The Impact of Tailored Water Chemistry Aqueous Ions on Foam Stability and Mobility Control

Abstract

AbstractThe in-situ generation of foam while injecting gas is well recognized due to its effectiveness in lowering the gas mobility and, hence, improving the sweep efficiency in porous media. Therefore, generating strong and stable foam is necessary to achieve in-depth conformance control in the reservoir. Besides other parameters, the chemistry of injection water can significantly impact foam generation and stabilization. The tailored water chemistry (formulated low salinity water) was found to have good potential to improve foam stability. The objective of this study is to extensively evaluate the effect of different aqueous ions in the selected tailored water chemistry formulations on foam stabilization and mobility control.In this experimental investigation, bulk and dynamic foam tests were conducted to evaluate the impact of different tailored water chemistry aqueous ions on foam generation and stabilization. For bulk foam tests, the stability of foams generated using anionic, amphoteric, and nonionic surfactants and different aqueous ions was analyzed and quantified using bottle tests. For dynamic foam test, the pressure drops and, accordingly, gas viscosity as a result of foam generation using different water formulations were measured using a microfluidic device (rock-on-a-chip).The experimental results clearly demonstrated that the ionic content of aqueous solutions can significantly affect foam stabilization. The results revealed that the foam stabilization in bulk is different than that in porous media. Depending on the surfactant type, the divalent ions were found to have stronger influence on foam stabilization when compared to monovalent ions. The bulk foam results expressed that the aqueous solutions containing calcium chloride salt (CaCl2) showed longer foam life with the anionic surfactant and very weak foam with the nonionic surfactant. The solutions with magnesium chloride (MgCl2) and CaCl2 salts displayed higher impact on foam stability in comparison to sodium chloride (NaCl) with the amphoteric surfactant. Less stable foams were generated with aqueous solutions comprising of both magnesium and calcium ions. In the microfluidic model, the solutions containing MgCl2 salt produced more stable and viscous foams when compared to those produced using NaCl and CaCl2 salts. The foam solutions obtained using MgCl2 showed higher resistance to gas flow and subsequently higher mobility reduction factor for the injection gas.This experimental study, for the first time, confirmed the impact of different aqueous ions in the tailored water chemistry formulation on foam generation and stabilization. Such a study focusing about the role of different aqueous ions in the injection water on foam could help in better understanding the foam stabilization process. The new knowledge gained can also enable the selection and optimization of the right injection water chemistry and suitable chemicals for foam field applications.