Esteban Oliva and Jordan Anderson
Tenaris Rods
Rod lift applications in deep unconventional wells have created a wide range of new challenges for all components of the RL system. In the case of the sucker rod, the increased compressive loads, especially in the deeper tapers, combined with the deviation of the wells result in very high contact forces between rod and tubing as well as effective stresses on the rods that range from very high to negative values. This scenario poses extreme challenges to operators who must choose between meeting their production goals in detriment of their system reliability or sacrifice production to avoid having holes in the tubing or deep rod failures.
This paper seeks to briefly describe buckling behavior in sucker rods, provide some best practices for sinker section design, and review the various sinker strategies available and their pros and cons. Euler’s equation is used to describe buckling behavior and show the variables involved in sucker rod buckling and a variety of data and specifications will be shared on sinker design and strategies. A short review of industry trends and the next steps will also be discussed.
The analysis reveals that there are several ways to reduce or eliminate buckling in a system by using various sinker design strategies with varying benefits and drawbacks and that further research and development would be beneficial to identify improvements on sinker section design.