Halliburton Energy Services, Inc.

Sergey Knizhnik

Manfred G Prammer

George David Goodman

Stefan K Menger

Edward J Harris, Iii

Earle Drack

Clive D Menezes

Edward J Iii Harris

Embodiments of a multi-axial antenna system and system for measuring subsurface formations are generally described herein. Other embodiments may be described and claimed. In some embodiments, the multi-axial antenna system comprising at least two co-located coils wound around a torroidal-shaped bobbin. Each coil generates a magnetic field in a mutually orthogonal direction. Signals provided to the coils may be adjusted to simulate a tilted-coil antenna system.

Multi-axial antenna and method for use in downhole tools

A nuclear magnetic resonance well logging tool, where some embodiments comprise two, oppositely oriented magnets separated by a pole piece to guide static magnetic flux into a sensitive volume, and another pole piece serving as a core for several antennas. For some embodiments, the antennas are solenoids. Two of the antennas serve as transmit and receive antennas, where they are driven to generate an elliptically polarized magnetic field, and their antenna responses are combined so that the combined response is sensitive to elliptically polarized magnetic fields, but with zero gradient in the z-direction. A third antenna serves as a receive antenna sensitive to magnetic field vectors having a sinusoidal spatial variation in the z-direction of period equal to the length of the third antenna. A fourth antenna serves as a receive antenna sensitive to sinusoidal magnetic field vectors with the same spatial-frequency as the third antenna, but phase shifted by 90 degrees. A fifth antenna may be utilized, which serves as a receive antenna sensitive to the next higher spatial-frequency component of the received signal. The receive antennas have good cancellation of mutual coupling. Other embodiments are described and claimed.

High-resolution wireline nuclear magnetic resonance tool

An NMR logging tool for conducting NMR measurements in a plurality of sensitive volumes ranging up to a meter from the tool. The tool comprises a magnetic assembly using one or more permanent magnets and at least one pole piece for extending a magnet pole and shaping the magnetic field to simulate a magnetic monopole in a sensitive volume within the formation. Different embodiments of a segmented antenna enable directional NMR logging. The tool embodiments and methods of their use are suitable for wireline or LWD logging, and can be used for directional drilling.

Systems and methods for deep-looking NMR logging

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Exton, PA, United States of America

Sergey Knizhnik