296 



Subsurface Geologic Methods 



No attempt has been made to discuss in detail all of the techniques 

 employed by the various research and commercial core-testing laboratories. 

 Analysis procedures vary for the formations being tested, the depth and 

 pressure of the reservoir, and the type of core sample. Formations usually 

 analyzed include sandstone and limestone. Chalk, serpentine, and con- 

 glomerate analyses require specialized techniques. The depth and pressure 

 of the reservoir are reflected in the residual saturation determinations. 

 Cores may be of the conventional and wire-line, full-diameter, core-barrel 

 type, or the smaller sidewall samples. 



Core analyses may be defined as the determination and evaluation of 

 the productive characteristics of a formation sample by the measurement 

 of porosity, permeability, and residual fluid saturations. Other tests in- 

 clude acidization, grain size, interstitial water content, and core-water 

 salinity. 



Core Sampling 



Any core-analysis report is only as reliable as the original sampling 

 and treatment of the core. 



Care should be taken to select representative samples, preferably one 

 sample from each foot of core recovery. If changes in the lithology occur, 

 additional samples should be taken. The core should never be washed 

 with water. Samples for analysis should be wiped clean of drilling fluid 

 and immediately sealed from the atmosphere to prevent fluid losses. 



CORE ENGINEERS 



Reservoir Core Analysts 



SAN ANTONIO. TEXAS 



6520.5 



21.5 

 22.5 

 23.5 

 2U.5 

 25.5 

 26.5 



27.5 



28.5 



29.5 

 30.5 

 31.5 

 32.5 



191 188 

 IW; 2^42 



278 

 U78 

 270 

 985 

 377 



18 

 336 



76 

 5 



830 loUo 



iceo 79 



856 96 



1060 872 



320 288 



186 2lt0 



22.5 

 2U.0 

 25.1 

 2U.2 

 25.U 

 21*. 

 2li.2 

 2U.3 

 21.3 

 23 .U 

 24.8 

 21+.2 

 26.U 



1.9 

 2.2 

 1.7 

 1.9 

 1.3 

 1.5 

 1.6 

 1.7 

 1.9 

 0.5 

 o.U 

 0.5 

 o.U 



U9.2 

 1*9.7 

 1+9.9 

 1+8.8 

 U9.3 

 U7.6 

 51.1+ 

 U3.lt 

 50.6 

 67.5 

 U7.i* 

 UU.5 

 U5.1 



5380 

 U610 

 3900 

 U350 

 Uooo 

 1+150 

 5000 

 U880 



1,880 

 9750 

 5070 

 6350 

 6230 



Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 

 Gas 



High water saturation 



r CORE ENSINE2R8. 



Figure 123. Tabulated core data and interpretation for well A. Although potential 

 had not been run, it was probable that some oil would be produced as a spray 

 with gas. 



