US Patent 10450829 Drillable plug

A drillable plug includes a mandrel having an upper end and a lower axial section, the lower axial section having a geometry transition point separating an upper circular mandrel profile from a lower non-circular mandrel profile, a seal element disposed around the upper circular mandrel profile, and a lower cone having an inner surface forming a passage, the lower cone disposed around the lower non-circular mandrel profile whereby the lower cone is rotationally locked with the mandrel and a lower slip assembly moveably disposed on a sloped outer surface of the lower cone.