I'd be more worried about safety. Cattle can be dangerous when they don't know you - most are not, just enough to make you forget to be careful. If you damage anything you are in trouble for it.

That said, if you can find the land owner most will be willing to give you permission and warn you about hazards to worry about. Figure out how to do it right and for free - with a good insurance that you won't harm their land and you will have more work where you can get permission than you lifetime will allow you to fix.

I'd think that if you touched old wells without permission or government support, you'd end up owning the well caps and future emissions, so if your "fixed" well is discovered to be leaking next year, the owner is going to say "We capped it off properly, those guys must have caused the leak when they "fixed" it, now it's their problem".

Properly "fixing" leaking wells involves getting a workover rig on site and pumping 10-1000 barrels of cement. Not to mention developing a plan and submitting it to the state for the well work permit, which hopefully comes before the rig gets on site. Rigs will not do work without a valid permit. I used to be a PM for well abandonment.

Minimum cost would be in the $80k-100k range. Double or triple that if you run into any issues. My most expensive abandonment was around $400k, which was for a simple, vertical 5000ft well.

Would it make sense to force new wells to pay a $500K deposit (can vary depending on size) to be held in escrow by the state/federal government in case of abandonment?

Good luck putting up any barriers to natgas extraction in texas, even if it would make sense.

Make sense to whom? The human race, or the profit seeking oil tycoons and the government benefiting from them?

That's already required, fwiw. Yes even in Texas. It's not the full costs, in practice, and ownership often gets tricky, but there are regulations to the effect. You have to put up a bond to operate oil and gas wells in TX and many other cases. That bond is seized and supposedly used to properly plug and abandon wells if you fail to do so, but it's not always sufficient.

Also, old infrastructure is really old. It's not things from 20 years ago. It's 50-100 years ago. The law requiring escrow or insurance (it has some holes) dates from the 70's.

Finally, it often isn't done properly. Either way, there are a ton of improperly plugged and abandoned wells and other leaky infrastructure that goes undetected.

The regulations you're describing have existed for a long time, but that's not enough to fix the full issue.

Thanks for the informative reply. It’s a real shame that this has gone on for so long.

There's a non-profit that does this:

https://welldonefoundation.org/faq/

Seems like the old wells effectively get defaulted to state ownership once the last owner goes bust.