The flocculation and deposition of asphaltenes in porous media and their interactions with rock and fluids represent complex phenomena which need to be investigated under dynamic flowing conditions. In this paper, experimental results are provided to determine the effect of asphaltene deposition on the dynamic displacements of heavy oil by water in consolidated as well as unconsolidated porous media. Dynamic method was used for in-situ asphaltene precipitation in the porous media.Several dynamic displacement experiments were conducted to understand the displacement of heavy oil by water at various degrees of asphaltene deposition.The results show that., while the increase in asphaltene deposition increased pore plugging and reduced the absolute permeability of the porous media, it also improved the displacement performance and oil recovery by water flooding. It is believed that the improvement in displacement performance may be partly due to improvement in the relative oil permeability caused by end point saturation and wettability changes and partly also due to the flow diversion effect of asphaltene deposition.

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In enriched gas drives, for correct interpretation of slim tube displacement (STD) tests and for determination of minimum miscibility pressure (MMP) or minimum enrichment (ME) required to achieve dynamic miscibility, it is extremely important to identify the correct mechanism of misciblity development. Traditional, pseudo-ternary diagram construction and limiting tie-line method or the criteria of very high (90-95% plus) ultimate oil recoveries or the criteria of breakover point in ultimate oil recovery versus pressure diagram in STD tests, used to determine MMP or ME are not always valid and can lead to solvents designed either too rich or too lean. In this study, STD tests supported by equation-of-state (EOS) predictions were used to evaluate the ability of various solvents such as CO2, n-butane and various mixtures of Prudhoe Bay natural gas (PBG) and natural gas liquids (NGL), to miscibly displace heavy, asphaltic West Sak crude. Results indicate that for enriched gas drives, the development of dynamic miscibility occurs via simultaneous vaporizing and condensing mechanisms. The solvent minimum enrichments for this dual mechanism were obtained from the solvent-oil, pressure-composition isotherms, compositional path in multicontact test (MCT) calculations and the methane spike disappearance phenomena in STD tests and were compared to those determined by condensing type, pseudo-ternary diagram construction method. STD test results indicate that the ultimate oil recoveries, even for first contact miscible (FCM) solvent were considerably lower due to asphaltene precipitation. Asphaltene tests were conducted for various solvent-West Sak crude mixtures to determine the amount of precipitation and it's effect on oil composition. STD results and EOS predictions indicate that CO2 was unable to develop dynamic miscibility with West Sak crude at reservoir pressure and temperature conditions and the process mechanism for CO2 drive is simultaneous vaporizing-condensing drive.

This volume represents the work achieved over a number of years during which many students and assistants provided their talents in the laboratory as well as onboard ship. Special thanks are extended to Miss Shalini Sharma and Mr. David Burbank who helped generously during collection and analysis of samples, data processing, and drafting.I am especially grateful to Dr. Joe S. Creager for providing sediment samples from some regions of the Chukchi and Bering seas and for his generous cooperation and assistance extended to me during my stay at the University of Washington.The computer analysis was performed under the supervision of Mr. Ivan Frohne, Dr. Dan Hawkins, and Dr. James Kelley, and their expert assistance is much appreciated.The book was reviewed by Dr. Tom Mowatt, Prof. AI Belon, Dr. D. M. Hopkins, and Prof. G. M. Friedman. These reviews deserve many thanks for their cooperation and quality efforts.Finally, I wish to thank my wife, Norma, for typing the original draft and for her patience.