The engineering behind the US Strategic Petroleum Reserve

jjohnjwang 1 day ago 21 commentsRead Article on johnjwang.com

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anigbrowl•about 1 hour ago

Salt contains the oil and helps seal small fractures. The rock salt surrounding the SPR’s caverns has extremely low permeability, meaning fluids have very little ability to pass through it. It also doesn’t react with petroleum. Under enormous pressures underground, salt also slowly deforms, which helps close small fractures. The salt itself can therefore contain the oil without a steel-and-concrete tank lining the cavern.

Oil floats on water, which means pumping water into the bottom of the cavern pushes the oil out. As fresh water is pumped into the bottom of the cavern, the oil gets displaced upwards into a delivery system.

The more water you pump in, the lower the quality of the oil that's pumped out; we are basically loaning the oil refiners money to buy SPR oil they don't really want. Also, the more water we pump in, the more salt leeches into the water and the more the bottom of the chamber deforms, creating shear forces in the upp walls that lower its overall structural integrity.

I've posted this before; it's a recent report on the status and maintenance of SPR facilities, which is very clearly written and well worth your time if you want to understand the topic better: https://www.gao.gov/products/gao-26-106918

gruez•8 minutes ago

We can't pump saturated salt solution to prevent more salt from being dissolved?

sokka_h2otribe•5 minutes ago

Hard to find that

mixmastamyk•2 minutes ago

I don't know, the article mentions having to deal with brine. Let it evaporate in a pool and you've got plenty.

nxobject•about 1 hour ago

I also think I've also replied this to you before, but +1 for the GAO report! I use the full report as my personal model yardstick on how I document technical decisions/issues for non-technical people. The PDF is attached here:

https://www.gao.gov/assets/gao-26-106918.pdf

FlowingRiver•22 minutes ago

It is funny seeing how the estimates of the lower end stability vary drastically. Have seen numbers between 70 and 150 million barrels. I have just called it half way between that and think 110 million barrels is probably the lowest they should go.

kulahan•18 minutes ago

I’m certain engineers have considered this, but it doesn’t seem answered anywhere: why not just pump the original brine back in to move around the oil? Wouldn’t that at least prevent eroding the storage unit and causing it to fail?

Unrelated: dang, he wasn’t underselling this being a pretty elegant solution! I never would’ve thought of it, for sure.

aesthesia•8 minutes ago

Wouldn't you then need to solve the similar problem of where to store the brine in the meantime?

LPisGood•12 minutes ago

One fun fact I’ve heard is that the strategic oil reserve requires like 100-150 million barrels of oil to maintain operational pressure and even be functional. This means we can’t draw it down to zero; not even close.

sklargh•20 minutes ago

Well worth your time if you are interested in a more detailed discussion https://www.construction-physics.com/p/how-the-strategic-pet...

Ellis_dev•about 1 hour ago

Makes you appreciate the physical infrastructure challenges, not just software. Bet the data logging and monitoring systems are ancient but robust.

bt1a•about 1 hour ago

Yea man the federal government is on top of protecting civilian groundwater supplies and communicating discoveries of contamination

hankbond•about 2 hours ago

Very cool, big fan of these bite size explainers. Has there been more cycling recently? Are the sizes of the caverns tracked anywhere?

FlowingRiver•20 minutes ago

Funnily enough, I guess the more you cycle them, the bigger they get until they just collapse. So you have a lot of potential storage just before you have none.

bt1a•about 1 hour ago

id imagine if you have the location of a site that the largest pipes visible from satellite photography would be consistently scaled in some manner with the tank size. this is guess

metrix•about 1 hour ago

What do they do with the brine when they fill it back up with oil?

And do they use fresh water?

analog31•about 1 hour ago

An interesting aside is that the process for making these salt domes is also used for mining salt. Drill a hole, pump water down, and up comes brine. The brine can be used as a chemical feedstock, e.g., for production of things like chlorine, sodium hydroxide (lye), and sodium carbonate for glass.

ivraatiems•about 1 hour ago

How long does the crude last uner these conditions? Refined oil products like gas have pretty limited shelf lives (I think 6-12 months for gas).

aqfamnzc•about 1 hour ago

Under ideal conditions - about 200 million years at least. In the salt, I'm not sure.

buckle8017•about 1 hour ago

well it's been underground in similar conditions for a couple dozen million years, so I think a while

recursivegirth•12 minutes ago

Politics, politics, politics... guess dang didn't see this one yet.

Not what the site is for (apparently):

> Off-Topic: Most stories about politics, or crime, or sports, or celebrities, unless they're evidence of some interesting new phenomenon. If they'd cover it on TV news, it's probably off-topic. [0]

[0] https://news.ycombinator.com/newsguidelines.html

aesthesia•9 minutes ago

This isn't a political article?