Patriciu climbed to the top spot from the eighth position last year, after he sold a 75% stake in his Dutch-registered oil company Rompetrol to Kazak state energy company KazMunaiGaz.
Bacali ranked third last year with an estimated $900-950 million, while Tiriac was second with $1.2-1.5 billion.
The fourth spot this year went to businessman Sorin Ovidiu Vantu ($2.1-2.3 billion), who kept his position from 2006, when his wealth had been estimated at $850-900 million.
The fifth position is held by the Micula brothers ($1.9-2.1 billion), up one position from last year, when they had an estimated $750-770 million.