1184 



EXPLORATION GEOPHYSICS 



Faults (continued) 



in spontaneous polarization method, 451, 452 

 in torsion balance survey, 286, 289, 290, 364 

 seismic mapping of, 738, 739 

 Ferromagnetic materials, 63, 64, 161, 167 

 Filters, seismic, 808, 822-825 

 Fluid -density determinations, 1130-1132 



average value of density, 1131 

 Fluid-level measurements: 



bottom-hole pressure determination, 1133, 1134 



casing-head pressure, effect on, 1136 



fluid density determination, 1130-1132 



for detection of collapsed casing and leaks, 



1141 

 for field development, 1139, 1140 

 for gas-lift installations, 1140 

 for pumping efficiency, 1138, 1139 

 for primary pressure control, 1140 

 for secondary recovery projects, 1140 

 history of, 1125-1127 

 in cementing operations, 1140, 1141 

 in water disposal and supply wells, 1141 

 low casing-head pressure, effect on, 1134, 1135 

 pressure-wave method {see Pressure-wave 



method), 1127-1129 

 pumping problems {see Pumping problems), 



1136-1139 

 Refiectogram equipment for, 1128 

 subsurface-pressure determinations, 1133, 1134 

 Fluid-pressure gradient, 1130-1132 

 Formation pressure determination, 1133, 1134 

 Fluorographic method, 953 

 Fluorologging, 961 

 Force, law of magnetic, 67 

 Franklinite, susceptibility of, 161, 164 

 Frequency analysis, seismic waves, 829-835 

 Frequency pattern correlation, 835, 836 



Galvanometer: 



Einthoven (string) type, 814, 815 



D'Arsonval (moving coil) type, 814, 815 



in electrical surveys, 445 



in seismic surveys, 814-815 



in well logging, 1048, 1049, 1071, 1072 



Sine, 94 

 Gamma counters, 997, 1002 

 Gamma counting, 1014 

 Gamma-ray curve, 1102, 1104 

 Gamma-ray logging, 1009 

 Gamma-ray logging instrument, 1097 

 Gas analysis, 940-942 



results of surveys, 941, 942 



sampling and analysis, 940, 941 



theoretical interpretation of anomalies, 942 

 Gas-lift installations, 1140 

 Gas casing-head pressure, 1131, 1132, 1133 

 Gauss (magnetic unit), 71, 72 

 Gauss meter, 159 

 Gauss positions, 83-87 

 Geiger counters: 



amplifiers for, 999, 1000, 1001 



laboratory, 1004 



Geiger counters (continued) 



portable, 999 



requirements, 1000 

 Geiger-Miiller counter, 997-1000 

 Geochemical {see Chemical) 

 Geodesy, 259 



Geodynamic (emanometric) method, 942 

 Geological correlations (seismic), 705 

 Geomagnetic {see Magnetic) 

 Geophone, 779, 794, 795, 796 



in offshore operations, 898 

 Geophysics, major problems of, 3 

 Geothermal {see Thermal) 

 Geovision, 828, 829 

 G-M tube, 997, 998, 999, 1000, 1003 

 Gneiss: 



density of, 264 



magnetic susceptibility of, 165, 166 



resistivity of, 441 

 Gradient sonde, 1025 

 Gradiometer, 341, 342, 343 

 Gradiometer, magnetic, 100 

 Graf-Askania gravity meter, 285, 286 



Granite: 



density of, 264 



magnetic susceptibility of, 165, 166 



resistivity of, 441 



velocity of, 660 

 Graphical analogue computer, 747, 748 

 Gravimeter parties, 8 



geological distribution of, 9 

 Gravimeters, 367-434 



Astatic hydraulic, 380 



Boliden, 378, 379 



calibration of, 389, 390 



classification of, 371, 372 



comparison with torsion balance, 368, 369 



corrections applied to measurements, 402-424 



diving bell, 387, 388, 389 



electric gauge type, 383 



field procedure, 398-401 



Gulf underwater, 386, 387 



Haalck, 379 



Hartley, 372, 373 



Hoyt, 374, 375, 376 



Mott-Smith, 380, 381, 382 



orientation and adjustment, 391 



portable, 382, 383 



sample field notes, 411-415 



station elevations and surveying {see Terres- 

 trial photogrammetric mapping), 392 



surveys, 426-434 



temperature effects, 390 



Thyssen, 376, 377 



Truman, 373, 374 



Wright, 378 



"Zero Length" spring, 377 

 Gravitational: 



constant, 250-252 



potential, 258, 294-298 



prospecting, 259 

 Gravitational separation of oil from fluid, 1130 



