The assets give Houston's Vanguard a new core area in the Haynesville and Cotton Valley shale plays.
Dallas' Mid-Con acquired 90% working interest and assumed operatorship of the unit.
Blackbird's total Montney prospective land position will stand at 74,880 net acres upon closing.
E-Spectrum Advisors LLC was retained to assist with the sale.
Eagle intends to re-deploy the capital to acquire other assets expeditiously.
Proceeds from the sale will be used to expand the company's 2014 capital program in the play by $18.4 million (C$20 million).
Radiant has already identified 21 areas where it can rework abandoned wells or drill new wells.
The venture includes an East Texas development agreement comprising Walker, Grimes, Madison, Trinity, and Houston counties.
ExxonMobil Corp. (NYSE: XOM) remains a non-operated working interest partner in the field.
Shell CEO Ben Van Beurden has already completed about $8 billion in asset sales this year.
Macquarie Tristone has been retained to provide financial advisory services for this transaction.
The block expands NuVista's land position to more than 220 gross (190 net) sections in the Wapiti Montney area.