Design of a structure does not seem, however, to be the only determinant of their safety. The Ocean Ranger, largest oil rig in the world and considered by some unsinkable, capsized during a storm on February 15, 1982, while operating offshore Canada. Designed to withstand winds up to 100 kt and waves of approximately 100 ft in height, The Ocean Ranger, went down in conditions well within its design capabilities: 90 kt winds and waves approximately 50 ft high. It was reported (Wall Street Journal, May 4, 1982) that, in addition to design faults, a broken porthole in the vessel during the storm combined with unpracticed evacuation procedures doomed the rig and its 83 crewmembers.

Wave heights and directions reflect the wind pattern over the area. Wave height is important in terms of oil spill cleanup and containment. It is generally recognized that the present upper limit of oil spill cleanup technology is in wave heights of approximately 6 ft. Thus, the percent frequency of specific wave heights is of particular concern. The area is subject to waves greater than 5 ft between 30 and 40 percent of the time during winter, with waves greater than 12 ft about 5 percent of the time, and greater than 20 ft about 2 percent. The median significant wave height during winter is 4 ft. At other times of the year, the sea normally is less rough, with waves greater than 5 ft occurring about 10 percent of the time and those greater than 12 ft about 2 percent of the time. The proposed sale area is not an area of noticeably high waves. However, these relatively low average wave heights do not preclude the possibility of occurrence of exceptionally high ones. Predictions indicate that once every 2 years a wave of 44 ft (13 m) may occur. Additionally, once every 100 years a wave of 103 ft (31 m) is anticipated. Figure IV.A.3-2 compares the maximum wave height and significant wave height in the mid-Atlantic, Alaska, and the North Sea, where petroleum operations have been conducted successfully since the 1960s (Tetra Tech, 1974). According to Tetra Tech (1974), if structures for the proposed sale area are designed to withstand the 100-year storm with a safety factor of 2.0, and presuming that field development will require 30 years, there is a 0.93 chance that they will survive without collapse. If designed to withstand the 200-year storm, again with safety factor of 2.0, the probability increases to 0.97. In the lease area, the highest waves are observed during the winter months. During January, wave heights equal to or greater than 6 ft occur approximately 35 percent of the time, and waves greater than 20 ft approximately 2.5 percent of the time. At other times of the year the sea is normally less rough except in case of extreme events accompanied by exceptionally high winds.

Using the assumption that the percent distribution of wave heights for January is representative of the winter season, and taking into consideration the reported limits of cleanup and containment equipment presently used offshore, estimates of cleanup capabilities during the winter season can be made. When the sea state is 6 ft or greater--35 percent of the time--attempts to clean up an oil spill will be of limited effect or impossible. The remaining 65 percent of the time--when significant wave height is 6 ft or less--the sea state is within the operational range of present equipment and effective cleanup is possible. Under the influence of wind, floating oil tends to slide over the ocean surface (EG&G, 1982). The direction of the movement is to the right of the wind direction through a varying angle between 0° and approximately 40°, depending on the wind speed. The prevalent winds in the region are out of the west during the winter, and from of the southwest in the summer. Thus, it seems that spills are likely to move out to sea under the influence of winds.

Although spilled oil generally remains at the surface, breaking waves can drive it into the water column. According to Naess (1980), the mixing depth of oil is highly dependent on the turbulent layer created by the breaking waves. In turn, wave breaking generally is dependent on water depth, wave length, and also on the wind. Thus, entrainment of oil is more likely to occur in winter and in those parts of the proposed lease area that are relatively shallow (less than 60-m in depth).

The effects of Gulf Stream eddies cannot be readily assessed. It seems certain that passage of these energetic phenomena will result in flushing and mixing of pollutants into greater volumes of water, reducing the substance's concentration. Also, it seems that depending on location relative to the eddy, such substances could be brought onto the shelf, or be redeposited in places where other mechanisms would determine their eventual fate. Regardless of the prevailing environmental conditions, a well blowout would inject oil into the water column.

Winter temperatures and wind chill factors, are not as severe as those encountered in the Alaska and North Sea operating areas and should pose little or no problem to the operation of equipment. Furthermore, OCS Order No. 2 (Federal Register, December 21, 1979) requires from the lessees evidence that drilling equipment, drilling safety systems, and other associated equipment and materials are suitable for operations in areas subject to subfreezing conditions. In general, it is required that the drill floor, the working area above it, pump rooms, mud room and pits, shaker room, moon pool area, and welding room be enclosed or heated.

Reduced visibility in the area could cause an increase in collisions between vessels (fishing and others) and offshore structures, and it could also limit the use of helicopters and delay supply boats, but should not interfere with day-to-day drilling or production activities.

Conclusion: The oceanographic and meteorological conditions that may be encountered by operators as a result of the proposed action should not present any hazards or difficulties that would be considered significantly greater than those encountered in existing operating areas.

Water depths greater than 3,000 m are found within the deeper portions of the proposed lease area. Semisubmersibles and drillships equipped with modern, computer-assisted positioning systems are presently capable of exploration in water depths as great as 2,400 m (8,000 ft). One semisubmersible rated to 10,000 ft water-depth is now under construction. Further refinement of drilling systems appears likely to extend the range of exploratory drilling to depths as great as 3,660 m (12,000 ft) in the near future (Steven, 1983). Recently, MMS approved exploratory drilling in water depths as great as 7,000 ft. The technology used to conduct these operations were made possible through the refurbishment of an existing drillship. Major modifications were made to dynamic positioning, riser tensioning, and various structural components to accommodate the increased weights. Additions included two 7,500 ft neutrally bouyant riser systems, a measurement-while-drilling tool, acoustic back-up control for blowout preventers, and two remotely operated vehicles for use in subsea repairs and maintenance. These and other capabilities provided the feasibility of safety

drilling in over a mile of water. Production technology typically lags behind exploration technology since an exploration discovery is needed to provide the development impetus. Conventional platform technology for production has been demonstrated in 1,025 ft of water by Shell's Cognac platform. Design of a conventional fixed platform for placement in 1,350 ft of water has been completed by a major offshore engineering firm. Studies to establish that the fixed platform concept is a feasible and economically viable solution to the development of offshore sites in 1,600 ft of water have also been completed. Prototype advanced production systems, including the guyed tower, tension leg platform, and remote trees are either being constructed or have recently been placed in water depths less than 1,000 ft to test concepts which may be applicable to much greater depths. Current pipe laying technology allows for placement of pipe in water depths as great as 6,000 ft. Research in vertical pipeline welding, combined with dynamic positioning of lay barges is likely to extend that depth considerably in the near future.

Much of the technology and equipment in place or projected for deepwater operations is discussed in a technical paper prepared in 1982 by MMS. Although advances in technology have occurred during the last few years, this paper is still helpful in describing the foundation on which these advances have been built. This report, which is incorporated herein by reference under 40 CFR 1500.4(j) and 1502.21, is available upon request from MMS and the complete_citation is as follows:

Drucker, B.S., 1982. Deepwater Technology: Exploration Production
and Blowout Prevention: MMS Technical Paper, 82-01; 30 pp.

Mitigating Measures and Regulations Regarding Deepwater
Operations

MMS regulation 30 CFR 250.10 requires the use of the best available and safest technologies economically feasible. OCS Order No. 2 further defines this concept for drilling and spells out specific procedures and equipment that shall be used for operations. As activities advance into deeper water, the MMS reviews new and unique technologies for safety and ensures that environmental consequences are minimized. Special conditions of approval for permits to drill can be enforced if unprecedented procedures or equipment are being used.

Well control is particularly sensitive in deepwater and is carefully scrutinized by the MMS. In deepwater, underground sediments are weaker than in shallow water or on land. This is because sea water is less dense than solid rock and there is correspondingly less weight on top of the drilled formations. Revised casing designs, precautionary drilling techniques, and special blowout prevention equipment can be used to compensate for these conditions and prevent hazardous situations. To further our understanding of these new concepts, the MMS is funding research in deepwater well control at Louisiana State University in Baton Rouge. The findings will then be used to regulate deepwater drilling even more safely and efficiently.

The MMS regulations require that all new fixed or bottom-founded oil and gas platforms to be installed on the OCS of the United States, or major modifications or repairs to existing oil and gas platforms, be subjected to a comprehensive verification process to ensure their structural integrity. In addition, it is required that existing oil and gas platforms be adequately maintained.

OCS Order No. 8 requires, within the context of the OCS Platform Verification Program (PVP), that all new OCS structures be evaluated in terms of their structural integrity. The PVP is designed primarily to evaluate new and unique technologies for the production of petroleum. Thus, guyed towers, tension leg platforms, and subsea completion systems proposed for installation within the proposed lease sale area will be carefully reviewed and evaluated prior to any actual emplacement.

The Platform Verification Program is designed to provide assurance of the structural integrity of offshore oil and gas production system. This means ensuring the survivability of offshore platforms so that structural failure will not be the cause of pollution, waste of natural resources, or injury or loss of life. This will be accomplished by ensuring that reasonable precautions have been taken by the lessee in the consideration of pertinent local and regional environmental, geological, geophysical, and bathymetric conditions, design procedures, fabrication procedures, and installation procedures. The Platform Verification Program is also intended to identify and assess the risks of a proposed development so that attention is focused on critical areas; be flexible enough to accommodate a variety of installations and OCS regions; have clear, attainable, and enforceable requirements; and require the use of proven technology without inhibiting innovation.

The Platform Verification Program is an integral part of the review and approval process for Plans of Development/Production in addition to addressing platform design, fabrication, and installation. The main elements of the Program are:

* the Platform Verification Staff (the technical in-house staff); and
* the Certified Verification Agents (independent third-party experts).

Independent third-party experts who are evaluated and certified by MMS, and who are selected from an approved list and hired by the lessee, will be utilized in the verification process. Such experts are evaluated and certified on the basis of technical competence and demonstrated experience in offshore engineering. The technologies involved in implementing the Program entail representation from such diverse disciplines as structural engineering, soil mechanics, geology, geophysics, oceanography, meteorology, hydrodynamics, quality assurance, statistics, and computer science.

The Certified Verification Agents (CVAS, independent third-party experts), will primarily be involved with the detailed structural aspects of platform design, fabrication, and installation. The MMS Platform Verification Staff will be responsible for the overall management of the Program, certification of CVAS, providing technical reviews and recommendations on lessee's applications (including Verification Plans), auditing CVA activities, performing limited in-house design, fabrication, installation, and structural inspection audits, resolving disagreements between CVAS and industry representatives, assisting in the investigation of accidents involving the structural integrity of platforms, and updating and revising the Program requirements.

In summary, all proposed deepwater production equipment will be examined within the context of the OCS Platform Verification Program. This Program, along with the safety devices required under various Operating Orders, should be effective in preventing damage to the environment or loss of human life during installation and operation of pioneer deepwater technologies.