WEST VIRGINIA GEOLOGICAL SURVEY. 1/5 



The wells range in depth from 1500 to 3000 feet, and drill- 

 ing is done entirely by the plunger type of bit. Salt water is 

 encountered often in the Salt Sands of the Pottsville Series 

 and frequently in other sands as low as the Fifty-foot of the 

 Upper Devonian, and in rare instances in some of the lower 

 sands, being much more abundant along the synclines than 

 along the anticlines. Three strings of casing are generally 

 used, 10-inch, &%-inch and 6^-inch, the latter being set in the 

 Big Lime, but sometimes a string of 5 3/16-inch is necessary 

 when water or caving shale is found below the Big Injun 

 Sand. 



The oil and gas fields of Lewis and Gilmer offer a fine 

 illustration of the general application of the structural theory 

 of gravity separation, as first definitely advanced by White. 1 

 Nearly all the oil pools of consequence in the lower, or non- 

 water-bearing sands, are found along the troughs of the syn- 

 clines or at the foot of steep structural terraces, while those in 

 the water-bearing sands are found farther up the structural 

 slopes above the water zone. The most important gas field ^ 

 are located either along the principal anticlines or in shallow 

 synclines that have a much higher general level than the struc- 

 ture shows farther west. The few exceptions to these general 

 occurrences are apparently accounted for by special conditions. 



The following classification of the various oil and gas 

 sands, taken from a previous Report of the Survey, 2 shows not 

 only the producing sands of Lewis and Gilmer, but also those 

 of other counties in the State, those known to be productive 

 in the two counties of this Report being printed in black type: 



'I. C. White, "Science," June 26, 1885, and Vol. HA), W. Va. G. S., 

 p. 48; 1904; and Vol. I, W. Va. G. S., pp. 159-187; 1899. 



"Ray V. Hennen, Monongalia-Marion-Taylor Rept., W. Va. G. S., p. 

 388; 1913. 



