Abstract: The method and apparatus for determining the conductivity of anisotropic formations surrounding a borehole. The method comprises measuring the gradient of the magnetic field by an electromagnet logging tool in a borehole in the subsurface formation. The instrument comprises one or several closely positioned parallel receiver coils and one or several closely positioned parallel transmitter coils with the magnetic direction of the transmitter coils parallel or different from the magnetic moment direction of the receiver coils. In an embodiment, a gradient induction instrument consists of a tri-axial transmitter array and up to 27 pairs of receiver coils, measuring some or all magnetic gradient components.

Abstract: The method and apparatus for determining the conductivity of anisotropic formations surrounding a borehole. The method comprises measuring the gradient of the magnetic field by an electromagnet logging tool in a borehole in the subsurface formation. The instrument comprises one or several closely positioned parallel receiver coils and one or several closely positioned parallel transmitter coils with the magnetic direction of the transmitter coils parallel or different from the magnetic moment direction of the receiver coils. In an embodiment, a gradient induction instrument consists of a tri-axial transmitter array and up to 27 pairs of receiver coils, measuring some or all magnetic gradient components.

Abstract: The method and apparatus for determining the conductivity of anisotropic formations surrounding a borehole. The method comprises measuring the gradient of the magnetic field by an electromagnetic logging tool in a borehole in the subsurface formation. The instrument comprises one or several closely positioned parallel receiver coils and one or several closely positioned parallel transmitter coils with the magnetic moment direction of the transmitter coils parallel or different from the magnetic moment direction of the receiver coils. In a preferred embodiment a gradient induction instrument consists of a tri-axial transmitter array and up to 27 pairs of receiver coils, measuring some or all magnetic gradient components: formula (I).

Abstract: The method and apparatus for determining the conductivity of anisotropic formations surrounding a borehole. The method comprises measuring the gradient of the magnetic field by an electromagnetic logging tool in a borehole in the subsurface formation. The instrument comprises one or several closely positioned parallel receiver coils and one or several closely positioned parallel transmitter coils with the magnetic moment direction of the transmitter coils parallel or different from the magnetic moment direction of the receiver coils. In a preferred embodiment a gradient induction instrument consists of a tri-axial transmitter array and up to 27 pairs of receiver coils, measuring some or all magnetic gradient components: formula (I).

Abstract: Mineral exploration needs a reliable method to distinguish between uneconomic mineral deposits and economic mineralization. A method and system includes a geophysical technique for subsurface material characterization, mineral exploration and mineral discrimination. The technique introduced in this invention detects induced polarization effects in electromagnetic data and uses remote geophysical observations to determine the parameters of an effective conductivity relaxation model using a composite analytical multi-phase model of the rock formations. The conductivity relaxation model and analytical model can be used to determine parameters related by analytical expressions to the physical characteristics of the microstructure of the rocks and minerals.