. Early geophysical papers of the Society of Exploration Geophysicists. Petroleum; Prospecting. ADVANCES IN OIL PROSPECTING in a. general: power sources As a source of power, one Radio B battery, or two, may be suffi- cient, depending on the length of the current basis, of course. If very great depth penetration is required, a generator is used, driven by a gasoline engine. When using a Megger, a hand-driven generator is used, which is incorporated in the meter box. Due to the fact that polarization must be eliminated, if non-polarized electrodes are not used, a commutator is provide
. Early geophysical papers of the Society of Exploration Geophysicists. Petroleum; Prospecting. ADVANCES IN OIL PROSPECTING in a. general: power sources As a source of power, one Radio B battery, or two, may be suffi- cient, depending on the length of the current basis, of course. If very great depth penetration is required, a generator is used, driven by a gasoline engine. When using a Megger, a hand-driven generator is used, which is incorporated in the meter box. Due to the fact that polarization must be eliminated, if non-polarized electrodes are not used, a commutator is provided in the measuring circuit, which brings it about that in reality the current used is not strictly. Potentiometer Mi///'ammeter Electrodes making contact with Earthy C,fe/'— a i|L/ a — -^41 \r7Wr? j^wwav >2 Earth Fig. 8.—Schematic diagram of Gish-Roonejr circuit. , but an alternating current of low frequency. Induction effects are, therefore, sometimes observed between the current and the potential leads; besides, not the ohmic resistance of the ground is obtained, but the impedance for the particular frequency employed, which for the commutators in Gish-Rooney outfits is approximately 16, and nearly 50 in Meggers. The only way to avoid polarization and induction effects is by using non-polarized electrodes, which consist of cups filled with copper sulphate and provided with a permeable bottom, made either of porous clay or of wood. The induction between leads is minimized when using the po- tential measuring line at right angles to the current basis, as already described. 441. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Society of Exploration Geophysicists. Tulsa
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Keywords: ., bo, bookcentury1900, booksubjectpetroleum, booksubjectprospecting
