Oil Pipeline Inspection – Case Study

In the following article we will follow the performance of a drone, equipped with a dual RGB/Thermovision camera, in the oil industry.

This case study is made with the purpose of demonstrating real usages of drones in the oil industry using thermovision sensors.

Our goal is to prove that typical issues like leaks of hot fluid could be detected remotely using drones in significantly less time than using old inspection methods.

Principal objectives:

  • Test #1 – Demonstrate the detection capabilities of a live leak with an active flow – from various altitudes
  • Test #2 – Demonstrate the detection capabilities of a leak by observing the ground thermal footprint  – from various altitudes

Although we could have offered a more comprehensive analyze, we were limited by the fact that the majority of piped were underground, the diameter of the pipes was very small and no pipes with insulation could be studied. More details about the analyzes that could have been made are at the end of this case study”.

Table of contents & Location

Satchinez

The location where we’ve carried out our tests.

View Map

Equipment used

Workflow

For the purpose of this test, a leak was simulated by a technician. The leaked fluid was a mix of water and salt. The fluid temperature was quite low, at 40.6°C as we will see below.

Then, at the request of technicians, the simulated leak was stopped so we can observe – in the high vegetation – the change in temperature of the surrounding soil where the fluid leaked.

A workflow with key points was establish before the initial testing. The data and conclusions were taken on site along with a live report demo, then post-processed with the appropriate thermal imagining software for a clear understanding of the data.

Location galley

These pictures offer an overview of the location and the analyzed site in the visible spectrum.

Test site galley

These pictures offer an overview of the pipes analyzed and used to simulate a leak in the thermal spectrum.

Test # 1

Demonstrate the detection capabilities of a live leak with an active flow – from various altitudes.

Methodology:

After the simulation begin, we started the detection by observing the liquid flow using the drone equipped with the thermal camera.

To establish a baseline for our testing, the water temperature was measured at ground level. The measurements resulted a temperature of 40.6°C.

The thermal camera we are using is equipped with 2 sensors:

  • RGB sensor – takes RGB images in the visual spectrum
  • Thermal sensor – takes thermal images in the infrared spectrum

When taking an image, the camera is is programmed to use both sensors at the same time thus giving us 2 separate images.

The next images were taken at a fixed position right above the leaking pipe with the camera pointed straight down. The procedure and observations were repeated at various altitudes.

Results:

10 meters height

The images below were taken moments after the leak flow was started.

Pipe leak - RGB (10 meters)Pipe leak - Thermal (10 meters)

As we can see, the ground didn’t heat yet and the gushing trail is quickly losing temperature to the surroundings as it is colder at the tip.

Although the liquid temperature was quite low (40.6°C) we didn’t encounter any difficulties spotting the “leak” quite the contrary actually, it was very obvious both in the thermal images and the RGB images.

25 meters height

The images below were taken moments after the leak flow was started.

Pipe leak - RGB (25 meters)Pipe leak - Thermal (25 meters)

The results here are the same as above, we can easily see and detect the leakage as the thermal footprint of the leak is bigger the pipe itself.

Pipes - RGB (25 meters)Pipes - Thermal (25 meters)

In this thermal image we actually discovered some pipelines under the vegetation that we didn’t know are there prior to this image and cannot be seen with the naked eyes or classic RGB images.

45 meters height

At this altitude everything stats to get smaller and the thermal footprint size of the leak it’s starting to get some context.

Pipe leak - RGB (45 meters)Pipe leak - Thermal (45 meters)

As we can observe from the images above, the leak is very noticeable on the thermal images. As the ground started to heat up the thermal footprint expanded, being a few times bigger than the pipelines themselves. This will be hard to miss when you’re looking for a leak.

Pipes - RGB (45 meters)Pipes - Thermal (45 meters)

The smaller pipes that we discovered earlier (at the 25m altitude) are still very noticeable here too. That’s quite impressive considering that the size of the pipes is below 5cm in diameter.

60 meters height

Considering the size of the pipes, at this altitude we are approaching the resolution limit of our camera.

Pipe leak - RGB (60 meters)Pipe leak - Thermal (60 meters)

Looking at the images, we can observe the same thing as before, just a bit smaller. The leak still has the biggest thermal footprint in the scene and can be spotted during an inspection.

Test # 2

In order to simulate an underground leakage, we will demonstrate the detection capabilities of a leak by observing the ground thermal footprint – from various altitudes

Methodology:

After the leaking simulation and the liquid flow was stopped, we started the detection by observing the remaining heat radiation given up by the ground. The images were taken using the drone (equipped with the thermal camera) in a fixed position right above the leaking pipe with the camera pointed straight down. The procedure and observations were repeated at various altitudes at regular intervals of time.

Results:

10 meters height

The image below was taken a few moments after the liquid flow was stopped. For a better understanding of the results, we choose this image to be our reference point of the moment when the simulated leak was stopped.  For now on going forward we will refer to this image as “the first image”.

Test site (Before) - RGB (10 meters)Test site (Before) - Thermal (10 meters)

The leak marks are pretty obvious in the images above, but that is to be expected considering how little time has passed.

Test site (After) - RGB (10 meters)Test site (After) - Thermal (10 meters)

To see how much thermal footprint the ground does loose over time we took the Images below at exactly 4 minutes and 48 second after the first photo. As we can see, there is a significant difference but, fortunately, not enough to not be detected even on a cold, cloudy day with an ambient temperature of 17°C.

Test site (Before) - Thermal (10 meters)Test site (After) - Thermal (10 meters)

Comparison of the before and after thermal images (with a distance between them of ~ 5 minutes).

25 meters height

The images below were taken a few seconds after the first image.

Test site (Before) - RGB (25 meters)Test site (Before) - Thermal (25 meters)

Not much has changed at this altitude, we can spot the leaking area without difficulties.

Continuing with our realistic approach regarding the thermal footprint, we took the Images below at exactly 4 minutes and 23 seconds after the first image.

Test site (After) - RGB (25 meters)Test site (After) - Thermal (25 meters)

We can spot the former leaking area with the naked eye even if the difference in thermal footprint is significant compared to the first image.

Test site (Before) - Thermal (25 meters)Test site (After) - Thermal (25 meters)

Comparison of the before and after thermal images (with a distance between them of ~ 5 minutes).

45 meters height

The images below were taken a few moments after the first image.

Test site (Before) - RGB (45 meters)Test site (Before) - Thermal (45 meters)

Although we almost doubled the height the results are the same as before, no issues spotting the hot area on the ground. Starting at this altitude we usually start to see other hot spots reflecting from the ground and for the untrained eye this can be misleading, but our certified pilot has no problems differentiating them.

Continuing our thermal footprint observation, we took the Images below at exactly 5 minutes and 34 seconds after the first image.

Test site (After) - RGB (45 meters)Test site (After) - Thermal (45 meters)

Interestingly, the difference doesn’t seem that high at this altitude due to small alteration to the general thermal footprint shape – they are very similar and we can still detect the area where the leak took place.

Test site (Before) - Thermal (45 meters)Test site (After) - Thermal (45 meters)

Comparison of the before and after thermal images (with a distance between them of ~ 5 minutes).

60 meters height

The images below were taken a few moments after the first image.

Test site (Before) - RGB (60 meters)Test site (Before) - Thermal (60 meters)

Even at this altitude we can observe the leak footprint.

We took the photo below after exactly 5 minutes and 47 seconds after the first image.

Test site (After) - RGB (60 meters)Test site (After) - Thermal (60 meters)

We can see the thermal footprint is losing some intensity, but the same as before, the shape is still there, and we can spot it.

Test site (Before) - Thermal (60 meters)Test site (After) - Thermal (60 meters)

Comparison of the before and after thermal images (with a distance between them of ~ 5 minutes).

If the spill area were larger, at 60m we would observe no significant difference in the detection capabilities compared to 25m.

To demonstrate that the limited size of the spill is the main cause, we took another set of images exactly 11 minutes and 26 seconds after the first image at the altitude of 9 meters.

Test site - RGB (after ~ 11 minutes)Test site - Thermal (after ~ 11 minutes)

We see the area where the liquid gushed out even after 11+ minutes the ground is still warm.

Final Conclusion

As demonstrated in the first case study, we continue to confirm our detection capabilities.

We were able to spot the leak both, with and active liquid flow – as seen on Test#1 – and without a liquid flow – Test#2, were we also did a successful 5 minutes observation of the leak area thermal footprint and showed that the we could see it not only after 5 minutes but even after 11 minutes.

Even in rough conditions with a liquid below the standard temperature and a high vegetation density the results were very clear: we can spot leaks. It’s science after all.

By testing at different altitudes, we observed that the best height and results depend on the size of the leak – but because we are using a drone, we can always change that on the fly. This is one of the many advantages the drone technology offers over conventional methods.

The use case of drones in inspections offers more benefits then then ones mentioned so far, including time savings, high efficiency and accuracy, low complexity, data quality and the most important one in this industry: safety. Drone inspection do not require human intervention and eliminates every risk associated with it.

Summary of tests:

  • Test#1 – We observed and detected the leak with an active liquid flow at all the chosen altitudes with no issues
  • Test#2 – We were able to spot the leak area without a liquid flow and did a successful 5 minutes observation of the leak area thermal footprint and showed that the we could see it not only after 5 minutes but even after 11 minutes.

Taking all the above in consideration, drone technology offers quick and easy identification with unbeatable accuracy and high-quality data output being indeed a viable option.

Other services

Pipe insulation issues

Although in the visible spectrum this hot-water pipeline is completely without defects, the measurement of thermal camera shows that on the left hot-water pipeline there are a series of insulation issues resulting in thermal losses.

Minimum requirements for this type of inspection:

The difference between the ambient temperature and the pipeline content of at least 20 C°.

Pipeline scale build-up

The dark purple areas of the pipes signify much lower temperatures, which is generally a strong indicator of scale in a pipe.

Minimum requirements for this type of inspection:

The pipe needs to be accessible (not underground) and should have a diameter of at least 30cm or more.

Questions?

Don’t hesitate to contact us!

+40 724 339 757
office@skylinedrones.ro