pressure the annulus can be pressurized to assist in obtaining the necessary pack off pressure the hydrostatic pressure continues to be available as a pack off force even when the pressure below the packing element depletes as the reservoir depletes the packing element which is mounted directly to the packer body eliminates leakpaths behind it while at the same time the packing element is set by opposed forces i e hydraulic from below and hydrostatic from above application_number US 69781396 A description as shown in fig1 a the apparatus a has a thread 10 on a mandrel 12 for proper positioning of the apparatus a in the wellbore the mandrel 12 extends from fig1 a through fig1 e at the lower end of the mandrel 12 is bottom sub 14 connected to mandrel 12 at thread 16 seal 18 seals between the mandrel 12 and the bottom sub 14 seal 20 seals between the bottom sub 14 and outer body member 22 the bottom sub 14 has a series of collet fingers 24 which have a thread 26 facing a mating thread 28 on outer body member 22 ring 30 which is held by shear pin 32 holds the threads 26 and 28 together the outer body member 22 has a lower end 34 which can accommodate further downhole equipment.