What is Nano Tech & Why use it
Current oil recovery methods with existing technologies are not satisfactory, and, depending on reservoir characteristics, an average of 50% of crude is left behind. Several enhanced oil recovery (EOR) methods have been investigated and proposed for field-scale implementations. The most widely studied EOR methods are based on surfactants, polymers, alkalis and their combinations as injection fluids.
EOR surfactants work on the principle of reducing interfacial tension (IFT) between crude oil and water, which helps to increase the capillary number and reduce residual oil saturation. Similarly, polymers also amplify the capillary number by increasing the viscosity of the injected fluid, which ultimately improves sweep efficiency.
However, conventional methods are not entirely adequate, due to poor recovery efficiency and the high cost of chemical injection, due primarily to shear degradation and excessive adsorption on rock matrix. Hence, a more efficient and economic EOR method is required.
What are nanofluids?
Nanofluids are composed of nanoparticles suspended in fluids. A nanoparticle is 1 to 100 nm in size. For comparison, a human hair is 80,000 to 100,000 nm in diameter. NTNU’s Nano-EOR petroleum group focuses on using silica nanoparticles because they are cheap to produce, can be easily modified to enhance desirable properties, and have a low capital cost for installation.
The researchers suspend the nanoparticles in saltwater at concentrations ranging from 0.01 to 1 weight percent. They also do research with metal oxide nanoparticles suspended in saltwater.
Why use nanofluids for EOR?
Most of the oil reservoirs in the North Sea use seawater to help produce oil. Seawater is injected into the reservoir and helps push the oil to the production wells. However, after the water reaches the production well (water break-through), additional injected water will mostly follow the water path and not push out more oil. This is mainly due to the differences in viscosity between the water and oil and also the interfacial tension between the oil and water phases.
Adding nanoparticles to the injected seawater can help scrub the remaining oil out of the reservoir. In lab tests at NTNU, special silica (sand) nanoparticles have increased oil recovery when added to seawater that is injected into oil-saturated sandstone blocks. These blocks are like miniature petroleum reservoirs and, combined with other experiments, they help the researches understand how the nanoparticles interact with the rock and oil.
How can nanofluids increase oil recovery?
There are many different mechanisms that the nanoparticles can use to enhance oil recovery including the following:
- Nanoparticles can increase the viscosity of the seawater to help push it through oil zones.
- Nanoparticles can lower the interfacial tension between the oil and seawater so oil that was lodged in tiny pore throats can be released into the water highways.
- Nanoparticles can create a wedge-film that strips the oil droplets off the rock surface.
- Nanoparticles and nano-gels can be used to selectively plug water paths, forcing the water to flow through oil–filled paths.
Application of Nano Technology
Nanotechnology has been successfully implemented in many applications, such as nanoelectronics, nano biomedicine, and nanodevices. However, this technology has rarely been applied to the oil and gas industry, especially in upstream exploration and production. The oil and gas industry needs to improve oil recovery and exploit unconventional resources. The cost of research and oil production is under immense pressure, and it is becoming more difficult to justify such investment when the crude oil price is weak and depressed. There is a widespread belief that nanotechnology may be exploited to develop novel nanomaterials with enhanced performance to combat these technological barriers. Increasing funding resources from governmental and global oil industry have been allocated to exploration, drilling, production, refining, and wastewater treatment. For example, nanosensors allow for precise measurement of reservoir conditions. Nanofluids prepared using functional nanomaterials may exhibit better performance in oil production processes, and nanocatalysts have improved the efficiency in oil refining and petrochemical processes.
Nanomembranes enhance oil, water and gas separation, oil and gas purification, and the removal of impurities from wastewater. Functional nanomaterials can play an important role in the production of smart, reliable, and more durable equipment. In this review paper, we summarize the research progress and prospective applications of nanotechnology and nanomaterials in the oil and gas industry.
Using NANO Technology
Removal of oily sludge from storage tanks can be carried out by using nano technology to reduce viscosity and promote water/oil or oil/ water emulsification. This process facilitates sludge pumping and allows crude oil recovery after emulsion is broken. Nano -biosurfactants are amphipathic molecules containing hydrophilic and hydrophobic moieties, found mainly on the cell surface or excreted to culture medium by a broad range of microorganisms. These products increase the aqueous dispersion of poorly soluble compound by many orders of magnitude and change the affinity between microbial cells and hydrocarbons by increasing cell surface hydrophobicity.
According to researchers, 3-7 per cent of all oil is lost during processing activities in the form of sludge or waste, representing a major environmental problem. Oil contamination of soil can have cytotoxic, mutagenic and even carcinogenic effects on the organisms that come into contact with it, either directly or indirectly. The physical properties of oil also evolve over time, with new toxins exposed as the material is weathered in the soil.
New techniques were used to evaluate an alternative process to removal of oily sludges, and many approaches were taken. But through the use of biosurfactants. We were able to reduce the viscosity and promote formation of oil/water emulsions, thus making sludge pumping easier and permitting crude oil recovery after breaking the emulsion.
Five bacterial isolates were selected for their biosurfactant production potential after screening microorganisms recovered from oil-contaminated sites. Supernatants obtained from autoclave cell suspensions (hereby referred to as autoclaved-supernatant) were mixed with oily sludge collected from fuel oil storage tanks to a final concentration of 0.01%, in order to separate the oil from the inert material. The process proved to be highly efficient for oil recovery, and resulted in up to 95% reduction in sludge volume. The use of cell-free supernatant medium obtained from biosurfactant-producing bacterial strains to treat oily sludges may be an economically and environmentally viable technology, considering the small volume of microbial culture required for the treatment.
The Nano Particle -Biosurfactants produced by five bacterial isolates from the proven culture creations and collection proved to be highly efficient for oily sludge treatment, and their use led to a 95% recovery of the oil contained in a fuel oil storage tank oily sludge.
Waste solids remaining after biosurfactant treatment contained an insignificant amount of residual oil. Such treatment on an industrial scale would reduce waste disposal cost and lower the risk of environmental contamination by oil present in disposed oily sludge residual solids.
The results showed that the isolates and its produced biosurfactants with effective surface and emulsifying properties represent a promising potential for application in bioremediation of soil environments polluted with hydrocarbons.
IPX can supply the latest in nanoparticle technologies, to provide a “Green” solution to the problem. With innovative chemistry, the zerovalent iron nanoparticles removed total petroleum hydrocarbons (TPH) by breaking down toxins in oil sludge through chemical oxidation, leaving behind only decontaminated materials and dissolved iron. Published in the journal Environmental Technology & Innovation, the study demonstrated over 90 per cent removal of TPH over a one-week treatment period.
The Nano Tech alternative for Enhanced Oil Recovery
Nanoparticle (NP)-based EOR (nano-EOR) is an alternative strategy. Nanoparticles, due to their relatively small size, large surface area and high surface charge density, have the potential to increase recovery efficiency at lower concentrations than conventional chemicals. Researchers globally have been studying various nanoparticles to assess their potential in EOR. Sustained efforts in the last several years have resulted in the discovery of several novel EOR mechanisms for nano-EOR such as: disjoining pressure log-jamming, wettability alteration, reduction of interfacial tension (IFT), viscosity enhancement and crude oil viscosity reduction.
Unlike surfactants and polymers, it is evident that there is no single, universally accepted mechanism for nanoparticles-enabled EOR. Although many mechanisms of nano-EOR have been proposed, a lack of direct connections between the pore-scale mechanisms and the macro-scale oil recovery performance makes it hard to determine which mechanisms are dominant. Nanoparticles are also increasingly studied for addressing key challenges to supplement conventional EOR methods by reducing surfactants adsorption, increasing polymer viscosity and reduce shear degradation. Therefore, it is important that a mechanism for nanoparticle-enabled recovery be identified, and pore-scale physics be validated and expanded in the pore-networks on a micro-model, then performance-validated in the reservoir core.