Swellable rubber element that also creates a cup packer

A method for establishing a seal between a mandrel and a borehole comprising:

• manufacturing a packer having:
• a constrained portion, and
• an unconstrained portion made of a swellable material and coupled to the constrained portion;
• coupling the constrained portion of a seal element to the mandrel leaving the unconstrained portion free to move with respect to the mandrel;
• positioning the mandrel and seal element in the borehole;
• providing a spring between the mandrel and the unconstrained portion, the spring configured to urge the unconstrained portion away from the mandrel and having a spring force less than a yield strength of the swellable material when the swellable material is in an unswelled condition;
• and
• energizing the packer so that the unconstrained portion swells away from the mandrel and against the borehole to form a cup.

An apparatus comprising:

• a mandrel;
• a packer, the packer including:
• a constrained portion made of a swellable material coupled to the mandrel, and
• an unconstrained portion made of a swellable material and coupled to the constrained portion, wherein the unconstrained portion is free to move with respect to the mandrel;
• and
• a spring positioned between the mandrel and the unconstrained portion and configured to urge the unconstrained portion away from the mandrel, the spring having a spring force less than a yield strength of the swellable material when the swellable material is in an unswelled condition.