Observations of Microdrop Decan and Oil on Mica Surface by AFM and VSI. Ueda, A. 1, Kunieda, M. 1, Fukunaka, Y. 1, Liang, Y. 1, Matsuoka, T. 1 and Okatsu, K. 2 1 Kyoto University 2 The Technology and Research Center, Oil, Gas and Metals National Corporation (JOGMEC)

-Background “EOR ⇔ NANO”- High recovery =EOR (Enhanced Oil Recovery) ⇒ Viscosity, Fluidity, Substitution efficiency… micro-phenomena controls the wettability (contact angle, surface tension) in oil-mineral-fluid

quartzcarbonateclay rock Oil quartzcarbonateclay Sea water quartzcarbonate Sea water ＋ chemical brine Water-oil-rock (Enhanced oil recovery) Vapor/fluid solid liquid （ Young’s equation ） clay

Comparison of computational and experimental results

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The previous results presented in 2008 （北京）

Contact angle vs Salinity of brine Cruide oil Higashi-Niigata LocalityNiigata Density(g/cm 3 )0.784 API49.0 Velosity(30 ℃ ) 1.2

Observation of oil droplet on mica by AFM (Oil diameter ;400nm)

Observation of oil droplet by VSI (Vertical Scanning Interferometry) in distilled water at 25 ℃ and 1 atm 9

The results in 2009 (A preliminary report)

Macro analyses R h Decane H 2 O droplet θ/2 method R = 159 μm h = 20 μm Θ= 28.2 ° C 10 H g/cm 3

mica H2O droplet Decane H2O 5m Decane 500ml Naturally deposition for 1 hour Cleanup mica surface with water Make Mica cleavage Splash by air compressor Soak mica in Decane for 1 day Mica preparation Contact angle measurement Small emulsion (~10 micro m) Large emulsion (10 micro m~) Decane H2O Ultrasonic bath Magnetic stirrer Sample preparation for micro droplet H2O ~1ml Decane 100ml

Cantilever: k=0.01 Pressure: 2.5nN Scan rate: 0.5Hz 1μm×1μm Root mean square Roughness Roughness; 0.75nm ⇒ smooth surface in nanoscale Mica surface in decan (AFM)

5μm×5μm Rms roughness; 0.32nm Cantilever: k=0.01 Pressure: 2.5nN Scan rate: 0.5Hz H2O droplet Water droplet in decan (AFM)

R=2.109 micro m H=92.25 nano m Contact angle 12.7 degree (θ/2 method) Contact angle of water droplet in decan 5μm×5μm R h θ/2 method

Contact angle of water droplet in decan on mica surface (f=2.5nN) Cantilever: k=0.01 Pressure: 2.5nN Scan rate: 0.5Hz

Effect of cantilever pressure on contact angle Is it a real contact angle? R~10 micro m h=456.6 nano m Contact angle= 10.7° F=2.5nN Cantilever: k=0. 1 Pressure: 25nN Scan rate: 0.5Hz F=25nN ×

Contact angle of water droplet in decan on mica surface C.Pressure(low) C.Pressure(high)

Error signal Topography Effects of scanning pressure Real surface Apparent surface cantilever F=25nN AA=15.4 micro m (Differential calculus)

Effects of scanning pressure cantilever Force curve near water droplet ApproachRetract Decan on mica surface In H2O droplet Approach Retract ＊

Correction of contact angle Error signal ⇒ contact angle correction Force curve ⇒ height correction

Contact angle vs. oil size (AFM) Modified Young’s equation Similar value to the observed one in macro scale

Vertical Scan Interferometry (VSI)

Reaction cell for high T and P (~200 ℃, ~20MPa)

Width ： 9.9μm Height ： 0.52μm Contact angle ＝ 12.0 ° Water droplet in decan (VSI)

27 hydrophilic no hydrophilic 5nm α-Quartz Hexane CH 3 (CH 2 ) 4 CH 3 H2OH2O

Thank for your attention.