A class action lawsuit filed in Stephens County seeks restitution for oil lease holders victimized during a conspiracy to rig bids and depress prices for oil and natural gas leaseholds. The petition filed by the Sill Law Group, an Edmond law firm, names Chesapeake Energy Corporation, Chesapeake Exploration L.L.C., Chesapeake Exploration L.P., SandRidge Energy and Tom Ward as defendants who…