Composite 3D Printing Allows for Optimization of Backup Rings for HP/HT Applications

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23353, “Backup-Ring Optimization for High-Temperature and High-Pressure Applications Through Dynamic Composition Modification in Composite 3D Printing,” by Joshua T. Green, SPE, and Ian A. Rybak, SPE, The University of Texas at El Paso, and Chad Glaesman, SPE, Halliburton. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ Performance optimization was demonstrated in thermoplastic sealing systems for oil and gas equipment using emerging technologies in 3D printing to manufacture multicomponent composite structures. A custom 3D printer was equipped with a patented print head designed for dynamic mixing of individual feed materials and paired with advanced print-planning procedures to enable fabrication of novel thermoplastic structures. In addition to supporting fabrication of sealing components for rapid response in oil and gas equipment, this technique provides a means of improving the overall performance of sealing systems without an increase in the size or complexity of the sealing assembly. Introduction The purpose of this study is to demonstrate the potential for performance improvements in sealing connections through innovation in flat-backup-ring (FBUR) architectures. A component-level approach to functional testing was taken with supplementation from more-traditional materials analysis. The focus of investigation for this study is sealing connections with static O-rings supported by a single FBUR. Filaments composed of base resin alone were paired with filaments reinforced with carbon fiber (CF) to enable control over fiber volume fraction. Pressure-vessel testing was used to measure peak extrusion pressure and deformation after long periods of steady-state loading using hydraulic differential pressure. This study explores the potential for gains with the goal of optimizing multiple performance metrics when constrained by other design inputs such as material selection and geometry. In effect, the authors investigate composite architectures that can improve performance without altering resin or reinforcement material and without changing the size or shape of the FBUR. Methods Materials Selection. Polyether ether ketone (PEEK) is a popular base resin for FBURs in completion tool applications, and chopped CF is a common reinforcement used to increase the modulus of PEEK. PEEK is a favored resin for applications in oil and gas because of its broad fluid compatibility and mechanical characteristics at high temperatures. PEEK components typically are machined from injection- or compression-molded stock; however, at the time of this study, no known commercial fused-filament-fabrication (FFF) filaments are solely composed of comparable grades of PEEK resin because most filaments include additives to assist with printability. PEEK and PEEK+CF filaments were selected for high-temperature printing with a conventional all-metal hot end. 4043D-grade polylactic acid (PLA) and PLA+CF were selected for printing at lower temperatures suitable for the active-mixing hot end. Each pair of filaments included an unfilled grade to serve as a base resin and a corresponding fiber-loaded grade. All filaments used in this study featured a nominal diameter of 1.75 mm.