160 



GRAVITATIONAL METHODS 



[Chap. 7 



usually good parallelism of production and gravity anomaly, after correct- 

 ing the observed values for regional variation. 



Fig. 7-51a shows a gravity (pendulum) survey of one of the most im- 

 portant oil regions of the world — the Apsheron Peninsula and adjacent 

 portions of Azerbeijan near the Caspian Sea. The oil fields near Baku 

 (Bibi Eibat, Balachany, and Surachany) are situated in a gravity trough 

 extending along the peninsula with an anomaly from 100 to 130 milligals. 





Fig. 7-51a. Pendulum observations of relative gravity in East Azerbaijan (southeast 

 Caucasus) (after Schlumberger). 



Details of the anticlines on which these fields are situated are not visible. 

 The general trend of the strata from NW to SE is indicated by the steep 

 gradient portion in the SW part of this area. 



The gravity map of the Wichita and Arbuckle Mountain area shown 

 in Fig. 7-516 is discussed at this time, although the greater portion of 

 the gravity data was derived from torsion-balance observations. The 

 gravity anomalies are caused largely by the crystalline basement rocks, 



