Abstract: Using electric conductivity(k_s)in searching for oil and gas fields(pools)is mainlybased on the magneto-electric current of oxido-reduction happened on the upper position ofoil and gas fields(pools)and oxidation column formed by oil-field wateracting on the bothsides of the oil and gas fields(pools).With the metal ions in the oxidation coltimn diffusing and migrating upward, part of cations in the side layer would enter the column andpromotes the conductivity(k_s)of the column. Under such a long-term geochemical processit would bring about ring-abnormality of K,around the peripheral surface of the oil and gasfields(pools). So high background area in the inner side of ring-abnormality indicates theeffective area of the distribution of oil and gas fields(pools).