A system for sealing a wellbore annulus, comprising: a base pipe having inner and outer radial surfaces (102a, 102b) and defining an elongate orifice; an opening seat arranged against the inner radial surface and having a setting pin coupled thereto and extending radially through the elongate orifice, the setting pin being configured to axially translate in a first direction within the elongate orifice as the opening seat axially translates; a piston arranged on the outer radial surface and being coupled to the setting pin such that axial translation of the opening seat correspondingly moves the piston, the piston having a piston biasing shoulder; a lower shoe extending about the outer radial surface and having a mandrel biasing shoulder; a packer disposed about the outer radial surface and interposing the piston and the lower shoe, the packer having adjacent first and second packer elements (108a, 108b), the first packer element being adjacent the piston and the second packer element being adjacent the lower shoe; and a wellbore device disposed within the base pipe and configured to engage and move the opening seat, wherein, as the opening seat axially translates in the first direction, the first and second packer elements are arranged to compress against the piston and mandrel biasing shoulders, respectively, and the first packer element is arranged to form a first seal in the annulus and the second packer element is arranged to form a second seal in the annulus, and wherein the first and second seals define a cavity therebetween, the seals being configured to trap fluid therein and to provide a hydraulic seal. a base pipe having inner and outer radial surfaces (102a, 102b) and defining an elongate orifice; an opening seat arranged against the inner radial surface and having a setting pin coupled thereto and extending radially through the elongate orifice, the setting pin being configured to axially translate in a first direction within the elongate orifice as the opening seat axially translates; a piston arranged on the outer radial surface and being coupled to the setting pin such that axial translation of the opening seat correspondingly moves the piston, the piston having a piston biasing shoulder; a lower shoe extending about the outer radial surface and having a mandrel biasing shoulder; a packer disposed about the outer radial surface and interposing the piston and the lower shoe, the packer having adjacent first and second packer elements (108a, 108b), the first packer element being adjacent the piston and the second packer element being adjacent the lower shoe; and a wellbore device disposed within the base pipe and configured to engage and move the opening seat, wherein, as the opening seat axially translates in the first direction, the first and second packer elements are arranged to compress against the piston and mandrel biasing shoulders, respectively, and the first packer element is arranged to form a first seal in the annulus and the second packer element is arranged to form a second seal in the annulus, and wherein the first and second seals define a cavity therebetween, the seals being configured to trap fluid therein and to provide a hydraulic seal.