Well completion method and apparatus

Abstract

An apparatus and method for the completion of wells through a production tube includes a tool body having cement flow ports and pressure displaced port closure elements. A perforated mandrel tube concentrically aligned within the production tube is secured to said tool body at its upper end. Concentrically within the mandrel tube is a dart transport tube. The dart transport tube is releasably secured to the tool body by a set of locking dogs. A first dart plug is placed in the production tubing bore at the well surface to be pumped or allowed to gravitate onto a closure seat in the lower end of the of the transport tube. This seat closure allows the production tubing to be pressurized for setting well annulus packers and opening of a cement port closure sleeve. After the production tube has been set by cement pumped down the production tubing bore and through the cement flow port, a second dart plug is positioned atop the cement column in the production tube. A pumped column of water or other well working fluid sweeps most of the production tube cement column into the well annulus and lower end of the transport tube. The second dart plug lands against an upper bore seat in the transport tube to enable another pressure increase in the production tube fluid column. This next pressure increase shifts a sleeve piston that closes the cement flow ports and releases the transport tube locking dogs. With the locking dogs released, the transport tube falls to the end of the perforated mandrel and opens the mandrel perforations to formation fluid flow from the screens into the production tube bore. Residual cement remaining in the tube bore is all displaced into the transport tube and removed from the production flow path without drilling.