A subterranean well tool seals along a section of a wall of the well and is carried on a conduit into the well. A plurality of anchoring elements and seals are provided for respective anchoring and sealing engagement along the wall of the well in concert and substantially concurrently with one another when the tool is shifted to the set position. When the well tool moves to the set position, a portion of the mandrel separates and is retrieved from the well bore, allowing the well tool to be reduced in overall length. The anchoring elements are sandwiched in between first and second, or upper and lower, sets of seals.