Saudi has been applying water flood, CO2 etc to some of the fields for many years trying to keep up the flow rate from those old fields.
I think Saudi went into the current price situation, well aware that it was coming. They were well prepared with cash reserves.
Saudi is far better than the typical national oil company in planning for the future. Taking advantage of declining cost for drilling and completion in the declining market is a sign of strong finacials and future planning.
Oil jumps on weaker dollar
http://www.reuters.com/article/2015/03/20/us-markets-oil-idUSKBN0MG07G20150320
Oil prices jumped on Friday, with U.S. crude up about 4 percent, after the dollar fell on interest-rate uncertainty, lifting demand for dollar-denominated commodities from holders of other currencies.