Self-assembled Structure Of Anionic Gemini Surfactant Solution

Fracturing technology in the oil and gas industry has been widely used.It is an improved production technology,which can be used in low permeability or ultra-low permeability hydrocarbon reservoir.Able to withstand high temperature and pressure,physical and chemical properties of stable,environmentally friendly fracturing fluid development have been a hot research topic in the field of fracturing technology.Most of the fracturing fluids currently used in the petroleum industry are water-based fracturing fluid,but the traditional water-based fracturing fluid has the disadvantages of poor resistance to high temperature,high cost and environmental pollution.It is particularly urgent to optimize the formulation and develop environmentally friendly clean fracturing fluids.In this paper,the structure of Gemini anionic surfactant solution for the optimization and modification of fracturing fluid is studied theoretically.By constructing the structural model of Gemini surfactant molecule,using the dissipative particle dynamics(DPD)computer simulation method.The structure evolution of the solution system was studied on the mesoscopic scale.The effects of additives such as alcoholic molecules and counterions on the self-assembly structure and critical micelle concentration(CMC)of surfactants were studied.And provide the basic data and theoretical guidance for the molecular design and experimental synthesis of the new clean fracturing fluid.The paper has obtained the following results:(1)When the length of the linker is 6 and the length of the hydrophobic tail chain is 9,the interaction between the surfactant and the water molecule is strong,and the structure of the micelle is clearly observed.It was found that the self-assembled structures such as spherical,worm-like and layered micelles appeared in the aqueous solution with the increase of the concentration of the surfactant.(2)The evolution of the microstructure of the solution system shows that the micelles of the cluster are divided into three stages.First,the monomer molecules are rapidly polymerized into small or disorder oligomer micelles until the number of micelles reaches the maximum.Then the oligomers micelles are gradually merged into larger aggregates and the number of micelles is decreasing.Finally,the micelles are combined into the largest aggregates and the number of micelles tends to be relatively stable.(3)The addition of alcohol molecules can improve the solubility of the surfactant hydrophobic group in the solution to increase the CMC of the surfactant solution,inhibit the formation of micelles.The addition of inorganic salts enhances the gelation properties of the surfactant solution.