Micro-simulation Research On The Multi-functional And Environment-friendly Fracturing Fluid

The compactness of unconventional oil and gas reservoirs determines that they must be fractured for effective exploitation.In recent years,the issue of environmental protection is increasingly important,which makes the fracturing fluid to be recycled and reused.In this thesis,the self-assembly structure and rheological properties of micelles in the multi-functional and environment-friendly fracturing fluid system are described by simulation combining mesoscopic dynamics(Meso Dyn)and molecular dynamics(Forcite).The viscosity of the fracturing fluid system and the effect of salt strength on the self-assembly behavior are investigated.Furthermore,the effects of the temperature field and shear field on the self-assembly behavior and viscosity of the fracturing fluid system are obtained.In addition,the influence mechanism of various factors on the performance of the fracturing fluid system is explained from both micro and macro perspectives.The results show that,with the increase of concentration,surfactants will self-assemble into different morphologies,such as spherical,rod-like,worm-like,layered micelles,etc.However,the performance of the multi-functional and environment-friendly fracturing fluid system is not positively correlated with the concentration.Besides,the addition of counter-ions promotes the gelation of surfactants in the fracturing fluid system,but more than 1% of the counter-ions will reduce the shear viscosity of the fracturing fluid system.Certainly,the increase of temperature will reduce the viscosity of the fracturing fluid system,but the viscosity will reach a peak again when the temperature near 392.15 K.And then the viscosity will decrease steadily with the further increase of temperature.With the increase of shear rate,the shear viscosity of the fracturing fluid system will generally decrease.On the contrary,the shear viscosity of the system will become stable when the shear time increases.Above all,molecular simulation is used to verify the relationship between the components and performance of fracturing fluid,and to analyze the influence of related factors on the performance of the multi-functional and environment-friendly fracturing fluid system,so as to provide theoretical support for the development of a new and efficient fracturing fluid system.