Experimental Investigation of Foam Flooding Using Anionic and Nonionic Surfactants: A Screening Scenario to Assess the Effects of Salinity and pH on Foam Stability and Foam Height

Abstract

Gravity override and viscous fingering are inevitable in gas flooding for improving hydrocarbon production from petroleum reservoirs. Foam is used to regulate gas mobility and consequently improve sweep efficiency. In the enhanced oil recovery process, when the foam is introduced into the reservoir and exposed to the initial saline water saturation and pH condition, selection of the stable foam is crucial. Salinity and pH tolerance of generated foams are a unique concern in high salinity and pH variable reservoirs. NaOH and HCl are used for adjusting the pH, and NaCl and CaCl 2 are utilized to change salinity. Through analyzing these two factors along with surfactant concentration, we have instituted a screening scenario to optimize the effects of salinity, pH, surfactant type, and concentration to generate the most stable state of the generated foams. An anionic (sodium dodecyl sulfate) and a nonionic (lauric alcohol ethoxylate-7) surfactants were utilized to investigate the effects of the surfactant type. The results were applied in a 40 cm synthetic porous media fully saturated with distilled water to illustrate their effects on water recovery at ambient conditions. This most stable foam along with eight different stabilities and foamabilities and air alone was injected into the sand pack. The results show that in optimum surfactant concentration, the stability of LA-7 was not highly changed with salinity alteration. Also, we probed that serious effects on foam stability are due to divalent salt and CaCl 2 . Finally, we found the most water recovery that was obtained by the three most stable foams by the formula of 1 cmc SDS + 0.5 M NaCl, 1 cmc SDS + 0.01 M CaCl 2 , and LA-7@ pH ∼ 6 from porous media flooding. Total water recovery for the most stable foam increased by an amount of 65% compared to the state of air alone. A good correlation between foam stability and foamability at higher foam stabilities was observed.

Review of the Application of Natural Surfactants in Enhanced Oil Recovery: State-of-the-Art and Perspectives

“…Foam flooding is a crucial mechanism of EOR that relies on the generation and utilization of foam using surfactants . Natural surfactants, with their unique foaming characteristics, have garnered attention for their potential in EOR applications.…”

Sulfonamide Derivatives as Novel Surfactant/Alkaline Flooding Processes for Improving Oil Recovery

“…40,41 Surfactants, also known as surface-active agents, provide several benefits that include reducing interfacial tension (IFT), 42,43 modifying rock wettability, 44,45 forming emulsions, 46 and controlling mobility. 47 A microemulsion can form when a surfactant solution, oil, and salt are present under specific conditions that make it thermodynamically stable. 48 Winsor presented a classification system for microemulsions based on their phase behavior, with three distinct types identified as type I, type II, and type III.…”

“…Surfactants, also known as surface-active agents, provide several benefits that include reducing interfacial tension (IFT), , modifying rock wettability, , forming emulsions, and controlling mobility . A microemulsion can form when a surfactant solution, oil, and salt are present under specific conditions that make it thermodynamically stable .…”

Investigation of Foam Flooding Assisted by Non-Newtonian and Novel Newtonian Viscosifying Agents for Enhanced Oil Recovery

“…The aim of enhanced oil recovery (EOR) is to mobilize oil left in the reservoir after primary recovery (depletion by pressure difference solely) and water flooding. Gas injection is one of the most applied techniques in EOR. , Gas injection often suffered from small volumetric (areal and vertical) sweep efficiency, resulting in the gas contacting only a small fraction of the oil present in the reservoir. − Due to its low viscosity, injected gas flows through the paths of least resistance in the reservoir, leaving low-permeable zones reservoir. On the other hand, gas and surfactant co-injection creates foam that leads to far larger mobility reduction, thus enhancing mobility control. , …”

“… 1 , 2 Gas injection often suffered from small volumetric (areal and vertical) sweep efficiency, resulting in the gas contacting only a small fraction of the oil present in the reservoir. 3 − 5 Due to its low viscosity, injected gas flows through the paths of least resistance in the reservoir, leaving low-permeable zones reservoir. On the other hand, gas and surfactant co-injection creates foam that leads to far larger mobility reduction, thus enhancing mobility control.…”