100 ALASKAN MINERAL RESOURCES IN 1906. 
and nonproductive wells it would then be possible to determine the 
relation of the occurrence of the oil to the geology and from the known 
facts of the geology to outline other possible productive areas in 
advance of drilling. For this reason it is of the utmost importance 
to obtain complete and accurate records of all wells, and to use the 
information and experience thus gained in locating subsequent wells. 
DIFFICULTIES OF DRILLING. 
CROOKED HOLES. 
Much difficulty has been encountered in keeping the wells vertical, 
and delay and expense have resulted from the necessity of frequently 
reaming out the holes in order to straighten them. The crooked 
holes are the natural result of the steep inclination of the beds, with] 
frequent alternations from hard to soft rocks. Whenever the drill 
passes from a soft rock to a harder one dipping at a steep angle the | 
drill tends to be deflected and a crooked hole results. This difficulty 
will always be encountered in this region and will increase the time 
and cost of drilling. It will, however, become less as the knowledge 
of the local conditions becomes greater, for the tendency of the drill to I 
deflect can be lessened by drilling slower when the deflecting bed is J 
struck and by special shaping of the tool, and the holes can be straight- 
ened more quickly when the 1 drillers have had more experience in the 
region. 
CAVING. 
When a well in soft or fractured rock stands uncased too long, the 
rock caves in, often burying and frequently causing the loss of the 
tools, and sometimes it is necessary to abandon the well. Much delay 
has been caused in this way at most of the local wells and it has added 
greatly to the cost of drilling. It has been impossible on this account 
to drill several of the wells as deep as they would otherwise have, gone. 
The only remedy is to case the well at the proper time, and when the 
drillers know better the rocks with which they are dealing they will 
be able to anticipate the caving and introduce casing at the time 
when it is needed. Conditions may in this way be expected to 
improve in the future, and thus the cost will become less and the 
speed greater and it will be possible to sink wells to greater depths. 
WATER. 
The rocks of this region are full of water, and consequently large 
amounts are encountered in all the wells. This is undesirable for two 
reasons — the pressure of the column of water in the well keeps the oil 
back in the rocks and prevents it from coming out into the well, and 
the water reduces the effective weight of the drill and acts as a cushion 
