The Design And Mechanical Analysis Of Flexible Drilling Tool For Ultra Short Radius Horizontal Well

Faced with the development of the old oil fields has entered in the latter part of the grim situation in China, the severe decline in oil production, how to reaserch a new method for tapping the potential of residual oil, improve the productivity of oil wells has become an urgent task to solve. Facing the trend of declining domestic oil field, that the ultra short radius horizontal well technology develop remaining oil technology is more and more popular in each big oil field. The core of ultra short radius horizontal well technology is whether there is a set of scientific and reasonable flexible drilling tool design. And the main parts of the flexible drill is guide screen and flexible drill rod, so guide screen and flexible drill rod structural design and mechanical analysis directly affects the drilling success. Therefore, based on the technical features of the ultra short radius horizontal well, the structure design of the flexible drilling tool for the ultra short radius horizontal well is carried out.By theoretical analysis method, consider guide screen oriented structure, the guide screen length of each section, slit angle, slit length, slit width and the transverse width of five main parameters were optimized, and establish guidance strength evaluation criterion, optimal structure is proposed. Considering contact between guide screen and wall, to guide screen and the wall as the research object, guide screen and wall contact nonlinear finite element model is established by the beam element. By the mechanical analysis guide screen dangerous section load is get. For the evaluation guide screen strength, single section of guiding screen as the research object, single section of guiding screen local finite element model is established by the solid element. Obtained the dangerous section load from whole model applied to the local model to evaluate the strength. Guide screen meet the strength requirements when window point axial force is 40 kN and drilling angle is 90°.Considering the flexible drill rod can be through the curvature radius of the hole, according to the geometric relations and strength condition, main parameters of single section flexible drill rod length, the ball head column keys diameter, internal diameter of ball head rod and the tee are designed. Considering contact between the ball head column keys and the ball head rod groove, tee and the ball head rod ball head. Take single section flexible drill rod as the research object, single section flexible drill rod nonlinear contact finite element model is established by the solid unit. By strength evaluation the flexible drill rod of whipstocking section can bear torque is less than 2kN?m torque, the flexible drill rod of the horizontal section can bear less than 40 kN drill pressure and less than 2kN?m torque.