Saudis initiated a number of processes, like larger discounts to oil price, which have to return the changing oil market to its long-term status. Historical oil producers (OPEC, Russia, ...) had a ten-year period of monopoly producing the highest profit for the countries with the lowermost net cost. The market was shared between the main producers. This was a good example of maximized monopoly profit.
Shale oil is not a challenge to monopoly profit, but bears some danger for the main producers to lose their market shares at the price level of $100. The response to this challenge was very well measured. Saudis waited before the investments in expensive energy technologies, like shale, oil Canadian tar, offshore Arctic, renewable energy, etc., reached the stage of mass production with the highest debt to be paid back. The expected effect of low oil price (we forecasted the possibility of $22 per barrel in 2016) is complete destruction of alternative oil/energy sources. Moreover, Saudis made it clear to investors that energy projects beyond conventional oil extraction are risky for decades. European countries with costly renewable energy paid from taxes (i.e. from consumer demand) will suffer most by suppressing investments in profitable businesses. I admire Saudis. They effectively use monop-oil-y.