Tubing strings, buckling, friction and axial efforts

This work proposes the numerical modeling of tubing strings in oil and gas wells to quantify friction and axial forces. From a one-dimensional numerical model of buckling with friction, the other effects involved in the problem under study are incorporated and modeled for an accurate prediction of the efforts acting in tubing. During the life of a well it is important that the tubing supports this type of effort. Thus, the need for workover is avoided and one of the first elements of the well barrier system remains intact. The buckling of tubing forms contact regions between the column and the casing, as well as frictional forces that impact axial efforts. Due to the variety of loadings, a general solution to the buckling friction problem requires numerical solutions. In directional wells, the weight and trajectory of the tubing naturally generate frictional forces along the casing. In the literature, there are models that evaluate these forms of friction in isolation, while others even propose a joint analysis, but only for specific cases and without evaluating the loading history. In this direction, a model with all these criteria allows a more realistic analysis of the phenomenon. To achieve the proposed objective, the adopted methodology is divided into four macro-steps: i) study of friction models and aspects of column buckling; ii) computational modeling of friction buckling for tubing; iii) incorporation of new effects into frictional buckling modeling; iv) carrying out case studies on directional wells. At the end of the work, it is expected to quantify the friction in the axial forces, as well as to compare it with the other effects in scenarios of directional wells with production and injection strings under different forms of restriction. The main contributions of this work are the adaptation of a numerical model of buckling with friction to evaluate other forms of friction, buckling criteria update for directional wells and development of a strategy for evaluating the piston effect of the string in the numerical model.