1.  Field of the Invention
The present invention relates generally to oil, gas, and coal bed methane well completions.  More particularly, methods and tool assemblies are provided for use in accessing, opening, or creating one or more fluid treatment ports within a downhole tubular, for application of treatment fluid therethrough.  Multiple treatments may be selectively applied to the formation through such ports along the tubular, and new perforations may be created as needed, in a single trip downhole. 
2.  Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98. 
Various tools and methods for use downhole in the completion of a wellbore have been previously described.  For example, perforation devices are commonly deployed downhole on wireline, slickline, cable, or on tubing string, and sealing devices such as bridge plugs, packers, and straddle packers are commonly used to isolate portions of the wellbore for fluid treatment. 
In vertical wells, downhole tubulars may include ported sleeves through which treatment fluids and other materials may be delivered to the formation.  Typically, these sleeves are run in the casing, tubing string, or production liner string, and are isolated using external casing packers straddling the sleeve.  Such ports may be mechanically opened using any number of methods including: using a shifting tool deployed on wireline or jointed pipe to force a sleeve open mechanically; pumping a ball down to a seat to shift the sleeve open; applying fluid pressure to an isolated segment of the wellbore to open a port; sending acoustic or other signals from surface, etc.  These mechanisms for opening a port or shifting a sliding sleeve are not always reliable, and are not intended for use with coiled tubing.