Operators in Western Canada continue to evaluate opportunities to improve thermal well efficiency while maintaining well integrity in increasingly demanding environments. Among the concepts receiving greater attention are extended-reach thermal wells with shallow vertical depths.
These wells have the potential to reduce surface footprints and simplify certain aspects of pad construction compared with traditional slant well developments, i.e., those that are drilled at an angle from the surface rather than vertically.
However, the adoption of these alternative approaches introduces a technical challenge. Thermal wells are exposed to elevated temperatures, cyclic loading, and long service lives, all of which place significant demands on casing strings and threaded connections. When combined with aggressive well trajectories and operational practices such as casing rotation during cementing, these conditions can generate bending and fatigue loads that differ from those typically encountered in conventional thermal well designs.
To better understand how premium connections perform under these conditions, Tenaris, a major thermal operator, and Noetic Engineering, the project partner, conducted a full-scale testing program focused on the behavior of thermal casing connections subjected to severe bending and low-cycle fatigue loading.
The objective was to generate physical performance data that could support engineering decisions related to future thermal well architectures, as well as support safer, more efficient, and sustainable operations.
This full-scale testing program explored new well designs that reduce land use, strengthened well integrity, and enabled more cost-effective well development. The results offer operators greater confidence to adopt next-generation thermal drilling strategies, backed by proprietary technical insight that supports performance, environmental stewardship, as well as capital efficiency across Canada’s evolving thermal oil sector.
The findings also provide new insight into connection behavior under loading conditions representative of extended-reach thermal wells with shallow vertical depths and contribute to the industry's broader understanding of thermal well integrity. The results were presented jointly by the key stakeholders at the SPE Thermal Well Integrity and Production Symposium held in Banff, Alberta, in December 2025.
The presentation emphasized the value of structured testing programs in reducing uncertainty associated with emerging well designs. It also highlighted the importance of incorporating physical testing into engineering decision-making when operating conditions extend beyond established design experience.
Background
The transition toward new thermal well architectures requires a detailed understanding of how critical well components perform under changing operating conditions.
To address a recognized knowledge gap, Tenaris and the project partners set out to conduct a full-scale testing program examining the performance of the TenarisHydril Blue connection technology (Fig. 1) in 9⅝- and 11¾-in. intermediate thermal casing subjected to severe bending and low-cycle fatigue loading.
Steam-assisted gravity drainage, or SAGD, and other thermal recovery methods have relied extensively on slant well designs for shallow developments. These wells have demonstrated reliable performance across a wide range of operating conditions and have become a standard approach throughout much of Canada's thermal oil sector.
As operators seek additional efficiencies, interest has grown in alternative drilling geometries capable of reducing the size of well pads and increasing development flexibility. One concept under evaluation involves vertical shallow wells that transition into the required reservoir trajectory while occupying less surface area than traditional slant well configurations.
While the potential operational benefits were understood, questions remained regarding connection performance under the mechanical loads associated with these designs. Existing industry experience provided substantial information regarding thermal casing performance during production and steam injection. However less information was available regarding the behavior of premium threaded connections when exposed simultaneously to high wellbore curvature and cyclic thermal loading conditions associated with emerging extended-reach shallow well architectures.
The lack of physical test data highlighted a potential knowledge gap needed for engineers to evaluate these concepts. A testing program was therefore developed to examine whether connection performance could support the requirements of future thermal well designs while maintaining the integrity standards expected in thermal operations.
Defining the Engineering Challenge
The project focused on a specific question: How would premium thermal casing connections perform when subjected to the bending and fatigue conditions anticipated in future extended‑reach thermal wells with shallow vertical depth designs?
Particular attention was given to operations occurring before steam injection, including casing rotation during cementing. In certain well configurations, rotation can improve cement placement, bond, and support overall well integrity. At the same time, the operation can introduce additional stresses that must be considered when evaluating connection performance.
The challenge wasn’t simply to determine whether a connection could withstand a single loading event. Thermal wells experience repeated loading throughout their life cycle. Engineers therefore sought to understand how connections would behave under a combination of severe bending and repeated strain cycles representative of field operations.
To address this question, the project partners elected to perform full-scale physical testing rather than rely exclusively on analytical models.
Testing Program Design
The testing program was conducted at Tenaris's research and development center in Veracruz, Mexico. Testing focused on two intermediate casing sizes commonly used in thermal developments: 9⅝- and 11¾-in. casing equipped with the newly developed connection technology.
The testing matrix was designed around loading conditions expected in shallow vertical thermal wells. Engineers from the participating organizations worked together to establish representative scenarios, drawing on previous experience with existing thermal testing protocols, such as ISO:TS 12835 (2022), and defined performance criteria before testing began. Two primary areas were evaluated.
- Connection sealability under severe bending loads.
- Connection performance under high-stress, low-cycle fatigue conditions.
The bending tests subjected the connections to curvature levels reaching approximately 25° per 30 m. These conditions were selected to better understand maximum load limits that could be built into future well architectures under consideration by thermal operators.
Additional testing introduced fatigue loading intended to replicate repeated stress cycles associated with drilling, cementing, completion activities, and early-life well operations. By combining bending and fatigue evaluations within the same program, the team sought to develop a more complete understanding of connection behavior than would be obtained through a single loading scenario. Throughout testing, connection performance was monitored to evaluate sealability and structural response under progressively more demanding conditions.
Results and Implications
The testing program demonstrated that the new connection maintained its performance under the bending and fatigue conditions evaluated during the study. One of the most significant engineering outcomes was the collection of full-scale performance data under loading conditions, which had not previously been studied in such detail for this type of application. The results showed that the connection design maintained sealability while subjected to severe bending loads representative of future shallow thermal well concepts (Fig. 2). The fatigue testing also provided additional information about connection behavior under repeated stress cycles.
For engineers involved in thermal well design, the value of the testing extended beyond pass or fail performance. The program established a data set that can be used to support future design evaluations and reduce uncertainty when assessing alternative well architectures. The findings also contributed to ongoing discussions about casing rotation during cementing operations. Improved understanding of connection performance under these conditions may support future efforts to optimize cementing practices while maintaining well-integrity objectives.
Historically, the absence of physical test data often required conservative assumptions when evaluating connection performance under extreme loading conditions. The results of this collaborative program provide an additional reference point for future engineering studies involving similar operating environments.
The testing program was initiated to answer a technical question regarding connection performance, but the findings also have implications for future field-development strategies.
Based on the results, the thermal operator was able to advance planning for a vertical shallow thermal well pad concept. Analysis associated with the project indicated that this approach could reduce the surface footprint of future slant well developments by as much as 25%, depending on project pad configurations.
For thermal operators, reductions in pad size can influence several aspects of project execution. A smaller footprint reduces the amount of land disturbed during development and may create opportunities to accommodate additional wells within a given surface area. Shallow horizontal wells require specialized slant drilling rigs which are not as plentiful as conventional rigs, limiting flexibility to react to volatile energy markets. Slant rigs are also required to run any tubing and completion activities, unlike most conventional and unconventional assets which utilize smaller and more mobile service rigs. Additionally, slant-drilled wells may require specially designed equipment such as well heads to tie into surface pipelines and support facilities.
Although the long-term benefits will ultimately depend on field implementation and operating experience, the testing program supplied engineering evidence that supports continued evaluation of these concepts. The project therefore illustrates how data generated from a connection performance study can ultimately inform discussions regarding well architecture, pad design, sustainability, and efficient future development planning.
As thermal operators continue to pursue cost reductions and improved development efficiency, the industry will likely encounter additional questions about the mechanical performance of critical well components under new operating conditions. Programs such as this one provide a framework for addressing those questions through measurable data rather than assumptions alone.
Conclusion
Several lessons emerged from the project. Firstly, the introduction of new well architectures can create technical questions that are not fully addressed by existing operating experience. Even when individual components have extensive field history, new loading conditions may warrant additional evaluation.
Secondly, full-scale testing remains an effective tool for assessing performance in applications where analytical modeling alone may not provide sufficient confidence. Physical testing can reveal how components behave under realistic combinations of loading conditions that are difficult to replicate through calculation alone.
Finally, collaboration between operators, engineering experts, and advanced tubular solutions providers like Tenaris can accelerate the evaluation of emerging concepts by combining field knowledge, testing expertise, and product performance understanding within a single program.
Testing demonstrated that strong connection performance under the evaluated conditions generates a unique data set relevant to future thermal well design studies. The findings provided additional confidence for the evaluation of vertical shallow thermal well concepts and contributed new information regarding connection behavior during demanding operations such as casing rotation while cementing.
As thermal operators continue to explore opportunities to improve development efficiency, the project demonstrates the value of structured testing programs in supporting engineering decisions, reducing uncertainty, as well as advancing well design innovation. JPT
Jonathan Olsen is technical sales manager for Tenaris in Canada. He has more than 20 years of experience with Tenaris, a global supplier of steel tubes and related services for the energy industry. For the past 13 years, he has worked closely with Canadian operators, providing technical expertise in well design and material selection across a range of resource plays, including unconventional developments, oil sands operations, and offshore projects. He helps customers optimize well performance, reliability, and operational efficiency in challenging environments. Olsen holds a BSc in mechanical engineering, with a minor in petroleum engineering, from the University of Calgary.
