Ask the experts: Oil slick sensors for drones?

Dec. 28, 2016
Sensor technologies show promise for low-cost, unmanned aerial monitoring.

Q: Regarding your recent article on oil film detection, I’m exploring methods of putting such an instrument on a drone platform. In this way, a vehicle could quickly assay and map the surface of petrochemical leaks from point sources. However, there are weight and size constraints for such a project. What are your thoughts? Which method do you think might lend itself to such a project, and how might I start to construct such a mobile instrument?

We have the drone design, building and flight operations expertise. We also have the software coding, data analysis and mapping technologies. We have some hardware and electronics expertise, so what we need is a laser and photodetector in a lightweight configuration to detect oil/water interfaces.

I’m presently developing “Sunflowers,” which are stationary, fixed-base, solar-powered, sensing stations that a drone could fly by and collect data from—like a bee gathering pollen. But I haven’t cracked the method of sensors that could go onboard. An optical approach would be best, one that I could drop and dip into the water, or an optical fiber that I can dip into an ocean or lake.

The methane sensor is easy, but it’s the water sensor that I’m having difficulty with. I live near water with local refineries (San Francisco Bay), and there would be good opportunities to try this out with some interested stakeholders (industry and government).

Jack P. Douglas, PhD / Paris Enterprises, LLC


A: Your application idea is a logical one and such drones are already in limited use as their size and weight problems have largely been solved. Lately, I’ve also been recomending the use of drone fleets in locating people, other floating objects or underwater derbis in cases of ocean accidents, and particularly for rescuing migrants from the Mediterranean Sea.

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Recently, I’ve also been looking at the sensors that serve computer vision applications in controling self-driving cars. There are many similarities between those and the drone applications. We can use drones for petrochemical leak detection, oil pipeline inspection, flarestack and gas emission monitoring, and in many other cases. When detecting ocean spills, these measurements can provide information on the rate and direction of oil movement. They can also assist in guiding cleanup and control efforts with drift prediction modeling. Underwater remote sensing instruments and technologies are also being developed based on acoustics, fluorescence polarization, in-situ fluorometry, non-dispersive infrared, and in-situ mass spectrometry for deployment with remotely operated vehicle (ROV) and autonomous underwater vehicle (AUV) applications.

For hydrocarbon detection, we can use a variety of optical sensors, thermal infrared imaging, airborne laser fluourosensors, laser radar devices, etc. The families of sensors that are suited for unmanned aerial vehicle (UAV) applications can be combined into all-in-one cameras and integrated area sensor (IAS) units that have 360° motion field views, and can be provided with Google’s Android platforms. One could write a book about this new field of automation, and who knows, I might do it one day.

Laser fluorosensor mearurement operates by emitting radiation at a particular wavelength that’s absorbed by oil, and in response, the oil emits another wavelength of radiation that is then detected by a laser sensor. This fluorescence allows measuring both the spectra and the the decay rate of the fluorescence given off. As a result, light, heavy and other oils can be separately identified.

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Thermal imaging (long-wave infrared, Figure 2) detects the thickest portion on the oil slick. As such, it can measure the size of the oil slick and the thickest portion of the slick when planning the clean-up effort.

Radar-based detector systems can identify the position of the spill and can track its drift to direct the recovery vessel to the location where most of the oil is. Their main advantage is that they can operate all day, under almost all visibility conditions.

It seems to me that our aim should be to integrate several of the optical and microwave sensors, while continuing to reduce sensor size, complexity and cost. We also need laser-based sensors that are less expensive and more energy-efficient, and we need further advances in the area of solid-state laser technology On the software end, we need true real-time processing.

I’ve summarized in Table I some of the features, capabilities and limitations of some sensors that are suited for drone-based oil slick detection applications. In my “Lessons Learned” column in January, I’ll discuss them in more detail in connection with their smart car applications.

A good summary of the teams doing research and development work in this fields can be found here

Béla Lipták

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A: I’ve been following the deployment of UAV and the regulations around the world for their use. Australian CASA has the most liberal drone regulations in the world, and that’s helping the entrepreneurs. GE, ExxonMobil and Maersk are some of the oil companies that have already developed and deployed UAVs in the oil industry. Some of the reading material cited below might be useful to you:

You might also try contacting Polaris. They seem to have an eTherm camera.

Raj Binney / [email protected]


This column is moderated by Béla Lipták, automation and safety consultant and editor of the Instrument and Automation Engineers’ Handbook (IAEH). If you have an automationrelated question for this column, write to l[email protected].

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