Hydraulic release system

Abstract

A hydraulic setting and release system for run in and cementing of a work string and tubular within a borehole has a small diameter pipe string extending from a release tool through a packer to within the tubular. The system forms at least one annulus between the pipe string and tubular. The pipe string includes a ported nipple and a seat subassembly downstream of the ported nipple. The pipe string allows the packer to anchor the tubular, by being inflated through the port even when the seat is blocked. The pipe string also forms a flotation annulus which is sealed by, and the pipe string is supported by, a drag/seal subassembly downstream of the seat assembly. The system also includes a safety release tool for reliable uncoupling. Uncoupling is accomplished after run in, displacing a cement slurry slug separated by a plug or dart using a following pump down fluid which can land on the seat and block further flow and displacement of cement slurry, and anchoring. The release tool is then actuated uncouple the drill string from the cemented tubular and removal of the drill string prior to well operation (e.g., oil production).