ConocoPhillips (NYSE:COP) has agreed to sell its interest in the Clyden oil sands leasehold in Canada to Imperial Oil (NYSEMKT:IMO) and ExxonMobil Canada, a unit of ExxonMobil (NYSE:XOM). The purchase price is roughly $720 million, from which ConocoPhillips expects to record a gain of roughly $450 million after taxes.

According to Imperial Oil's press release on the transaction, Imperial Oil is acquiring a 27.5% stake, while ExxonMobil Canada is purchasing the remaining 72.5%. ExxonMobil Canada will reduce its stake to become an equal partner with Imperial Oil once ExxonMobil brings on a third partner.

Clyden is a 226,000-net-acre area of undeveloped land in the Athabasca oil sands region of Alberta, Canada, close to Imperial's existing Corner lease holdings. Imperial highlights the land's amenability to an in-situ recovery technique called steam-assisted gravity drainage.

ConocoPhillips characterizes the sale as part of its efforts to rebalance its oil sands portfolio. ConocoPhillips currently holds approximately 1.1 million net acres of land in the Athabasca Region of northeastern Alberta. Including this transaction, ConocoPhillips has announced expected proceeds of approximately $13.5 billion from the sale of nonstrategic assets as part of its 2012-13 asset disposition program.

Imperial described the acquisition as a "high-quality addition" to its existing in-situ portfolio.

The transaction remains subject to Canada's Competition Bureau review, and is contingent upon approval.