REALISTIC STABLE WATER-IN-OIL EMULSIONS AT OHMSETT

Transcription

1 REALISTIC STABLE WATER-IN-OIL EMULSIONS AT OHMSETT Karen Stone Oil Spill Response Engineer Oil Spill Preparedness Division December 6, Conference and Exhibition environment and conserve resources offshore through vigorous regulatory

2 Implications of emulsions in spill response Study objective & overview of Ohmsett Lab-scale Large-scale Photooxidation Density & viscosity results Lessons learned & next steps

3 Physical properties of emulsified crude oil can differ greatly from the parent crude oil Emulsification increases the volume of the mixture significantly Increases viscosity and changes to rheological properties

4 Goals and Objectives Methods Expand Testing Capabilities at Ohmsett: Stable Emulsions

5 Goal: Expand Testing Capabilities at Ohmsett

6 Parent Oil: HOOPS Pipeline Blend Hoover Offshore Oil Pipeline System Parameter - Units Method Results API 60 ASTM D Flash Point, closed cup - F ASTM D93 74 Paraffin - wt. % <0.01 Pour Point - F ASTM D97-22 Sulfur - wt. % ASTM D Saturates - wt. % ASTM D Aromatics - wt. % ASTM D Asphaltenes - wt. % ASTM D Polar Compounds (Resins) - wt. % ASTM D Special thanks to ExxonMobil for helping BSEE purchase HOOPS to the Ohmsett facility for Oil Spill Research.

7 Mass Loss due to Weathering 633-W2 Target 10 Room Temperature % M a s s y = x x R² = L o s s Time (min) % W1 Extended Room Temperature Mass loss to approximately 10% over time of HOOPS crude oil exposed to air sparging at 1 L/min in the lab at approximately 20 C. M a s s y = ln(x) R² = L o s s Time (hours) Mass loss of HOOPS crude oil over extended time (148 hours) with air sparging at 1 L/min in the lab at 20 C (room temperature).

8 Physical Properties after Weathering: Description Sample # Density 20C) Viscosity 20C) S.T 20C) I.F.T (dynes/ 20C) FRESH HOOPS HOOPS WEATHERED 10% BY WEIGHT 633-W HOOPS WEATHERED 20% BY WEIGHT 633-W HOOPS WEATHERED 24% BY WEIGHT 633-W

9 In Situ Measurement Methods:

10 Remote Sensing Platforms:

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12 Day 8 Day gallons HOOPS Day 5 Wave Making Begins Day 7 Day 6

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14 Physical Properties Large Scale after Weathering & Emulsification TEST FLUID PROPERTIES NOMINAL OIL (PRE-TEST) TEST OIL: SAMPLE # 20C 20C) 20C 20C) WATER QUANITITATIVE SAMPLE # % WATER FRESH HOOPS WEATHERED HOOPS WEATHERED HOOPS WEATHERED HOOPS WEATHERED EMULSIFIED HOOPS D01 79 WEATHERED EMULSIFIED HOOPS D02 75 WEATHERED EMULSIFIED HOOPS D03 84 WEATHERED EMULSIFIED HOOPS D04 82 WEATHERED EMULSIFIED HOOPS D05 75 WEATHERED EMULSIFIED HOOPS D06 74

15 Drum Scale: Photooxidation & Emulsification Photooxidation, the degradation of the surface of the crude oil in the presence of oxygen by ultraviolet (UV) energy, is suspected to play a role in the rate of weathering and subsequently the formation of emulsions. Photooxidation Methodology Shearing Energy Methodology Stability Measurement

16 Photooxidation

17 Lessons Learned Photooxidation Cumulative Surface Exposure & Time Date Exposure Start Time Exposure Stop Time Exposure Time (hrs) Exposure Time (min) RPM Test Surface Exposure (m)¹ Total Cum. Surface Exposure (m)² Cumulative Exposure Time (hrs)³ 08/28/ , , , , , /30/ , , , , , , , /31/ , , , , , /12/

18 Irradiance vs. Time Time Time Date and Time of Def. Integral Irradiance Day Val. Energy min hours W/m² kwh/m² MJ /28/ : /28/ : /28/ : /28/ : /28/ : /28/ : /28/ : /28/ : /28/ : /28/ : /28/ : Σ= kwh/m² MJ/m²

19 Density during Photooxidation Density 20C Density--weathered, no UV (lab) Density--weathered & UV Cumulative Time (Hours) Density at 147 hours (24% weathered) was.0905 g/ml

20 Viscosity during photooxidation Viscosity 21C Viscosity--weathered & UV Viscosity--weathered, no UV (lab) Cumulative Time (Hours) Viscosity at 147 hours (24% weathered) was cp

21 Lessons Learned Lab Scale Mass loss from evaporation eventually leveled off. Increases in viscosity and density were consistent with weathering prior to emulsification. General trend of higher densities and viscosities as water content increased.

22 Lessons Learned Large Scale Emulsification proved quite fleeting and obtaining representative samples across the tank within the emulsion thicknesses themselves proved problematic. Stability of the emulsions changed during transport of samples from the tank to the nearby on-site lab. Color change, as seen in emulsions formed in the marine environment, changed as a result of water content/stability.

23 Lessons Learned Photooxidation No observed color change due to photooxidation Evaporation of lighter components required adjustment of skimmer rpms as HOOPS became more viscous Continued skimmer adjustments needed as viscosity/density increased due to photooxidation

24 Next Steps Create mass quantities of stable, reproducible W/O emulsions using commercial mixers Determine length of time of stability Place drum emulsions onto the Ohmsett tank to determine if quasirealistic emulsions with a color change can be achieved Conduct SARA analysis of photooxidized HOOPS to identify any new products as a result of photooxidation

25 Visit the BSEE Booth 521 & the Ohmsett Booth 523. BSEE Website: BSEEgov Bureau of Safety and Environmental Enforcement BSEEgov environment and conserve resources offshore through vigorous regulatory