Structural Design of a New Multi-stage Variable Diameter Eyeball Spreader While Drilling
In this paper,a new type hydraulic multistage variable diameter reamer is designed,which uses the pressure difference of the drilling fluid on the mandrel to push the reamer blade out,so as to realize the expansion of multiple hole sizes in one trip and solve the problem of the blade sticking by holding down the pressure by throwing the ball.In order to ensure that the reaming tool blade can extend smoothly and complete the operation in the reaming section,the flow model of the drilling fluid in the borehole assembly and the borehole annulus is established.The influence of the mandrel size on the drilling fluid acting on the mandrel and the influence of the drilling fluid flow on the mandrel are obtained,and the diameter of the mandrel and the flow rate of the drilling fluid are determined.Based on the theory of axial symmetry,the influence of the interference between the ball seat and the mandrel on the contact pressure is obtained,and the interference between the ball seat and the mandrel and the height of the ball seat are determined.Based on the momentum theorem and mass conservation,a calculation method of the impact pressure of the drilling fluid is proposed,and the influence of the initial velocity of the drilling fluid on the impact pressure is obtained.
multi-stage variable diameterhydraulicdrill-while-drilling eye expanderstructural designinfluence the law
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