Research On Flowback Mechanism And Optimization Method Of Working System After Hydraulic Fracturing

Hydraulic fracturing technology is an important stimulation technology in oilfield production process.Fracturing fluid backflow as an important process in hydraulic fracturing construction also affects the overall fracturing effect.If the fracturing fluid flows back too fast,it will cause a large number of proppants to flow back,detracting from the fracturing effect and causing damage to the equipment.If the fracturing fluid flowback speed is too slow,it will lead to the long-term retention of fracturing fluid in the formation,which can cause the reservoir damage.Besides,it can prolong fracture closure time.It will cause most of proppants to sediment when the fracture closes,resulting in unsatisfactory proppant placement.However,in actual production,the working system of fracturing fluid backflow often depends on the experience of personnel,lacking scientific theoretical guidance.In view of the above problems,this paper makes a thorough study of the fracturing fluid flowback process.Firstly,the mathematical model of fracturing fluid backflow is established by combining the calculation model of fracturing fluid filtration volume,the calculation model of fracturing fluid backflow volume and the calculation model of the change in fracture volume.On this basis,the influencing factors of fracturing fluid backflow are analyzed.Then,the migration mechanism of proppant in fracturing fluid is studied.A new calculation model of critical proppant flowback velocity and a calculation model of proppant settling are established,and the influencing factors are analyzed.Finally,on the basis of the above theoretical models study and the optimization method of backflow working system,an fracturing fluid flowback optimization software is developed.The software can simulate the data in the fracturing fluid flowback process according to the given working system,and also output the optimal flowback working system according to the given parameters.Finally,the software is used to carry out the comparative calculation of the field production examples and the accuracy of the software calculation results is verified.This study provides a scientific basis for fracturing fluid backflow construction,and has an important theoretical guiding role for actual fracturing construction.