Processing high-frequency electromagnetic logs from conducting formations: linearized 2D forward and inverse solutions with regard to eddy currents

Abstract

High-performance algorithms and software have been designed for fast 2D forward modeling and inversion of high-frequency electromagnetic logs to recover the patterns of electrical conductivity and relative permittivity (dielectric constant) of rocks. Forward modeling implies linear representation, with regard to eddy current, of attenuations and phase shifts of electromagnetic fields propagating in 2D conducting formations. In order to improve the modeling quality, the background model is chosen proceeding from the eddy current pattern in a heterogeneous subsurface. The inverse solution is obtained by pseudoinversion of the sensitivity matrix of relative amplitudes and phases. Joint 2D inversion of phase shifts and attenuations improves the reliability of the inferred spatial conductivity distribution and allows estimating permittivity. The reported numerical experiments on inversion of synthetic and field EM logs prove the possibility of estimating the permittivity of complex terrigenous and carbonate reservoirs with water- and oil-filled porosity.

Numerical Simulation and Application of Response Characteristics of High-Frequency Dielectric Logging Instrument

“…The magnetic dipole model is usually used for electromagnetic calculations in simulations of dielectric logging instruments [17][18][19]; this approach uses a magnetic dipole that is equivalent to the transmitting receiving antenna, without considering the influence of the engineering parameters of the instrument, such as the antenna size, filling material, and instrument framework. Thus, the problem of the formation response characteristics of a high-frequency dielectric logging instrument is simplified to the problem of the electromagnetic field of a magnetic dipole in a multilayered medium.…”

Theoretical-Algorithmical Base and Computer Simulation of Dielectric Logging Data to Study Frequency Spectrum of Electrophysical Parameters of Geological Environment

“…Наряду с аппаратурой ДК изучение ДП горных пород проводят по данным электромагнитного каротажа в диапазоне частот от сотен килогерц до единиц мегагерц. При этом основные результаты интерпретации данных ЭМК связывают с выявлением эффекта частотной дисперсии комплексной УЭП, определением ДП для оценки характера насыщения пород-коллекторов и изучением глинистых отложений [16][17][18][19][20][21][22][23][24][25][26].…”