Crude oil is important and perhaps the sole source of income for the Libyan state, so we researchers have to pay attention to the oil installations to preserve and protect them from damage caused by corrosion. As reservoirs are the main part of any oil facility, and because of their importance, it necessary to search for a method to prevent corrosion, in reservoirs. In order to avoid the damage and losses that may occur as a result of the erosion of these reservoirs. Cathodic protection is an effective corrosion protection technique that uses the electrochemical properties for equipment protection. The protection is achieved via the cathode of the electrolytic cell whereby the other end is the anode of the cell. The purpose of this design study is to how reduce erosion of metal structures using cathodic protection. The study examined the design and calculation of all important points in the internal cathodic protection of the base of the reservoir using the method of AL-1-23H-Type Aluminum anodes. It has been revealed through the results of the design this method was designed to suitable requirements of the crude oil industry which was rapidly development in the recent period