Biosurfactants have great potential for increasing oil recovery. They show superior ability mobilizing oil otherwise trapped in reservoir rocks. Rhamnolipids and lipopeptides, for example, have become important constituents in EOR injection fluids. Biosurfactants reduce surface and interfacial tension, thereby overcoming resistant capillary forces, and can alter wettability to lift oil adhering to rock surfaces. We have conducted a number of fundamental experiments as well as oilfield tests that demonstrate the successful application of rhamnolipid or lipopeptides in the context of EOR.
Details of case studies follow.
|Reservoir description:||low-energy and sandstone reservoir|
|Fluid characteristics:||Wax Appearance Temperature 45 °C, high-content wax 20% formation oil viscosity of 6.3 cp, 26 API|
|Development description:||9 Oil wells and 2 water wells. Average oil production of single well was 8.4 bbl / day, 93.4% of Water-cut|
|Measures to enhance oil recovery||Water flooding with the mixtures of rhamnolipid (0.2-1.0% ), chemical surfactant ( 0.01-0.2% ) and polymer ( 0.05-0.1% ). Slug injection with the first slug high concentration and the second low concentration.|
|Result||During the 14 months, oil production of a single well was enhanced from 8.4 bbl / day to 11.6 bbl / day. Water-cut was decreased by 1.6%, and cumulative incremental oil was more than 14100 bbl.|
|Reservoir description:||low-energy and sandstone reservoir, temperature 58 °C|
|Fluid characteristics:||Wax Appearance Temperature 34 °C, high-content of wax, 30%; formation oil viscosity of 80 cp, 26 API|
|Development description:||Wax deposition of oil wellbore has become a serious problem in this oilfield. Hot-washing sometimes caused the oil production to decrease and damage the reservoir formation, and is not cost-effective. And also chemical methods were harmful to health.|
|Measures||Microbial paraffin removal with the rhamnolipid and lipopeptide of fermentation liquid. The concentration of injection is 2000-7000 ppm.|
|Result||Greatly extended the cycle of hot-washing ( from 30 days to 168 days), thereby reducing the number of hot-washing treatments; provided economic benefits of $ 400,000|
Due to their superior performances in separating hydrocarbons from water and sediments and their superior performances in emulsification, rhamnolids and lipopeptides are becoming the important ingredients in the tank cleaning, in enhancing pipeline flow efficiency and in the fracturing fluid. Clean-up based on biosurfactants successfully removes hydrocarbons or sludge or organics from tank or pipeline, and emulsify the hydrocarbons and reduce the flow resistance. Biosurfactant solutions can outperform synthetic surfactants in this application and they avoid all harmful environmental impact and dramatically reduce the wastes at the end of the process.
Millions of tons of waste crude oil come from crude oil recovery, transportation, storage and refinery process were highly stable because of the presence of indigenous surface active components (asphaltenes, resins, naphthenic acids, etc.), the residual chemical surfactants and the natural solid particles (slay, waxes, etc.). Such waste crude oil presents as a complex water-in-oil type emulsion. it can not be directly used due to a high content of water or released into environment due to their hazard to natural-biodegraders and even human health. Our research results showed that some iosurfactant could effectively demulsify the waste crude oil. In full consideration of its properties on high demulsification activity, nontoxicity and the commercial availability, biosurfactants should be potential applied in the industry as a demulsifier of great prospects.