Research On Hydraulics Optimization Design For Coiled Tubing Sidetrack Drilling

In recent years,with the continuous research and development of coiled tubing(CT)technology and drilling technology,the quality of CT has been greatly improved,and the application range is more and more widely,the technology has become the focus of foreign drilling technology.CT is widely used in many fields,such as workover,well completion,well logging,drilling and stimulate.Known as the“universal machine”in oil industry.The research and development of CT technology is great significance to the petroleum industry.In this paper,the mathematical model of the flow pressure loss for the CT is inductived and studied,and the distribution of the pressure and friction coefficient in each layer and the total pressure loss of the bent tube section are calculated by the example.Draw the curve of the total pressure consumption of the bent pipe and the pressure consumption curve of each section during the drilling under different displacement,and provide a reference for the data query of the construction site.By using the FLUENT numerical simulation software,analyze the influence of displacement,drilling fluid density,viscosity and curvature on the pressure drop and friction coefficient of CT bent tube section,by the control variable method.According to the well condition,the Paper analyzes the possible force of cuttings in the annulus,considering the gravity,buoyancy,drag force,extraneous force,lift force,plastic force and other forces,derive the cuttings critical toss velocity model and the critical suspension velocity model by the torque equilibrium equation,and analyze the influence of drilling fluid density,cutting density and cutting diameter on the critical toss velocity and the critical suspension velocity.By using the FLUENT numerical simulation software,analyze the influence of displacement,drilling fluid density,viscosity,eccentricity,cutting density and cutting diameter on the hole cleaning of annulus by the control variable method.By using a practical example,calculate the optimum range of displacement.Provide effective theoretical guidance for practical drilling operations.