Abstract: A packer tool for use in a wellbore having a bottomhole pressure p, includes: a mandrel assembly; a stabilizer on the mandrel assembly, for releasably engaging the wellbore; a packing element in an annular recess having a floor and two facing walls, the annular recess being transversely compressible into a compressed position and disposed about the mandrel assembly; and a piston assembly for driving compression of the packing element annular recess. The piston assembly has a plurality of piston faces moveable together in the same direction, the plurality of piston faces having a total piston face surface area a such that an application of pressure of p? to the piston assembly generates a force f greater than p.