They are operated for Shell Petroleum Development Company between Lagos and Osubi, near Warri where EC155 operate onward shuttles to the local rigs in the swamp. The 328 Jets are certainly maintained by Bristow Nigeria, and were upgraded from vanilla prop 328s a few years back, and previously replaced Bristow DHC-6s I believe. I guess operations will be managed by Shell Aircraft (not Aviation - a very different BU).