96 
SANTA MARIA OIL DISTRICT, CALIFORNIA. 
The production of the wells ranges from 300 to something over 
2,000 barrels per day. Those wells which penetrate the lowest or C 
zone are the best producers. It is said that where a number of wells 
are located comparatively near together the production of each well is 
largely dependent on whether or not the adjacent wells are producing, 
a fluctuation of 50 per cent resulting from this cause in some instances. 
PINAL-FOX HOBBS AREA. 
LOCATION AND STRUCTURE. 
The area comprising the Fox lease, the southwestern part of the 
Hobbs lease, and the northeastern portion of the Pinal property, 
occupies the ridge and two adjacent canyons which extend north¬ 
ward from the central portion of Graciosa Ridge. The wells are 
located in an area of considerable structural disturbance caused by 
the development of two local anticlines on the northwestern flank of 
the main Mount Solomon anticline. These two minor flexures have 
been named after the companies under whose property they are best 
developed. Although the position assigned to them on the map is 
more or less hypothetical, the evidence in favor of it is fairly complete, 
and their location explains some of the variations in production of 
adjacent wells. 
GEOLOGY OF THE WELLS. 
Practically all the wells within this area start in the Monterey 
shale, and this is the prevailing formation to their bottoms. Certain 
portions of the shale are burnt to a brick-red color by the combustion 
of their hydrocarbon contents, the burnt shale being encountered as 
low as 330 feet in one of the wells. The burning has so hardened the 
shale in places as to render drilling in them more difficult. A hard 
limestone “ shell ” layer was encountered in one of the wells just above 
the second (B) oil zone. Tar or asphaltum occurs in some of the wells 
at a depth of about 600 feet, in others at various depths from 200 to 
1,200 feet. The tar is in many wells associated with black shale. 
Gas accumulations under “shell” and other impervious layers are of 
common occurrence both in the oil zones and locally in the barren 
overlying shale. Water is encountered in some of the wells at 
depths ranging from 150 to 270 feet. This occurrence is noteworthy, 
as the wells in the group to the east are, so far as known, quite free 
from water in the shale. Its occurrence in the Fernando sands and 
conglomerates is to be expected, but its presence in sands inter- 
bedded with the shale is unusual for this field. 
The first oil zone (A) is penetrated in the wells in this area at 
depths ranging from a little more than 1,600 to 2,650 feet, or between 
400 and 600 feet above zone B. (See PI. X, p. 92.) Petroliferous 
strata occur in some of the wells above this horizon, but they are of 
