METHOD OF ELECTROMAGNET SURVEY OF ROCKS BEHIND PRECIPITATION COLUMN Russian patent published in 2008 - IPC G01V3/30 

FIELD: geophysical survey.

SUBSTANCE: method can be used for surveying rocks behind well, seated by metal column. Super lower frequency lateral-magnet type electromagnet field, efficient within 1-10 Hz range, is excited by receiving-transmitting device of well device's aerial. Simultaneously with excitation, current is measured at input of aerial, which current is proportional to φ-component of magnetic field H_φ(rs), where r_s is radius of excitation source. Efficiency coefficient k=(2πr_sH_φ(r_s)/-_Iz,k)-1 is measured, where I_z,_k is current going along column. Borders of beds are determined from efficiency coefficient curve of device along depth. Iteration process of minimization of closing error of efficiency coefficient of device is built, which values were achieved during process of measurement, as well as of theoretical values and values of electrical conductivity of any bed is determined. Improvement in precision of measurement of relative contribution of useful signal is achieved. Survey can be made in redial direction for value of 1-5 m. Electrical resistance of beds with thickness up to 1 m can be measured with precision of 10-15%.

EFFECT: improved efficiency.

2 cl, 5 dwg