Expansion set packer

A packer element has a biasing member incorporated with it. The element is either fabricated with the biasing element in a relaxed condition and then the element is stretched prior to insertion downhole or the element is created around the stressed biasing member and is held in that position until allowed to relax downhole. In either event the release of the element increases its diameter while shortening its length. Preferably, an advancing swage triggers the release to allow the element to expand as much as it can go or to the maximum relaxed diameter, whichever is larger. The swage then, preferably, drives the relaxed element toward the borehole wall or the casing.