146 
KIRTLEY F. MATHER AND MAURICE G. MEHL 
drainage area. In our illustration, for example, the Wheeler 
dome near the center of 24-8 has about the same area within 
the lowest closed contouf line as has the northeastern bump on 
the Wooster anticline in 27-25-9; the latter has 50 feet of clo- 
sure, the former only 30, and hence the latter would be considered 
by many as a more valuable structure; but the oversheet draws 
attention to the fact that the drainage area contributory to the 
Whoeler dome is more than twice that which may have fed this 
portion of the Wooster anticline, and hence, other things being 
equal, the Wheeler dome should contain more than twice as 
much oil. 
Outlining the possible gathering ground for each anticlinal 
fold, as on the accompanying plate, serves also to depict clearly 
certain of the peculiarities of distribution of producing wells in 
the Osage Reservation. In general, it is noted that the folds 
are so closely crowded that the drainage areas are all very small. 
In certain parts of the Reservation good production is obtained 
from pools so situated that none of the oil which they contain 
could have come from a greater distance than miles. On 
the average, oil beneath Osage County has probably migrated 
only 2 or 3 miles from its point of entrance into the reservoir 
stratum to its resting place in an oil pool. Few accumulations 
are so situated as to have drawn oil or gas from points more 
remote than 4 miles. 
Again, the asymetrical situation of the effective trap, almost 
invariably much nearer the eastern than the western margin of 
the drainage area, is forcibly presented. Experience indicates 
that production extends much farther down the longer flanks of 
the anticlinal folds than the shorter. Where the east flank is 
less than a mile long, little oil is found east of the crest of the 
fold; the area from which that portion of the anticline may have 
been supplied was insufficient to permit a commercial accumu- 
lation. In general, the amount of production from the various 
parts of an anticlinal fold seems to depend largely upon the 
length of the slope from the margin of the drainage area. 
