EMERGING PETROLEUM-ORIENTED NANOTECHNOLOGIES FOR RESERVOIR ENGINEERING

By

John Pack

Greg Pudewell

Jaynesh Shah

Edwin L. Youmsi Pete

Petroleum-Oriented Nanotechnology Many nanotechnology

applications have become standard in petroleum refining.

Most obvious application for upstream operations is development of better materials

http://www.ngoilgas.com/media/media-news/news-thumb/091127/nanotechnology.jpg

Petroleum-Oriented Nanotechnology Lighter, stronger and more

resistant equipment can be produced using nanotechnology.

It could also be used to develop new metering techniques with tiny sensors to provide improved data about the reservoir

https://publicaffairs.llnl.gov/news/news_releases/2006/images/membrane409x299s.jpg

Petroleum-Oriented Nanotechnology Other emerging applications of

Nanotechnology in reservoir engineering include;Development of “smart fluids” for

enhanced oil recovery and drilling.Development of “nanofluids” which are

used to enhance some of the properties of a fluid.

Nanotechnology in reservoir engineering is however still under-investigated.

http://www.cpge.utexas.edu/nesp/

What exactly is Nanotechnology?

A lot of confusion fueled partly by science-fiction.

Currently, there is no distinction between “true” nanotechnologies and other domains of atomic and molecular science/engineering.

http://www.thelensflare.com/gallery/p_nanobot_223.php

What exactly is Nanotechnology? Fairly representative definitions include;

“Nanoscience is the study of phenomena and manipulation of material at atomic, molecular and macromolecular scales where properties differ significantly from those at a larger scale.”

“Nanotechnologies are the design, characterization, production and application of structures, devices and systems by controlling shape and size at a nanometer scale.”

Colloidal Suspensions and Association Nanocolloids in Petroleum

Importance of Native Colloids for Petroleum Properties Specialists argue that there is no

novelty Importance was emphasized

several decades ago, esp. with bitumen

Any petroleum medium represents a colloid system with a dispersed colloidal phase composed mainly of asphaltenes

Important milestones in the research of asphaltene colloidal characterization: Publications of books based on

materials of the 1993 International Symposium on the Characterization of Petroleum Colloids

A Russian-language book on disperse systems in petroleum

Asphaltene molecule from http://www.seas.harvard.edu/projects/weitzlab/aggregation_files/asphaltene.jpg

Previous Colloid Models No earlier or more recent

models include a concept of asphaltene self-assembly into a variety of nanocolloidal configurations with a well-structured phase diagram

Most models from the start consider asphaltene as a solid (quasispherical) colloidal particle with diameter between 2-10 nm

There are no complex phase diagrams of hard sphere colloids

The “only critical” boundary being not a specific phase transformation, but a precipitation onset

http://www.lloydminsterheavyoil.com/Asphaltene3.gif

Previous Colloid Models Only one additional “critical

boundary” appears in previous models

Colloidal particles are not permanently present in petroleum but are formed from molecular solutions of asphaltenes at certain critical conditions as a result of some association processes

These association processes were regarded to be similar to micellization phenomena of simple surfactants for a long time

http://www.pharmainfo.net/files/images/stories/article_images/MicelleComposedOfAmphiphilicSurfactants.jpg

Different Classes of Disperse Systems The assumption of

micellization places asphaltenes into a principally different class of disperse systems

Colloidal suspension A system of solid particles

dispersed in a liquid Association colloids

Systems with particles which are formed by reversible micellization

Usually exhibit a very rich phase behavior ranging from the simplest isotropic micellar phases to highly organized supramolecular nanostructures

http://sites.google.com/site/molecularsystemsengineering/asphalteneschains.jpg

For Example… Note the appearance of

enclosed phase domains (“closed loops”) at the phase diagram, representative of a so-called reentrant phase behavior

“Closed loops” are indicative of polymorphism of a system

Loops originate in liquid-liquid immiscibility phenomena and are characteristic signatures of directional noncovalent bonding in associating species

Fig 3. A complex temperature-concentration (T-C) phase diagram for nonionic surfactant penta-ethyleneglycol dodecyl ether (C12E5) in water from I. Evdokimov, SPE

Future Research into Association Colloids

Even after introducing the concept of micellization for nanoparticles of asphaltenes, petroleum researchers still remained content with the idea of single critical concentration (CMC) in surfactants

Possible analogies with known complex properties of association colloids has not been investigated

Although well-known published experimental results and recent publications provide multiple data in support of the concept of asphaltenes as “association colloids”

http://miam.physics.mcgill.ca/miam/images/research/complex/Hill_colloid_charges.jpg

T-C Phase Diagram of Asphaltenes in Petroleum – Data Accumulation

Asphaltene Phase Diagrams Phase changes in

asphaltene-containing systems can be identified by revealing “specific points” in experimental concentration and temperature dependencies of system’s parameters

Fig 4. Concentration and temperature effects on Herschel-Bulkley’s rheological parameters in asphaltene –rich model oil from I. Evdokimov, SPE

“Specific Points” The T-C area of practical importance is wide:

Pour point temperatures Asphaltene decomposition/coking “Infinitely diluted petroleum solutions” Solid Asphaltenes

This research group investigated concentration effects in dilute solutions with asphaltene contents from ~1 mg/L to ~1 g/L, close to room temperature

Detailed studies of temperature effects have been performed in the range from -50°C to ~400°C with bitumen and precipitated asphaltenes (concentrations used were from ~140 g/L to ~1200 g/L)

“Specific Points” Specific concentrations/temperatures were neither

noticed nor discussed in original publications but corresponding “specific points” are clearly seen in the published data plots

E.g., SANS study of asphaltene aggregation Provided detailed concentration dependencies of the radii of

gyration RG in solutions of asphaltenes with concentrations 3.4-117 mg/L at temperatures from 8°C to 73°C

Provided qualitative discussion of concentration/temperature effects

Did not specify obvious RG maxima at concentrations ~5, ~20-22 and ~70 g/L

Replotting their original data on RG vs. T graph clearly indicate the presence of “specific temperatures” round 28-32°C

T-C Phase Diagram of Asphaltenes in Petroleum – Current Version

Current T-C Phase Diagram Asphaltenes in Petroleum First cumulative T-C plot

of all “specific points” Fairly well-defined phase

boundaries Limited data does not

allow for statistical analysis○ Numerical values of

“critical” parameters

should Be regarded as approximate Concentration-Defined Phase Boundaries Temperature-Defined Phase Boundaries

Fig. 5 from I. Evdokimov, SPE

Concentration-Defined Phase Boundary Primary aggregation boundary (Line 1 in diagram)

Ca. 7-10 mg/l (20oC) Obtained by measuring

○ UV/vis absorption○ Viscosity○ NMR relaxation

Attribution of boundary to

primary association of

asphaltenes

monomers recently Also confirmed by fluorescence technique

Fig. 5 from I. Evdokimov, SPE

Concentration-Defined Phase Boundary Liquid-liquid demixing boundary (line 2 in diagram)

Ca. 100-150 mg/l (20oC) Revealed for solutions of

solid asphaltenes and of

heavy crudes by:○ Optical absorption○ NMR relaxation○ Viscosity○ Ultrasonic velocity, etc.

Closed loop phase boundary is

a well known feature of demixing systems○ Boundaries 2 and 3 in diagram seem to be part of a closed loop

“Upper” and “lower” “critical solution temperatures” present in diagram

Fig. 5 from I. Evdokimov, SPE

Concentration-Defined Phase Boundary “Former CMC” boundaries (lines 3a and 3b in diagram)

Most documented one ~ 1-10 g/l Published “CMC” data tend to

concentrate at 2 sub-ranges ○ 1-3 g/l and 7-10 g/l

Asphaltenes do not exhibit

true CMC behavior so CNAC

(critical nanoaggregrate

concentration) was introduced Diagram shows that “Former CMC” boundaries reflect phase

transformations in secondary systems of complex nanocolloids formed at the demixing boundary

At least one of the “former CMC” lines may be just a continuation of a demixing (liquid-liquid separation)closed loop

Fig. 5 from I. Evdokimov, SPE

Concentration-Defined Phase Boundary

Highest-Concentration boundaries (lines 4 and 5 in diagram) Strong effects observed at

20-35 g/l and contributed to

a “second aggregation

concentration”

Detailed SANS studies “Dilute regime” (from 3 to 4)

○ Aggregates are independent

entities with radii of few nanometers “Semi-dilute regime” (above boundary 4)

○ Internal structure of aggregates remains unchanged○ Aggregates interpenetrate and form soft fractal objects, imparting high fluid

viscosities “Concentrated regime” (above boundary 5, above 70-90 g/l)

○ Large flocculated asphaltene domains may form “spatially-organized two-phase textures”

Fig. 5 from I. Evdokimov, SPE

Temperature-Defined Phase Boundaries Several temperature-controlled phases of aggregated asphaltenes

(right-hand side of diagram) Freezing

○ Exhibit heat capacities consistent with an ordered solid α-phase (25-30 °C)

○ Amorphous (glassy) phase○ Structure controlled by interactions between polar alkane side chains

β-phase (30-100°C)○ Phase transition acquire more dense structures○ Controlled by bonding to pericondensed aromatic segments

γ-phase (100-150°C)○ Phase with crystalline order

Higher Temperatures○ Amorphous asphaltenes soften and

liquefy○ Crystalline domains melt at 220-240°C○ Above 350°C asphaltenes decompose

and form liquid crystalline mesophaseFig. 5 from I. Evdokimov, SPE

Immediate Relevance to the Properties of Native

Petroleum

Immediate Relevance to the Properties of Native Petroleum Some skeptics wonder why we need these scientific

speculations and nice picturesIt is true that we cannot make any suggestion about the

details of nanocolloid phases in “live” petroleum○ More complicated and costly experiments are needed

Detailed inspection of the world’s “dead” petroleum fluids show surprisingly strong

effects which may originate in

the phase diagram of

asphaltene nanocolloids (fig 5)○ Highlights some of the

previously overlooked featuresFig. 5 from I. Evdokimov, SPE

Plot of viscosity vs asphaltene content Log- log plot for 200 crudes of various

geographical/geological origin Solid line is insignificant, only to

emphasize apparent viscosity

extreama Stastics have to be improved,

especially in the low asphaltene

contents Even “raw” data in fig 6 clearly demonstrate a coincidence of shaprp

viscosity anomalies with all but one phase boundaries (phase 1) Applies to 0.001 wt% Most current databases classify <0.01 wt% as “zero asphaltene content”

Almost absence of native free-flowing crude oils with asphaltene contents above the phase boundary 5 May be a natural “solubility limit” of asphaltene in native crude oils

Fig. 6 from I. Evdokimov, SPE

Well-known interdependence of viscositiesand densities in crude oils

Noticeable peaking of specific gravities at asphaltene phase boundaries showin in fig 7

Asphalene decomposition table with “Resin and Asphaltene Content of various Crude Oils” (from source)○ Properties of 20 crudes with non-zero

asphaltene content from diverse

locations (Canada, Venezuela, Mexico,

USA, Russia, Brazil, Iraq, France, Algeria)○ Plot of specific gravity vs asphaltene

content from table shown in fig 8○ When compared to figures 6 and 7, one

can see the same peaks of specific

gravity to the same asphaltene phase

boundaries○ Boundary 3b not seen due to lack of

data points

Specific Gravity vs Asphaltene Content

“Asphaltene Deposition and Its Control”: http://tigger.uic.edu/~mansoori/Asphaltene.Decomposition.and.Its.Control_html

Fig. 7 from I. Evdokimov, SPE

Fig. 8 from I. Evdokimov, SPE

PropertyTransformations

Fig 9: Properties from boundary A in fig 5 Left Hand Side

Variations of the pour point of a Tatarstan crude

after 1 hour thermal pre-treatments, Temp close to phase boundary A Properties

○ 895 g/l 3.5 wt% asphaltenes○ 20 wt% resins 0.3 wt% waxes

Most Dramatic Pour point Deviation

○ -16.2 to +11.2 oC (at pre-treatment Temp of 36.5oC) Right Hand Side

Dramatic Density Deviation near

boundary A in fig 5 Measured by refractive index With no phase boundary, expected

gradual decrease with density at top

marginally smaller than the bottom Expected behavior below 28oC and above

37oC Between 28 and 37oC (at boundary A) there

is a strong transient stratification of density

and presumably of composition of the oil

Fig. 5 from I. Evdokimov, SPE

Fig. 9 from I. Evdokimov, SPE

Deposits at steel surfaces

Study of deposits from petroleum fluids with high asphaltene content (12.3 g/l) on steel surfaces

Fig. 10Filled in symbols

○ Deposits from fluids which “thermal history” never crossed boundary A

Open symbols○ Deposits from a fluid that

was heated at least once

above 28-29oC○ Afterwards, Increase of

deposition persisted below the

phase boundary (at 12-29oC)

for at least one month

Fig. 10 from I. Evdokimov, SPE

Nanophase-Resembling Phenomena in Brine-Petroleum Dispersions

Nanophase-Resembling Phenomena in Brine-Petroleum Dispersions

Oil well output typically consists of water in a crude oil

Water/oil mixtures are not “nanosystems” as are nanocolloids but there are similaritiesBoth have well-defined phase diagramsWater/oil dispersion controlled by oil’s

“indigenous surfactants” including nanocolloidal asphaltenes

ips.org

Water/Oil Mixtures “Nano-Resemble” Nanoemulsion Systems

Microwave heated from 20-25 °C

Sharp variations of specific heat due to abrupt changes in morphology Resembles those observed

in nanoemulsion systems “Percolation threshold” at

water cuts ≈ 0.2 “Bicontinuous morphology”

at water cuts ≈ 0.4 “Close packed” at water cuts

≈ 0.6

I. Evdokimov, SPE

Water/Oil Mixture Measurements of Density

Water cuts from 0.4-0.6 indicative of an asphaltene-mediated “middle phase”

T-C contours of excess, non-ideal densities show strong correlation to the bicontinuous domains of the T-C phase diagram for association nanocolloids

I. Evdokimov, SPE

Demulsification Efficiency Demulsification: Breaking of liquid-liquid emulsions Improved demulsification efficiencies attributed to

“percolation” (0.2) and “bicontinuous” (0.4-0.6) phenomena

I. Evdokimov, SPE

How Nanocolloidal Research can be Useful in Reservoir Engineering

Avoid any lengthy operations in the vicinity of the temperature-defined boundary “A” (Fig. 5) to avoid increase in viscosity and pour point (Fig. 9)

However, storage at this boundary “A” may result in increases stratification of petroleum light/heavy components (Fig. 9)

Approaching a nanophase boundary by blending crude oils may result in viscosity and density peaking (Figs. 6,7)

ere2007.com

Conclusions

Conclusions In petroleum engineering,

nanotechnologies are not considered important enough for widespread use, except for in refineries and “smart fluids” for EOR

This research shows there is enough evidence to consider oils as “association nanofluids”

Emerging technologies should account for complex phase diagrams of nanocolloids

capp.ca

Further Research This research is far from complete Much more investigation need be done on the complex

phase diagrams regarding asphaltene nanocolloids Other types of nanocolloids should be investigated and

their phase diagrams drawn up as well Various other colloids (such as water) should be

investigated in regards to property changes

careers-scotland.org.uk

References Evdokimov, Igor N., Nikolaj Yu. Eliseev, Aleksandr P. Losev, and

Mikhail A. Novikov. "Emerging Petroleum-Oriented Nanotechnologies for Reservoir Engineering." (2006). Society of Petroleum Engineers. Web. 10 Mar. 2010. <http://www.onepetro.org/mslib/servlet/onepetropreview?id=SPE-102060-MS&soc=SPE>.

Ratner, M. A., and Ratner, D.: Nanotechnology: A Gentle Introduction to the Next Big Idea, Prentice Hall, New Jersey, 2002.

Crane, C., Wilson, M., Kannangara, K., Smith, G., and Wilson, W.: Nanotechnology: Basic Science and Emerging Technologies, CRC Press, 2002.

Jackson, S. A.: Innovation and Human Capital: Energy Security and the Quiet Crisis. Am. Petrol. Inst., 2005.

Asphaltene Deposition and Its Control”: http://tigger.uic.edu/~mansoori/Asphaltene.Decomposition.and.Its.Control_html

Questions