Subsurface Laboratory Methods 



341 



increasing pressure as being fundamental in compaction studies. There- 

 fore, density data may be applied to the estimation of porosity in shales 

 (fig. 146). 



Shale density adds another valuable tool to geologic investigation, 

 especially when used with other geologic data and interpreted from a 

 broad viewpoint. 



GRAPH FOR ESTIMATING WET DENSITY 

 AND POROSITY FROM DRY DENSITY DATA 



ASSUMING 



l.MAIN DENSrTY = 2.70 

 a. WET DENSITY REFERS TO A ROCK 



DRY DENSITY 



Figure 146. Density-porosity relationship. Wet density = dry density X .615 + 1.04. 

 This is a poor substitute for the method of obtaining wet densities at the well. 

 (After Skeels, Standard Oil Company of New Jersey.) 



Questions 



1. In what ways has micropaleontology aided the oil industry? 



2. What are Foraminifera, ostracodes, diatoms? 



3. The vertical distribution of microfossils and their relative abundance 

 at various stratigraphic positions may be graphically illustrated as 

 shown in figures 37 to 39. How are such charts prepared? 



4. What is meant by a "facies log"? 



5. May microfaunal assemblages differ along any given time surface? 

 What effect does this have on correlation problems? 



6. What morphological features are treated in describing ostracodes? 



7. What are calcareous algae, and in what type of environment do they 

 develop? 



8. What are conodonts, Radiolaria, and otoliths? 



9. Study the flow chart of a medium-sized micropaleontological labora- 

 tory given in figure 50, 



10 Should a micropaleontologist in evaluating a stratigraphic section be 



