Emerging Petroleum-Oriented Nanotechnologies for Reservoir Engineering

1. By John Pack Greg Pudewell Jaynesh Shah Edwin L. Youmsi Pete Emerging Petroleum-Oriented Nanotechnologies for Reservoir Engineering

2. 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

3. 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

4. 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/

5. 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

6. 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.”

7. Colloidal Suspensions and Association Nanocolloids in Petroleum

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

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

15. 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

16. “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)

17. “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

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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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 mesophase Fig. 5 from I. Evdokimov, SPE

25. Immediate Relevance to the Properties of Native Petroleum

26. 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 asphaltenenanocolloids (fig 5) • Highlights some of the previously overlooked features Fig. 5 from I. Evdokimov, SPE

27. Plot of viscosity vsasphaltene content 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 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

28. Specific Gravity vs Asphaltene Content 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 vsasphaltene 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 Fig. 8 from I. Evdokimov, SPE “Asphaltene Deposition and Its Control”: http://tigger.uic.edu/ ~mansoori/Asphaltene.Decomposition.and.Its.Control_html

29. 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

30. Deposits at steel surfaces • Study of deposits from petroleum fluids with high asphaltene content (12.3 g/l) on steel surfaces • Fig. 10 • Filled 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

31. Nanophase-Resembling Phenomena in Brine-Petroleum Dispersions

32. 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 similarities • Both have well-defined phase diagrams • Water/oil dispersion controlled by oil’s “indigenous surfactants” including nanocolloidal asphaltenes ips.org

33. 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

34. 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

35. 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

36. 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

37. Conclusions

38. 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

39. 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

40. 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

41. Questions