$user_id='CUSTOMER_USER_ID_HERE';
$customer_orders = get_posts( array(
'meta_key'    => '_customer_user',
'meta_value'  => $user_id,
'post_type'   => 'shop_order',
'post_status' => array_keys( wc_get_order_statuses() ),
'numberposts' => -1
));