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Special Topics & Reviews in Porous Media: An International Journal

ISSN Print: 2151-4798
ISSN Online: 2151-562X

Special Topics & Reviews in Porous Media: An International Journal

DOI: 10.1615/SpecialTopicsRevPorousMedia.2016017437
pages 373-376

EXPERIMENTAL STUDY ON THE WETTABILITY ALTERATION MECHANISM OF ION TUNING WATERFLOODING

Shijing Xu
Research Institute of Petroleum Exploration and Development, Beijing 100083, China; State Key Laboratory of Enhanced Oil Recovery, Beijing 100083, China
Jiazhong Wu
Research Institute of Petroleum Exploration and Development, Beijing 100083, China; State Key Laboratory of Enhanced Oil Recovery, Beijing 100083, China
Weifeng LV
State Key Laboratory of Enhanced Oil Recovery, Research Institute of Petroleum Exploration & Development, CNPC
Jingyao Wang
Research Institute of Petroleum Exploration and Development, Beijing 100083, China; State Key Laboratory of Enhanced Oil Recovery, Beijing 100083, China
Qingjie Liu
Research Institute of Petroleum Exploration and Development, Beijing 100083, China; State Key Laboratory of Enhanced Oil Recovery, Beijing 100083, China

ABSTRACT

Ion tuning waterflooding has been a promising technology used in enhanced oil recovery (EOR) in recent years. The general agreement among researchers is that ion tuning waterflooding causes reservoirs to become more water-wet. Although different mechanisms have been proposed to explain wettability alterations, the primary mechanisms are still uncertain. Therefore, this paper investigates this major mechanism of wettability alteration and shows how it is involved in the EOR process. In the present study, divalent ions were introduced into liquid films and the ion tuning effects at the molecular level were revealed. Atomic force microscopy and zeta potential measurements were used to analyze the influencing factors of disjoining pressure as well as the zeta potential at the oil/brine/rock interfaces. It has been shown that decreasing the divalent cations and salinity makes the electrical charges at both the oil/brine and brine/rock interfaces become strongly negative, which results in elevation of the repulsive forces between oil and rock. As a result, the rock becomes more water-wet. In conclusion, the double-layer expansion caused by the highly negative zeta potential as a result of lower salinity plays a major role in recovering additional oil.