Schlumberger Technology Corporation

Krishnamurthy Ganesan

Peter Speier

Martin E Poitzsch

Robert Freedman

Bruno Luong

Nicholas J Heaton

Shu-Kong Chang

Douglas W Grant

Jaideva C Goswami

Reza Taherian

Yi-Qiao Song

Anatoly Dementyev

Ralf Heidler

Steven F Crary

Payam Tabrizi

Gabriela Leu

Abdurrahman Sezginer

Robert L Kleinberg

Martin D Hurlimann

Soumyajit Mandal

Boqin Q Sun

Abdel Kharrat

Henry N Bachman

Vassilis Varveropoulos

Vivek Anand

Daniel Catina

Yuesheng Cheng

Christian Straley

Eugene Janssen

Van D M Koroleva

Ricardo Y Torres

Martin Erich Poitzsch

Diogenes David Molina

Li An

A method can include triggering an assessment of pulse width of an X degree pulse of a downhole NMR tool; responsive to the assessment, determining an optimal pulse width of the X degree pulse; acquiring NMR measurements using the downhole NMR tool and the optimal pulse width; and characterizing a formation using at least a portion of the NMR measurements.

Downhole NMR system

A method for measuring one or more properties of a formation includes applying a magnetic field to a subterranean formation using a downhole tool. A radiofrequency signal is transmitted into the subterranean formation that is exposed to the magnetic field. The radiofrequency signal induces a transverse magnetization in the subterranean formation, and the transverse magnetization induces an initial voltage signal in the downhole tool. The initial voltage signal is amplified using a first amplifier in the downhole tool such that the first amplifier outputs a first amplified voltage signal. The first amplified voltage signal is introduced to an input of the first amplifier, such that the first amplifier amplifies the first amplified voltage signal and outputs a second amplified voltage signal.

Active damping for NMR logging tools

An arrangement for shielding an NMR tool from electromagnetic noise, having a nuclear magnetic resonance tool configured to send and receive signals, a first shield configured around a nuclear magnetic resonance antenna of the nuclear magnetic resonance tool and a second shield configured to reduce the effects of eddy currents in the first shield.

Composite noise shield for magnetic resonance tools

A method to calibrate a nuclear magnetic resonance tool is disclosed having steps of starting a nuclear magnetic resonance sequence from the nuclear magnetic resonance tool, disabling an active damping circuit in the nuclear magnetic resonance tool, collecting auxiliary calibration data for the nuclear magnetic resonance tool, estimating a natural Q value for the nuclear magnetic resonance tool, determining an optimal active damping setting for the tool, deploying the optimal active damping setting for the tool, collecting nuclear magnetic resonance response data generated from the nuclear magnetic resonance sequence and calibrating the nuclear magnetic resonance data.

Variable damping control for nuclear magnetic resonance data acquisition system to enhance oilfield logging performance

A nuclear magnetic resonance (NMR) measurement system for high pressure and temperature measurements on fluids is disclosed. The system has a sensor assembly that includes a sample holder having a body formed from a non-magnetic metal and defining an interior cavity for receiving a fluid sample, a frame member disposed in the interior cavity of the sample holder, an antenna coil disposed in the interior cavity about the frame member, an inlet that allows the fluid sample to enter the interior cavity, an outlet that allows for the fluid sample to be flushed from the interior cavity, and a magnet assembly having a central bore in which the sample holder is disposed. Adjacent to the sample holder are pulsed field gradient coils for performing diffusion measurements. The system further includes pulse sequencer circuitry that supplies signals to the antenna coil. When the interior cavity of the sample holder is filled with the fluid sample, the antenna coil and the frame member are at least partially submerged in the fluid sample, and the antenna coil obtains NMR measurements of the fluid sample in response to the signals. Related methods and apparatuses are also disclosed herein.

System and method for obtaining nuclear magnetic resonance measurements on reservoir fluids for prediction of fluid properties

A downhole micro MR analyzer for use in a wellbore, having a micro sample tube, a micro RF coil in close proximity to the micro sample tube, and one or more magnets disposed about the micro sample tube is disclosed. The micro MR analyzer can be used for nuclear magnetic resonance or electron spin resonance experiments to ascertain formation properties and chemical compositions.

Downhole micro magnetic resonance analyzer

A method and apparatus to determine the fractional amount of at least one constituent of a hydrocarbon mixture, comprising dissolving the hydrocarbon mixture in a substantially hydrogen free solvent to produce a diluted solution, the diluted solution having sufficient solvent to render a NMR property of the diluted solution to be predictably related to the constituent concentrations of the hydrocarbon mixture; making NMR measurements on the diluted solution; and determining the fractional amount of at least one constituent of the hydrocarbon mixture from the NMR measurements.

Method and apparatus for analyzing a hydrocarbon mixture using nuclear magnetic resonance measurements

The present invention pertains to an apparatus and method for conducting magnetic resonance measurements on fluids at high pressures and/or high temperatures. The apparatus can be used in conjunction with or as part of a downhole fluid sampling tool to perform NMR measurements on fluids withdrawn from petroleum reservoirs, or can also be used for laboratory measurements on live reservoir fluids. The apparatus can perform all of the measurements made by modern NMR logging tools, including multi-dimensional distribution functions of spin-spin (T) and spin-lattice relaxation (T) times and molecular diffusion coefficients. The spin densities of hydrogen and other NMR sensitive species can be computed from the distribution functions. The apparatus can also be used to predict the apparent conductivity of the fluids in the flowline from measurements of the quality factor ('Q') of the NMR circuit. The apparent conductivity can be used to predict water cut or water salinity.

High pressure/high temperature magnetic resonance tool

An apparatus and method to perform measurements on fluid in a wellbore fluid sample tool in which at least a portion of the flowline of the sample tool is made of a non-magnetic and non-conductive material.

Non-conductive and non-magnetic flowline for electromagnetic measurements on reservoir fluids at high pressures

A method to obtain a free induction decay signal using includes inducing a static magnetic field in a sample volume. A radio frequency (RF) magnetic field is then induced in the sample volume. The RF magnetic field has parameters selected to minimize the contribution of inhomogeneity in the static magnetic field to a free induction decay time. The free induction decay signal is then detected from the sample volume. In one example, prior to inducing the RF magnetic field, a reorienting radio frequency magnetic field is induced in the sample volume to reorient magnetic spins by a first selected angle. The inducing the RF magnetic field in this example has parameters selected to reorient spins by a second angle. The inducing the RF magnetic field and detecting the free induction decay signal are repeated until nuclear magnetic equilibrium is substantially attained.

Method and apparatus for measuring free induction decay signal and its application to composition analysis

The present invention is directed to a nuclear magnetic resonance apparatus and method for generating an axisymmetric magnetic field having long, straight contour lines in the resonance region. A magnetically permeable member is used to shape the static magnetic field generated by an array of permanent magnets. The magnetically permeable member minimizes variations of the static magnetic field in the formation due to vertical motion of the apparatus while obtaining a nuclear magnetic resonance measurement. Further, the magnetically permeable member may minimize variations of the static magnetic field in the formation due to lateral motion of the apparatus while obtaining a nuclear magnetic resonance measurement.

Method and apparatus for generating an axisymmetric magnetic field

A nuclear magnetic resonance (NMR) method is used to determine a velocity distribution or velocity image of a flowing fluid in a downhole environment. The method comprises applying a radio frequency pulse sequence; applying a magnetic field gradient magnetic field and a gradient pulse duration; measuring a NMR signal; determining a phase characteristic of the NMR signal; and determining the velocity distribution or image of the fluid using the determined phase characteristic, the magnetic field gradient pulse parameters, and a time delay between gradient pulses.

Flow measurement using NMR

A method for estimating a concentration of a substance in a test sample of formation fluid, comprising measuring an NMR parameter of a first sample of formation fluid to obtain a first measurement, adding a known quantity of the substance to the first sample to produce a modified sample, measuring the NMR parameter of the modified sample to obtain a second measurement; and determining a relation between the concentration of the substance and a function of the NMR parameter using the first and second measurements and the NMR parameter of the substance.

Estimating the concentration of a substance in a sample using NMR

A method for determining a property of a substance in a downhole measurement region includes the following steps: providing a static magnetic field having a static magnetic field gradient in the measurement region; applying, in the measurement region, a pulse sequence that includes a tipping pulse, a re-focusing pulse, and a pulsed field gradient pulse train; wherein the pulsed field gradient pulse train includes a first portion and a second portion; the first portion comprising a first pulse or set of pulses having a first polarity and a second pulse or set of pulses having a second polarity, the second polarity being opposite to the first polarity, and wherein the first portion occurs before the re-focusing pulse; the second portion comprising a third pulse or set of pulses having the first polarity and a fourth pulse or set of pulses having the second polarity, and wherein the second portion occurs after the re-focusing pulse; and receiving one or more spin echoes from the measurement region.

Method for determining more accurate diffusion coefficient distributions of reservoir fluids using Bi-polar pulsed field gradients

A method for obtaining nuclear magnetic resonance measurements includes inducing a static magnetic field in a formation fluid sample; applying an oscillating magnetic field to the fluid sample according to a preparation pulse sequence that comprises a J-edit pulse sequence for developing J modulation; and acquiring the nuclear magnetic resonance measurements using a detection sequence, wherein the detection sequence comprises at least one 180-degree pulse. The method may further include acquiring the nuclear magnetic resonance measurements a plurality of times each with a different value in a variable delay in the J-edit pulse sequence; and analyzing amplitudes of the plurality of nuclear magnetic resonance measurements as a function of the variable delay to provide J coupling information.

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Sugar Land, TX, United States of America

Krishnamurthy Ganesan