Your "fields" look non-standard.

A standard Merge field would look like { MERGEFIELD home_address1 }, and a
local REF field would look like { REF home_address1 } or { home_address1 },
with the {} being the special field braces you can insert using ctrl-F9.

So are your "fields" just pieces of text that are processed by some existing
program? Do they start with two /ordinary/ {{ characters and end with two
ordinary }} characters?

Either way, you could start by adapting the macro at
http://word.mvps.org/FAQs/MacrosVBA/BatchFR.htm, but to look through every
part of a document (main body, headers, footers etc.) in the middle of that
you need a loop that does...

Dim objRange as Word.Range
For each objRange in ActiveDocument.StoryRanges
   Do
     ' whatever it is that you need to do
      Set objRange = objRange.NextStoryRange
   Loop until objRange is Nothing
Next

(Although you would need more than that to detect fields and text contained
in objects such as text boxes, other shapes, and frames).

Peter Jamieson