wp_rewrite help

I’m not too familiar with wp_rewrite and need some help creating a simple rewrite. I’ve looked at the codex and it’s very limited on rewrite help for doing something simple.

I want to take the url:
https://mysite.com/tutorial/chp/1

and rewrite it to:
https://mysite.com/tutorial/?chp=1
The catch is that I want the url all the way up to /chp in tact so that no matter what comes before /chp/ it’s used in the new url and the vars are added in.

I have my permalinks set to the following:
/%category%/%postname%/

I’m trying the current rewrite:

// URL rewrite

// flush rules
add_filter('init','wpngfb_flush');
function wpngfb_flush() {
	global $wp_rewrite;
	$wp_rewrite->flush_rules();
}

// Add a new rule
add_filter('rewrite_rules_array','wpngfb_rules');
function wpngfb_rules($rules) {
	$newrules = array();
	$newrules['^(.*)/chp/([0-9]+)$'] = 'index.php?pagename=$matches[1]&chp=$matches[2]';
	return $newrules + $rules;
}

// Add the chp var so that WP recognizes it
add_filter('query_vars','wpngfb_var_insert');
function wpngfb_var_insert($vars) {
	array_push($vars, 'chp');
	return $vars;
}

This works some what, but it’s dropping the /chp/1 from the url completely and ignoring the var include