Аңдатпа
The paper proposes a method for spatial localization of NMR signal sources during downhole studies of oil reservoirs in the Earth's natural magnetic field. The method is based on the combined use of electromagnetic wave arrival time differences (TDOA) and signal intensity measurements recorded by a system of four receivers placed on the day surface. It is shown that the time delay method provides high geometric accuracy, but is sensitive to the uncertainty of the wave velocity propagation in an inhomogeneous medium, while the amplitude method is more resistant to velocity variations, but is subject to noise and errors in the attenuation coefficient. A weighted average combination of the results of the two methods is proposed. The simulation results showed a decrease in the error in determining the coordinates of the source from 3–5 m (TDOA) and 8–12 m (amplitude method) to ~2 m with a combined approach. In addition, it was found that the use of fixed time delays allows for coherent signal accumulation, increasing the signal-to-noise ratio. The proposed approach can be used to create areal monitoring systems for oil fields based on off-hole NMR studies.