eli5 Why is Fracking fluid returned to the hole after extracting the resources?

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eli5 Why is Fracking fluid returned to the hole after extracting the resources?

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After you’ve pulled a bunch of liquid out of the area, you need to re-introduce a similar amount of liquid to avoid instability.

The oil wells aren’t exactly bottles filled with oil that we then empty out, but the analogy is pretty good. There’s space where there wasn’t space before, even if it’s not *really* a gaping void.

1) so that subsequent fracking can spread the cracks and get more oil.

2) because it’s hazardous and needs to be disposed of.

Because it’s a cheap way to dispose of it. They often contain huge amounts of salt and other chemicals that you don’t want to dump in some farmer’s field or a river. But also because leaving the hole empty will eventually result in undesirable seismic activity.

Edit: I’m referring here to raw water and it’s disposal. Which isn’t technically frac fluid but it would be understandable for a layman to use them interchangeably. They actually are very different.

Short answer – it’s not.

When you frac a formation you use a gel like liquid to suspend what is known as proppant in the liquid. This gets pumped down into the formation under high pressure which is slowly increased until a fracture happens. This means that the solid rock is fractured and when that happens, the liquid is continually pumped down into the well to increase the size and reach of the fracture.

This fracture cannot go on indefinitely and eventually the pressures rise so much that you realize you’ve reached the limit of the fracture. When that occurs a “breaking agent” is pumped down into the well and this “breaks” the gel like liquid into a much less viscous liquid more like water and that liquid is then pumped out of the well. After breaking the proppant stays in the fracture and holds it open thereby getting the name proppant because it “props” open the fracture.

Sometimes when a frack is broken the pressure from the well causes it to flow on it’s own but many times a pump needs to be placed into the hole.

When turned on the pump will continue to pull the liquid from the hole and eventually oil will flow, if the frack job is successful and they’ve connected multiple oil reservoirs so that it can flow into the 1 well bore.

However you never then pump the frac fluid back down into the hole because it’s now producing so that wouldn’t make sense at all.

Frac fluid may need to be disposed of and in that case it may be pumped down a disposal well but that’s not usually the same hole you just fracked.

Keep in mind it may take many months from when you frac a well until it starts producing oil again.

NG wells are perforated (directional explosion) then filled with sand to become a passage way for the gas. Pushing the sand with pressure behind it also opens up the perforated holes allowing sand to fill most everything up. Btw that sand I’m mentioning is synthetic making each individual particular uniform, to allow ease of movement for whatever gas is being extracted.

Source = ran a cement pump for years, and occasionally got sucked into frac work when things were slow or very busy.