[8] The proposal was accepted by shareholders in September under interim chief executive Kevin Reinhart,[9] but was a matter of significant public and political debate in Canada.

[10][11] Prime Minister Stephen Harper approved the deal in December 2012 but simultaneously announced more stringent guidelines for foreign acquisitions of Canadian oil sands companies.

As of 2019[update] the company had "shrunk considerably" since the CNOOC acquisition, having gone through multiple rounds of layoffs amid a difficult Canadian oil and gas industry as a whole.

[16] In 2019 the company moved its headquarters within downtown Calgary from its former namesake Nexen Building to The Bow, subleasing 8 floors from Cenovus[17] and reducing its office space from approximately 620,000 sq ft to approximately 300,000 sq ft.[16] Nexen has interests in Canada (including the Athabasca oil sands through a 7.23% ownership of Syncrude and the Long Lake project), the UK North Sea (including the Buzzard oil field), the United States, and offshore West Africa.

Beginning in February 2013, Nexen took accountability for managing approximately $8 billion in CNOOC Limited assets located throughout North and Central America.

[19] The Long Lake site has had a troubled history, including OPTI's near-bankruptcy in 2011 (with Nexen growing its ownership stake to 65% and eventually 100%),[20] a significant oil spill in 2015,[21] and an explosion in 2016 that resulted in two deaths and the permanent shutdown of the upgrader.