It is important to complete thermal and high-pressure/high-temperature (HPHT) wells with tubular connections that possess adequate structural integrity and sealing capacity under the severe load conditions typically experienced by these wells throughout their life cycle. Individual premium connection designs are required to be evaluated and qualified through physical tests to broadly adopted industry protocols, such as ISO/PAS 12835: 2013 for thermal wells that experience temperatures from 180°C to 350°C, and ISO 13679:2019 and API RP 5C5:2017 for HPHT wells which experience peak temperatures up to 180°C and pressures greater than 70 MPa. Recognizing the time and capital expenses associated with completing full-scale physical testing of product lines with multiple connection designs of different tubular diameter, weight, and grade, industry is developing a hybrid approach that supplements results from physical qualification tests with numerical/analytical simulation, such as Finite Element Analysis (FEA). The key challenges associated with analytical evaluation are the lack of evaluation criteria and suitable guidelines for analysis methodologies.

This paper provides a review of recent work related to the development of sealability evaluation criteria; and presents guidelines to facilitate performance evaluation of tubular connections in thermal and HPHT wells through advanced FEA. For thermal well applications, this paper presents a methodology for quantitative evaluation of sealability of casing connections, as a supplement to the determination of a biased test population using FEA following ISO/PAS 12835:2013 requirement. For HPHT wells, this paper presents considerations for analyzing various testing loads, such as Test Series A (internal and external pressure cycles), Test Series B (internal pressure with bending), Test Series C (thermal and mechanical cycles), and Limit Load Cases. Analysis examples with generic premium connections are presented to demonstrate the use of the proposed analysis methodologies.

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