dates = '23-SEP-2015 and 23-09-2015 and 23-09-15 and Sep 23, 2015'
for x in re.finditer(
    '((\\d{2}-([A-Z]{3}|\\d{2})-(\\d{4}|\\d{2}))|([a-zA-Z]{3}\\s\\d{1,2},\\s\\d{4}))'
    , dates):
    pass
Using Python and Regex to extract different formats of dates