Prospects for Offshore Petroleum Resources

EXTENDED ABSTRACT Extending the geographic scope of offshore exploration has traditionally been perceived as the frontier for offshore petroleum development. Correspondingly, the focus in assessing world offshore petroleum potential has been on assessing the potential of unexplored or lightly explored areas. This focus is highly understandable. The history of offshore development is one of pushing back the geographic frontier of exploration. Offshore development began with gradual steps seaward into shallow waters immediately offshore known onshore producing provinces such as the Mississippi Delta, the Maracaibo Basin, the Arabian/Persian Gulf, the Ventura Basin, the East Natuna Basin, and the Niger Delta. By the mid-1960's, the offshore industry had attained sufficient competence and confidence to tackle offshore basins with little or no corresponding onshore production such as Cabinda, Gippsland, Gulf of Suez and Southern North Sea basins during the late 1960's, Carnarvon, Northern North Sea, and Sverdrup basins in the 1970's, the Beaufort Sea, Campos Basin, Gulf of Campeche, and Northeast Newfoundland Shelf during the late 1970's, and the central and northern Norwegian coastal basins in the early 1980's. This continuing record of progress in the offshore industry over the past several decades now poses a major problem. The geographic frontier of offshore exploration has been pushed back so far that it will soon disappear. Practically every geologically attractive sub polar offshore province has now experienced exploratory drilling. In the process, many offshore basins are now known to have unfavorable geologic conditions and thereby lack major potential. By the end of this decade, nearly all of the Arctic offshore basins other than deepwater ones in continuous pack ice regions will also have been drilled. If the geographic frontier of exploration were the only frontier facing the offshore industry, the future would look bleak. Fortunately, it is not. Increasingly, the ultimate size of offshore petroleum resources will be determined by how successful the offshore industry is in pushing back other frontiers. Three interrelated frontiers the conceptual, the economic, and the technologicalare the critical frontiers facing the offshore industry during the next decades. The principal conceptual frontier requires a change of focus for offshore industry activity. Traditionally, the industry has thought that the best way to add new reserves is to and new fields. But, it has become increasingly apparent onshore that the most effective way to add reserves is to find and develop more reserves in old fields. Offshore, the use of close-grid seismic for field development and subsequent re-exploration offers opportunities for new pool discoveries and better drainage f known reservoirs by selective infill drilling and peripheral subsea completions. While the existing infrastructure is still in place, secondary and enhanced oil recovery potential offshore needs to be pursued vigorously as well.