Expandable retaining shoe

An improved downhole tool apparatus for limiting the extrusion of a packer element. The apparatus includes a packer mandrel having a packer element assembly disposed in a wellbore. Packer retaining shoes are disposed about the packer mandrel at the ends of the packer element assembly. The packer retaining shoes have an inner retainer and an outer retainer. The inner retainer has a plurality of segments having gaps therebetween that expand in width when the retaining shoe is moved from an initial position in which it is disposed about the packer mandrel to an expanded position wherein it engages the wellbore to limit the extrusion of the packer element assembly. The outer retainer is likewise made up of a plurality of segments having gaps therebetween that will expand. The outer retainer engages the wellbore to limit the extrusion of the packer element assembly. The inner retainer segments cover the gaps that exist between the outer retainer segments and the outer retainer segments cover the gaps that exist between the inner retainer segments so that extrusion is limited. The packer retaining shoes also include a wedge disposed about the packer mandrel at the upper and lower ends of the packer element assembly. The retaining shoes provide enhanced high temperature and higher pressure performance in that extrusion in wells having high temperature and high pressure is severely limited if not completely prevented.