284 REPORTS ON THE STATE OF SCIENCE, ETC. 



Determination of Geothermal Gradients. 

 By K. C. Heald. 

 The Oil and Gas Journal, December 5, 1929, pp. 90, 91, 191, 192. 



This paper is a report of progress made in determining the relationship 

 between variations in earth temperatures and oil-field structures. 



The research has been undertaken by the American Petroleum Institute 

 in order to determine whether or not chemical reactions between petroleum 

 and other substances really are the causes of abnormally high temperatures — 

 a theory which has been popular with many European students. 



Different types of structures have been considered, such as the gentle 

 folds of Oklahoma, the faulted monoclines of the Balcones fault zone of 

 Texas, the compressed and crumpled strata of the California fields, as well 

 as the extreme deformation that occurs around the salt domes of Texas and 

 Louisiana. 



The work, which has been in progress since 1927, has been centralised 

 in areas where results will be most significant to the petroleum industry. 



Oklahoma. 



Temperatures were measured in wells extending from about 18 miles 

 east of the town of Okemah to Oklahoma City. A temperature of ioo° F. 

 has been observed in a hole less than 1,500 ft. deep near Okemah and at a 

 depth of 4,100 ft. near Oklahoma. The author notes, although it may be 

 pure coincidence, that the rocks slope in the same direction as the ioo° 

 temperature line, at a rate only slightly more abrupt. Future work is 

 necessary to establish or disprove this relation. 



Local structure. — The work in Oklahoma offered an opportunity to learn 

 whether local structures — anticlines and synclines — in gently folded rocks 

 are reflected by the temperatures in those rocks or not. Heald is of the 

 opinion that van Orstrand's earlier work in Wyoming and particularly on 

 the Salt Creek anticline has been substantiated by McCutchin's work in 

 Oklahoma, leaving no doubt that in steeply tilted beds such a reflection 

 can be detected in many cases. 



Chemical action.— The work in Oklahoma has not yet progressed far 

 enough to justify any definite statements on the theory that temperatures 

 higher than normal will be found above oil-fields because of heat released 

 through chemical reactions involving oil. 



Water circulation. — The regional picture seems to support the conception 

 that waters deeply buried in a syncline would move up the dip and would 

 result in making the temperatures in the ' up-dip ' areas somewhat higher 

 at a given depth below the surface of the ground than are those in the 

 syncline whence the waters came. 



Effects of unconformities. — No particular study of unconformities has 

 been made in Oklahoma, but conditions there are suitable for determining 

 whether or not unconformities can be detected by temperature measure- 

 ments. 



Effect of strong faulting. — Whether the faulting activity may be detected 

 by temperature measurements cannot be determined by the Oklahoma 

 work, since conditions there are not particularly favourable. 



Texas. 



Stratigraphic conditions. — Measurements now available almost, if not 

 quite, justify the conclusion that the age of the sediments has nothing to do 

 with the temperature conditions. 



