MAGNETIC RESURVEY OF OKLAHOMA CITY FIELD 3 
There has been no material published, with one exception, on the 
measured change in the vertical component of the magnetic field in 
an area surveyed both before the discovery of production and after 
development had reached maturity. Barret! has published an interest- 
ing summary of such work in the Sligo field, Bossier Parish, Louisiana, 
which must be considered inconclusive because of the small number of 
control points. With the permission of the management of the Indian 
Territory Illuminating Oil Company, the results of two magnetic 
surveys in the vicinity of Oklahoma City are presented. 
In December, 1927, a magnetic survey of the vertical intensity 
anomaly was completed in the vicinity of Oklahoma City, with the 
use of a Schmidt vertical intensity variometer manufactured by the 
American Askania Corporation. The results of this survey contoured 
on a so-gamma interval are shown in Figure 1. The dominant feature 
is an area of negative relief centered around the west half of Sec. 12, 
T. 11 N., R. 3 W. Here a 110-gamma closure is the maximum ob- 
served. No attempt is made to interpret this feature with respect to 
the existence of Permian, Pennsylvanian, Ordovician, or pre-Cambrian 
structure. The structure was undoubtedly there and the magnetic 
picture appeared as shown. 
The discovery well of the present Oklahoma City field was spudded 
in near the center of the SE. 14 of the SE. 4 of Sec. 24, T. 11 N., 
R. 3 W., June 12, 1928, and was completed December 4, 1928. An in- 
tensive drilling campaign followed and by January 1, 1932, a total of 
867 wells had been completed, of which 5 had been abandoned. This 
represents, according to Charles,” a development of 80 per cent of all 
acreage which is thought to have possibilities of becoming produc- 
tive. The structural conditions of Oklahoma City have been de- 
scribed by Charles* and others. 
In mid-January, 1932, a resurvey of the vertical component of 
the earth’s magnetic field was made. The results are shown in Figure 
2, also contoured on a 50-gamma interval. 
There appears, at first glance, to be a marked discrepancy be- 
tween the work of 1927 and that of 1932. This becomes less noticeable 
1 William M. Barret, “(Magnetic Disturbance Caused by Buried Casing,” Bull. 
Amer. Assoc. Petrol. Geol., Vol. 15, No. 11 (November, 1931), pp. 1387-88. 
2H. H. Charles, verbal communication. 
3 H. H. Charles, “Oklahoma City Oil Field,” Bull. Amer. Assoc. Petrol. Geol., Vol. 
14, No. 12 (December, 1930), pp. 1515-33. 
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