Experimental Validation of a Pore-Scale Derived Dimensionless Capillary Pressure Function for Imbibition under Mixed-Wet Conditions

Y. Zhou, J. O. Helland, D. G. Hatzignatiou, R. Ahsan, A. Hiorth

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We validate experimentally a dimensionless capillary pressure function for imbibition at mixed-wet conditions that we developed recently on the basis of pore-scale modeling in rock images. The difference from Leverett’s traditional J-function is that our dimensionless function accounts for wettability and initial water saturation after primary drainage through area-averaged, effective contact angles that depend on the wetting property and distribution of oil- and water-wet grain surfaces. In the present work, we adopt the dimensionless function to scale imbibition capillary pressure data measured on mixed-wet sandstone and chalk cores. The measured data practically collapse to a unique curve when subjected to the dimensionless capillary pressure function. For each rock material, we use the average dimensionless curve to reproduce the measured capillary pressure curves and obtain excellent agreement. We also demonstrate two approaches to generate different capillary pressure curves at other mixed-wettability states than that available from the data used to generate the dimensionless curve. The first approach changes the shape of the spontaneous- and forced-imbibition segments of the capillary pressure curve whereas the saturation at zero capillary pressure is constant. The second approach shifts the vertical level of the entire capillary pressure curve, such that the Amott wetting index (and the saturation at zero capillary pressure) changes accordingly. Thus, integrating these two approaches with the dimensionless function yields increased flexibility to account for different mixed-wettability states. The validated dimensionless function scales mixed-wet capillary pressure curves from core samples accurately, which demonstrates its applicability to describe variations of wettability and permeability with capillary pressure in reservoir-simulation models. This allows for improved use of core experiments in predicting reservoir performance. Reservoir-simulation models can also use the dimensionless function together with existing capillary pressure correlations.
Original languageEnglish
Article numberSPE-180088-PA
Pages (from-to)1338-1348
Number of pages11
JournalSPE Journal
Volume22
Issue number5
Early online date7 Feb 2017
DOIs
Publication statusPublished - Oct 2017
Event78th EAGE Conference and Exhibition 2016: Efficient Use of Technology - Unlocking Potential2016 - Reed Messe Wien Vienna; Austria, Vienna, Austria
Duration: 30 May 20162 Jun 2016
Conference number: 127575

Keywords

  • dimensionless capillary pressure function
  • pore scale modeling
  • experimental validation
  • mixed-wet
  • imbibation

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