BULLETIN OF THE AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS 
VOL. 19, NO. 1 (SANGARY, 1935), PP. 25-36, 2 FIGS. 
PREDICTION OF OVERHANG AT BARBERS HILL, 
CHAMBERS COUNTY, TEXAS: A STUDY IN 
QUANTITATIVE CALCULATIONS FROM 
TORSION-BALANCE DATA! 
DONALD C. BARTON? 
Houston, Texas 
ABSTRACT 
A study of the possibility of prediction of the overhang at Barbers Hill was based 
on quantitative calculations from a diametral torsion-balance profile across the dome 
and the drilling data in regard to the top of the cap and salt. A series of three alternative 
positions of the flank of the salt on the left and four on the right were assumed. All 
combinations of the assumed left and right alternative positions of the edge of the 
salt were tested. Several variations of the assumed density relations were tested. Several 
variations of the regional gradient were tested. The gradient profiles which would be 
produced by the respective assumed forms of the dome were calculated by the writer’s 
graphical method. For the calculated gradient profiles which had the closer fit to the 
observed gradient profile, the mean-square difference between the calculated and ob- 
served profiles was used as the test of the relative closeness of fit. The form of the 
dome which had considerable overhang on the right and slight overhang on the left 
consistently had the least mean square. The conclusion therefore is that the overhang at 
Barbers Hill could be predicted in advance of drilling solely on the basis of torsion- 
balance data and of whatever data in regard to the cap and salt might be available from 
drilling. 
PURPOSE OF STUDY 
This study was made to see whether or not the presence of the 
overiuang at such a dome as Barbers Hill could be determined by cal- 
culation from the data of a torsion-balance survey, in advance of 
determination of the overhang by the drill. The study was based 
on the assumptions that the form of the top of the cap and the depth 
to the top of the salt table were known but that there were no drill- 
ing data available to show whether or not overhang actually was 
present. Calculations were then made from the results of the torsion- 
balance data to see whether or not the presence or absence of over- 
hang could be determined with good, fair, or poor probability of 
accuracy. 
1 Read before the Geophysics Division of the Association at the Dallas meeting, 
March 23, 1934. Manuscript received, November 12, 1934. Original data released 
through the favor of Sidney A. Judson and the permission of the Rio Bravo Oil Com- 
pany, Sun Oil Company, and Texas Gulf Producing Company. 
2 Humble Oil and Refining Company. 
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