Making Production database as Publisher and Distributor for Snasphot Replication
Since your database is 100GB, you can use backup and restore method with compression (make sure Instant file Initialization is enabled). 

Another approach will be to use logshipping with delaying the restoring of log files on the standby server and having the database in standby read mode ( WITH STANDBY).

The way you do is - 


take your regular log backups on your primary (in your case every 15 mins)
keep the copy job as is to copy log files to network share.
Choose the option to delay the restoring of logs as per your threshold.
To speed up restoring the logs - change the setting of logshipping to norecovery
once done restoring the logs, change it back to standby.


If you want to automate the entire process, use dbatools - Log Shipping functions/cmdlets