Page 160 - Basic Well Log Analysis for Geologist
P. 160
LOG INTERPRETATION CASE STUDIES
CALIPER DIAM. IN INCHES POROSITY INDEX (%) LIME MATRIX
COMPENSATED FORMATION DENSITY POROSITY
20 10 °
GAMMA RAY api UNITS
125 COMPENSATED NEUTRON POROSITY
250
Figure 55. Combination Neutron-Density Log with Gamma Ray Log and caliper, Pennsylvanian Atoka Sandstone, Permian
basin. Values from this log are used in work Table A.
From a depth of 14,600 to 14,625 ft. note:
1. Strong gas effect. tracks #2 and #3 (i.e. density log reads much higher porosities than the neutron log) and
high porosity values on neutron-density logs in tracks #2 and #3.
2. Mudcake on caliper log in track #1 (dashed line). Mudcake is indicated because the hole diameter, as shown
on the caliper log, is getting smaller.
