Effectively plug back zones with a firm elastomer seal

The PosiSet mechanical plugback tool is used in through-tubing recompletion applications with a mast or crane to eliminate the need for a workover rig, saving costs. The tool runs through tubing and is set in casing to plug off fluid flow in the casing below the plug.

The casing seal is similar to that produced by a cast-iron plug, but instead of an explosive charge, a downhole electric motor within the mechanical plugback tool setting unit (MPSU) is used to contract the elastomer sealing assembly to form a firm seal against the casing wall. The expansion ratio is typically 3:1. An anchoring system keeps the tool in place and enables it to withstand higher differential pressure while cement is placed on top of the plug to a height of 10 ft [3 m] or more.

Because the PosiSet tool does not need a vent, it eliminates a slickline run that vented plugs require and increases reliability. The PosiSet tool is drillable. The smallest tool can withstand 25,000-lbf [111,205-N] force. The largest (9 5⁄8-in [24.45-cm]) plug can withstand 90,000-lbf [400,340-N] force.

With a temperature rating of 302 degF [150 degC], the positive displacement dump bailer is used to place the required cement plug on top of the PosiSet tool. Release of a weight bar displaces cement from the bailer sections. The PosiSet tool can be pressure tested 24 hours after the last bailer run, when the cement is at approximately 90% of its ultimate compressive strength.