As from the flexibilization of the petroleum monopoly, which took place in the second half of the 1990`s, the petroleum and gas sector in Brazil has undergone a series of changes which have directly impacted the commercial relations among the companies in the sector. There has been a continuous growth in the number of petroleum companies and suppliers of goods and services that have been setting up operations in the country. In this new petroleum sector context, the increase in operational efficiency and reduction of costs have become basic factors for the companies wishing to compete in this market, thereby, reinforcing the importance of logistics to the sector. The companies need precise and appropriate data on costs in order to be able to make strategic decisions and reach operational enhancements (Kaplan, 1998). This dissertation presents a study whose objective is to map, model and determine the costs involved in the processes for internal movement in a warehouse used as logistics support to offshore petroleum production. Based on the description of the internal movement processes for product storage, the main resources are identified. Then, a mathematical model based on Activity-Based Costing is drawn up, in which the results generated with this model comprise the values for internal movement costs for each type of product moved in the warehouse.