shows the mobile rigs which would be required to drill this footage. Wells are assumed to be 10,000 feet and each well is assumed to take 45 days including travel, etc. t o d r i l l. In 1975 approximately 74 mobile rigs would be required and this would increase by about 9 to 10 rigs per year reaching a level of about 166 rigs by 1985. For comparison, the existing number of mobile rigs (domestic) are shown at the leftin the figure . The annual increase of 9 to 10 rigs per year represents about 20 to 25 percent of the present world rig building capability of 40 to 50 rigs per year. Figure 58 shows the number of 25 well fixed-platforms required again assuming 10,000-foot wells. S teel tonnages are also shown for 200,300, and 400-foot water depth structures. Although the water depth distributionis not known, itis reasonable that the tonnages would certainlyfall somewhere inthi srange, perhaps averaging near the 300-foot line. By 1985, the tonnage would increase to about 500,000 to 950,000 tons per year or a 3 to 6 fold increase over existing Gulf Coast capability of approximately 150,000 to 200,000 tons per year. This corresponds to an annual growth rate (over the next 12 years) of from 9.5 to 15 percent. Although no doubt additional facilities would come into play during this period (West Coast, East Coast, etc.), The rate of growth and the mobilization of additional facilities would require significant long range planning and a great amount of assurance to attract investment capital and trained manpower.two, examples above (mobile rigs and fixed platforms) represent but a fraction of the totaleffort required to support a perhaps rather nominal increase in present activity (NPC Case I ). There are literally hundreds of supporting industries who must be attuned to any escalating effort and who will also require firm assurance that a market for their goods and services will be available.
Summary
the early beginning of offshore drilling and production activities, the technology to provide the necessary safe and reliable systems has very adequately kept pace with our economic needs. Existing technology related to all aspects of these activities has reached a high level of competence through the inter - relatedefforts of research and development, engineering, and practical experience. The technological «muscle», capable of working is almost one-half of the nation's continental margins, now stands ready to be flexed to help provide vital domestic petroleum resources to meet our growing energy needs.
Acknowledgement
author acknowledges the many technical reports by those in the industry, the-academic community and the government who have made valuable contributions to the development of offshore technology and the many others who have supplied the equipment and services to support this new technology. The e f f o r t s of I. B. Boaz, C.A. S e l l a r s, and G. A. S terlingin preparing this paper are gratefully acknowledged, and the author thanks Shell O il Company for permission to make this presentation.
References
1. 1971, Future Petroleum Provinces of the United States - Their Geology and Potential: Memoir 15, Volumes I & 11, AAPG, Tulsa, Oklahoma.
. December 1972, U.S. Energy Outlook: Preprint National Petrole...
