Pioneer Natural Resources ($29 billion company and largest player in the Spraberry/Wolfcamp formation) has detailed information on this oil formation. Spraberry/Wolfcamp is often categorized with the Permian oil basin.
It is now producing 500,000 bpd and is projected to reach 2 million bpd by 2023 and then increase to 2.5 million bpd in 2033.
EIA survey of world shale oil and gas included an analysis of US shale oil. The Permian basin estimate included the Wolfpack/Spraberry had a total of 9.7 billion estimated to be recoverable. The 50 billion barrel estimate would double the estimated recoverable shale oil from the US. The Bakken formation estimate is also on the low end of recent estimates. There are estimates of 35 billion barrels of recoverable oil for the Bakken/Three Forks The DOE/EIA estimate is more conservative for the Bakken at about 7.4 billion barrels and 13 billino barrels for all of the North Dakota oil formations.