Abstract: A wellbore system with a tubular string extending from an earth surface down into a wellbore in the earth, a packer system with a selectively settable packer element, and a disconnect located between an end of the tubular string and the packer system, the disconnect operable from the surface by imposing a downward force on the tubular string. In one aspect the packer system's packer element is a tension-set packer element. A wellbore disconnect with a top sub, a piston having an upper end secured to the top sub and a portion below the upper end releasably secured with at least one releasable member to a carrier member, the carrier member having apparatus for selectively gripping the piston, the apparatus for selectively gripping the piston also selectively gripping a bottom sub within which the piston is movable, the at least one releasable member releasable in response to a downward force on the disconnect.