Oil and Water Interactions during Low-Salinity Enhanced Oil Recovery in Water-Wet Porous Media

Abstract

The role of emulsions should be an important factor in additional oil recovery during low-salinity water flooding (LSWF); however, it has been rarely discussed in previous studies. In this study, the contributing behavior of the oil/water interaction to the oil recovery process was investigated through core- and microscale experiments involving high-polar-component oil. Two tertiary coreflood experiments with high- and low-salinity water were conducted using cores from the same reservoir formation, where the behavior of oil recovery and that of differential pressure differed significantly. The results of core and water analyses indicate that the emulsions predominantly caused this difference. Thus, microfluidic experiments were conducted to visualize the emulsion-based oil recovery mechanisms; two phenomena of emulsions contributed to oil recovery: pore blockage and microwater dispersion. In addition, we studied the stability of emulsions in terms of the surface electric charge through the use of ζ potential measurements; emulsions were more stable in the lower salinity and higher pH conditions. These experimental results demonstrate that emulsions are important during LSWF for additional oil recovery in water-wet porous media.

Fabrications and Applications of Micro/Nanofluidics in Oil and Gas Recovery: A Comprehensive Review

“…In addition, Morishita et al. claimed that emulsions caused by LSW should be an important factor since they visualized the pore blockage and microwater dispersion phenomena of emulsion that contributed to oil recovery during LSW flooding . Although low-salinity waterflooding is a cooperative process in which multiple mechanisms acting on different length and time scales, micromodels have attracted increasing attention in LSW studies. ,− …”

Synergistic effect of salt ions and water‐soluble amphiphilic compounds of acidic crude oil on surface and interfacial tension

“…Low salinity and smart water flooding have been investigated as an independent method and its various aspects have been studied. [ 1–10 ] The modification of the ionic composition of water can be examined by reducing the salinity of the injected water, reducing some monovalent ions such as Na + and Cl − , or increasing some divalent ions such as SO 4 2− Ca 2+ and Mg 2+ . [ 11–15 ] These modifications can enhance oil recovery by changing fluid/fluid and fluid/rock interactions.…”

Pressure Attenuation Law of Low-Frequency Pulse Pressure Flooding and Its Influence on Oil Recovery

“… 24 At the same time, with the aid of automation technology, acidizing, hydraulic fracturing, and other enhanced stimulation measures, the near-well treatment effect of this method has been further strengthened. 25 …”

“…24 At the same time, with the aid of automation technology, acidizing, hydraulic fracturing, and other enhanced stimulation measures, the near-well treatment effect of this method has been further strengthened. 25 Nowadays, improvement of crude oil production by pulse water injection has already been verified by many experiments, but the specific factors which affect the production are still relatively unknown. Mohebbi et al 26 proposed that the frequency parameter of the pulse wave affects the recovery rate by controlling the asphaltene deposition through the ultrasonic experiment.…”

“…With the development of science and technology, the range of vibration intensity (increasing) and frequency (decreasing) of a hydraulic vibrator is gradually expanding and improving . At the same time, with the aid of automation technology, acidizing, hydraulic fracturing, and other enhanced stimulation measures, the near-well treatment effect of this method has been further strengthened …”