$re = '/(
[^ \n].{23}
)/xm';
$str = 'База Базовая добыча (вЯк 8) 42370
Бурение well_obj1_1_prod (вЯк 8) 42370
Бурение well_obj1_1_inj (вЯк 8) 42430
"';
$subst = "$1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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