Well completion method and apparatus

Abstract

Method and apparatus for completing a highly unconsolidated formation located downhole in a cased borehole in one trip. A tool string is run downhole into the borehole on the end of a tubing string. The tool string includes a perforating gun, a gravel packing tool, and packer means. The gravel packing tool includes a removable mandrel and a sand screen. The casing is perforated by running a gun firing device down through the tubing string and mandrel, and the well is free flowed to clean up the perforated formation. The sand screen is next positioned near the perforations and the packer means employed at each end of the screen to straddle and pack-off the perforated pay zone. The mandrel is then manipulated to form an isolated flow path which extends from the surface of the ground into the annulus behind the screen, and then back uphole from the screen to the casing annulus located between the tubing string and the casing, so that gravel admixed with fluid can flow down the tubing string into the screen annulus where the gravel separates from the fluid. The carrier fluid returns through the screen, back up through the tool string, into the casing annulus, and to the surface of the ground. The tool string is left downhole in the borehole as a permanent completion device. Produced fluid flows through the perforations, through the gravel and sand screen, and back uphole through the tubing string.