Euler Loads and Measured Sucker Rod / Sinkerbar Buckling

Abstract

The Petroleum Industry is experiencing an increased awareness and understanding of sucker rod compression. This awareness has evolved during the past twelve years, from initial recognition of rod buckling, to a current desire to quantify (measure) the amount of compression required to initiate rod buckling. Recent attention has focused on true or effective compressive loads in sucker rod strings. Measurement of these loads is being documented and data collection is ongoing with improved technology. This paper will provide a more accurate understanding of the amount of compression required to buckle sucker rods and sinkerbars of various diameters. This will be accomplished by presenting the following; 1. Predictive compressive loads that buckle various diameters and lengths of sucker rods and sinkerbars utilizing Euler loads. 2. Measured compressive loads that are required to buckle various diameter sucker rods and sinkerbars. 3. A comparison of predictive compressive loads to measured compressive loads. Knowledge regarding the amount of rod string compression required to buckle various diameter sucker rods will provide the industry better rod string design guidelines. Use of these guidelines will help identify dangerous compressive rod string loads which initiate rod-tubing contact, provide associated wear, and result in rod and/or tubing failure.