WELL K 



Figure 7-8. Correlation of thermalogs. 



3. Similar variation in the high-temperature endothermic reactions (well 

 E at 1425-1485 feet, well F at 1830-1890 feet) . 



Another example of correlation is presented in Figure 7-8 on which similar 

 progression of calcite appearances (high-temperature endothermic peak) is 

 strikingly obvious. This alone, however, would not be sufficient for accurate 

 correlation. Additional markers, though less obvious to the untrained eye, are 

 required for substantiation. These included such points in wells J and K, re- 

 spectively, as the small mid-temperature exothermic peak at 2320 and 2580 feet, 

 the tendency for a mid-temperature exothermic plateau at 2360 and 2620 feet, 

 and the generally similar variations with depth of the large low-temperature (or- 

 ganic) hump. 



DTA vs OTHER No tool in the petroleum industry is 100 per- 



CORRELATIVE TOOLS cent successful in correlation work. This ap- 



plies to the DTA and other types of cuttings 

 analysis as well as to in-the-hole logging techniques. Whenever possible, all avail- 

 able sources of potentially correlative information should be used and properly 



132 



