A system and method for controllably separating a conduit into an upper portion and a lower portion. The system includes a first valve in the upper portion of the conduit above a point of separation, and a second valve in the lower portion of the conduit below the point of separation. When the conduit is separated, the valves are actuated to cease flow therethrough and prevent loss of fluids into the seawater. A hang-off tool in the lower portion of the conduit engages the well and supports the lower portion of the conduit.