Analysis of Microscopic Displacement Mechanisms of Alkaline Flooding for Enhanced Heavy-Oil Recovery

Abstract

In this study, the microscopic displacement mechanisms of alkaline flooding for enhanced heavy-oil recovery are investigated using a micromodel. It has been observed that alkaline flooding exhibits a better sweep efficiency than waterflooding, and the serious viscous fingering is significantly reduced. The main microscopic mechanisms of alkaline flooding for enhanced heavy-oil recovery are that the alkaline solution penetrates in crude oil and water drops are, subsequently, formed inside the oil phase, which can improve the mobility ratio and, thus, lead to the improvement of sweep efficiency. The higher the alkaline concentration, the more easily the alkaline solution penetrates in the oil phase. Therefore, a greater improvement in sweep efficiency can be obtained using a higher concentration of alkali. The primary mechanism of the formation of the water drop inside the oil phase during alkaline flooding is related to the interfacial interaction between alkali and heavy oil, which not only results in the drastic reduction of oil–water interfacial tension but also leads to the non-uniform enrichment of in situ surfactants activated by alkali.

Review of surfactant-assisted chemical enhanced oil recovery for carbonate reservoirs: challenges and future perspectives

“…This phenomenon is particularly relevant for heavy oil recovery as observed in the works of Pei et al (2011), and later, by Dong et al (2012). A bank of viscous (W/O) emulsion forms when an acidic heavy oil is displaced by an alkaline solution prepared in a high-salinity brine in a porous medium.…”

Experimental Study of Enhancing Oil Recovery with Weak Base Alkaline/Surfactant/Polymer

“…In other words, the formation of emulsion is conductive to the recovery of residual oil [16]. Pei et al [17,18] and Dong et al [18] studied the alkali flooding mechanism through microscopic model, which implied that alkali permeated into the oil phase to form emulsion was important for EOR.…”

Investigation of synergy between nanoparticle and surfactant in stabilizing oil-in-water emulsions for improved heavy oil recovery

“…Numerous studies have shown that the emulsions, either generated in situ or injected externally have the tendency to block the swept out pores and divert the flow to the bypassed region [3][4][5]. On the other hand, in some other situations emulsions help to entrain the oil into the flowing aqueous phase [6][7][8][9].…”

“…However, the surfactant-stabilized emulsion do not have a good 3 stability under harsh reservoir conditions, and the mobility of a surfactant-stabilized emulsion is generally much larger, thus the mobility control of these emulsions have a certain degree of limitations. Nanoparticle can also be used to stabilize emulsions and have several advantages compared to surfactant-stabilized emulsions.…”