Oil Saturation in Residual Oil Zones and Its Effect on CO2 WAG Injection Strategies
- Bo Ren (The University of Texas at Austin) | Frank Male (The University of Texas at Austin) | Yanyong Wang (The University of Texas at Austin) | Vinyet Baqués (The University of Texas at Austin) | Ian Duncan (The University of Texas at Austin) | Larry Lake (The University of Texas at Austin)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 30 September - 2 October, Calgary, Alberta, Canada
- Publication Date
- Document Type
- Conference Paper
- 2019. Society of Petroleum Engineers
- CO2-EOR, Water Alternating Gas, Oil Saturation, Residual Oil Zone
- 5 in the last 30 days
- 329 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 5.00|
|SPE Non-Member Price:||USD 28.00|
The objectives of this work are to understand the characteristics of oil saturation in residual oil zones (ROZs) and to optimize water alternating gas (WAG) injection strategies. ROZs occur in the Permian Basin and elsewhere, and operators are using CO2 injection for enhanced oil recovery (EOR) in these zones. ROZs are thought to be formed by the flushing effect of regional aquifer flow acting over geological time. Both the magnitude of oil saturation and the spatial distribution of oil differ from water-flooded main pay zones (MPZs).
We conducted flow simulations of CO2 injection into both synthetic and realistic geologic reservoirs to find the optimal injection strategies for several scenarios. These simulations of CO2 injection follow either man-made waterflooding or long-term natural waterflooding. We examined the effects of CO2 injection rates, well patterns, reservoir heterogeneity, and permeability anisotropy on optimal WAG ratios. Optimal is defined as being at minimal net CO2 utilization ratios or maximal oil production rates).
Simulations of CO2 EOR show that the optimal WAG ratio for the ROZs is less than 1 (ratio of injected water and CO2 in reservoir volumes), and it depends, but in qualitatively different ways, upon the well pattern and reservoir heterogeneity. The optimal WAG ratio tends to increase with changing from inverted 9-spot (80-acres) to inverted 5-spot (40-acre) or increasing reservoir heterogeneity. The ratios for ROZs are consistently less than those observed in the same geologic models experiencing CO2 injection after traditional (man-made) waterflooding. This is because the water saturation caused by slow regional aquifer flow (~1ft/yr) differs from that created by traditional waterflooding. In ROZs, water prevails almost everywhere and thus it is less needed to ease CO2 channeling as compared to MPZs.
This work demonstrates that optimal WAG ratios for oil production in ROZs are different from those in traditional MPZs because of oil saturation differences. Thus, commingled CO2 injection into both zones or directly copying WAG injection designs from MPZs to ROZs might not optimize production.
|File Size||1 MB||Number of Pages||21|
Afzali, S.,Rezaei, N. and Zendehboudi, S. 2018. A Comprehensive Review on Enhanced Oil Recovery by Water Alternating Gas (WAG) Injection. Fuel. 227, 218-246. https://doi.org/10.1016Zi.fuel.2018.04.015
Aleidan, A.,Kwak, H.,Muller, H.,Zhou, X. 2017. Residual-Oil Zone: Paleo-Oil Characterization and Fundamental Analysis. SPE Reservoir Evaluation & Engineering, 20(02), 260-268. https://doi.org/10.2118/179545-PA
Ambrose, W.A.,Lakshminarasimhan, S.,Holtz, M.H.,Nunez-Lopez, V.,Hovorka, S.D.,Duncan, I. 2007. Geologic Factors Controlling CO2 Storage Capacity and Permanence: Case Studies Based on Experience with Heterogeneity in Oil and Gas Reservoirs Applied to CO2 Storage. Environmental Geology. 54, 1619-1633. https://doi.org/10.1007/s00254-007-0940-2
Bermudez, L.,Johns, R.T.,Parakh, H.C. (2007). Parametric Investigation of WAG Floods above the MME. SPE Journal. 12(02), 224-234. https://doi.org/10.2118/84366-PA
Bunge, A. L.,Radke, C. J. 1982. CO2 Flooding Strategy in a Communicating Layered Reservoir. Journal of Petroleum Technology. 34(12), 2746-2756. https://doi.org/10.2118/10289-PA
Chang, Y.B.,Lim, M.T.,Pope, G.A.,Sepehrnoori, K. 1994. CO2 Flow Patterns Under Multiphase Flow: Heterogeneous Field-Scale Conditions. SPE Reservoir Engineering. 9, 208-216. https://doi.org/10.2118/22654-PA
Chen, S.,Li, H.,Yang, D.,Tontiwachwuthikul, P. 2010. Optimal Parametric Design for Water-Alternating-Gas (WAG) Process in a CO2- Miscible Flooding Reservoir. Journal of Canadian Petroleum Technology. 49(10), 75-82. https://doi.org/10.2118/141650-PA
Chen, B. and Reynolds, A.C., (2016). Ensemble-based Optimization of the Water-Alternating-Gas-Injection Process. SPE Journal. 21(03), 786-798. https://doi.org/10.2118/173217-PA
Christensen, J. R.,Stenby, E. H.,Skauge, A. 2001. Review of WAG Field Experience. SPE Reservoir Evaluation & Engineering. 4(02), 97106. https://doi.org/10.2118/71203-PA
Egermann, P.,Vizika, O.,Dallet, L.,Requin, C.,Sonier, F. 2000. Hysteresis in Three-phase Flow: Experiments, Modeling and Reservoir Simulations. Paper SPE-65127-MS presented at SPE European Petroleum Conference, Paris, France, 24-25 October. https://doi.org/10.2118/65127-MS
Element, D. J.,Masters, J. H. K.,Sargent, N. C.,Jayasekera, A. J.,Goodyear, S. G. 2003. Assessment of Three-phase Relative Permeability Models Using Laboratory Hysteresis Data. Paper SPE-84903-MS presented at SPE International Improved Oil Recovery Conference in Asia Pacific, Kuala Lumpur, Malaysia, 20-21 October. https://doi.org/10.2118/84903-MS
Ettehadtavakkol, A.,Lake, L.W.,Bryant, S.L. (2014). CO2-EOR and Storage Design Optimization. International Journal of Greenhouse Gas Control. 25, 79-92. https://doi.org/10.1016/j.ijggc.2014.04.006
Harouaka, A.,Trentham, B.,Melzer, S. 2013. Long Overlooked Residual Oil Zones (ROZ's) Are Brought to the Limelight. SPE-167209-MS presented at SPE Unconventional Resources Conference Canada, Calgary, Alberta, Canada, 5-7 November. https://doi.org/10.2118/167209-MS
Holtz, M.H. (2002). Residual Gas Saturation to Aquifer Influx: A Calculation Method for 3-D Computer Reservoir Model Construction. SPE- 75502-MS presented at SPE Gas Technology Symposium, Calgary, Alberta, Canada, 30 April-2 May. https://doi.org/10.2118/75502-MS
Honarpour, M.M.,Nagarajan, N.R.,Grijalba Cuenca, A.,Valle, M. and Adesoye, K. 2010. Rock-Fluid Characterization for Miscible CO2 Injection: Residual Oil Zone, Seminole Field, Permian Basin. SPE-133089 presented at the Annual Technical Conference and Exhibition, Florence, Italy, 19-22 September. https://doi.org/10.2118/133089-MS
Koperna, G.J.,Melzer, L.S. and Kuuskraa, V.A. (2006). Recovery of Oil Resources from the Residual and Transitional Oil Zones of the Permian Basin. SPE 102972 presented at the Annual Technical Conference and Exhibition, San Antonio, Texas, 24-27 September. https://doi.org/10.2118/102972-MS
Kulkarni, M. M.,Rao, D. N. 2005. Experimental Investigation of Miscible and Immiscible Water-Alternating-Gas (WAG) Process Performance. Journal of Petroleum Science and Engineering. 48(1-2), 1-20. https://doi.org/10.1016/j.petrol.2005.05.001
Leverett, M.C. (1941). Capillary Behavior in Porous Solids. AIMEPetroleum Transactions. 142: 152-169. https://doi.org/10.2118/941152-G.
Li, D.,Lake, L. W. 1995. Scaling Fluid Flow through Heterogeneous Permeable Media. SPE Advanced Technology Series. 3(01), 188-197. https://doi.org/10.2118/26648-PA
Malik, Q. M.,Islam, M. R. 2000. CO2 Injection in the Weyburn Field of Canada: Optimization of Enhanced Oil Recovery and Greenhouse Gas Storage with Horizontal Wells. SPE-59327-MS presented at SPE/DOE improved oil recovery symposium, Tulsa, Oklahoma, 3-5 April. https://doi.org/10.2118/59327-MS
Nwachukwu, A.,Jeong, H.,Sun, A.,Pyrcz, M., & Lake, L. W. 2018. Machine Learning-Based Optimization of Well Locations and WAG Parameters under Geologic Uncertainty. SPE 190239 presented at the SPE Improved Oil Recovery Conference, Tulsa, Oklahoma, USA, 14-18 April. https://doi.org/10.2118/190239-MS
Rassenfoss, S. 2017. New Permian Oil Play Requires Pumping and Persistence. Journal of Petroleum Technology. 69(02), 28-31. https://doi.org/10.2118/0217-0028-JPT
Ren, B. 2017. Local Capillary Trapping and Permeability-Retarded Accumulation during Geological Carbon Sequestration. Ph.D. Dissertation, The University of Texas at Austin, Austin, Texas. pp.17-18. https://repositories.lib.utexas.edu/handle/2152/62236
Ren, B.,Duncan, I.J. 2019a. Reservoir Simulation of Carbon Storage Associated with CO2 EOR in Residual Oil Zones, San Andres Formation of West Texas, Permian Basin, USA. Energy. 167, 391-401. https://doi.org/10.1016/j.energy.2018.11.007
Ren, B. and Duncan, I.J. 2019b. Modeling Oil Saturation Evolution in Residual Oil Zones: Implications for CO2 EOR and Sequestration. Journal of Petroleum Science and Engineering. 177, 528-539. https://doi.org/10.1016/j.petrol.2019.02.072
Rogers, J. D.,Grigg, R. B. 2001. A Literature Analysis of the WAG Injectivity Abnormalities in the CO2 Process. SPE Reservoir Evaluation & Engineering. 4(05), 375-386. https://doi.org/10.2118/73830-PA
Shehata, A. M.,El-banbi, A. H.,Sayyouh, H. 2012. Guidelines to Optimize CO2 EOR in Heterogeneous Reservoirs. SPE-151871 presented at the North Africa Technical Conference and Exhibition, Cario, Egypt, 20-22 Feburary. https://doi.org/10.2118/151871-MS.
Skauge, A.,Sorbie, K. 2014. Status of Fluid Flow Mechanisms for Miscible and Immiscible WAG. SPE-169747 presented at SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 31 March - 2 April. https://doi.org/10.2118/169747-MS
Song, Z.,Li, Z.,Wei, M.,Lai, F.,Bai, B. 2014. Sensitivity Analysis of Water-Alternating-CO2 Flooding for Enhanced Oil Recovery in High Water Cut Oil Reservoirs. Computers & Fluids. 99, 93-103. https://doi.org/10.1016/j.compfluid.2014.03.022
Spiteri, E. J.,Juanes, R. 2006. Impact of Relative Permeability Hysteresis on the Numerical Simulation of WAG injection. Journal of Petroleum Science and Engineering. 50(2), 115-139. https://doi.org/10.1016/j.petrol.2005.09.004
Stalkup, F.I., (1970). Displacement of Oil by Solvent at High Water Saturation. SPE J. 10(4): 337-348. https://doi.org/10.2118/2419-PA
Stone, H.L. (1970). Probability Model for Estimating Three-Phase Relative Permeability. Journal Petroleum Technology. 22(2): 214-218. SPE-2116-PA. http://dx.doi.org/10.2118/2116-PA.
Walsh, M. P.,Lake, L. W. 1989. Applying Fractional Flow Theory to Solvent Flooding and Chase Fluids. Journal of Petroleum Science and Engineering. 2(4), 281-303. https://doi.org/10.1016/0920-4105(89)90005-3
Wu, X.,Ogbe, D. O.,Zhu, T.,Khataniar, S. 2004. Critical Design Factors and Evaluation of Recovery Performance of Miscible Displacement and WAG Process. PETSOC-2004-192 presented at the Canadian International Petroleum Conference, Calgary, Alberta, 8-10 June. https://doi.org/10.2118/2004-192
Zuo, L.,Chen, Y.,Zou, D.E.,Kamath, J. 2014. Three-phase Relative Permeability Modeling in the Simulation of WAG injection. SPE Reservoir Evaluation & Engineering. 17(03), 326-339. https://doi.org/10.2118/166138-PA