Schlumberger Technology Corporation

Timothy Hopper

Yi-Qiao Song

Martin D Hurlimann

David G Cory

Anatoly Dementyev

David T Oliver

Methods and systems are provided that enable logging while drilling NMR measurements to be made with magnets placed outside of the drill collar and magnetically permeable members to control the magnetic field gradient. A set of magnets can be disposed on and/or embedded on a drill collar, with an antenna disposed axially therebetween. Alternatively, a set of magnets and an antenna disposed therebetween can be disposed on a sleeve that is slid onto a recess in a drill collar. Additionally, a permeable member can be axially positioned between the set of magnets for affecting the depth of investigation.

Nuclear magnetic resonance tool with external magnets

An NMR apparatus disposed in a wellbore and having an array of two or more NMR sensors located at substantially the same axial position on the NMR apparatus and having different directional sensitivities is used to acquire an NMR signal from at least two of the two or more NMR sensors. The NMR signals are combined to obtain borehole information. The borehole information may include an azimuthal image of the formation surrounding the borehole. The azimuthal image may be a formation porosity image, a formation bound fluid image, a T2 distribution image, a T2 log mean image, a formation permeability image, or a formation fluid viscosity image. If two or more pre-amplifiers and receiver circuitry are also provided, the NMR signals may be combined prior to passing through the pre-amplifiers and receiver circuitry to improve the signal to noise ratio of the total signal from the desired sample space.

Three or more multiple figure-eight coils for NMR well-logging measurements with azimuthal directional sensitivity

Methods and related apparatuses of a downhole micro nuclear magnetic resonance (NMR) device having a resonant tuning (LC) circuit for use in a formation for collecting NMR signals from a fluid in the formation while under downhole pressures and temperatures. The downhole micro NMR device includes: a micro tube for the flowing fluid to flow therethrough; at least one magnet disposed about the micro tube; and at least one micro RF coil structured and arranged approximate to the micro tube and tuned to a Larmor frequency corresponding to a applied magnetic field from the at least one magnet.

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Shenton Park, Australia

Timothy Hopper