are preferred. If gas is not of sufficient quality to justify pipeline, 

 it is put back into the structure to increase oil recovery or, if not 

 useful, flared. 



Investment Tradeoffs 



If the offshore oil reserves are large a pipeline will almost 

 assuredly be constructed. If the field is far offshore and remote from 

 other oil fields, a pipeline may not be possible and alternatives 2 to 5 

 (described above) will be given careful consideration. The economics of 

 using tankers for floating offshore storage tanks have improved enormously 

 during the past six years due to improvement in design and construction 

 of these offshore storage facilities. Alternative two is additionally 

 attractive if the oil stream arriving from offshore were to be split, 

 some being refined in the adjacent region and the rest being transported 

 elsewhere for refining. 



Unless an offshore gas field is large enough or near enough to 

 shore to justify a pipeline to shore and from there to consumption 

 centers, it will probably not be developed. Liquefaction of gas to 

 reduce its volume for transport is expensive, and probably prohibitively 

 so, when done offshore. Development of an offshore gas field becomes 

 slightly more feasible if a pipeline from offshore to an onshore lique- 

 faction plant can be justified, but the associated capital costs may 

 also preclude development. In the North Sea, every gas field which has 

 been developed is piping its gas, not to the nearest onshore location 

 for liquefaction and shipment, but considerably farther to demand centers 

 in England and Germany. 



The determination of the proper diameter for an offshore pipeline 

 involve economic tradeoffs between the cost of pipe, the feasibility 

 and cost of erecting interim booster pumping platforms offshore, and the 

 cost of operating pumping stations. A given pipeline can handle greater 

 volumes of oil or gas if more and larger horsepower pumping stations are 

 added along the pipeline route. 



Corridor selection is made so as to minimize the total cost and 

 logistical difficulties involves in constructing and operating an entire 

 oil transport system. Therefore, it is important that the selection of 

 a pipeline corridor be evaluated in the context of its full potential 

 impact on an area. 



The selection of a pipeline corridor is often considered simulta- 

 neously with the selection of a site for an oil transfer terminal and, 

 to a lesser extent, the onshore support base (including materials staging) 

 for the construction of the pipeline. Decisions as to the acceptability 

 of the corridor must be made on the basis of the whole range of impacts 

 and changes the corridor will induce during its construction and 

 operational lifespan. 



104 



