The Friction Analysis Of Horizontal Wells In Low Permeability Oilfield Of Yanchang

This paper is based on the theoretical framework of the small deformation and largedisplacement of the thin rod, taking into consideration of the project characteristics ofhorizontal wells, the influence of axial force, torque on blending, and the target position andthe change of the direction of the forces caused by deformation, aiming at coming out thebasic differential equation of the static problem of drill string. For the use of towingcoordinates, the whole deduction process is very concise and clear. In dealing with theproblem of the connection between the tubbing and the drill stirng, the thesis treats the tubbingas elastomer, which is much closer to the real situation. Due to the quality of double non-linearof large displacement and connecting, the basic equation that needs to be solved is alsonon-linear. In order to solve this problem, the thesis first employs complex functions toconvert basic functions to non-linear ordinary differential equation with variable coeiffcient，and then converts iterative coeiffcient equation to linear differential equation with constantcoefifcient，targeting at getting the approximate solution on the complex plane. The actualcalculation result shows that this method is eiffcient in convergence. Based on the aboveanalysis, the thesis not only ifnishes the development of the computer sotfware of analyzingthe fiction of the drilling column of the horizontal well by using the database technology, butalso analyzes the different stresses under different assemblies of different drilling tools,various operating parameters, and different boreholes. The result of the calculation shows thatthe established calculation model of calculating the strength of the drill string and frictiontorque is reasonable and practical with sound precision. The designed application can not onlycalculate and predict the friction of drill string, the torque, and the hook load, but also canprovide an important analytical calculation approach to the design and construction ofdirection well, preventive measures of accidents, and the choice of the drill strings and drillrigs.