OCCURRENCE OF WATER IN OIL FIELDS. 19 
the propulsive effect of a body of compressed gas, but it is doubtless 
more widespread and causes some waters to flow that might not 
otherwise quite reach the surface. 
In the oil fields of the west side of the valley much of the water is 
under high initial head or pressure, but hi the main Kern River field 
on the east side of the valley the pressure is notably lower. Its pres¬ 
ent pressures are not comparable with those in the more recently 
developed fields of the west side, but even in the early period of its 
development fewer flowing waters were found. Most of the impor¬ 
tant factors influencing head or pressure have probably entered into 
this difference; the geologic structure in the Kern River field is more 
gentle, and the sands are thicker and more persistent, the under¬ 
ground circulation is freer, and the initial gas pressures were con¬ 
siderably lower. 
TEMPERATURE. 
The temperature of the oil-field waters generally increases with 
depth at about the rate that is normal in most regions, or possibly at 
a slightly higher rate. The temperature of the shallow waters is gen¬ 
erally between 80° and 90° F., and that of the waters near the oil 
sands between 95° and 110° F. The waters from depths of 3,000 to 
4,000 feet in several wells have a temperature of 120° to 130° F., 
though that from similar depths in other wells is cooler. The geo¬ 
thermic gradient is fairly regular, so that the source of the water is indi¬ 
cated in a general way by its temperature, and a sand receiving much 
surface drainage is generally abnormally cool. The temperatures of 
some of the waters discussed in this report are given in the tables of 
analyses on pages 63, 66, 70, 73, 74, 76, and 77. The cooling effect of 
expanding gas, as well as several minor factors, may injure the value 
of temperature measurements made at the mouth of a well, so that 
some variation would be expected, and in addition it seems certain 
that the waters undergo chemical changes, probably exothermic in 
character, which may locally disturb the normal gradient still more. 
Measurements of the geothermic gradient have been made in sev¬ 
eral localities in North America and Europe, and it is interesting to 
note that Koenigsberger and Miihlberg 1 after studying and correcting 
these measurements conclude that the gradient is abnormally high 
in oil fields, and that temperature measurements may therefore be 
used in prospecting for oil. Their conclusions have not been gen¬ 
erally accepted, owing to the facts that the data available are deemed 
inadequate and that there are apparent exceptions. Although the 
average of the gradients measured by Koenigsberger and Miihlberg 
in oil fields is slightly higher than that of gradients in other regions, 
• Koenigsberger, Joh., and Miihlberg, Max, On the measurements of the increase of temperature in bore 
holes: Inst. Min. Eng. (England) Trans., vol. 39, pp. 617-644,1910; also liber Messungen der geothermischen 
Tiefenstufe: Neues Jahrb., Beilage Band 31, pp. 107-157, 1911. 
