Gulf Oil Spill
June 8th, 2010
It has been 50 days since the Gulf oil spill started and the news media and the internet have since then been inundated, often confusingly, with various estimates of the amount of oil leaking into the ocean every day. We heard 1000 barrels in the beginning, then 5000, then 12000-25000. I was watching CNN today where they were showing a high quality video of the oil spill as shot by a remotely operated vehicle. This video has only recently been made available and hopefully it would help in actually fixing the speculations once and for all.
As I was watching the news, an expert mentioned that the orifice through which the oil is gushing out is as big as a circular trash can. I remembered that a very similar looking trash can sits outside my own apartment. So I went out and measured its diameter which happens to be half a meter. From the HD video one can approximately measure how much the oil is rising up vertically every second. Now this measurement has at least two sources of errors,
1. The only way to measure distance in the video is to measure it with respect to the diameter of the orifice which I hope is not too different from .5 meters.
2. The height that oil rises up per second changes as one measures at different heights in the video. This is because the oil gushes out not as a cylinder but as a truncated cone.
Moreover, only a rough estimate of the rise of height/per second can be made. Anyway, by looking at the frames corresponding to 36,37, and 38 seconds, it seems that the oil is gaining about .15 meters per second. This, along with the fact that the diameter of the orifice is half a meter, means that .03 cubic meters of oil is gushing out every second. This figure is equivalent to about 16,000 barrels every day (1 barrel of oil is 42 US gallons).
Even though this is an extremely rough calculation, it would be hard to imagine how the actual figure could be any less. In all probability, this is some sort of a lower bound. The reason for thinking this is that I could only estimate the rise of height/second at a height of about 1.5 meters from the vent. Anyone who has held a water hose knows that under pressure the stream of water flares out. Since the volume of water passing through a cross-section is same at every cross-section and the cross-sectional area of the water increases with distance, it covers lesser distance forward at a point further away from the hose. A height estimate at the source of the vent would, therefore, most certainly give a higher value. Anyway, that was my two cents towards ongoing confusion.
What was shocking to me was BP's initial statement that the amount of oil gushing is irrelevant. That's not just bad PR. That's just bad engineering. And lack of common sense.
Well, the amount of oil gushing out is very relevant to how much penalty BP would have to pay. I think it's applied to every barrel that spills in the ocean. They had a vested interest in reporting a low number. But I'm inclined to see their point when it comes down to how relevant reporting true numbers are to what BP's response could have been. True numbers to you and me and most other people doesn't mean much. Where BP truly messed up was hiding those true numbers from people who could have helped, like scientists who work in the field of ocean engineering etc.
But I agree, people ought to know the truth, even if they cannot do much...
The estimate of the amount of oil leaked impacts everything, from how far it could travel to what degree of containment measures would be required. They might have lost precious time and resources in being so laissez faire about this. Quite a tragedy this.
Good job. Even with some crude assumption, you arrived at a reasonable number. What shrouds the mystery is the content of natural gas in that concoction. Some of it gets dissolved in sea water, while rest escapes to the atmosphere.