Patent ID: 7637330

Claim:
A process for retrieving a bottom hole assembly through a casing string, the method comprising: installing a casing string in a borehole, the casing string including a bottom hole assembly releasably engaged thereto and moveable through an inner diameter of the casing string; releasing the bottom hole assembly from engagement with the casing string; reducing hydrostatic pressure in the casing string inner diameter above the bottom hole assembly so that the casing string inner diameter hydrostatic pressure immediately above the bottom hole assembly is lower than a hydrostatic pressure below the bottom hole assembly, creating a differential pressure on the bottom hole assembly by an amount sufficient to lift the bottom hole assembly; the differential pressure permitting reverse circulation down through an annulus between the casing string and the borehole to permit the bottom hole assembly to rise up through the casing string toward the surface; and retrieving the bottom hole assembly from the casing string.