A Beginner’s Guide To Calculating Oil Storage Tank Occupancy With Help Of Satellite Imagery

At TankerTrackers.com, our mission statement is to present a bird’s eye view of the physical oil market with help of tanker-tracking, storage changes and official government statistics. We affectionately call it our “oil painting”. We gather a lot of data and analyze many events that will help professional and amateur traders on understanding the latest shift and trends in oil. We present four categories of data that appeal to our audience; those being oil tanker traffic, government statistics, EIA oil inventory forecasts and lastly, a visual confirmation of storage changes with the help of fresh satellite imagery. We chose Planet because of their global network of small satellites that provide access to daily updates in many locations of interest.

So, how and why does one put such technology to use? Well, let’s first cover the “why”. The global oil market is not entirely transparent. Many of the oil producing nations don’t like to voice their production, storage and export figures as it might put them in a bad spot at a negotiating table in for example Vienna, the HQ of OPEC (Organization of Petroleum Exporting Countries). If we can conclude with help of satellite imagery that a storage buildup has not occurred during a time when the country announced it would lower exports while maintaining production, then we will cross-check it with our tanker-tracking data and figure out whether the oil has gone into refining (into gasoline, for example) or if it was transferred by pipeline to a neighboring country’s storage/refinery.

As to “how” we use this technology, the answer is hidden in the shadows, quite literally.

Reference point: Diameter
First thing we need are reference points. The easiest to acquire is the diameter of the tank. You can use Google Earth’s ruler for that. Just drag and drop the line from one end of the tank’s rooftop to the other. Keep the line as straight as possible. In this example, we see 82 meters on most of the tanks we tested in the selected tank farm.

Reference point: Height

The second reference point is a bit trickier, but oh-so-necessary, and that is to find out the height of the storage tank. It is not obvious at first glance, but you have options; one of them even includes Googling the storage tank owner’s website, such as an oil company, refinery, storage facility, etc. Many post such information as it is part of their public marketing. However, if you are unable to find that information, then you can always try either contacting them or look for further clues. We never call around. We just Google or figure it out ourselves. Oh look, a photo of a storage tank in Ningbo, China is available on Google Earth! It actually shows the storage tank from its side. Lovely!

If we paste that image into a spreadsheet and crop it, we’ll get the width and height dimensions figured out. Make sure to not include the rear rim of the tank when cropping it. Just use the front. In our example, the width comes out as 2.57”, while height is 0.79”. We then crunch the numbers as shown below.

Psst! The alternative to this method is to actually hold up a ruler on your screen while no one is looking and just measure it quickly that way.

Next up, we’re calculating occupancy! By the time we’re done with this, you’ll quickly be able to approximate (with rough accuracy) how many barrels there are in each storage tank. To do so, we will need to rely on shadows. Below are some examples of what to look for. The shadow on the north side of the tank is a reference point for the total height of the tank whereas the shadow within the tank clues you in on the depth of the floating rooftop. What’s a floating rooftop, you wonder? In order for crude oil storage tanks to avoid a buildup of explosive gases, the rooftop rests on the oil directly. When oil enters the tank, the rooftop rises. When oil leaves the tank, the rooftop lowers. The more shadow you see within the tank, the less oil it contains.
Now that you got the gist of it, let’s have a look at a couple of images of Ningbo taken recently by Planet. One was taken on August 19th, 2017 and the other was taken exactly a month later. If you slide the center line to the left and right, you will spot the differences. Although not as clear as in the other images, we have a rough idea of the storage change over the past month between these three 837K barrel tanks.

Images ©2017 Planet Labs, Inc. cc-by-sa 4.0

If you look carefully, you will see that there has actually been NO CHANGE in the amount of barrels between these three storage tanks because the September image shows two half-full tanks along with an empty one, whereas August shows two empty tanks and a full one.

And that’s how it’s done.

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