Abstract

A Body Lock Ring (BLR) is a critical component that prevents the relative sliding of cylindrical elements, often utilized in equipment for oil and gas well construction, specifically designed to operate within low clearance wellbore environments. As demands for pressure and axial load ratings continue to escalate, a comprehensive study was undertaken that integrated analytical calculations and Finite Element Analysis (FEA). This combined approach confirmed the accuracy of a set of equations aimed at enabling performance predictions, ultimately contributing to the development of a more reliable design. 

An analytical model was developed to assess the performance of the BLR system, incorporating various failure modes into the evaluation. This model underwent validation through Static FEA using Abaqus Standard, followed by a statistical analysis of the resulting data. Nine distinct BLR systems were created to illustrate geometric variations, considering non-linear material properties, contact interactions, and friction effects. The FEA models were subjected to stress until the system's stiffness reached an unstable condition. Axial reaction force and displacement data were extracted and analyzed to generate a stiffness response curve. A scripting program was employed to discretize the data, formulate an offset curve, and calculate the "FEA Failure Point." The predicted ratings were then assessed as a percentage of the FEA failure point, resulting in a relative error. The analytical calculations predicted the FEA failure point with 98% accuracy on average (Mean: 102%, Standard Error of the Mean: 3.2%, Standard Deviation: 9.6%) showcasing their effectiveness and reliability in predicting BLR design ratings.

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Presenter Bio

Christopher Cookston, Senior Engineer, Baker Hughes

Chris Cookston is a licensed professional engineer with 13 years in the Oil & Gas Industry, specializing in the design of downhole equipment. He holds a Bachelor's Degree in Mechanical Engineering from Oregon State University, as well as one patent, one publication, five children, and a faithful wife. He aims to explore new ideas and efficiencies, pushing the limits of current technology to uncover innovative solutions.