Let us just assume, without any loss of generality, that it is OPEC nations who can produce oil most cheaply. That is, the cost per barrel for all OPEC nations is homogeneous and is lower than the cost per barrel for any other oil producing nation or entity.
Then OPEC can continue to allow the price of oil per barrel to fall until other oil producing nations and entities are not gaining enough revenue to cover variable costs. This is because, in general, a firm will shutdown whenever marginal revenue is lower than average variable cost at the profit maximizing output.
For example, If US oil companies have total costs of 20 US dollars per barrel of oil and half of those are variable but they can only sell a barrel of oil for 9 dollars, then the US firm will stop producing oil. This is because continuing to extract oil causes larger loss than not extracting oil. If, however, the company could sell a barrel of oil for 12 dollars, they would continue extracting oil since doing so would 'eat away' some of the fixed costs.
The techniques you mentioned do cause oil producing entities to incur significantly higher costs than most OPEC nations. And most economists interpret OPEC's decision to not cut production as a predatory strategy meant to drive out marginal producers.
If you are seeking a concrete numbers, you could probably find some company reports and do a bit of math to calculate these things and develop a rough estimate of what price-per-barrel might cause these firms to make the shutdown decision.
So to actually answer your final question:
You should probably be happy that oil prices are falling. Those techniques are expensive. If oil continues its downward plunge most of those marginal producers will have to exit the market.
Something to consider is what this might mean over a longer time horizon. If many of these firms leave infrastructure in place (meaning there are relatively low barriers to re-entering the market), they could do a bit of hit-and-run until oil prices once again fall. This is assuming this situation arises while they are still incurring some fixed costs and are therefore seeking to minimize losses. Or perhaps it rises enough for them to even eek out a bit of profit etc.