I think you need to skip
screen -d -m 'php process.php param1 param2'
It's also useful to give the session a name, especially if you're
screen -d -m -S mysession 'php process.php param1 param2'
-X is for sending commands to
See also: this
QA here on SO
screen session will only exist as long as your
command is running. When
php process.php ... exits,
screen will also exit.