A sign having a surface area of not less than two (2) square feet and not more than six (6) square feet bearing the current name and number of the well and the name or insignia of the operator shall be displayed at all times from the commencement of drilling operations until the well is abandoned. In the event there are more than two (2) producing wells on one (1) leasehold, it shall be sufficient if the entrances to such leasehold are posted with a sign not less than eighteen (18) inches by twenty-four (24) inches bearing the name of the operator together with the name or designation of the lease, together with an openly visible sign on each producing well designating the particular number thereof.