Coiled Tubing Hydraulic Jet Fracturing Stress And Erosion Analysis

Coiled tubing hydraulic jet fracturing technology is a new type of hydraulic fracturing technology,bonding with coiled tube technology and the hydraulic jet fracturing technology,having advantage of a short cycle and saving tripping times,which can realize fracturing and hydraulic jet perforation at the same time.Coiled tubing hydraulic jet fracturing technique in shale gas development has a broad application prospect.However,because of the weak tubing stiffness,it’s difficult to bear vertical compression load and easy to generate sine or helical buckling instability.In addition,the coiled tubing would have been serious eroded by sand in the process of fracturing.Therefore,master the mechanism of coiled tubing in well and the erosion of coiled tubing is very important,which related the coiled tubing technology for application and promotion.In order to solve this problem,the mainly work has been done as following.(1)Establish mechanical model of Coiled tubing.Firstly,using the data of cubic spline curve fitting model to fit into a smooth curve.Next,use static equilibrium method and energy method to establish the coiled tubing deformation equation,considering the friction force,fluid pressure,upward force and gravity load.(2)Solving the differential equation of coiled tubing.After simplifying the differential equation of coiled tubing.we get the result of the coiled tubing in the sinusoidal buckling and spiral buckling critical equation,which includes data of positive pressure,shear force and bending force of the coiled tubing under different space state.(3)The analysis of stress and elongation of coiled tubing.The fourth strength theory is used to analyze the stress of the coiled tubing.Considering the tensile or compressive axial load,thermal elongation,elongation due to fluid pressure,analyze the total elongation of coiled tubing,As well as the fracturing tools through the largest hole curvature.(4)On the basis of analysis and mathematical model,use VB computer language to develop coiled tubing hydraulic jet fracturing string stress analysis software.(5)Based on the Fluent software,use DPM model to study the erosion rule of coiled tubing.Research is mainly focused on the erosion of the winch winding coiled tubing and mechanism of the gooseneck frame.