2-D model of BHA mechanical analysis for automatic vertical drilling

In order to direct the research development and field application of automatic vertical drilling tools and also provide the theoretical criterion for optimum design of the automatic vertical drilling bottom hole assembly(BHA),and on base of the research and analysis of the structural features and operating principles and also combined with 1-D mechanical model of automatic vertical drilling BHA,the 2-D mechanical model of the automatic vertical drilling BHA was built up using crisscross bending method.The boundary condition between the up cut-point and bit was built,the equation for bit side force and rotation angle calculation was derived. The bending deflection at each point on the beam and introvert torque at stabilizer pivot point can be accurately calculated by using the established mechanical model.At the same time,for a given condition,the bit side force and rotation angle can be calculated,and how the drilling parameters will affect the build-up ability during vertical drilling can be obtained through the research of how the bit side force and rotation angle will change if the drilling parameters change.This will provide theoretical criterion for the field application of automatic vertical drilling tools.