PETROLEUM AT CONTROLLER HAY. 99 
oil is then confined between these forces and will escape under pressure 
rt the first opportunity. 
The most favorable conditions for the occurrence of petroleum over 
large and regular areas are the following: 
1 . A large and widely distributed original source of oil-yielding material. 
2. Thick, extensive, and regular porous beds in which the oil can move freely and 
accumulate. 
J 3. I mpervious beds above and below the porous beds. 
4. Small angles of dip and fairly regular structure. 
5. Absence of deep fracturing or of irregularities of structure. 
, G. Absence of water in the rocks if the oil-bearing beds are synclinal; or presence of a 
moderate amount of water if they are anticlinal. 
Such conditions are favorable to the occurrence of petroleum in 
; large, regular, and easily outlined pools, to moderately large produc- 
tion and long life of the wells, and to a large degree of certainty in oil 
I prospecting. 
These conditions probably nowhere exist in their entirety, at least 
not over any broad area. Some of the Mississippi Valley and Appa- 
lachian oil fields come nearer to satisfying these conditions than any 
others in North America. It is very evident that few of these condi- 
tions .re met in the Controller Bay region, and therefore nothing will 
J be gained from further comparison with regions in which simple 
structure predominates. 
Some of the California, Wyoming, and Colorado oil fields are charac- 
terized by complex and broken structure, in this respect being not 
I unlike the Controller Bay region. These western fields show that it 
lis possible for large accumulations of oil to exist in rocks with steep 
idips, irregular folds, and large faults. They show that the structure 
does not make it impossible for oil to exist in quantity in the region 
under discussion, but they show also the difficulties of drilling and of 
j locating the pools in such a field, and demonstrate very clearly the 
need of careful operating and the risks which are necessarily involved. 
OUTLOOK FOR PROFITABLE EXPLOITATION. 
PROBLEM OF LOCATING POOLS. 
If oil is found in quantity it will almost certainly be in circum- 
scribed areas, and the location and boundaries of these areas will be 
of the utmost importance in the development of the field. The posi- 
tion, size, and shape of these productive areas can not be foretold in 
advance of all drilling or at the present stage of development. The 
wells which have been drilled in this region are so few, most of them 
are so shallow, and so little oil has been obtained that they give almost 
no light on the occurrence of oil in the rocks. But if at least one area 
were outlined wholly or in part by the known position of productive 
