Following a comprehensive review in 2002 that led to a sweeping change programme, PDO laid out ambitious production-recovery plans based not only on waterflooding but also on enhanced oil recovery (EOR) techniques: the application of heat, chemicals or gas solvents to alter the way oil or injected water flows in a reservoir. But, in order for them to be sustainable in the long run, the plans had to be executed for substantially less money than originally envisaged, making them all the more challenging. A total of $2 billion in cost savings over the five-year period 2002–2008 were incorporated into the Company's budget. Fortunately, because of the long-term nature of investments that would be required, the Omani Government agreed at the end of 2004 to extend PDO's exploration and production concession and operating agreements for 40 years – until 2044.