US crude is sold at market prices and is NOT specifically dependent on Saudi Arabia supply increases (e.g. another oil producer could cut production and zero out that increase).
Also, the price fell long BEFORE Saudi Arabia increased production (about a year). This was due to excess supply and why Saudi Arabia tried to cut production in 2014.
You have it exactly backwards. Saudi Arabia removed production caps in 2014. Shale fields cannot produce oil profitably at the resulting prices and are shutting down. http://mobile.reuters.com/article/idUSKCN0JA0O320141128
