$re = '/(?<key>\w+)\.nomv="|(?!^)(?<=\G)(?<val>.+?)(?:\|\|\||")/m';
$str = 'page_name="xxx.com", page_type=other, thread_id=1152236, geo_locality.nomv="Seattle|||San Francisco|||Chicago", user_reference_count=0,';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php