VALUE OF PETROLEUM FOR MARITIME FUEL' 179 



gas under the propulsive force of their buoyancy in water, as well as the 

 migration of oil, either up- or down-dip, caused by hydraulic currents are 

 among the primary factors influencing both the accumulation and the recovery 

 of oil and gas. 



"The terms 'up-dip migration' and 'down-dip migration,' as used in this 

 paper, apply to migrations that are in accordance with the configuration of 

 the tops of the sands, regardless of actual structures. It must be remembered 

 that there are many subsurface conditions, such as the domelike tops of lenses, 

 irregularities in the tops of sands, and irregular textural barriers, which bear 

 no consistent relations to structure, but whose influence upon oil and gas ac- 

 cumulation are analogous to those of true anticlines and domes. The writer's 

 remarks apply to these conditions which he terms structural analogies. 



"In concluding this paper, the writer calls attention to the views recently 

 set forth in the literature,2 that the migration and accumulation of oil in 

 water-saturated strata are caused mainly by capillary forces ; that oil does 

 not migrate up the dip, due to the difference in specific gravity between oil 

 and water, and that oil is not propelled through sand by hydraulic currents. 

 It is further maintained that oil has been forced out of the fine bituminous 

 shales adjacent to the reservoir rocks by the capillary action of water, and 

 that no wide lateral movements of oil have subsequently taken place. 



■'The writer can not accept these views as generalizations. They may 

 appear to hold true under exceptional conditions, as in small-scale laboratory 

 experiments, where the conditions of experimentation are especially favorable 

 to the hypotheses, but they do not generally hold true, either in the laboratory 

 or in the field. Capillary adjustments between oil and water in saturated 

 strata are restricted within short lateral ranges, amounting to only a few 

 centimeters in the writer's experiments. The principal r61e of capillary, in 

 saturated strata, is to retard rather than to promote flui.d movements." 



This thorough and careful investigation and experimental proof of 

 the preponderance of gravity in oil and gas accumulation, as well as 

 the demonstration of the very small effect of the capillarity factor, 

 should dispose once for all of the claims that capillarity has played the 

 principal role in the movement of oil and gas into pools of commercial 

 value. 



Value of Petroleum for maritime Fuel 



It was during the present 20-year epoch that the maritime nations of 

 the world have realized the great value of liquid fuel, not only in the 

 arts of peace, but also in the arts of war. Some one has Avell said that 

 during the late World War "The navies of the allies floated to victory 

 on a sea of oil." The lessons of the war with respect to the use of 



2 A. W. McCoy : "Notes on principles of oil accumulations." .Tour, of Geology, vol. 27, 

 1919, pp. 2.52-262. 



W. F. .Tones : "The relation of oil pools to ancient shorelines." Economic Geology, 

 vol. 15, 1920, pp. 81-87. 



