ELECTRIC LOG 



THERMAL LOG 



MUD LOG 

 Oil 



CALIPER LOG 



RADIOACTIVITY LOG 



Short spacing 16 Medium 63 Long 24 

 Self-Potential mvs. Impedance ohms m'm. Degrees F. Drilling rate Total gas 



ion 10 160° 165° 170° 175° (feet per hour) Methane - 



6,300 



Inches Radioactivity increases — *• 



» Gamma ray Neutron 



CORE ANALYSIS 



Permeability 

 (in millidarcys) 

 % of porosity Prl. to b.p. 



30 20 10 500 1,000 1 500 



J y-i- 



SAMPLE LOG 



Fig. 1. Methods of 



logging subsurface strata. An illustration of seven fundamental ways in *° ^"surface strata can be logged, either in a borehole or from rock materials brought to the surface. 

 Direct comparisons can be made of these logs as they are all i' cl '° the same well. (Courtesy of Humble Oil & Refining Company.) 



