How to use mysqli in WordPress

I need to know how to use mysqli in WordPress. I don’t want to use wpdb or PDO any thing else. Actually the issue is there are 190+ quries written in mysql and i need to convert them to mysqli, i know the better solution is to go with wpdb. But it would be more time taking. So i just i need to know how to use mysqli in WordPress. I have googled it lot but every where every one is suggesting to use wpdb, but i want to stick with mysqli. So right now my code is e.g :

mysql_query("select * from wp_users);
if i write in mysqli it would be

mysqli_query($HOW_TO_GIVE_CONNECTION_HERE,"select * from wp_users);
Thanks!!