Abstract
We use a Darcy-scale simulator to extract residual oil saturation, forced
imbibition capillary pressure, and relative permeability by history matching to
measured pressure drop and cumulative oil production during multi-speed centrifuge experiments and constant-rate waterfloods in Indiana limestone cores under four different wettability states established by adding different naphthenic acids to the oil phase. Residual oil saturation decreases monotonically as advancing bulk contact angle increases from θa = 110◦ to 150◦, in sharp contrast to the nonmonotonic dependence displayed by the core-averaged oil saturation which are often mis-interpreted to be representative of true residual saturation. The magnitude of the capillary pressure required to establish a particular water saturation increases with θa. Saturation-normalized water relative permeability exceeds one at θa ≥ 125◦ , with equivalent slip lengths of up to O(200) nm. The simulations indicate that capillary end effects may be significant during displacement experiments under typical laboratory conditions, even in mixed-wet media of relatively low permeability, and highlight the importance of using numerical simulation to interpret displacement experiments under capillary-dominated conditions.
imbibition capillary pressure, and relative permeability by history matching to
measured pressure drop and cumulative oil production during multi-speed centrifuge experiments and constant-rate waterfloods in Indiana limestone cores under four different wettability states established by adding different naphthenic acids to the oil phase. Residual oil saturation decreases monotonically as advancing bulk contact angle increases from θa = 110◦ to 150◦, in sharp contrast to the nonmonotonic dependence displayed by the core-averaged oil saturation which are often mis-interpreted to be representative of true residual saturation. The magnitude of the capillary pressure required to establish a particular water saturation increases with θa. Saturation-normalized water relative permeability exceeds one at θa ≥ 125◦ , with equivalent slip lengths of up to O(200) nm. The simulations indicate that capillary end effects may be significant during displacement experiments under typical laboratory conditions, even in mixed-wet media of relatively low permeability, and highlight the importance of using numerical simulation to interpret displacement experiments under capillary-dominated conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 121–148 |
| Number of pages | 28 |
| Journal | Transport in Porous Media |
| Volume | 129 |
| Issue number | 1 |
| Early online date | 5 Apr 2019 |
| DOIs | |
| Publication status | Published - 15 Aug 2019 |
Bibliographical note
MC was supported by the University of Aberdeen College of Physical Sciences studentship. The authors gratefully acknowledge CYDAREX for providing an evaluation license for their software CYDARTM , Koon-Yang Lee for the n-decane/brine static contact angle measurements on calcite (Supplementary Material S3), and Steffen Berg for his insightful comments and suggestions as a reviewer for conference paper Christensen and Tanino 2018 on which this paper builds. Finally, the authors thank the three anonymous reviewers for their detailed comments. All data used in this study are available from the corresponding author on reasonable request. In addition, the centrifuge data generated during this study are included as a Excel spreadsheet in the supplementary materials for this published article. One set of mercury injection capillary pressure measurements by Tanino and Blunt (2012) analysed in Text S2 are available in the Mendeley data repository, https://data.mendeley.com/datasets/9f4898jfr9/1.Keywords
- capillary trapping
- multiphase flow
- slippage
- residual saturation
- history matching
- Slippage
- 2-PHASE FLOW
- Multiphase flow
- WETTABILITY
- CONTACT-ANGLE
- OIL-WET
- Residual saturation
- RECOVERY
- History matching
- PRUDHOE BAY
- SURFACE
- POROUS-MEDIA
- SATURATION
- Capillary trapping
