The rapid build-up of the British National Oil Corporation (BNOC) since its establishment in 1975/76 and the pressing need to handle and assimilate the massive volume of geological, geophysical and related data to which it has access, afforded the opportunity of identifying natural priorities in the introduction of computer systems and files of digital data in support of hydrocarbon exploration (and development) offshore. Following the installation of a computer in the Exploration Department of BNOC in 1978, data files were quickly established and used. A two-phase plan for the introduction of data handling systems included, first, the setting-up of fundamental software for report generation and limited selective retrieval from individual files, in order to feed application programs and to enable immediate use of data as it was progressively compiled. Secondly, and following review of data and systems during this initial phase, a generalized DBMS was selected to enable the efficient integration and use of the broad range of data components involved in the conceptual exploration database. The nature of these data types, their structure and inter-relations is summarized in relation to applications, based on both conventional files and the formal data base, and the role of these data systems in the exploration process is indicated.