In recent years, the front has only made occasional hit-and-run attacks against government troops, making Tuesday's attack its most significant one.
Formed from Ethiopia's minority Somalis, the Muslim group has fought for the secession of the Ogaden region, an area the size of Britain with four million people, since the early 1990s.
They also have been battling alongside members of the Union of Islamic Courts in Somalia.
Ethiopia is not an oil-producing country. But companies such as China's Zhongyuan Petroleum Exploration Bureau, whose facility was attacked on Tuesday, and Malaysia's state-owned oil giant Petronas have signed exploration deals.