PUENTE HILLS: YIELD AND GRAVITY OF OIL. 133 
oil bearing in some degree is recognized, that the Puente sandstone is 
also impregnated with bitumen is evident, but that the shale and the 
associated sandstone are everywhere impregnated to such an extent 
as to render them of economic value, under structural conditions that 
would be regarded as favorable, is improbable. 
PETROLEUM OF TIIE PUENTE HILLS DISTRICT.** 
YIELD AND GRAVITY OF OIL IN DIFFERENT FIELDS. 
The yield of the individual productive wells in the Puente Hills 
varies from 1 to over 1.000 barrels per day, those in the Puente 
field giving the lowest averages and those in the Brea Canyon held 
the highest. The wells of the Whittier field produce oil varying 
from 14° to 24° B., the yield of the individual wells running from 
2 or 3 barrels to nearly 175 barrels per day (in one well), although 
it is said that one or two wells went as high as 400 barrels at the 
start. The gravity of the Puente field oil runs from 28° to 34° B., 
but the average yield of the wells is lower than in any other part of 
the district, and none of the wells have gone much over 100 barrels 
per day, even in their prime. In contrast with the low production 
and high-grade oil of the Puente field is the high production and 
medium-gravity oil of the adjacent Brea Canyon field. The gravity 
here ranges from 18° to 26° B., while some of the wells yield as high 
as 1,000 barrels per day. Several flowing wells have been struck in 
this territory, one at least, it is said, gushing with a pressure of 
more than 250 pounds to the square inch. The Olinda field fur¬ 
nishes both high and low grade oil, the high grade, with a maxi¬ 
mum of 35° B., coming from wells in the northeastern part of the 
field yielding from 2 or 3 to 150 barrels per day, and the low grade, 
with a range of 18° to 20° B., coming from wells in the west end. 
Six “gushers” have been developed at Olinda, one of which is said 
to have flowed at the rate of 20,000 barrels per day for a short time. 
One of the flowing wells on the Santa Fe property is now (October, 
1905) flowing under a pressure of 100 pounds to the square inch. 
FACTORS IN YIELD OF WELLS. 
The factors governing the yield of oil wells, aside from the natural 
conditions—porosity of rock, pressure, etc.—are usually those con¬ 
nected with the manipulation of the wells, such as size of casing, 
loss of tools, caving in of casing, or accidents of one kind or another. 
Sometimes, however, the condition of the oil market has a most 
potent influence on the production by causing the partial or total 
shutting off of the wells; this has been the cause of a decline in the 
production of several groups in the Puente Hills district during 1905. 
a For a discussion of the physical and chemical properties of the oil of the Puente Hills, see pp. 
210-217. 
Bull. 309—07-10 
