Design And Simulation Of Electronically Controlled Diameter Changing Stabilizer For Drilling

Stabilizer is a new tool for downhole drilling trajectory control,which is widely used in horizontal Wells,extended reach Wells and other complex drilling operations.When changing the trajectory of wells,conventional stabilizers require frequent tripping,increasing the cost of drilling.A new type of tapering stabilizer is needed to meet the requirements of fast drilling operations.According to the working principle of the downhole tapering stabilizer,an electrically controlled tapering stabilizer is designed,based on pulse control of drilling fluid.By receiving the pressure pulse signal from the wellhead mud pump,the stabilizer drives the large torque motor to perform the corresponding action.The corresponding action drives the radial piston to expand and shrink to change the diameter of the stabilizer,so as to change the lateral cutting force of the bit and adjust the drilling trajectory.Firstly,the three-dimensional structure of the variable diameter stabilizer is developed using Solid Works software.,The dynamics simulation and static calibration of the radial piston,the wedge surface of the axial drive,the stabilizer casing and the stabilizer are carried out in ADAMS and Workbench software.According to the working conditions of the signal transmission mode of the stabilizer,the command information is transmitted between the bottom of the surface through the negative pulse of mud drilling fluid pressure.The downlink communication scheme of the stabilizer is designed and the schematic diagram of downlink communication of the stabilizer is finished.The structural parameters of the hollow brushless DC motor are preliminarily designed,and then the finite element simulation analysis of the motor is carried out in Maxwell software.Finally,the force analysis of bottom hole assembly is carried out in the twodimensional well environment.The mechanical model of BHA is established by vertical and horizontal bending method.The three-moment equation is established by considering the influence of various factors comprehensively.According to the continuous condition and boundary condition,the equations of bit lateral force and bit inclination are obtained.The bit side force and the bit inclination are solved in Matlab software,and then substituted into the formula of the bit building slope.The influence laws of drilling parameters such as stabilizer diameter,bit weight,well inclination Angle and piston wall support force on drilling tool deviation correction behavior are discussed.The results show that the maximum deviation control of the stabilizer is 2.96°/100 m.Reducing the diameter of the stabilizer,reducing the weight on bit and increasing the supporting force of the piston wall are helpful for the bottomhole BHA's lowering function.When the actual well inclination becomes larger,the downhole BHA's downslope characteristics are gradually enhanced.