Corrosion Resistant Alloy (CRA) pipes like Sandvik’s SAF 2507® have traditionally been run in singles because the threaded connections exhibit a higher tendency to galling and require a more careful make-up compared to carbon steel pipes.
However, an international operator recently used Dopeless® technology to conduct the first ever run of CRA tubulars in stands of three pipes (triples). This provided additional robustness to the connections and minimized galling risks.
The operator managed to increase efficiency, reduce rig time by up to a day per string, improve well productivity and achieve environmental and HSE benefits.
The two deepwater wells are offshore Angola. The wells had several chemical, mechanical and thermal loads necessitating the use of CRA. Sandvik’s SAF 2507® super duplex stainless steel was selected for the production tubing to meet these loads due to its ability to perform reliably and its excellent compatibility with Dopeless® technology in threaded connections.
A total of 243 joints of 5½“ Sandvik’s SAF 2507® production tubing string with Dopeless® premium threads were run in triples. Running the CRA tubing with the Dopeless® technology in stands and using special handling equipment resulted in faster installation – reducing operational risk and rig time. The special handling equipment configuration included special thread protectors, non-marking dies, fluid grip tongs and weight compensators. Other benefits included savings in jet-wash water, zero dope discharge, reduced personnel exposure to risk, re-usability of non-contaminated thread protectors and improved well productivity.
Avoiding the cost of galling
The impact of galling (localized) welding of pin and box threads/seal due to high friction) on connections can range from slower running rates and a high number of rejections and lay-downs to more serious effects, such as leaking connections in the well.
Running pipes in stands increases the weight on the threads being made-up and increases the risk of connection damage. However, using Dopeless® technology provides additional robustness to the connections and minimizes galling risk.
The dope-free solution
Dopeless® technology is a dry, multi functional coating applied to premium connections in the mill that adheres to the steel substrate both in pin and box sides. It avoids the occurrence of hot spots in non-lubricated zones, which can be susceptible to galling when using liquid or greasy lubricants on the rig.
Deploying Dopeless® threaded connections enabled the CRA tubes to be run in triple stands into the wells. This created drillship time savings of 20 to 24 hours per string (eight hours saving for each 1000m string run in hole), which directly translated into financial savings.
This project proved that running dope-free CRA tubes in stands is achievable and can generate operational improvements. It also demonstrated the reliability of Sandvik’s SAF 2507® super duplex stainless steel in the oilfield. The reliability of CRA tubular installations in stands in oil and gas wells increases with the use of dope-free threaded connections handled with special tubular equipment – offering rig time savings for operators.