A Study on the Adsorption Behavior of Different Surfactants in Carbonate Using Different Techniques

Abstract

AbstractSurfactant based foams are used as one of the most effective techniques in controlling gas mobility during gas injection processes. Foam reduces gas mobility in porous media by increasing the gas apparent viscosity and decreasing the gas relative permeability, and hence it helps in improving sweep efficiency. However, one of the critical encounters when using foam in reservoirs is the adsorption of the surfactant on the rock surface. The loss of surfactant to the rock surface will lead to destabilizing the foam and accelerating the collapse rate of foam films. The objective of this paper is to study the behavior of surfactant adsorption in carbonate.The adsorption of various surfactants in contact with carbonate was evaluated. We compared two different techniques to evaluate the adsorption of surfactant components onto the rock surface. The first method is using a total organic carbon (TOC) analyzer to measure the carbon number in each surfactant over time after being in contact with rock. The second method is using UV-spectroscopy in which the light absorbance at a certain wavelength is measured. The measurements are then used to calculate the total surfactant adsorption onto the rock surface. This paper presents the adsorption behavior of each surfactant studied in detail.The results obtained by the techniques were compared for two different surfactants. An amphoteric surfactant and an anionic surfactant were used in this study. Results illustrated that both surfactants were adsorbed by the rock minerals. Surfactant 1 showed a higher adsorption value than the surfactant 2. However, the two used techniques to measure the adsorption showed different adsorption values for both surfactants. Using TOC, surfactants 1 and 2 showed a total adsorption of 0.746 and 0.428 mg/grock, respectively. While, using UV-spectroscopy, surfactants 1 and 2 showed a total adsorption of 1.149 and 0.306 mg/grock, respectively.Understanding the surfactant adsorption behavior is an essential step in the surfactant selection process. Selecting a surfactant with minimal loss to the rock surfaces will lead to keeping the generated foam stable for a longer time in the reservoir and therefore, result in having a higher sweep efficiency.