U5: Emerging Petroleum-oriented nanotechnologies for reservoir

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
Petroleum-Oriented Nanotechnology
Lighter, stronger and more
resistant equipment can be
produced using
It could also be used to
develop new metering
techniques with tiny sensors
to provide improved data
about the reservoir
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 underinvestigated.
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
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
Colloidal Suspensions and
Association Nanocolloids in
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
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
 A Russian-language book on
disperse systems in petroleum
Asphaltene molecule from
Previous Colloid Models
No earlier or more recent
models include a concept of
asphaltene self-assembly into
a variety of nanocolloidal
configurations with a wellstructured 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
The “only critical” boundary
being not a specific phase
transformation, but a
precipitation onset
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
 These association
processes were regarded
to be similar to micellization
phenomena of simple
surfactants for a long time
Different Classes of Disperse
 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
 Usually exhibit a very rich
phase behavior ranging from
the simplest isotropic
micellar phases to highly
organized supramolecular
For Example…
Note the appearance of
enclosed phase domains
(“closed loops”) at the
phase diagram,
representative of a socalled reentrant phase
 “Closed loops” are
indicative of polymorphism
of a system
 Loops originate in liquidliquid immiscibility
phenomena and are
characteristic signatures of
directional noncovalent
bonding in associating
Fig 3. A complex temperature-concentration (TC) phase diagram for nonionic surfactant pentaethyleneglycol dodecyl ether (C12E5) in water
from I. Evdokimov, SPE
Future Research into Association
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
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”
T-C Phase Diagram of
Asphaltenes in Petroleum – Data
Asphaltene Phase Diagrams
Phase changes in
systems can be
identified by revealing
“specific points” in
concentration and
dependencies of
system’s parameters
Fig 4. Concentration and temperature effects on HerschelBulkley’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
“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
 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 2832°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
 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
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
monomers recently
 Also confirmed by fluorescence technique
Fig. 5 from I. Evdokimov, SPE
Concentration-Defined Phase
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
Fig. 5 from I. Evdokimov, SPE
○ Boundaries 2 and 3 in diagram seem to be part of a closed loop
 “Upper” and “lower” “critical solution temperatures” present in
Concentration-Defined Phase
“Former CMC” boundaries (lines 3a and 3b in diagram)
1-10 g/l
 Published “CMC” data tend to
concentrate at 2 sub-ranges
 Most documented one ~
○ 1-3 g/l and 7-10 g/l
 Asphaltenes do not exhibit
true CMC behavior so CNAC
(critical nanoaggregrate
concentration) was introduced
Fig. 5 from I. Evdokimov, SPE
 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
Concentration-Defined Phase
Highest-Concentration boundaries (lines 4 and 5 in diagram)
 Strong effects observed at
20-35 g/l and contributed to
a “second aggregation
 Detailed SANS studies
 “Dilute regime” (from 3 to 4)
○ Aggregates are independent
entities with radii of few nanometers
Fig. 5 from I. Evdokimov, SPE
 “Semi-dilute regime” (above boundary 4)
○ Internal structure of aggregates remains unchanged
○ Aggregates interpenetrate and form soft fractal objects, imparting high fluid
 “Concentrated regime” (above boundary 5, above 70-90 g/l)
○ Large flocculated asphaltene domains may form “spatially-organized twophase textures”
Temperature-Defined Phase
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
○ Crystalline domains melt at 220-240°C
○ Above 350°C asphaltenes decompose
and form liquid crystalline mesophase
Fig. 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 pictures
 It 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 features
Fig. 5 from I. Evdokimov, SPE
Plot of viscosity vs asphaltene
Fig. 6 from I. Evdokimov, SPE
Log- log plot for 200 crudes of various
geographical/geological origin
Solid line is insignificant, only to
emphasize apparent viscosity
Stastics have to be improved,
especially in the low asphaltene
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
Specific Gravity vs Asphaltene
Fig. 7 from I. Evdokimov, SPE
 Well-known interdependence of viscosities
and 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
○ Boundary 3b not seen due to lack of
data points
Deposition and Its Control”: http://tigger.uic.edu/
Fig. 8 from I. Evdokimov, SPE
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
○ 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
Fig. 5 from I. Evdokimov, SPE
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
Between 28 and 37oC (at boundary A) there
is a strong transient stratification of density
and presumably of composition of the oil
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
Fig. 10
 Filled in symbols
○ Deposits from fluids which “thermal history” never
crossed boundary A
Fig. 10 from I. Evdokimov, SPE
 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
Phenomena in Brine-Petroleum
Phenomena in Brine-Petroleum
Oil well output typically consists of water
in a crude oil
Water/oil mixtures are not “nanosystems”
as are nanocolloids but there are
 Both have well-defined phase diagrams
 Water/oil dispersion controlled by oil’s
“indigenous surfactants” including
nanocolloidal asphaltenes
Water/Oil Mixtures “NanoResemble” Nanoemulsion
Microwave heated from 2025 °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
I. Evdokimov, SPE
Water cuts from 0.4-0.6
indicative of an
“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
Demulsification Efficiency
Demulsification: Breaking of liquid-liquid emulsions
 Improved demulsification efficiencies attributed to
“percolation” (0.2) and “bicontinuous” (0.4-0.6)
I. Evdokimov, SPE
How Nanocolloidal Research can
be Useful in Reservoir
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.
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
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
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.
 Ratner, M. A., and Ratner, D.: Nanotechnology: A Gentle
Introduction to the Next Big Idea, Prentice Hall, New Jersey,
 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”: