86 THE UNIVERSITY OF OKLAHOMA 



Surface Geology and Structure 



The surface rocks of the Robberson field are of Permian age, 

 consisting of buff shales and mottled gray and red sandstones, 

 grading towards conglomerates. In places these conglomerates are 

 arkosic. Much float, quartzitic material is present. These forma- 

 tions in a general vi^ay, can be traced to the Duncan field and form 

 the surface rock there. 



The nature of the surface rock is such that structural work 

 is accomplished with great difficulty. However, geologists have 

 been in the area since 1917 and more or less satisfactory results 

 have been obtained. The major structural features in the produc- 

 ing field are a dome in sec. 16 and an anticline in sees. 24 and 13 

 and extending northward. Gas is found in the w^est structure and 

 oil low on the flank of the cast structure; its apex is being tested 

 at the present time. 



Character of the Producing Sands 



Production is being obtained from various depths indicating 

 numerous lenticular reservoirs. Two fairly constant producing oil 

 horizons and a, gas sand can be traced. All are of the Permian age. 

 These sands are found at 1,120 feet, 1,240 feet and 1,400 feet. The 

 character of the producing sands varies erratically from fine sand- 

 stones to loose coarse sands containing arkose material as large as 

 peas. This is the first production known to come from arkose in 

 Oklahoma. 



Probably Undeveloped Territory 



The present limits of the field are not definitely set on the' 

 west nor the east and it is probable that extension will be made 

 in both directions. Sees. 13, 24, and perhaps 11 and 12 should prove 

 productive. Additional pools may be opened in sec. 8, T. IN., R. 

 2W., and sec. 24, T. 2N., R. 3W., where separate structures have 

 been mapped. 



XXXVIII. THE PERCENTAGE OF SQUARE MILE 



PRODUCTION IN OKLAHOMA 



Bess U. Mills 



From the Oklahoma Geological Survey. 



The paper constitutes a statistical guide to the quantity of oil 

 recovered from the areas making up the oil producing territory 

 of the state, and shows the relation of the number of square miles 

 in the possible producing territory to the number of square miles 

 actually having production. 



At present there are 4038 sections which are productive of oil 

 or gas or both ; 2227 sections are dry, abandoned or shut down 



