THERMAL CONDUCTIVITIES OF ROCKS 287 



Determination of Geothermal Gradients in Oil Structures. 



By the American Petroleum Institute. 

 Oil and Gas Journal, November 14, 1929, pp. 105-106. 



This paper is a report of the research division of the American Petroleum 

 Institute on the progress toward determining geothermal gradients in oil- 

 fields. 



The report concerns the Oklahoma, Texas, Santa Fe, and Long Beach 

 fields. 



Oklahoma. — One of the most outstanding facts in connection with earth 

 temperatures in Oklahoma is the apparent agreement of the dip of the 

 isothermal surfaces and the formations. 



The reciprocal gradients vary widely from area to area, but show small 

 variations within the same area. The lowest gradient found was i° F. in 

 149 ft. (Healdton) ; the highest, i° F. in 36^ ft. (Glenn Pool). 



Data collected in two fields, Haverhill, Kansas, and Glenn Pool, Okla., 

 indicate that the temperatures are higher at corresponding depths in wells 

 located in the producing area than in wells located outside the producing 

 area. 



Texas. — Temperature measurements were obtained from wells in all 

 parts of the State. A complete report on the results of the work has been 

 submitted to the American Petroleum Institute. The relationship between 

 the normal rate of increase of temperature and the structure is especially 

 noteworthy in salt domes and in anticlinal structures carrying much under- 

 ground water. 



Temperature measurements obtained in salt domes were especially 

 interesting. The following results were obtained in the Humble Salt 

 Dome, Harris County : 



1 . At equal depths temperatures are higher on the top of the dome than 

 on the flanks. 



2. Rate of increase in the temperature with depth is relatively greater on 

 top of the dome than on the flank. 



3. The difference in temperature at the same depth and the greater 

 temperature gradient on top of the dome are found not only near the 

 s.alt, but also above the salt (at depths of 100 and 250 ft.). 



4. Drill holes on top of the salt domes have approximately the same 

 temperatures at equal depths. 



Santa Fe Springs field. — Fourteen wells were measured, bringing the 

 total number tested to thirty-three. The following conclusions were drawn 

 from the computed data : 



1. Depth temperature relations are irregular as compared with other 

 fields. 



2. Shallow temperatures vary within rather wide limits. Temperatures 

 at a depth of 100 ft. range from 65 -9 to 74-9° F. 



3. The elevations at which a temperature of ioo° F. occurs define an 

 irregular isothermal surface. 



4. Reciprocal gradients computed over the depth interval 100 to 2,000 ft., 

 vary from 47-5 to 56-6 ft. per degree. 



5. Reciprocal gradients recomputed over the same depth interval after 

 eliminating certain abnormal temperatures, show a less pronounced 

 irregularity. 



