| 摘要 |
A downhole tool includes a swellable core, and a coating that encapsulates the swellable core, wherein the coating is made of a material comprising a component soluble in a selected fluid and a component insoluble in the selected fluid. A method for controlling a downhole tool includes disposing a downhole tool in a wellbore, wherein the downhole tool includes a swellable core, and a coating that encapsulates the swellable core, wherein the coating is made of a material comprising a component soluble in a selected fluid and a component insoluble in the selected fluid; and exposing the swellable device to the selected fluid to increase the permeability of the coating to allow the swellable core to swell.
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