CHEMICAL RELATIONS OF THE OIL-FIELD WATERS IN 
SAN JOAQUIN TALLEY, CALIFORNIA. 
PRELIMINARY REPORT. 
By G. Sherburne Rogers. 
INTRODUCTION. 
CONCLUSIONS AND RECOMMENDATIONS. 
During the rapid rise of the petroleum industry in the last 50 years 
the geologic occurrence of petroleum has received a great amount of 
study, and the interesting problems involved in its origin and migra¬ 
tion have engaged the attention of many geologists. It has long 
been known that oil and gas are commonly associated with water, 
and the great importance of the water as a physical agent in the migra¬ 
tion of the oil has been recognized in all geologic theories of the 
accumulation of oil. Of the chemical relations between the water 
and the oil, however, we know little, and scientific literature con¬ 
tains only a few references even to the chemical character of the 
waters themselves. Apparently many of the current ideas on this 
subject either are erroneous or can be accepted only with important 
modifications. 
In the oil fields of San Joaquin Valley, Cal., the oil and water are 
found in practically unconsolidated rocks. At most localities several 
water-bearing sands are intercalated in the shales above the oil 
measures, and there is also a water sand a short distance beneath 
them. In some places a water sand occurs in the shale that sepa¬ 
rates the oil sands, and less commonly oil and water have been found 
in the same stratum. In sinking a well through this complex it is 
difficult to prevent the water, which in places is under high head, 
from entering the oil sand, in which event it may drive the oil some 
distance back and so ruin a considerable tract of land. The writer 
studied the physical and chemical relations of the water and oil in 
these fields during the summers of 1914 and 1915. The chief con¬ 
clusions concerning the chemistry of the waters, deduced by him 
from a study of several hundred analyses of water from different 
depths, are as follows: 
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