135 



One of the important factors in the expansion of off- 

 shore operations has been the development of marine 

 seismic techniques for locating structures favorable for 

 the occurrence of oil and gas. Although tlie numbei of 

 marine crews operating offshore is only about 15 per- 

 cent of the land crews, a marine crew can gather sub- 

 stantially more data than a land crew. 



TOTAL fkii WORID 



Fig. 6 — Seismic Surveys (Land and Marine) — Miles 

 Surveyed 



One measure of the amount of data being obtained is 

 the number of miles surveyed per year. As shown, the 

 marine crews are currendy sur\'eying more miles than 

 the land crews. The sudden spurt of marine activity in 

 the 1962-65 period was caused by the rapid expansion 

 of offshore leasing. During the past four years the total 

 data gathered per year has remained essentially con- 

 stant; however, the value of these data has been in- 

 creased substantially through new data processing 

 techniques. 



i'JMMiiitBasms^i;:^ifijii^m 



Fig. 7 — Marine Seismic Surveys (Domestic and For- 

 eign) — Crew {Months 



As you might expect, foreign marine seismic activity is 

 currently greater than the total domestic activity — by 

 a factor of 2 lo 1. This trend is expected to continue. 

 The number of offshore rigs operating throighout the 

 world has more than doubled during the past five years. 

 These mobile units are used primarily for exploration 



M06ILE I 



,-'* 



■58 '59 '60 '61 '6J '63 '64 '65 '66 '67 'b» 

 YEAR? •«"' 



Fig. 8 — Offshore Drilling Rigs (Platform and Mobile 

 Rigs) 



while the platform rigs are used to develop the reser- 

 voirs after they have been discovered. Some platforms 

 use two rigs to reduce the time required to place the 

 field on production. 



Fig. 9 — Offshore Drilling Rigs (Percent Domestic and 

 Foreign) 



The number of rigs operating ofTshore in foreign areas 

 has been increasing rapidly during the past few years. 

 It is anticipated that these lines will cross in five years 



or so as the overseas operations continue to expand. 



Fig. 10 — Offshore ripeiaymg trperience 



One important aspen of tl>e mov. ic deeper water has 

 been the installation of pipe lines to connect the pro- 



