing the viscosity of the displacing fluid, i.e. CO₂. * Foam reduces the mobility of the CO₂ phase, which creates a more favorable mobility ratio between the displacing (CO₂-water) and displaced fluids (oil). Surfactants are classified into three categories: Anionic, Cationic, and Nonionic surfactants.
- Cationic Surfactant
- Cationic surfactant is a surfactant that carries a positive charge in the water phase.
- CO₂ Foam
- CO₂ has been widely used in the petroleum industry for decades as the proven enhanced oil recovery technique. Several challenges are faced such as low sweep efficiency, unfavorable mobility ratio, gas breakthrough or viscous finfering, etc.
- Foam is introduced as a dispersion of gas bubbles in a liquid phase stabilized by surfactants. The gas phase is CO₂, and the liquid phase is water.
- Foam mechanism in CO₂ injection involves the generation and stabilization of foam within the reservoir to improve oil recovery. The foam acts as a mobility control agent, reducing the mobility of the CO₂ gas phase and improving the sweep efficiency. Key mechanisms include: * **Mobility Reduction**: Foam reduces the mobility of CO₂ by increasing its apparent viscosity, which helps to mitigate gas channeling and viscous fingering. * **Improved Sweep Efficiency**: Foam diverts CO₂ to unswept areas of the reservoir, enhancing contact with the oil. * **Stabilization by Surfactants**: Surfactants stabilize the foam by reducing the interfacial tension between the gas and liquid phases, preventing bubble coalescence. * **Capillary Effects**: Foam creates a capillary pressure barrier that helps to block high-permeability zones, forcing CO₂ into lower-permeability zones.
- Total Dissolved Solids
- Total dissolved solids (TDS) in water refers to the total concentration of dissolved inorganic and organic substances present in a water sample (Na+, K+, Ca2+, Mg2+, Cl-, SO42-, HCO3-, etc.). * TDS is used to estimate the salinity of water. * **Measurement**: TDS is measured by electrical conductivity (EC), and convert it to TDS value in parts per million (ppm) or milligrams per liter (mg/L)
- Aqueous Stability
- Aqueous stability is the ability of a substance (i.e. surfactant) to remain unchange in an aqueous (water-based) environment over time. It includes the resistance to hydrolysis, oxidation, precipitation, thermal degration and microbial degradation. **Analysis**: Aqueous stability is analyzed by measuring the concentration of the surfactant over time using analytical techniques such as Hyperformance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance (NMR), Infrared Spectroscopy (IR), etc. **Quantification**: Aqueous stability is quantified by calculating the half-life of the surfactant in the aqueous phase or the amount of precipitate formed over time.
This is a glossary page which encompasses the acronyms about Surfactant and CO2-Foam Enhanced Oil Recovery (EOR).