Applications of nanotechnology in enhanced heavy oil recovery
1. Applications of Nanotechnology in
Enhanced Heavy Oil Recovery
Presented by
ENG: Elsayed Raafat Mohamed
Engineering Department.
Faculty of Petroleum & Mining Engineering.
Suez University.
Egypt.
Elsayed.Raafat@yahoo.com
2. Nanotechnology
Nanotechnology, in engineering terms, is concerned
with the fabrication and use of devices and materials
so small that the convenient unit of measurement is the
nanometer (10-9 meter).
Nanotechnology is the science of materials in a
range very close to molecular dimensions (1-100 nm)
3. Properties Of Nanoparticles
The properties of materials change as their size approaches the
nano-scale and as the percentage of atoms at the surface of a
material becomes significant.
Large surface to volume ratio: enhanced activity and contact area
Chemically modified surfaces (wettability alteration at nano-scale)
Enhanced thermal properties (Heat transfer)
4. Nanotechnology in oil industry.
The most obvious application of nanotechnology for upstream
operations:
Development of better materials.
By building up such substances on a nanoscale, it could produce
equipment that is lighter, more resistant, and stronger.
Develop new measuring techniques with Nano-sensors to provide
more detailed and accurate information about the reservoir.
Developing new types of “smart fluids” for improved/enhanced oil
recovery, and drilling.
5.
6. Nanotechnology in EOR.
Nanoparticles can drastically increase oil recovery by
improving both:
The injected fluid properties
Viscosity enhancement
Density
Surface tension reduction
Emulsification improvement
Thermal conductivity and specific heat improvements
Fluid-rock interaction properties
Wettability alteration
Heat transfer coefficient
7. Heavy Oil: Resources & Recovery
Heavy Oil: Oil with API gravity between 10 API and 20 API inclusive
and a viscosity greater than 100 cP.
Extra-heavy oil: Oil with API gravity less than 10 API and whose
viscosity is commonly less than 10,000 cP.
Lower H, higher S, N and metals than light crudes.
• Total resources of heavy oil in known
accumulations are 4 trillion barrels of
original oil in place.
• The largest heavy oil accumulations
in the world are located in Canada
and Venezuela. These are estimated to
contain three trillion barrels of original
oil-in-place.
9. Conventional Heavy Oil Recovery
Thermal Recovery Methods
Cyclic Steam Injection (CSS)
Steamflooding
In Situ Combustion Processes
Steam-Assisted Gravity
Drainage (SAGD)
Nonthermal Recovery Methods
Polymer Flooding
Vapor-assisted petroleum
extraction (VAPEX)
Alkali-Surfactant Flooding of
Heavy Oil
Miscible CO2 Flooding.
Nonthermal methods have a lower recovery factor than thermal methods and are
used only with moderate viscous heavy oil (less than 200 cp) and for reservoirs
that are not feasible for thermal recovery( i.e. thin reservoirs)
10. Applications of Nanotechnology in EHOR
Smart Fluids
There are three major branches for the benefits of nanotechnology in
enhanced heavy oil recovery:
1.
Nanofluids: for wettability alteration.
2.
Nanoemulsions: for mobility control.
3.
Nanocatalyst: for enhancing steam injection.
11. 1. Nanofluids
Nanofluids are made by dispersing the nanoparticles in a base fluid.
The most widely used nanoparticles is silicon nanoparticles with a
different wettability( HLPN, LHPN or NWPN)
The base fluids for stabilized dispersion depends on the nanoparticles
wettability
(alcohol was selected to disperse NWPN and HLPN while water is best
for LHPN in the formation. , etc..)
12. Role of Nanofluids:
The main role of nanofluid is the wettability alteration from oil wet to
neutral wet or water wet or vice versa.
Wettability alteration is achieved by adsorption of nanoparticles of the
desired wettability on the rock.
This adsorption is occurred due to disjoining pressure.
HLPN alter the rock from water wet to oil wet.
LHPN alter the rock from oil wet to water wet.
NWPN alter either oil wet or water wet rock to neutral wet.
13. The main Concept:
When they come into contact
with a discontinuous phase,
such as an oil-rock interface,
these particles self assemble to
form a thin film known as a
wedge layer.
This wedge film then exerts a
pressure on the discontinuous
phase, called a disjoining
pressure, which effectively
works to separate the oil from
the rock surface and carry it
out of the rock pore.
14. Case Study: Petroleum University of Technology, Tehran,
Iran; 2012
• Dispersed silica
nanoparticles in water
(DSNW) (14 nm)
• At ambient pressure and
temperature.
• Micromodel: K=200md
Φ=.33 API=19o at 26 oc
&oil wet
16. Effect of adsorption of silica on permeability of porous
medium
Due to adsorption of silica nanoparticles pores and throats,
a reduction in absolute permeability is observed.
17. Factors affecting Nanofluid in EOR
applications
1.
Size of nanoparticles: with increasing particle size the surface area decreases .So
the disjoining pressure will decrease.
2.
Concentration of nanoparticles: A dramatic increase in the spreading of the
nanofluid is seen with the increasing nanoparticle concentration (wt.%). The
nanofluid viscosity also increased with increase in nanoparticle volume
fraction.
3.
Wettability of nanoparticles:
4.
Brine Concentration: with increasing the brine concentration, the disjoining
pressure decreases.
5.
Brine PH: with increasing the brine PH, the disjoining pressure decreases.
6.
Rock composition: Considering the reservoir rock as a charged surface and in
the absence of gravitational forces influencing these tiny particles, charge
interactions become more pronounced.
7.
Oil Composition: The optimum concentration depends on the oil composition.
18. 2. Nanoemulsions
Nanoemulsion is emulsions that is stabilized by nanoparticles.
Nanoemulsions are a class of emulsions with a droplet size in the
range of 50–500 nm.
Due to small droplet size, they are small enough to pass typical
pores, and flow through the reservoir rock without much retention.
Emulsions in practice are generally stabilized with surfactants, but
emulsions can also be formed using colloidal solids as stabilizers.
Emulsions that are stabilized by particles and colloidal are not new
and they are called “Pickering Emulsions”
19. Role of Nanoparticles:
Emulsions stabilized with nanoparticles can withstand the high
temperature reservoir conditions for extended periods.
A significant difference between surfactants and particles is the
attachment of particles at the oil/water interface.
While surfactants adsorb and desorb relatively easily, particles require
high energy for attachments to the interface and are consequently
virtually irreversibly adsorbed.
20. Study: Berea core with water flooding followed by nanoemulsion
flooding
SPE 136758 Texas A&M University 2011
Nanoemulsion containing 90.48wt%
brine, 1.71wt% solvent, 3.05wt%
surfactant and 4.76wt%
nanoparticles.
The nanoparticles make up 4.76wt%
of the whole emulsion weight which
could thicken the emulsion 3 to 8
times.
The residual oil saturation could be
reached after 2.1 PV water injections
which recovered 76.2% OOIP heavy
oil.
Then another 1 PV nanoemulsion was
injected and produced additional
19.2% oil in crude oil emulsion.
21. Similar to Nanoemulsions, CO2 Nanofoams can be formed
Adding surfactant to the water injected during CO2 flooding reduces
mobility and improves both areal and vertical sweep efficiency by
stabilizing viscous fingering and flow through the more permeable
zones.
However, surfactant-stabilized CO2 foams have potential weaknesses,
such as high surfactant retention in porous media and unstable foam
properties under high-temperature reservoir conditions.
The foams made by solid nanoparticles are stable over long periods (up
to a year), in contrast with foams stabilized by surfactant molecules
whose lifetime is on the order of a few hours
22. 3. Nanocatalysts
In situ upgrading
According to Hyne et al.(1982), viscosity reduction of heavy oil
during steam stimulation is not only a physical process.
There are chemical reactions occurring among steam, oil and
sand that cause in-situ upgrading of heavy oil .
“ aquathermalysis”
The so-called in-situ upgrading is accompanied by decreasing the
asphaltenes and resins content, molecular weight and sulfur content,
and by increasing saturates and aromatics content and H/C ratio.
Aquathermolysis results in irreversible lowering of heavy oil viscosity.
Aquathermolysis window ranges from 200 oC to 300 oC
23. Chemical Reactions of
Aquathermolysis
According to the theory of chemical valence, among C-O, C-S, and CN chemical bonds, the C-S bond energy is the least.
Because of this, the C-S bond will break in the process of
aquathermolysis and result in a low amount of sulfur and heavy
components such as resin and asphaltene.
The hydrolysis of aliphatic sulfur linkages is the main characteristics
of these reactions.
24. Chemical Reactions of
Aquathermolysis
Hydrolysis is achieved by transferring hydrogen from water to
the oil via water gas shift reaction (WGSR) :
Recently it has been suggested that gaseous H2S may promote the
WGSR through the intermediate formation of carbonyl sulfide
(COS) also it produces hydrogen so it can act as hydrogen
donor.
25. Catalysis of Aquathermolysis
Clark et al. (1990) noted that using
aqueous metal salts instead of
water in steam
stimulation
improves
the properties of the
recovered oil such as viscosity and
asphaltene content.
The observed improvements are due
to the catalytic effect of the metals
on the aquathermolysis reactions
which can further upgrade heavy oil
under steam stimulation.
26. Nanocatalysts
Hence, unsupported dispersed catalysts via nanotechnology
have been developed. This technology of the use of ultradispersed metals or nanoparticles as catalysts for in situ
upgrading of heavy crude oil and bitumen/tar sands.
The analysis found that all transition metal species have the ability
to accelerate the decomposition of the sulfur compounds.
Among all the transition metal species, VO2+ , Mo3+ ,Ni 2+ and Fe3+ are
the most effective for aquathermolysis of heavy oil.
Nano-sized transition metal can easily transported through the porous
media of micron-sized.
Nickel nanoparticles improved the recovery of the steam stimulation
process by 10%.
27.
Although, nano-particles have high mobility in porous media
because their size are quite smaller compared to the pore
size, but some proportion of the catalyst are retained in the
sand (Zamani, et al., 2010).
Because of the unique properties of nano-particles such
large surface area; they have the potential to
adsorb asphaltenes present in the heavy oil and bitumen
(Nassar, 2010; Nassar, et al., 2011).
However, there are still hurdles facing it, which include
determining the effective size of the nano-catalyst to secure
penetration in the porous reservoir matrix, changes in
temperature during operation may result in settling,
separation, and possible agglomeration of the nano-catalyst
(Pereira-Almao, 2012), synthesis and delivery of the nanocatalyst particles.
29. Case Study: Liaohe oil fields, northeastern China, 2002
Pilot wells
Liaohe oil fields, in northeastern China
Used Catalyst with cyclic steam stimulation
Catalyst contained a 1:1:5 molar ratio of VO 2+ , Ni 2+ , and Fe 3+.
The viscosity decreased by more than 70%
30. Results
After the catalytic treatment, the oil has more saturate and aromatic
components, which are lighter, and less resin and asphaltene
components, which are heavier.
At the end of aquathermolysis, the water-gas shift reaction is a
major reaction for forming CO2 and H2 .
The results indicate that both the sulfur and oxygen content
decreased. This is because the aquathermolysis usually occurs in the
hetroatom compounds in heavy oil.
The decrease in average molecular weight indicates that cleavage
takes place in the treatment.
31. Another Case Study in China (2007): Field Test
Using molybdenum oleate (MoO3 )as a catalyst
33. Nanoparticle type.
Adding a variety of metal species at 0.02M
concentration to oil(14.7 oAPI), aquathermolytic
experiments were carried at 240 oC
34. Nanoparticle Size &
Concentration
Since metal particles act as catalyzers, their surface to
volume ratio is of great importance. Therefore smaller size
particles are desired for the chemical aspects of the process to
be efficient.
Also, the size of the particles may affect the injectivity.
Heavy oil with API gravity of 14.7
122 oF
36. Improving the heat transfer to the
oil
o Low thermal conductivity of heavy oil is an important limitation
for energy efficient thermal recovery techniques.
o Improvement of thermal conductivity of the in-situ
hydrocarbon or the porous medium can provide faster
recovery.
Thermal
conductivity of
the mixture has
been increased
more than 1.25
times
Heavy oil with API gravity of 14.7
37. Crude Oil Composition
The amount of CO2 produced is higher when the crude oil
has a high oxygen content.
The more asphaltene contents the more the gases produced
With increasing the asphaltene content, the degree of
viscosity reduction will be higher.
As these reaction occur on the C-S bond in asphaltenes.
38.
Core mineralogy played an important role in the
generation of CO2 and the amount of H2S
produced was dependent on oil composition,
mineralogy, and time.
Gas production was observed to be largely
associated with the conversion of the heavy oil
and asphaltenes oil fractions.
39. Porous Media
The reservoir permeability.
A lower permeability porous medium has an impact on the
retention.
Transportation of particles in very tight reservoirs might be
challenging. However, most heavy oil reservoirs have enough
permeability for the method to be applicable.
The reservoir Rock minerals.
The presence of calcite, kaolinite and clays lead to the
production of more carbon dioxide.
This important CO2 production results from a reaction
involving the decomposition of the calcite .
40. Porous Media
The reservoir Rock minerals.
Oil reservoirs are large porous medium that contain
sands, clay minerals, and non-clay minerals.
The clay mineral surface has a negative charge.
When the catalyst solution is injected into the oil reservoir, the
metal ions, such as VO 2+ and Ni 2+ , can be adsorbed on the
surface of clay minerals via the electrostatic force.
Under this circumstance, the minerals support the catalyst
in a similar manner as in a typical refinery process.
41. Porous Media
The reservoir Rock minerals.
At the same time, the steam injected into the oil reservoir
reacts with most of the rock minerals and clay minerals.
Clay minerals are silica-aluminate compounds that under
high temperature can react with steam.
mineral reaction with steam can yield products with the
structure and properties similar to amorphous silicaalumina catalysts that commonly are used for catalytic
cracking in an oil refinery.
Notes de l'éditeur
Nanometer particle material has a large specific surface area, which increases rapidly with the decrease in diameter of particle. The large surface area leads to an increase in the proportion of atoms on the surface of the particle, which results in an increase in surface energy. The deficiency of atomic coordination and high surface energy leads to the unsteady, high activity of atoms on the particle, the increase in tendency of combination with other atoms, and the appearanceof active cores.
Viscosity of liquids is due to intermolecular forces. Larger molecules in heavy oil give more interaction. Asphaltene fraction gives aggregates in the oil phase, size 5-20 nm. Overlap of aggregates gives very high viscosity.
Enhancement of oil displacementefficiency by increasing of nanoparticles concentration can beoccurred because of increasing in viscosity and spreading of nanofluids on the surface. However, beyond a specific limit ofnanoparticles concentration, around 3 wt%, ultimate oil recoverydecreases due to blockage of pores and throats by dispersed silicananoparticles.The hydrophilic nature of selected silicananoparticles causes a wettability alteration of the micromodelfrom oil-wet to water-wet. This is a reason for the incensementof oil recovery for DSNW solution injection.Flow of DSNW in the mediumcould remove oil from the walls of pores and throats and thereforean increase in oil recovery was observed.A reason for fluid flowbehavior during DSNW flooding is the adsorption of silica nanoparticles onto medium surface and their ability to alter the surfacewettability from oil-wet to water-wet.
It reveals that if silica nanoparticles absorb on surface, they can alter wettability.As the results showed, withincreasing silica nanoparticles weight percent, the value of contactangles decreased to approximately zero and it can justify andconfirm the recovery enhancement in flooding tests and fluidsdistribution in pores and throats.
Due to adsorption of silica nanoparticles on the glass surface in pores and throats, a reduction in absolute permeability isobserved.
The key attribute that enables both surfactants and particulate solids to serve as emulsion stabilizers is an affinity for the water/oil, or aqueous/non-aqueous, interface. The hydrophile-lipophile balance (HLB) quantifies the relative preference of surfactants to water and oil. The contact angle serves the same purpose for colloidal particles and nanoparticles. Particles with contact angle close to 90° show surface activity useful for emulsification.A contact angle less than 90° means that the particle is hydrophilic and will make the oil/water interface curve toward oil, thus creating an oil-in-water emulsion. If the contact angle is greater than 90°, the particle is hydrophobic and will create a water-in-oil emulsion. A significant difference between surfactants and particles is the attachment of particles at the oil/water interface. While surfactants adsorb and desorb relatively easily, particles require high energy for attachments to the interface and are consequently virtually irreversibly adsorbed.
Such nanoparticles have a number of advantages over conventional colloidal solids. First, the small size allows the nanoparticles, and the micron-size emulsion droplets stabilized by them, to flow without retention in reservoir rocks of a wide range of permeability. Second, the polymer coating on the particle surface can make the particle stay at the aqueous/non-aqueous phase interface with a desired contact angle. This allows formation of the emulsion droplets of desired interfacial curvature, and also helps to reduce their retention in reservoir rock. Third, with the uniform size of the spherical nanoparticles, they can form a compact, well-structured monolayer at the aqueous/non-aqueous phase interface. This renders the emulsion extremely stable, even under harsh reservoir conditions such as high temperature. The same structure also offers the possibility of the controlled de-stabilization of the emulsion as described below. Fourth, the nanoparticles being solid, they can be magnetic, magnetostrictive, or piezoelectric, raising the possibility of external control for emulsion quality, texture and de-stabilization. Fifth, the nanoparticles can be catalytic, reactive, or associative with water-soluble polymer orsurfactant molecules.
without the presence of water, minerals have no effect on oil properties (Fan, 2004)
The water-gas shift reaction (WGS) is a chemical reaction in which carbon monoxide reacts with water vapor to form carbon dioxide and hydrogen:CO(g) + H2O(v) -> CO2(g) + H2(g)The reaction is slightly exothermic,The WGSR has only recently been shown to occur at temperatures below 400°C. In the absence of added metal salts as catalysts there is evidence to suggest that the mineral content of the sand contains sufficient appropriate (e.g. vanadium) catalysts to promote the WGSR at these lower temperatures.Added metal salt catalysts can enhance this important source of oil upgrading reagent - hydrogen.
The aquathermolysis reaction leading to cleavage is subject to metal ion catalysis likely through the complexing of the metal ion with the sulphur centre thus activating this moiety to attack by water. The metal ion may well be hydrated thus also assisting in carrying the water molecule into the reaction site.However, that use of certain metal salts as catalysts for the various component reactions of aquathermolysis results in a significant reduction in released H2S .This we suspect is due to the scavenging of the H2 S by the metal to form metal sulphides. While these will be subject to hydrolysis, releasing H2S again, a substantial amount of the H2S available will still be tied up as metal sulphide in the hydrolysis equilibrium. It is also worth noting that metal sulphides are known as good WGSR catalysts!
Nano-sized particles werefound to have a remarkable effect on heat transfer through heavy oil.Hascakir (2008) reduced heavy oil viscosity without adding water at ambient condition. Obviously, aquathermolysis is not the main mechanism of the viscosity reduction in this case. Viscosity reduction requires breakage of big molecules, like asphaltene by breaking its weak C-S bonds. The energy required to break these bonds can be provided by exothermic chemical reactions between metal particles and oil phase (Hascakir, 2008). The well-known rusting reaction of iron is one example of such reactions.
But why should pump output for nanotechnology injection must be greater than steam pressure?Because it is necessary that nanotechnology pump output pressure overcomes steam pressure. Otherwise, nanotechnology would not enter in steam stream.
When catalyst is added in the reaction system, the sample produces more gases because the catalyst can lead to some pyrolysis occurred in lower temperature. This is consistent with earlier results from other researchers. C 2 -C 7and H 2 S mainly come from the decomposition of the components containing S in the heavy oil. CO 2 may partly attribute to the aquathermalysis, the decarbonxylation of carbonxylic derivatives and the decomposition of humiccompounds in the heavy oil, partly come from water-gas reaction in the present of CO and steam. C 2 -C 7 light hydrocarbons can act as solvents to reduce the viscosity of the heavy oil. CO 2 can reduce the viscosity of heavy oil and improve the flow ability in oil reservoir.
Reaction temperature: As well known, the higher the temperature, the better effective of aquathermolysis reaction has. The temperature 240°C is usually adopted in the literatures, which is close to the situation in the reservoir during steam injection.
The concentration, type, and size of the particles were found to be highly critical on viscosity reduction.The presence of calcite, kaolinite and clays lead to the production of more carbon dioxide.The more asphaltene contents the more the gases produced.Therefore we expect an optimum concentration of the particles in which the effect of the reactions is the maximum. In other words, this optimum concentration gives the maximum reduction of the viscosity by the applied particles metal type.With increasing the asphaltene content, the degree of viscosity reduction will be higher. As these reaction occur on the C-S bond in asphaltenes.
Therefore we expect an optimum concentration of the particles in whichthe effect of the reactions is the maximum. In other words, this optimum concentration gives the maximum reduction of the viscosity by the applied particles metal type. As the particles size drops into nano scale, they tend to be affected by the behavior of atoms or molecules themselves and show different properties than the bulk of the same material. On the other hand, the micronization of solid particles increases the ratio of the surface to volume of the particles. Both of the mentioned attributes improve the physical and chemical properties of nanoparticles. Another important benefit of using nanoparticles is that they are much smaller than the size of the pores and throats in the porous medium. Therefore, in future applications for the heavy oil/bitumen recovery, injectivity of the nanoparticles would be less problematic.Nano-sized particles showed higher viscosity reduction than the micron sized particles. This is due to the larger specific surface area that results in more reactivity of the nanoparticles compared to micron-sized particles. In other words, larger surface areas of the particles result in an increase in the contact area of the particles with oil phase and thereby better interaction between two phases.
The major contribution of the metal particles is expected to improve viscosity reduction by reducing the amount of the required energy.Nano-sized particles were found to have a remarkable effect on heat transfer through heavy oil.Thermal conductivity of the mixture has been increased more than 1.25 times
Comprehensive Kinetic Models for the Aquathermolysis of Heavy Oils J.D.M. BELGRAVE Triton-Vuko Energy Group Ltd. R.G. MOORE, M.G. URSENBACH The University of Calgary
