The subsea intervention system (SIM) includes a BOP module 10 and CT module 20. A tool positioning system 76 is used for positioning a selected subsea tool 22 stored within a rack 18 with a tool axis in line with the BOP axis, while a marinized coiled string injector 80 is moved by positioning system 81 to an inactive position. Power to the subsea electric motors 162 is supplied by an electrical line umbilical extending from the surface for powering the pumps 164, with the hydraulic system controlled by power control unit 198. The injector 80 preferably includes a pressure compensator roller bearing 220 and a pressure compensated drive system case 254.