QR Energy is focused on the acquisition, production and development of onshore crude oil and natural gas properties in the US.
Upon completion of transaction, Breitburn will have an average production of 57,300boe/d, 67% liquids, based on second-quarter results.
Breitburn Energy chief executive officer Halbert Washburn said: "This world-class portfolio of conventional properties in large, oil-rich basins fits perfectly with our asset base and improves our ability to deliver shallow, predictable decline rates that generate industry-leading margins."
QR Energy chief executive officer Alan Smith said: "We consider Breitburn an ideal merger partner and believe this combination creates an unrivaled operator of mature assets with exposure to nearly every conventional basin in the US."
Breitburn will create the largest oil-weighted upstream master limited partnership with a pro forma enterprise value of approximately $7.8bn.
