the line and detect leaks. The primary leak detection system in use (required on all lines built after March 31, 1970 by 49 CFR Part

195.404 and 195.408) is a set of automatic pressure sensing recorders on both ends of each pipeline system. These recorders are equipped with a built in alarm system which either shuts down the flow automatically or sounds an alarm to alert personnel of an abnormal In this way, a leak of substantial rate is detected immediately. This system is insensitive to very small leaks which

pressure level.

do not produce a decrease in line pressure.

The second system of leak detection is the routine patrolling of the offshore and wetlands routes by boat or aircraft, and onshore by wheeled vehicle or aircraft. A minimum patrolling frequency of intervals between inspections not exceeding 2 weeks is required by 49 CFR Part 195.412, but in actual practice is performed more often. This type of monitoring would result in the detection of all sizes of leaks of course, but would be of little consequence in preventing the loss of a large amount of petroleum in the event a large line were severed. The appeal of a system of regular pipeline patrolling is that it allows detection of small leaks and therefore compliments the pressure-sensing system described above.

The third system for leak detection consists of a series of volumerecording flow meters on either end of a pipeline system.

Because

nearly all crude oil moves from OCS areas to shore by common carrier lines, it must be metered in the offshore pipeline gathering system and again at the onshore pipeline terminal in order that each producer is properly credited for his share of the common stream. This flow monitoring system has been designed so that the flow sensors continually indicate net input and output in real time so that attendant personnel are able to discover a decrease in output and alert appropriate stations of the possibility of a leak.

One more safety feature which would be built into all pipelines resulting from this proposal, according to industry spokesmen, is that remotely operated mainline block valves will be provided remotely controlled pipeline facilities in order to allow isolation of segments of the pipelines. 1/

b.

Anticipated Modes of Transportation for Oil and
Gas Recovered as a Result of This Sale

No transshipment of production by tankers or barges

is anticipated for this proposed sale.

The prediction of the number and routes of new pipelines is difficult because another OCS lease sale (OCS Sale No. 30) was also held in this area and development has just begun. The pipelines resulting

1/ American National Standard Liquid Petroleum Transportation Piping Systems ANSI B34.4-197 434.15, In press.

from previous sales can also serve to carry production reserves from this proposal. At the most, one new oil and one new gas

pipeline may be constructed.

Assuming that development follows the timetable set forth in the

following subsection (subsection 6.) production can be started approximately 2 1/2 years after the first discovery.

5. Termination of Offshore Oil and Gas Operations

According to industry estimates, with proper place

ment of wells and sufficient pipeline capacity, a gas reservoir could be profitably drained in as little as ten years. In contrast, some oil reservoirs have been producing for over twenty years in offshore areas. When the reservoir has been depleted to a level where it cannot be profitably produced, operations are terminated. During abandonment, the wells are plugged with cement, the casing severed at least 15 feet below the mudline, the platform is removed, and all obstructions are cleared from the area. All that remains is the pipeline system. Frequently, major trunklines can be used for future oil and gas production from adjacent areas, but smaller spur lines are abandoned in place. Pipeline abandonment consists of first purging the lines of entrained hydrocarbons by water flushing, and then severing the ends below the mudline.

Figure 45 shows the expected timetable and develop

ment sequence for a typical tract which would be leased at the proposed sale. This timetable, developed from a survey of industry representatives, is based on the information about the tracts under

consideration and industry experience in the Louisiana offshore

area.

The final platform design is completed and fabrication begins after a discovery is made, with installation during the second year of the operations on the lease. After the installation of the first platform, development drilling on the tract will begin. Development drilling in the area will begin, therefore, at the end of the second year after the sale and continue into the seventh year.

Platform

oil, gas and water treating facilities are installed after the wells are completed.

For this development scheme, it was assumed that pipelines would be installed with the first platform, which would allow production to be started approximately two and one-half years after the first discovery. It was also assumed that production would be separated and treated onshore. Under these assumptions production would begin during the third year after the sale and, after the completion of development drilling, level off at the maximum production rate during the eighth year.