Oklahoma's oil and gas production, while overshadowed by the surge in unconventional production in North Dakota and Texas, has doubled since 2005 and reversed 20 years of declining rates.

According to a Bernstein Research report, Oklahoma oil production reached about 300,000 barrels per day in 2013, up from about 230,000 per day in 2012.

The greatest amount of activity has been in the Mississippian and Granite Wash (Pennsylvanian) plays, which represent approximately 70% of the horizontal oil completions since 2009.

“Oklahoma is home to multiple plays, including the Mississippi Lime, Granite Wash, Woodford, and other emerging plays. Granite Wash, the youngest, straddles the Texas/Oklahoma panhandle,” the report notes.

The Oklahoma portion of the Granite Wash gas play in the western part of the state is dominated by Linn Operating Inc. and Apache Corp.

Chesapeake Operating Inc. is the largest operator in the state (24,380 barrels per day) followed by Apache Corp (6,260 barrels of oil per day) and Le Norman (4,640 barrels per day), with the majority of production coming from Mississippian.

The unconventional Granite Wash is the second-most productive formation, with Chesapeake at 8,640 barrels per day, Apache at 5,100 barrels per day and Le Norman at 4,640 barrels per day. The Woodford is next, with Devon Energy at 2,140, Chesapeake at 1,650 and Cimarex Energy at 1,520 barrels per day.

Other top-producing formations include the Marmaton, Mississippi Lime and Hunton , where Unit Petroleum (4,440 barrels per day) and Charter Oak Production (1,910 barrels per day) lead.

According to IHS Inc., the Caney shale looks like another new commercially viable play: XTO Energy Inc. completed a Marietta-Sherman Basin well in Love County, #1-18H Cathey, which produced 337 barrels of condensate and 991,000 cubic feet of gas per day.

Two XTO completions in Carter County (#1-22H15 Beckham at 328 barrels of oil and 497,000 cubic feet of gas and #2-2H Sweeten at 131 barrels of condensate and 2.24 million cubic feet of gas) are the first Caney producers in the township. XTO has been developing Woodford reserves via horizontal drilling in the region.

“The majority of the state's rig activity has been occurring in the Mississippian with approximately 65 rigs,” the report notes. “Although part of the play extends into Kansas, only 12 rigs are there as of mid-October 2013. Granite Wash currently has 21 rigs in Oklahoma with another 42 in Texas.

“The 'other' category represents potential newer plays, notably Marmaton in Beaver County, where Unit Petroleum has been very active, and Hunton shale, neighboring the Mississippi Lime play in Central Oklahoma.”

The rig count in the Sooner State has remained flat for several years, but horizontal oil rigs now represent 70% of the state's total of operating rigs.

Assuming that the number of horizontal rigs (150) remains at the current level, “We have fore-casted the expected daily oil production in Oklahoma will increase to about 400,000 barrels per day by 2020 and then flattens,” the Bernstein analysts say.

—Larry Prado