Title : Stress-Strain analysis of a tubing and packers system in 3-D wells
Abstract:
During well operations such as injection and production a string of tubing with packers is used. The system usually contains multiple packers and ports. The number of packers can be up to 20. Tubing is exposed to severe loads caused by string weight, pressures inside and outside the tubing and temperature. The objective of this study is to perform stress-strain analysis of the tubing set on multiple packers of various types under the action of external loads. The prediction of tubing forces and tubing movement is based on calculations and allows to avoid damage to the tubing or packer, failure of remedial operations and prevent tubing buckling.
Model is based on system of differential equations describing tubing static equilibrium. It takes into account the viscous friction acting on the tubing walls and temperature changing along the well. Pressure distributions inside and outside the tubing along the well are calculated due to a hydraulics model specially adapted for a multi-packer system. Several types of packers with different constraints are modeled by different boundary conditions. The equations are solved by numerical integration over the string length. Solution for the whole tubing presents a number boundary value problems or initially value problems for intervals of tubing concluded between packers which are fixed both on casing and on tubing. Based on the obtained distribution of axial effective load and elongation along the string length, stress-strain analysis and buckling analysis are performed. This analysis allows to determine the tubing force and length change due to piston, ballooning, temperature and buckling effects. Software was developed. The results of the study will help users to select correct initial conditions to perform successful injection and production operations.
Audience Take Away:
- A full model of well operations such as injection and production consisting of hydraulic model specially adapted for multi-packer system and a model of tubing will be presented.
- The presented model allows to predict tubing forces change and its length change during well operations as well as to prevent damage to tubing and packers and to avoid tubing buckling.
- Software is developed. It will help to carry out simulation of the process in 3-D well and make stress-strain analysis of a tubing. The user will be able to estimate a contribution of piston, ballooning, buckling and temperature effects to the system. It will help to select the optimal initial parameters for the system in order to perform successful operation and lower operation costs and time.
