Critical Parameters Affecting Water Alternating Gas (WAG) Injection in an Iranian Fractured Reservoir

Document Type : Research Paper

Authors

1 Research Institute of Petroleum Industry

2 Pars Oil and Gas company

Abstract

Microscopic oil displacement of water flooding and sweep efficiency of continuous gas injection could be improved by water alternating gas (WAG) injection. The WAG injection process aims to squeeze more oil out of the reservoirs; in this method, water and gas are alternatively injected into the reservoir. Also, availability of hydrocarbon or CO2 gases in the field makes it attractive for gas-based enhanced oil recovery (EOR) methods such as water alternating gas (WAG) injection. Conducting some simulations are required to optimize EOR methods for investigating the effect of parameters affecting WAG injection. Reducing and controlling the mobility ratio, creating stable front, and preventing early fingering of gas are the advantages of water alternating gas injection, which have promoted extensive applications throughout the world. Critical parameters, including WAG ratio, injection rates, gas composition variation, cycle times and some others which affect the WAG injection as an enhanced oil recovery method are studied thoroughly in this paper. Because of higher mobility of water relative to gas, injected water has more efficiency, but the excess use of water will cause early breakthrough. This study suggests that injecting proper volume at suitable times with different rates during injection time provides a 10 -15 % improvement in the recovery factor for one pore volume which is injected by using commercial reservoir simulator ECLIPSE 300. The best rate variation during a cycle time of WAG injection and choosing of first injection phase are discussed in this paper.

Keywords

References

Esmaiel T. E., Fallah S., and Kruijsdijk C. V., “Determination of WAG Ratios and Slug Sizes Under Uncertainty in a Smart Wells Environment,” SPE 93569, Presented at the 14th, SPE Middle East Oil & Gas Show and Conference, Bahrain Exhibition Center, Bahrain, 2005.
Willhit G. P., “Enhanced Oil Recovery,” Society of Petroleum Engineering, Texas University, United States, 1998.
Esmaiel T. E., Fallah S., and Kruijsdijk C. V., “Determination of WAG ratios and slug sizes under uncertainty in a smart wells environment,” Paper SPE 93569 Presented at the 14th SPE Middle East Oil and Gas Show and Conference, Bahrain, 2005.
Dalen V., Instefjord R., and Kristensen R., “A WAG Injection Pilot in the Lower Brent Formation at the Gullfaks Field,” 7th EAPG IOR Europe, Moscow, Russia, 1993, 460-468.
Udosen E. O., Ahiaba O., and Aderemi S. B., “Optimization of Gas Condensate Reservoir Using Compositional Reservoir Simulator,” SPE Paper 136964, 2010.
Chen S., LI H., Yang D., and Tontiwachwuthikul P., “Optimal Parametric Design for Water-Alternating-Gas (WAG) Process in a CO2 Miscible Flooding Reservoir,” PETSOC, 2009.
Haajizadeh M., Narayanan R., and Waldren D., “Modeling Miscible WAG Injection EOR in the Magnus Field,” Paper SPE 66378 Presented at the SPE Reservoir Simulation Symposium, Houston, 2001.
Bermudez L., Johns R. T., and Parakh H., “Parametric Investigation of WAG Floods above the MME,” SPE Journal 84366, 2007.
Tehrani D. H., Danesh A., and Sohrabi M., “Water Alternating Gas Injection Studies-Phase 1,” Department of Trade and Industry, Improved Oil Recovery Research Dissemination Seminar, 2001.
Christensen J. R., Stenby E. H. and Skauge A ., “Review of WAG Field Experience,” SPE 39883, 1998.
Hallam R. J., Ma T. D., and Reinbold E. W., “Performance Evaluation and Optimization of the Kuparuk Hydrocarbon Miscible Water-Alternating-Gas Flood,” 7th EAPG IOR Europe, Moscow, Russia, 1993, 403-415.
Ma T. D. and Youngren G. K., “Performance of Immiscible - Water- Alternating-Gas Injection at Kuparuk River Unit, North Slope, Alaska,” 1994.
Danesh A., “PVT and Phase Behavior of Petroleum Reservoir Fluids,” Department of Petroleum Engineering, Heriot Watt University, Edinburgh, Scotland, 1998, 215-230.
Sulaiman W. R., “A Numerical Simulation Study to Evaluate the Use of Water Alternating Gas (WAG) As a Pilot EOR Method in Dulang Unit, Malaysia,” Ph. D. Thesis, Imperial College, London, 2003, 93-99.
Larsen J. A. and Skauge A., “Simulation of the Immiscible WAG Process Using Cycle- Dependent Three Phase Relative Permeabilities,” Paper SPE 56475 Presented at the ATCE, Houston, 1999.
Van Poollen H. K., “Enhanced Oil Recovery,” Pennwell Publishing Company, 1980, 118-119.
Alvarado V., Ranson A. and Hernández K., “Selection of EOR/IOR Opportunities Based on Machine Learning,” Paper SPE 78332, Presented at the SPE 13th European Petroleum Conference held in Aberdeen, Scotland, U. K., 2002.
Rehman T., “A Techno Economical Evaluation of Miscible Flooding,” Dalhousie University, 2008, 12.
Safdarian M., “Parametric Study of WAG Process its Performance over the Synthetic Fractured Model,” Master of Science Thesis, Petroleum University of Technology, 2009.
Farzaneh S., “Parametric Investigation of WAG Injection Process in Naturally Fractured Reservoirs,” 6th International Congress on Chemical Engineering, Iran, 2010.
Jafari M., Badakhshan A., Taghikhani V., Rashtchian D., et al., “Experimental Study and Simulation of Different EOR Techniques in a Non-Fractured Carbonate Core from an Iranian Offshore Oil Reservoir,” Iranian Journal of Chemical Engineering, 27(2), 2008, 7-9.

Files

Share

How to cite

Statistics