336 



Subsurface Geologic Methods 



MOTATAN NO 1 (VENEZUELA) 



4000 5000 



DEPTH IN FEET 



Figure 139. Average shale densities in Motatan No. 1, Maracaibo Basin, Venezuela. 

 Note density decrease at unconformity indicating that Eocene shales had at- 

 tained present density before uplift and erosion. It is estimated that about 4,000 

 feet of sediments were removed by erosion and that subsequent burial under 

 8,100 feet of Miocene sediments had not been sufficient to renew the compactior 

 process. (After Refshauge and Skeels.) 



DRY DENSITY - DEPTH CURVE 

 OF THE EOCENE SHALE IN THE MARACAIBO BASIN 



PEPARED BY B C SEFSHAUGE 



3000 4000 



I20}0 13000 



Figure 140. Dry densities versus estimated depth of burial in two Eocene wells in 

 Maracaibo Basin, Venezuela. Over 500 samples are represented by these curves. 

 This interpretation conforms to the generalized regional geological data. (After 

 Refshauge and Skeels.) 



