2 8o REPORTS ON THE STATE OF SCIENCE, ETC. 



surface of the earth and the depth of i m. ; (2) the yearly course of 

 the temperature down to 12 m. of depth ; (3) temperature variations 

 at greater depths. 



In his resume the author says : 



' In representing the diurnal course of the temperature in the upper 

 strata of an almost homogeneous sandy soil it is proved that the distribution 

 of the heat is not as uniform as could be expected. In connection with this 

 the author points out that the vertical temperature gradient in the soil 

 shows several changes during the greatest part of the year ; these changes 

 must probably be attributed partly to the distribution of the underground 

 waters and partly to the after-effects of greater air anomalies occurring in 

 the deep strata.' 



Determination of Geothermal Gradients in Oklahoma. 

 By John A. McCutchin. 



Bulletin of the American Association of Petroleum Geologists, vol. 14, no. 5, 



1930, pp. 535-555- 



This paper deals with the data of geothermal gradients collected from 

 temperature surveys carried on since June 1928, in approximately 150 wells 

 located in twenty-four separated fields in Oklahoma and Kansas. The 

 purpose of this investigation is to determine the possibility of using the 

 temperature data for the location of oil pools. 



Description of methods and apparatus. — The van Orstrand method has 

 been closely followed in the collection of data. A brief description of the 

 method is given. 



Wells suitable for temperature tests. — As a rule, the wells that have been 

 drilled with rotary tools are the most unsatisfactory wells in which to make 

 temperature observations because the circulation of the rotary mud in the 

 wells so disturbs the temperature distribution in the formations surrounding 

 the hole that the hole must remain idle for a considerable time (about 30 days) 

 before reliable temperature data can be obtained. 



Temperature tests can be made in wells drilled with standard tools at 

 any time the tools are out of the well. Temperature observations should not 

 be made near the bottom of drilling wells as the action of the drill may 

 produce an abnormally high temperature at this point. 



Depth-temperature curves. — An example of a depth-temperature curve 

 taken from a deep well in the Tonkawa field is shown. Depth-temperature 

 curves representing wells in temperature equilibrium may, for all practical 

 purposes, be considered as straight lines. However, when a close examina- 

 tion is made the curves are seen to be slightly curved at the shallower depths, 

 the curvature increasing with increasing depth. 



Shallow temperatures. — The most important temperature data in a well 

 are to be obtained from the first 1,000 feet. As the shallow temperatures 

 act as a guide to the reliability of the data from the entire well, they should 

 be given careful consideration by those endeavouring to correlate temperature 

 data from well to well or area to area. 



Explanation of cross sections. — Variation in depth to the 8o°, 90° and ioo° F. 

 isothermal surfaces for several places are shown in two figures. The gradient 

 ranges from i c in 107-0 ft. for the wells located near Oklahoma City to i° 

 in 36 ■ 5 and 40-0 ft. for the wells located near Tulsa and Okemah. Several 

 possibilities as to the reason for this difference are suggested. 



An explanation of the table showing the variations in the gradient com- 



