The hydraulic energy-storing workover rig is a new type of rig invented by the authors of this paper. The first experimental rig has passed through field test (see Fig. 1). This rig differs from other types of workover rigs not only in appearance but also in working principle.
There is an energy-storing system, so some energy issued from motors or from running down pipestring can be stored and used later when needed. This new invention has obtained a lot of advantages such as energy saving, safety, less noisy, possibility of using hydraulic tubing tongs without another hydraulic system, etc.