DOWNHOLE TOOLS AND METHODS OF SETTING IN A WELLBORE

摘要

A downhole tool disposed in a drillstring includes a bypass valve unit including at least one bypass port, wherein the bypass port is configured to control fluid flow from a central bore of the drillstring to a wellbore annulus, and an activation sub having a frangible obstruction disposed in a central bore thereof and configured to prevent fluid flow to an anchor downhole during a circulation mode, wherein the frangible obstruction is configured to break at a specified fluid pressure in the central bore to allow fluid communication to below.