Field-Scale Simulation of WAG Using Pore-Scale Network Modelling


In recent years the interest in water alternating gas (WAG) injection as tertiary recovery method has increased. This method has been applied successfully in many fields around the world. The WAG process results in three-phase flow, of which the mechanisms are still not well understood. Therefore; it is important to understand and properly describe the multi-phase flow properties (relative permeability and capillary pressure) which controll the WAG process.

In this study we have used pore-scale network modeling to describe the multi-phase flow properties for use in reservoir simulation of WAG injection at the field scale. Network models are being used as alternative for empirical methods to describe the multi-phase flow properties, since the former are physically-based tools which integrate the relevant pore-scale mechanisms while the latter often  have little physical basis. A recently developed three-phase flow pore-network model has been used, which integrates the formation and collapse mechanism for oil layers, represents more complexity of the pore structure and incorporates so-called multiple displacement process. In the reservoir simulation we have studied the effect of WAG on recovery factor for different injection scenarios. We additionally studied the effect of different WAG ratios on improving overall WAG performance.

Keyword: Pore-network model; capillary pressure; three-phase; interfacial tension; residual; ternary; ratio; breakthrough; clusters.

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  • Al-Dhahli, A., Geiger, S., and van Dijke, M. I. J. (2011). “Three-Phase Pore-Network Modelling for Mixed-Wet Carbonate Reservoirs.” SPE Reservoir Characterisation and Simulation Conference and Exhibition, Society of Petroleum Engineers, Abu Dhabi, UAE.
  • Al-Dhahli, A., Geiger, S., and van Dijke, M. I. J. (2012). “Accurate Modelling of Pore-scale Film and Layer Flow for Three-phase EOR in Carbonate Rocks with Arbitrary Wettability.” SPE Improved Oil Recovery Symposium, Society of Petroleum Engineers, Tulsa, Oklahoma, USA.
  • Al-Ghanim, W., R. Gharbi, and M.K. Algharaib, Designing a Simultaneous Water Alternating Gas Process for Optimizing Oil Recovery, in EUROPEC/EAGE Conference and Exhibition. 2009, Society of Petroleum Engineers: Amsterdam, The Netherlands.SPE 120375-MS.
  • Andrews, J., M. Hettema, and T. Nesse, Injection Wells: A Case Study From the Statfjord Field, in SPE Annual Technical Conference and Exhibition. 2004: Houston, Texas.SPE 90949.
  • Baker, L .E. (1993). Three-Phase Relative Permeability of Water-Wet, Intermediate-Wet, and Oil-Wet Sandstone. Seventh European Improved Oil Recovery Symposium, Moscow, Russia.
  • Baojun, F., D. Xingjia, and Y. Cai, Pilot Test of Water Alternating Gas Injection in Heterogeneous Thick Reservoir of Positive Rhythm Sedimentation of Daqing Oil Field. SPE Advanced Technology Series, 1997. 5(1).
  • Blunt, M. J. (2000). An Empirical Model for Three-Phase Relative Permeability. Soc. Pet. Eng. J., 5 (4), 435-445.
  • Blunt, M. J. (2001). “Flow in porous media – pore-network models and multiphase flow.” Current Opinion in Colloid & Interface Science, 6(3), 197-207.
  • Blunt, M. J., Jackson, M. D., Piri, M., and Valvatne, P. H. (2002). “Detailed physics, predictive capabilities and macroscopic consequences for pore-network models of multiphase flow.” Advances in Water Resources, 25(8-12), 1069-1089.
  • Christensen, J. R., Stenby, E. H., and Skauge, A. (2001). “Review of WAG Field Experience.” SPE Reservoir Evaluation & Engineering (04).
  • Fatt I. The network model of porous media I. Capillary pressure characteristics. Trans AIME 1956;207:144_159.
  • Fatt I. The network model of porous media II. Dynamic properties of a single size tube network. Trans AIME 1956;207:160_163.
  • Fatt I. The network model of porous media III. Dynamic properties of networks with tube radius distribution. Trans AIME1956;207:164_181.
  • Fenwick, D. H., and Blunt, M. J. (1998a). “Network Modeling of Three-Phase Flow in Porous Media.” SPE Journal, 3(1), 86-96.
  • Fenwick, D. H., and Blunt, M. J. (1998b). “Three-dimensional modeling of three phase imbibition and drainage.” Advances in Water Resources, 21(2), 121-143.
  • Forrest, J.K., et al., Samarang Field – Seismic To Simulation Redevelopment Evaluation Brings New Life to an Old Oilfield, Offshore Sabah, Malaysia, in International Petroleum Technology Conference. 2009: Doha, Qatar.SPE 13162
  • Gorell, S.B., Modeling the Effects of Trapping and Water Alternate Gas (WAG) Injection on Tertiary Miscible Displacements, in SPE Enhanced Oil Recovery Symposium. 1988: Tulsa, Oklahoma.SPE 17340
  • Hui, M.-H., and Blunt, M. J. (2000a). “Pore-Scale Modeling of Three-Phase Flow and the Effects of Wettability.” SPE/DOE Improved Oil Recovery Symposium, Copyright 2000, Society of Petroleum Engineers Inc., Tulsa, Oklahoma.
  • Hui, M. H., and Blunt, M. J. (2000b). “Effects of wettability on three-phase flow in porous media.” Journal of Physical Chemistry B, 104(16), 3833-3845.
  • Juanes, R., & Spiteri, E. (2004). Impact of Relative Permeability Hysteresis on WAG Injection. SPE 89921.
  • Oak, M. J. (1990). “Three-Phase Relative Permeability of Water-Wet Berea.” SPE/DOE Enhanced Oil Recovery Symposium, Tulsa, Oklahoma.
  • Øren, P.-E., and Bakke, S. (2003). “Reconstruction of Berea sandstone and pore-scalemodelling of wettability effects.” Journal of Petroleum Science and Engineering, 39(3-4), 177-199.
  • Oren, P.-E., Bakke, S., and Arntzen, O. J. (1998). “Extending Predictive Capabilities to Network Models.” SPE Journal, 3(4), 324-336.
  • Øren, P. E., Billiotte, J., and Pinczewski, W. V. (1994). “Pore-Scale Network Modelling of Waterflood Residual Oil Recovery by Immiscible Gas Flooding.” SPE/DOE Improved Oil Recovery Symposium, 1994 Copyright 1994, Society of Petroleum Engineers, Inc., Tulsa, Oklahoma.
  • Paterson, L., Lee, J.-Y., and Pinczewski, W. V. (1997). “Three-Phase Relative Permeability in Heterogeneous Formations.” SPE Annual Technical Conference and Exhibition, 1997 Copyright 1997, Society of Petroleum Engineers, Inc., San Antonio, Texas.
  • Pereira, G. G. (1999). “Numerical pore-scale modeling of three-phase fluid flow:Comparison between simulation and experiment.” Physical Review E, 59(4), 4229–4242.
  • Peters, L., Arts, R., Brouwer, G., Geel, C., Cullick, S., Lorentzen, R. J., Chen, Y., Dunlop, N., Vossepoel, F. C., Xu, R., Sarma, P., Alhuthali, A. H. H., and Reynolds, A. (2010). “Results of the Brugge Benchmark Study for Flooding Optimization and History Matching.” SPE Reservoir Evaluation & Engineering(3), pp. 391-405.
  • Piri, M., and Blunt, M. J. (2005a). “Three-dimensional mixed-wet random pore-scale network modeling of two- and three-phase flow in porous media. I. Model description.” Physical Review E, 71(2), 026301.
  • Sohrabi (2000) ‘Pore scale study of water alternating gas (WAG) injection using high-pressure micromodels with different conditions of wettability’, SPE, (95594).
  • Sohrabi (2001) ‘Visualisation of Oil Recovery by Water Alternating Gas (WAG) Injection Using High Pressure Micromodels – Oil-Wet & Mixed-Wet Systems’, SPE, (71494-MS), pp. 1429-1435.
  • Stone, H. L. (1970). Probability Model for Estimation Three- Phase Relative Permeability. Journal of Petroleum Technology, 20, 214-218.
  • Stone, H. L. (1973). Estimation of Three-Phase Relative Permeability and Residual Data, Journal of Canadian Petroleum Technology, 12, 53-61.
  • Suicmez, V. S., Piri, M., and Blunt, M. J. (2006). “Pore-Scale Modeling of Three-Phase WAG Injection: Prediction of Relative Permeabilities and Trapping for Different Displacement Cycles.” SPE/DOE Symposium on Improved Oil Recovery, Society of Petroleum Engineers, Tulsa, Oklahoma, USA.
  • Van Dijke, M. I. J., M. Piri, J. O. Helland, K. S. Sorbie, M. J. Blunt, and S. M. Skjæveland (2007), Criteria for three-fluid configurations including layers in a pore with nonuniform wettability, Water Resour. Res., 43, W12S05.
  • Van Dijke, M. I. J. (2003) ‘Pore-scale modelling of three-phase flow in mixed-wet porous media: multiple displacement chains’, Journal of Petroleum Science and Engineering,39(3-4), pp. 201-216.