If you have made a custom post type (CPT) called portfolio and want to convert to Jetpack`s portfolio type, simply run the following SQL command
UPDATE `wp_posts` SET `post_type` = 'jetpack-portfolio' WHERE `wp_posts`.`post_type` = `portfolio`;
If you have made a custom post type (CPT) called portfolio and want to convert to Jetpack`s portfolio type, simply run the following SQL command
UPDATE `wp_posts` SET `post_type` = 'jetpack-portfolio' WHERE `wp_posts`.`post_type` = `portfolio`;