Enhanced Oil Recovery (EOR) is well known for its potential to unlock up to 80% of the world’s otherwise unrecoverable oil reserves. Current EOR methods include:
| Thermal EORSteamHot water floodingIn situ combustion | Gas EORCO2 injectionAir injectionOther gas injectionInjection of light hydrocarbons |
| Chemical EORSurfactant floodingPolymer displacementAlkaline displacementAcid displacementChemical reagents displacementMicrobiological treatment | Hydrodynamic EORDevelopment of by-passed oil reservesBarrier floodingCyclical floodingAccelerated productionStepwise-Thermal flooding |
| Combined EORA combination of thermal, gas, chemical, hydrodynamic and other EOR methods in a regime optimised for the oil reservoir’s characteristics | |
Main Chemical EOR Techniques
Surfactant Flooding boosts oil production by lowering interfacial tension, increasing oil mobility thus allowing better displacement of the oil by injected water. Surfactant EOR improves the wetability of porous rocks allowing water to flow through them faster displacing more oil.
Polymer Displacement increases the viscosity of water injected into the oil reservoir enabling it to exert more pressure on the oil without forcing its way past and simply flowing through. Because this method relies on increasing the viscosity of water it is less effective on low permeability rock structures.
Alkaline Displacement relies on the chemical interaction of alkali, oil and rock. When introduced to an oil field the alkaline agent reacts with the oil, forming surfactants which reduce interfacial tension. This allows oil to pass through porous rock more effectively.
Microbiological Treatment introduces specific micro-organisms to an oil field which metabolise some of the hydrocarbon, in turn producing byproducts which assist in oil recovery. These bi-products include solvents, acids, alcohols, bio-polymers, bio-surfactants and gasses.
Advantages of Surfactant Flooding in Enhanced Oil Recovery
Recent developments in Surfactant Enhanced Oil Recovery have greatly reduced the surfactant concentration required for effective oil recovery. Initial development in the 1970’s and 80’s used anywhere between 2-12% surfactant concentration which, when combined with the cost of the surfactants themselves proved cost prohibitive.
Recent advances in both research and surfactant product technology have lowered chemical concentrations within the range of 0.1-0.5% dramatically lowering the amount or chemical required. Surfactant manufacturing is now also delivering more advanced and safer EOR products at a lower cost than ever before.
The best news is that these new advances have actually come at an overall improvement for the environment and human health. Some of the newest and most effective EOR surfactants are derived from plant resources such as sunflower oil, soy and corn oil. Envirofluid’s Triple7 EOR, for example, is comprised of amine reacted free fatty acids, fatty alcohols, esters and wax esters derived from soy, corn and seed oil fractions. It is readily biodegradable, non-toxic and non-hazardous.
Effective Where Polymers and Alkali Don’t Work
There are many instances where Polymer Displacement and Alkaline Displacement are ineffective.
Because polymer injection increases the viscosity of the flood medium it is generally only effective on highly porous rock. In low permeability rock, polymer displacement quickly reaches a point at which it no longer produces results.
Some oil reservoirs also present environments such as high salinity, which is not suitable for common alkalis.
