Abstract

Significant research focus has recently been directed toward energy-saving and emission-reduction practices, as well as the unique benefits of an integrated working fluid in the oilfield industry. Surfactants cannot be widely used in engineering practice due to cost constraints. At the same time, there is no proper solution to the flowback liquid problem. SY-JS, a multifunctional surfactant, was developed to broaden the application of surfactants in the oilfield industry. It still meets the field operation requirements of a good fracturing fluid thickener with a shear rate of 170 s-1 at 140�C and salinity (NaCl or KCl) of 12-13%. When the fracturing fluid has finished its job and returns to the ground, the molecular structure of the surfactant in the flowback fluid was found to be complete after laboratory evaluation of the fracturing and oil displacement integrated working fluid systems. Surfactants with an intact molecular structure should retain their distinct lipophilic and hydrophilic properties. When groundwater and produced water are compounded and re-injected into the reservoir for oil displacement, 0.2 percent anionic surfactant B1-12 is used to balance the charge and reduce interfacial tension. The rock`s contact angle can be reduced by 56.95 percent, and the recovery rate can be increased by 6%. Based on these findings, the surfactant`s dynamic self-healing mechanism was proposed. Furthermore, the capillary force, interfacial tension, and wettability were combined to propose wettability determines capillary force direction and interfacial tension determines capillary force magnitude. Furthermore, it provides favorable evidence that interfacial tension does not always reach ultralow levels during reservoir exploitation.

Highlights

  • It is worth noting that surfactant as a fracturing fluid thickening agent and oil-displacing agent with enhanced oil recovery has been a hot topic in the petroleum industry in recent years [1,2,3]

  • Fracturing fluid performance test Surfactants use as thickeners of clean fracturing fluids in deep wells and high-temperature wells remain difficult

  • When water flooding is performed on the core, the results show that the average oil displacement efficiency is 29.51 percent

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Summary

Introduction

It is worth noting that surfactant as a fracturing fluid thickening agent and oil-displacing agent with enhanced oil recovery has been a hot topic in the petroleum industry in recent years [1,2,3]. The main agents used for thickening or strengthening foams in conventional water-based and foam fracturing fluid systems are macromolecular polymers, such as guar gum, which form insoluble residues under formation conditions. Schlumberger invented a new clean fracturing fluid based on self-assembly theory in 1997 [4, 5]. Wormlike micelles join together to form a three-dimensional (3D) network structure, which increases the viscoelasticity of the fluid. The molecular weight of viscoelastic surfactant is only a few 100–1000, which is 3-5 orders of magnitude lower than that of conventional polymers, resulting in almost no residue of VES clean fracturing fluid after gel breaking [6]. A fracturing fluid must maintain a certain viscosity during the construction process and

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