From Tom Kool at oilprice.com:
The great Kingdom of Saudi Arabia—the long-time dictator of crude oil prices for the world—is struggling on all fronts.
The Saudis are losing their proxy wars in both Syria and Yemen; their OPEC leadership is under threat; they are not winning the crude oil price war; and its long-running alliance with the West is in question.
From Saudi Arabia’s perspective, Iran seems to be gaining ground everywhere. Saudi Arabia has several weaknesses that help explain the current anxiety emanating from Riyadh.
1. Saudi Arabia losing its leadership in the OPEC
Saudi Arabia has been the default leader of OPEC; however, despite Saudi insistence to the contrary, the U.S. shale boom, increased Russian oil production, and a very resolute Iran are challenging this leadership.
The result is that Saudi Arabia now finds itself powerless in supporting oil prices. Instead of the much-needed production cuts, during the 4 December 2015 meeting, the OPEC nations refused to adhere to any ceiling, which has been the practice for years.
2. Burning through reserves—fast

Source: http://www.tradingeconomics.com
Iran is waiting for the lifting of sanctions, expected sometime in 2016, to pump more oil to improve its economy, whereas the Saudi’s are losing they are burning through their cash reserves quickly. The above chart speaks for itself, depicting the kind of damage low oil prices are inflicting on Saudi reserves. By the most optimistic opinion, Saudi Arabia can survive low oil prices only for four years.
To continue reading: Saudi Arabia: A Weak Kingdom On Its Knees