Neutrons detect clogs in pipelines

Copyright Nord Stream 2 / Paul Langrock

Industry and private consumers alike depend on oil and gas pipes that stretch thousands of kilometers underwater. However, it is not uncommon for pipelines to become clogged. With collaborators at the Research Neutron Source FRM II and the consulting company, Science S.A.V.E.D, scientists from TechnipFMC (a company specialising in subsea pipelines) demonstrated that neutrons are an ideal probe to locate blockages in underwater pipes.

The challenge

For a clog to be remediated in-situ, the affected section of the pipeline must be found. However, locating clogs from the outside is challenging, particularly when underwater pipelines are laid at depths of up to 2000 metres. While thermal imaging cameras and gamma rays can be used to detect clogs, neither work underwater. Ultrasound, on the other hand, has no problem penetrating water but blockages can only be detected near the pipeline wall.

The experiment

Using the Prompt Gamma Activation Analysis instrument at FRM II in Germany, the researchers established that neutrons can be used to differentiate between oil and gas and the blockage.

Additionally, neutron radiography and tomography, and fast neutron-induced gamma ray spectroscopy, showed that a sufficiently large number of neutrons can penetrate the metal walls of the pipelines to enable measurements underwater.

The results

The experiments demonstrate that neutrons are ideal for locating plugs in a non-contact, non-destructive and reliable way, despite thick pipe walls. Moreover, the technique can distinguish an incipient blockage from a fully developed one, enabling preventative measures to be taken. In practice, a mobile detector with a small neutron source can move back and forth along the pipeline to look for plugs.

Especially when a pipeline is idle for a longer time at low temperatures, hydrate plugs can form, similar to the methane hydrate core shown in the picture. © Bill Schmoker (PolarTREC 2010), Courtesy of ARCUS.
“We are very pleased that, with the help of the measurements at the research neutron source, we have now found an efficient method that makes it much easier to detect these plugs in the future."

Xavier Sebastian