Retrievable bridge plug tool and method for plugging off a well casing therewith

摘要

A bridge plug tool for temporarily plugging off a well casing to perform a downhole operation, such as cementing, or acidizing which includes a mandrel (10) having separate and spaced threaded segments (29,30) thereon. During running-in of the tool into the well casing, one threaded segment (30) engages a set of control members (31) to keep the mandrel in place and to prevent it from shifting longitudinally with respect to the tool. In the set position the control members are disengaged from the mandrel and the other threaded segment (29) engages a set of lock members (32). By applying a weight on the mandrel after threaded engagement of the mandrel with the lock members, a set of slip members (36) and packing elements (19, 20, 21) are caused to engage an inner surface ofthe casing wall to set the tool in position in the well casing. When the downhole operation is finished, the mandrel is rotated to disengage from the lock members (32) and to re-engage the control members (31). This sequence disengages the slip members (36) and packing elements (19, 20, 21) from the casing wall (22) so that the tool (T) can be retrieved from the casing, or re-set at another position in the casing.