Premium Semi-premium Connections Design Optimization for Varied Drilling-with-Casing Applications

摘要

As high resistance to fatigue loading together with highrnovertorque and compression capacities are at the top of a listrnof required features for connections to be used in new drillingrnand completion techniques such as casing drilling, then specialrnconnections with enhanced performance need to be developed.rnOn the other hand, a cost-effective solution should be chosenrnto balance the performance when considering low-demandingrnshallow wells for which sophisticated premium connectionsrncould be uneconomical.rnThis paper describes the development and evaluation ofrnpremium and semi-premium connections for tubing/casingrnwhich were developed to stand cyclic loads and reach anrnextended number of cycles under such conditions. Therndevelopment process of an integral connection for casing sizesrntargetting very demanding applications comprised FiniternElement Analysis (FEA) and Full Scale Fatigue Test (FSFT)rnshowing Stress Concentration Factors (SCF) lower than 2. Inrnaddition, during the development of the semi-premiumrnconnection to cover less demanding applications, some ofrnthese techniques were used to optimize the results until gettingrnSCF lower than 3, good enough when low doglegs are present.rnThe results of the tests are plotted in S-N (Alternating Stressrnvs Number of cycles to failure) curve with a standard curve asrna reference.rnAs per the results, both types of connections achieved thernobjective set at the beginning of the development process nowrnbeing suitable alternatives for low and high demandingrndrilling/completion operations.