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Scaling equations for oil/gas recovery from fractured porous media by counter-current spontaneous imbibition: From development to application

Mirzaei-Paiaman, A ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1021/ef400990p
  3. Abstract:
  4. Spontaneous imbibition, the capillary-driven process of displacing the nonwetting phase by the wetting phase in porous media, is of great importance in oil/gas recovery from matrix blocks of fractured reservoirs. The question of how properly scaling up the recovery by counter-current spontaneous imbibition has been the subject of extensive research over decades, and numerous scaling equations have been proposed. As a convention, the scaling equations are usually defined analytically by relating the early time squared recovery to squared pore volume. We show this convention does not apply to common scaling practices and, if used, causes nontrivial scatter in the scaling plots. We explain that for three common scaling practices, where the recovery is normalized by (1) final recovery, (2) pore volume, or (3) initial oil/gas in place, this convention should be redefined accordingly. The main contribution is to emphasize that during the development of any scaling equation, its consistency with common applications should be considered. Such consistency has been historically neglected in literature works. Using this new insight, we consider the latest scaling published in the literature to present three different consistent scaling equations for three corresponding scaling situations. The new scaling equations, which are valid for both gas-liquid and liquid-liquid systems, incorporate all factors influencing the process and resolve all limitations of scaling groups published during past decades. These scaling equations are rewritten in terms of two physically meaningful dimensionless numbers, Da1/2/Ca (Da, Darcy number; Ca, capillary number), and validated against experimental data from the literature. This approach enables us to scale all data perfectly and represents all recovery curves by a single master curve. We further highlight the necessity of incorporation of directional permeability effects in scaling equations by defining the new concept of characteristic permeability
  5. Keywords:
  6. Capillary numbers ; Dimensionless number ; Fractured porous media ; Fractured reservoir ; Liquid-liquid systems ; Permeability effects ; Scaling equations ; Spontaneous imbibition ; Calcium ; Enhanced recovery ; Porous materials ; Recovery
  7. Source: Energy and Fuels ; Vol. 27, issue. 8 , July , 2013 , p. 4662-4676 ; ISSN: 08870624
  8. URL: http://pubs.acs.org/doi/abs/10.1021/ef400990p