Laser milling system for concentric casing string cement repair

Abstract

A method includes setting a primary plug within a wellbore flowpath defined through a radially innermost casing string of a plurality of concentric casing strings, operating a laser milling tool within the wellbore flowpath to discharge a laser beam into the wellbore flowpath to thereby mill a window through the radially innermost casing string and radially outward towards a radially innermost cement column of a plurality of respective cement columns surrounding each of the concentric casing strings, discharging an abrasive fluid from an abrasive jetting tool into the wellbore flowpath and cleaning out the radially innermost cement column to expand the window radially, flowing a secondary plug material into the window and the wellbore flowpath above the primary plug, solidifying the secondary plug material to form a solidified secondary plug within the window, and drilling out the solidified secondary plug to restore the wellbore flowpath through the solidified secondary plug.

Dependencies are inferred from the claim text.