Risers are the pressurized pipes which receive oil from the wellhead. The problem with my design is that I didn’t want there to be any pressure on the wellhead containment (ie, spillinator). So instead, I have an ROV (remote operated vehicle) connect an unpressurized tank to one of the containment valves. The tank fills with oil, and since oil is lighter than water, it floats to the surface.
The general idea is that there can be multiple tanks, so that one is always filling from the containment. Once they reach the surface, the oil is drained. Water takes the place of the oil, which causes the tank to sink to the bottom again, where the ROV retrieves it and connects it to the containment.
This is a very crude picture, of course. And of course those guys at the base need to go sometime too.