80 THE UNIVERSITY OF OKLAHOMA 



XXXVI. SUBSURFACE STUDIES 

 R. D. Reed 



From the Department of Ceology of the University of Oklahoma. 



The practice of using well records to supplement the informa- 

 tion that may be gained from surface studies is probably as old 

 as the science of geology. In a good many instances unfortunately 

 the work has been rather carelessly and uncritically done. In the 

 last few years, however, the phenomenal rise of subsurface work 

 in the oil fields of the Mid-Continent has directed attention as 

 never before to this source of information. "Subsurface geologists" 

 now have a place on the ordinary oil company geological staffs. 

 Courses in "subsurface geology" are given more or less adequately 

 in the colleges. So much attention to the subject has naturally 

 developed the technique of extracting information from well records. 

 At the same time, the average standard of well records is probably 

 higher than ever before. 



These facts, combined with the ever-increasing number of well 

 records available, make it probable that there is now on hand more 

 definite information in regard to the actual stratigraphic relations 

 of the. formations encountered in drilling in Kansas and Oklahoma 

 than about any area of similar size and structure in the world. 

 Whether or not this information will ever be made available to the 

 general geologist is doubtful. Some general studies of note, iind a 

 few detailed studies of small area have already been published. The 

 vast majority of the data is still gathering dust in the archives 

 of the oil companies and of the Geological Surveys. 



In the belief that these data have much value to the stratigraphy 

 and to the general geologist, this paper is submitted as a study of 

 weU records and their possibilities. 



The deficiencies of well records, as compared with well-made 

 columnar sections, are innumerable. Some of the records are hope- 

 lessly bad, — made, in some cases, for the purpose of misleading the 

 curious. Others fail to discriminate between such tolerably dissimi- 

 lar rocks as sandstone and limestone. In some of them, measure- 

 ments of depths and thicknesses, particularly of the non-petrolifer- 

 ous beds, are very inaccurately given. In the best of them there is 

 a lack of fine discrimination that is very annoying. The most dis- 

 similar types of sandstone are all lumped together as "sand.' The 

 more than two and seventy types of limestone are all "lime." Shales, 

 which as a matter of fact are commonly not examined at all by the 

 driller, are subdivided more commonly, but not much more usefully. 



In spite of these and other deficiencies, the most far-reachini; 

 rlccisions as to drilling, care of wells, and so forth, are habitually 



