254 



ALEX. W. McCOY 



such a great pressure to make the bulging that tubes of brass and softer 

 metals were tried. The results were substantially the same. Details of this 

 work will be described in some later paper.^ 



The experiment is referred to here in order to show how Hquid 

 hydrocarbons may be formed in the shales from the soHd bitumi- 

 nous material at ordinary temperatures and under pressures of 

 5,000 to 6,000 pounds, such as exist at the depth of oil-bearing 

 horizons; and that the only places where such compounds would 

 be forr^ied are in areas of differential movement. 



Before Compression Apter Compression 



Fig. I. — Longitudinal section through steel cylinder inclosing rock column 



After the oil is once formed in the shales, it is collected in the 

 porous zones by water. The action is one commonly called 

 "Capillary Concentration."^ Water, having a greater surface 

 tension and adhesion for shale particles than oil, moves into the 

 smaller openings of the shale, and the oil is thus forced into the 

 larger openings of the porous water horizons. Before this can 

 take place, the water sand or reservoir rock must come in direct 



^ Unpublished manuscript of E. A. Trager and the author. 



2 C. W. AVashburne, American Institute Mining Engineers, 1914, p. 830. 



