What is PD ISO/TS 12835 - Casing connections for thermal wells about?
PD ISO/TS 12835 provides procedures for the assessment of casing connections for those field applications in which the operating temperatures cyclically vary between minimum values appreciably below 180 °C and maximum values that range from 180 °C to 350 °C or above, and in which the primary axial loading on the casing-connection system is strain-based and driven by constrained thermal expansion and leads to a stress state that exceeds the casing-connection system's yield envelope.
PD ISO/TS 12835 contains an evaluation procedure for a candidate connection comprising of the uniquely defined pin, box and interfacial components. The evaluation procedure includes:
- Material property tests to assess relevant properties of the candidate connection pin and box components
- Analytical tasks to determine the configuration of connection samples for physical tests, which are chosen based on worst-case combinations of the connection geometry and material properties
- Full-scale testing tasks to measure the candidate connection galling resistance, structural integrity and sealability under loading representative of connection assembly and thermal well service
Note: PD ISO/TS 12835 does not address impacts of external pressure, incomplete lateral pipe support, rotational fatigue, formation-induced shear, or environmentally-induced corrosion or cracking.
Who is PD ISO/TS 12835 for - Casing connections for thermal wells?
PD ISO/TS 12835 on the qualification of casing connections for thermal wells is useful for:
- Manufacturers of casing connections
- Operators of thermal wells
- Testing and inspection personnel
Why should you use PD ISO/TS 12835 - Casing connections for thermal wells?
PD ISO/TS 12835 is the culmination of a thorough review of factors contributing to the performance of casing connections in thermal well applications.
The evaluation procedure adopted in PD ISO/TS 12835 has been developed using input from operators’ descriptions of field practices, manufacturers’ feedback on connection design and production, available literature, knowledge of past connection qualification programs, and additional analytical and experimental work performed in support of the protocol development.
Thus, PD ISO/TS 12835 facilitates the assessment and qualification of threaded casing connections for service in intermediate or production casing strings in thermal recovery wells and in other wells experiencing significant temperature excursions such as in geothermal applications.
What’s changed since the last update?
PD ISO/TS 12835:2022 supersedes ISO/PAS 12835:2013, which has been technically revised. The main changes are as follows:
- All optional tasks moved to Annex D
- Added option to perform thermal cycle test with cooling to intermediate temperatures
- Changed the specification for to-failure portions of bend test and limit-strain test, allowing them to be performed with water only
