Releasing mechanism for downhole sealing tool

A releasing mechanism for releasing a hydraulic setting tool from a bridge plug within a wellbore, the releasing mechanism supporting a mandrel on the bridge plug while the bridge plug is being set, the mandrel having an essentially circumferential bore therein, the releasing mechanism comprising:

• an adapter having a body, a top end above the body connected to the setting tool, and a shoulder disposed within the body;
• a tubular retaining sleeve disposed around a lower portion of the body and connected the shoulder of the adapter at a top end of the retaining sleeve, the retaining sleeve further having a bottom end and a dog intermediate the top end and the bottom end of the retaining sleeve;
• a collet defining a tubular member disposed essentially concentrically within the retaining sleeve below the adapter, the collet having a plurality of radially spaced-apart collet fingers, the collet fingers being held closely to the mandrel by the lower end of the retaining sleeve;
• and
• a frangible body having a top end threadedly connected within the bore of the tubular portion of the adapter, and a lower end threadedly connected to the collet, and having a shear plane fabricated between the top end and the lower end, the shear body failing long the shear plane in response to tensile forces when the hydraulic setting tool is actuated.