REPORT OF THE DIRECTOR, 1922 7 
in character at the different depths, and to notice the direction and 
rate at which the flood is moving away from his water wells. 
Methods used in one pool where the sand is loose and deep may fail 
altogether in another pool where the sand is of a different character, 
especially where the sand is tight and shallow. The velocity of the 
flood depends to a large extent upon the porosity and especially the 
size of the grains of the sandstone. Both of these are likely to vary 
considerably from well to well, causing the flood to travel faster in 
some directions than in others. As a rule the velocity of the flood 
is greatest in the northeast-southwest direction. The cause of this 
is not clearly understood although it is believed that it is due to 
variations in the sand rather than to joints in the rock to which the 
ereater velocity in that direction is generally attributed. What rela- 
tion the actual structure of the oil sands bears to the velocity of the 
flood has not been definitely determined. — 
Cross flooding is a method used to obtain additional oil which is 
left in the sands after tne first flood has passed. It consists in 
changing the original flood wells to producing oil wells by reversing 
or changing the direction of the flood. The process consists in 
putting water pressure against the older flood which forces the oil 
toward the original well which is then again pumped. In this stage 
of flooding the pump is usually placed at a higher level than in the 
original well. Results from cross flooding are far from uniform. 
On some leases this method has produced excellent results, others 
are reported to have met with no success at all. Considerable study 
of reasons for the failures and successes of cross flooding should be 
carried on to determine the methods used where the best results have 
been obtained and to determine, if possible, the cause of the failures 
in cross flooding. It may be that the failures have been due to some 
extent to the structure of the sand rather than to the method used, 
but at least the reason for the failure to get results should be 
determined. | 
~ The control of the water in a flood well is of utmost importance. 
To obtain the best results the water must be applied directly to the 
sand which contains the oil and care must be exercised that the 
water does not escape through loose streaks of sand, above the oil 
sand proper, and pass to adjoining wells which are intended to 
receive the flood oil. These loose streaks of sand may be consider- 
ably above the oil-producing sand or directly above it and in either 
case these higher sands may contain natural gas. Sometimes loose 
streaks of sand are found within the oil-bearing sand through which 
