Patent ID: 7703539

Claim:
An expandable downhole tool for hydraulically isolating a first section of a well bore from a second section of the well bore, the expandable downhole tool comprising: a base pipe configured to connect to a means of conveying the expandable downhole tool to a selected depth in the well bore; and, an enclosure formed from a permeable membrane and an impermeable element, the impermeable element having a first side fixedly connected to the base pipe, the enclosure being sized and configured to hold a preselected volume of at least one naturally occurring organic material that increases from the preselected volume to a second volume as the naturally occurring organic material interacts with at least one of water or heat proximate the enclosure, the water or the heat communicating through the permeable membrane into the enclosure, the impermeable element effecting a hydraulic seal against the well bore as the naturally occurring organic matter increases in volume and urges the enclosure into contact with the well bore.