A comprehensive review of recent advances on surfactant architectures and their applications for unconventional reservoirs

Abstract

Abstract The depletion of conventional resources and steady increase in the global oil demands has led to the shift of attention to the unconventional resources which are difficult to extract due to poor permeability, low porosity and extreme heterogeneity of their reservoirs. For the unconventional reservoirs to produce at an economic rate, the invention of stable oilfield chemicals tailored for drilling, stimulation by multi-stage hydraulic fracturing, and enhanced oil and gas recovery activities should be scaled up. The extreme reservoir conditions of high temperature, complex heterogeneity, salinity, and high-water saturation pose a challenge to the use of currently available chemicals. In this review work, the latest surfactant formulations with enhanced properties are presented. A detailed review of surfactant s application on unconventional resources are included. A comprehensive description of various surfactants architect, applications, and their corresponding influence on the interfacial tension reduction (IFT), wettability alteration, emulsion and microemulsion phase behaviors, surfactant adsorption are also included. By using several surfactants, laboratory experimental results and field study data obtained, useful conclusions have been drawn. The correlation between the experimental data and the isotherm models suggested that the Freundlich model could certainly predict the loss of surfactants due to high adsorption behavior. This revealed that the adsorption of surfactants occurs on the heterogenous surfaces and showed multi-layered behavior. On the other hand, the kinetic behavoir of the surfactant adsorption exhibited pseudo-second order kinetic model. Their conclusions on Freundlich and pseudo-second order models were supported by the correlation values (R2) which were 0.9815and 0.98583 respectively. The detailed discussion on this work is intended for researchers and professionals in the relevant field to gain insights on the existing progress in surfactants application of unconventional resources and pave the future path of current methodologies. The outcomes of this study will help the oil industry practioners to expand their understanding of surfactant selection based on the structures, adsorption behavior and various reservoir conditions and optimize the oil recovery during surfactant flooding.