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“Don’t Forget Viscosity” Dave Bergman BP America July 28, 2004

“Don’t Forget Viscosity” Dave Bergman BP America July 28, 2004. Core Laboratories and The Petroleum Technology Transfer Council 2nd Annual Reservoir Engineering Symposium. “From the Matrix to the Market – What You Don’t Know CAN Hurt You”. Viscosity Important to: Reservoir Modeling

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“Don’t Forget Viscosity” Dave Bergman BP America July 28, 2004

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  1. “Don’t Forget Viscosity”Dave BergmanBP AmericaJuly 28, 2004 Core Laboratories and The Petroleum Technology Transfer Council 2nd Annual Reservoir Engineering Symposium. “From the Matrix to the Market – What You Don’t Know CAN Hurt You”

  2. Viscosity Important to: Reservoir Modeling Production Rates Mobility for water Flooding Flow Assurance Rates Heat Transfer Facility Pump Design Equipment Sizing Pipeline Diameters Heat Transfer Area Just about any calculation you make will be dependent on Viscosity. As Many Correlations as “Fish in the Sea” Are all equally valid for your data? Without data, +_50% (1 STD) errors in Prediction Background

  3. Export Pipeline Example: Pressure Drop by Correlation

  4. Neither Correlation was Correct BR correlation used LOG(T,F) so Viscosity= Infinity at T=0F Wrong temperature Dependency over all temperatures, but most noticeable below 70F, resulting is too much change with Temperature Thodos also had wrong temperature Dependency, under estimating change with Temperature. New Correlation Needed for extrapolation Versus temperature, <70F. Review Calculations

  5. Check viscosity vs temperature for pure compounds. Beggs and others had plotted Log Log (Viscosity+1) versus Log(T) Started there. Best Linear fit obtained with Log Log (Viscosity+1) vs Log(T,F+310) What should New Correlation look Like?

  6. Correlation for Pure Hydrocarbons

  7. Dead Oil Viscosity vs Temperature

  8. Over 30 in the Literature Many developed on limited data set for a given area of the world. Inputs Dead Oil: API, Temperature, Watson K, Molecular weight. Compositional Correlations not covered in this presentation Correlations available for Calculating Viscosity

  9. Correlations available for Calculating Dead Oil Viscosity

  10. Correlations available for Calculating Saturated Oil Viscosity

  11. Correlations available for Calculating Under Saturated Oil Viscosity Kouzel 1983 API Data Book

  12. Dead Oil Correlations

  13. Dead Oil Correlations

  14. Dead Oil Correlations

  15. Dead Oil Correlations

  16. Live Oil Correlations

  17. Live Oil Correlations

  18. Under Saturated Oil Correlations

  19. How Accurate are They? Dead Oil Correlations Standard Deviation is around +-50% independent of Correlation given a wide data set. Having 1 data point will significantly reduce your error to about the error in the Data, assuming using reasonable correlation Live Oil +- 15% Biggest difference is curvature. Related to Temperature and Gas Gravity Under Saturated Oil +- 20% Pressure range very dependent on Correlation

  20. Expected Errors in Prediction of Dead Oil Viscosity 1 Std 1 Std

  21. Expected Errors in Prediction of Live Oil Viscosity 1 Std 1 Std

  22. Comparison of Under Saturated Errors: Live Oils

  23. Comparison of Under Saturated Errors: Dead Oils

  24. Export Pipeline Example: Pressure Drop with Improved Correlation

  25. Well Flow rate vs Viscosity Correlation

  26. Viscosity by Correlation

  27. Flow Rate vs Viscosity

  28. No correlation will always be the best, and none will ever be perfect. Experimental data near temperature of interest very important to minimizing errors. Dead Oil correlation determines the accuracy of your results. Using a better correlation may not give significant improvement Using a bad correlation can be disastrous Correlations are very dependent on range of data used in Development. Compositional Correlations are less predictive than Field Parameter ones. Conclusions

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