Petroleum Science >2020, Issue 5: - DOI: https://doi.org/10.1007/s12182-020-00455-9
Low-tension gas process in high-salinity and low-permeability reservoirs Open Access
文章信息
作者:Alolika Das, Nhut Nguyen & Quoc P. Nguyen
作者单位:
Affiliations
Hildebrand Department of Petroleum and Geosystems Engineering, University of Texas at Austin, 200 E. Dean Keeton, Austin, TX, 78712, USA
Alolika Das, Nhut Nguyen & Quoc P. Nguyen
Corresponding author
Correspondence to Quoc P. Nguyen.
投稿时间:2019-11-28
引用方式:Das, A., Nguyen, N. & Nguyen, Q.P. Low-tension gas process in high-salinity and low-permeability reservoirs. Pet. Sci. (2020). https://doi.org/10.1007/s12182-020-00455-9
文章摘要
Polymer-based EOR methods in low-permeability reservoirs face injectivity issues and increased fracturing due to near wellbore plugging, as well as high-pressure gradients in these reservoirs. Polymer may cause pore blockage and undergo shear degradation and even oxidative degradation at high temperatures in the presence of very hard brine. Low-tension gas (LTG) flooding has the potential to be applied successfully for low-permeability carbonate reservoirs even in the presence of high formation brine salinity. In LTG flooding, the interfacial tension between oil and water is reduced to ultra-low values (10−3 dyne/cm) by injecting an optimized surfactant formulation to maximize mobilization of residual oil post-waterflood. Gas (nitrogen, hydrocarbon gases or CO2) is co-injected along with the surfactant slug to generate in situ foam which reduces the mobility ratio between the displaced (oil) and displacing phases, thus improving the displacement efficiency of the oil. In this work, the mechanism governing LTG flooding in low-permeability, high-salinity reservoirs was studied at a microscopic level using microemulsion properties and on a macroscopic scale by laboratory-scale coreflooding experiments. The main injection parameters studied were injected slug salinity and the interrelation between surfactant concentration and injected foam quality, and how they influence oil mobilization and displacement efficiency. Qualitative assessment of the results was performed by studying oil recovery, oil fractional flow, oil bank breakthrough and effluent salinity and pressure drop characteristics.
关键词
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Enhanced oil recovery;Foam;Microemulsion;Carbonate;High salinity;Low permeability