COLLECTION OF ENVIRONMENTAL DATA BOREHOLE GEOPHYSICS APPLIED TO GROUND-WATER INVESTIGATIONS 109

11. To determine porosity from a gamma-gamma log, one must have a. Data for grain density. b. Calibration data for a similar lithology. c. Data for fluid density. d. Data for borehole-diameter corrections. 12. When compensated neutron and gamma-gamma logs are calibrated in limestone, a. The porosity for dolomite indicated on the neutron log will be less than that indicated on the gamma-gamma log. b. The two logs will indicate the same porosity for sandstone. c. The porosity for shale indicated on the neutron log will be less than that indi