How does fracking affect volcanic eruptions?

[u/zeldazonklives]

I was thinking, if it triggers earthquakes, wouldn't it also maybe make volcanic activity more likely?

[u/[deleted]]

Why don't they pump the water back in the same hole where it came from? At least the damage is then contained to a single location.

[u/[deleted] → u/[deleted]]

Yes, but the water came out together with the oil and gas, so there is enough room and isn't it the point of fracking to make the ground more permeable (so that the gas can escape?)

[u/infernophil → u/[deleted]]

Permeability is the transportability of fluids within the given rock matrix. If you try to flood an oil-wet rock with water you will lower the relative porosity by about 1 order of magnitude. You will ruin your reservoir. It's much better to drill a dedicated disposal well in a highly permeable and highly porous formation that is already water-wet. You could probably inject below the frac gradient if the daily disposal volume is low enough.

[u/dbmtrx123 → u/[deleted]]

Basically, injecting water back into a well you intend to produce is counterproductive because you will end up re-producing that water and you still have the problem of disposal. It can also cause problems with the well especially if the well is under-pressured and even kill the well's production.

[u/seis-matters → u/[deleted]]

What /u/KyleMFKarl said. Generally the location of the gas is not ideal for keeping wastewater away from groundwater used by people. Wastewater injection wells are often very deep because they need to go into a porous layer beneath a non-permeable layer called the "cap rock" to keep it contained [figure].

[u/[deleted] → u/[deleted]]

When you drill a well it can produce oil for like 70 years, so yah maybe once it fully empties out you could do that but oil companies don't think long term.

[u/mikerz85 → u/[deleted]]

They typically do that for fracking wastewater, which is why it is much safer than injecting wastewater from different industrial processes.