Swellable packer assemblies, downhole packer systems, and methods to seal a wellbore

A downhole packer system, comprising:

• a conveyance;
• a mandrel coupled to the conveyance;
• a sealing material disposed about a portion of the mandrel, the sealing material formed from a material that radially expands from the mandrel in response to exposure to a fluid;
• a cover that is initially disposed about a portion of an outer surface of the sealing material, wherein the cover prevents the sealing material from being exposed to the fluid while the cover is positioned about the portion of the outer surface of the sealing material;
• and
• a pressure-actuated piston configured to shift from a first position about the mandrel to a second position about the mandrel, wherein the sealing material is exposed to the fluid after the pressure-actuated piston shifts from the first position towards the second position.

A method to seal a wellbore, the method comprising:

• running a swellable packer assembly to a downhole location of a wellbore;
• applying a threshold amount of pressure through a mandrel of the swellable packer assembly to actuate a pressure-actuated piston of the swellable packer assembly;
• and
• shifting the pressure-actuated piston from a first position about the mandrel to a second position about the mandrel to expose a sealing material of the swellable packer assembly to a fluid, wherein the sealing material radially expands from the mandrel towards the wellbore in response to exposure to the fluid.