FLORIDA GEOLOGICAL SURVEY


5,292 psig (pounds per square inch gage). This also is essentially the
pressure existing in the Sunniland producing interval at the present time
in areas adjacent to the field but far enough removed from it that they
are not affected by its production. The difference between this original
bottom hole shut-in pressure and the present bottom hole shutin pressure
in the field (4,638 psig) is 654 psig. This pressure difference, which
is equivalent to the pressure exerted by a head of water 1,510 feet high,
provides the energy for the active water drive by which the field is pro-
duced. The Division of Geology has no information about the artificially
induced gradient along which this pressure as discussed above is distri-
buted.


 SALT-WATER ENCROACHMENT

 Levorsen states (1958, p. 452) that the velocity of salt-water
encroachment in a water drive pool varies within the range of 100 to
1,000 feet per year. It is hoped that the average rate of encroachment
in the Sunniland field is so low that pockets exist in which oil originally
in place has not been adversely affected by salt-water incursion.


 EXPLORATION

 In 1962 three exploratory wells were completed, and all three have
 been plugged and abandoned. Data onthese wells are given in appendix 1,
 and the wells are spotted on figure 1, a generalized location map.

 During 1962 an amount of '6,378 feet of exploratory footage was
 drilled in three wells, whereas in 1961, a footage of 87,737 feet was
 drilled in nine exploratory wells.

 A summary by counties of the highlights of exploratory drilling in
 1962 follows:


 GADSDEN COUNTY

 The Prince and Munroe, No. 1 La Corona well, located about l
 miles south-southwest of Quincy, was permitted with a proposed depth
 of 7,500 feet. However, the well proved to be 95 feet lower, on top of
 the Lower Tuscaloosa section of Upper Cretaceous Woodbine Age, than