Abstract: The present invention discloses a diffusion edited pulse technique that allows information about a fluid to be extracted, comprising: a) obtaining a fluid sample; b) generating a sequence of magnetic field pulses in the fluid, the sequence comprising an initial magnetic field pulse, a first portion that follows the initial magnetic field pulse, and a second portion that follows the first portion; c) detecting magnetic resonance signals using the second portion of the sequence; d) modifying the first portion of the sequence, and repeating steps (b) and (c); and e) extracting information about the fluid by determining relaxation and diffusion characteristics and their correlation based on the signals detected in steps (c) and (d). Also disclosed is a logging tool equipped with a processor to implement the diffusion edited pulse technique.

Abstract: The present invention provides an improved NMR sequence for detecting small amount of a substance having short NMR transversal relaxation in the presence of a large amount of a substance having long NMR relaxation. A sequence of pulses enables the original z-oriented magnetization vector of a substance to experience differing reorientation effects based on the relative transverse relaxation rate of the substance. After said pulse sequence, a substance with long transverse relaxation experiences a substantial inversion of its nuclear magnetization vector, while a substance with short transverse relaxation experiences a nearly zero value of its vector. After a determinable wait time, said vectors can be shown to experience recognizably different behavior under the application of a CPMG sequence of pulses. Appropriate wait time can be determined by zeroing out spin echoes during the CPMG pulse sequence.

Abstract: A method for determining the variations of the resistivity index (RI) of a family of rock samples of complex pore structure with at least two pore networks, as a function of the water saturation (Sw), and in the presence of a non-oil conducting fluid. The volume fraction (f1, f2, f3) occupied by each pore network and the distribution of the pore throats in the various pore networks are determined for each sample of the family. The values of coefficients relating the variation of its electrical resistivity as a function of its water saturation (Sw) are experimentally determined on a sample of the family used as a reference sample. The resistivity index (RI) of all the samples of the family is then determined on the basis of the variation of parameters describing the layout of the pore network, and using the values of the coefficients measured on the reference sample.

Abstract: A method for detecting hydrocarbons in a fluid sample includes deriving a difference measurement from a first nuclear magnetic resonance measurement and a second nuclear magnetic resonance measurement, wherein the first nuclear magnetic resonance measurement and the second nuclear magnetic resonance measurement have difference values in an acquisition parameter such that molecular diffusion affects the first nuclear magnetic resonance measurement and the second nuclear magnetic resonance measurement to a different extent; and determining a presence of hydrocarbons from the difference measurement.

Abstract: A method for determining properties of a mixture of fluids includes: (a) acquiring a plurality of nuclear magnetic resonance measurements from the mixture of fluids, each of the plurality of nuclear magnetic resonance measurements having a different value in an acquisition parameter for which at least one relaxation selected from the group consisting of longitudinal relaxation and transverse relaxation affects magnitudes of the nuclear magnetic resonance measurements; (b) generating a model of the mixture of fluids; (c) calculating a synthesized nuclear magnetic data set based on the model; (d) comparing the synthesized nuclear magnetic data set with the nuclear magnetic resonance measurements; and (e) adjusting the model and repeating (c) and (d), if difference between the synthesized nuclear magnetic data set and the nuclear magnetic measurements is greater than a minimum.

Abstract: A method for determining a molecular property of each constituent in a mixture of hydrocarbons includes deriving at least one dynamic parameter for each constituent in the mixture from NMR data measured on the mixture; and calculating the molecular property for the each constituent in the mixture from the at least one dynamic parameter for each constituent. The step of deriving the at least one dynamic parameter may include generating a model that includes a plurality of components for the constituents of the mixture and iteratively modifying the model components to optimize the model with respect to the NMR data. The at least one dynamic parameter includes a parameter selected from the group consisting of a longitudinal relaxation time, a transverse relaxation time, a ratio of longitudinal to transverse relaxation time, and a diffusion rate.

Abstract: When NMR spin echo measurements are obtained with one or more of (i) different echo intervals, (ii) different static field gradients, (iii) different polarization times, or (iv) noise levels, due to fluid diffusivity, the spin echo measurements cannot be simply combined. However, by applying a correction factor, such a combination is possible, giving an improved interpretation of the formation properties.

Abstract: The present invention relates to a method and apparatus for measuring a property relating to fluid flow in an earth formation, more specifically to directly measuring formation permeability and other fluid characteristics. The present invention provides a method for determining the permeability of a hydrocarbon bearing earth formation, which method comprises the steps of: locating a tool at a selected position in a borehole penetrating the earth formation; inducing a flow of fluid within the earth formation to said tool; creating at least two MRI images of said fluid while flowing within the earth formation to said tool, said at least two images being created at different times; determining displacement of said fluid within the earth formation between said different times, using the at least two MRI images.

Abstract: In one embodiment of the present invention, a method of measuring the molecular displacement of a fluid is disclosed comprising: (a) applying a strong magnetic field gradient to the fluid; (b) applying a sequence of oscillating magnetic field pulses to the fluid wherein the sequence includes a first portion followed by a second portion, wherein the first portion spatially modulates the magnetization state of the fluid and the second portion monitors the evolution of the modulation; (c) detecting magnetic resonance signals from the fluid; and (d) analyzing the detected signals to determine the molecular displacement of the fluid. This method may be used to determine the diffusion of the fluid or the restricted diffusion of the fluid through the porous media if the fluid is within a porous media (such as earth formation, bone, wood or other material). Also disclosed is a logging tool configured to implement this methodology.

Abstract: The present invention provides a novel use of a material having a high internal magnetostrictive damping and/ or using material with explicitly low magnetostriction as a NMR probe core material. The probe structural geometry facilitates the use of material, which has a relatively low magnetic permeability.

Abstract: A method and an apparatus for obtaining NMR measurements are disclosed. An NMR measurement apparatus, the measured sample, or both elements may be subjected to motion during the measurement. The envelope of an RF carrier signal is modulated according to an envelope to generate a first sequence of RF pulses. The envelope, the phase of the RF signal, and/or a static magnetic field may be varied during the radiation of the first sequence to substantially saturate a first region of the sample. The first sequence may include additional RF refocusing pulses that, when coupled with movement of the NMR measurement apparatus or sample, may also be used to substantially saturate the first region. A second sequence of RF pulses is radiated to establish a resonance region within the first region and measure an attribute of the sample.

Abstract: A method of using nuclear spectroscopy measurements acquired while drilling a subsurface formation including: measuring indicators of a plurality of absolute or relative formation elemental concentrations; processing the measurements to determine a petrophysical parameter associated with the subsurface formation while drilling, and using the petrophysical parameter to determine a drilling parameter. The petrophysical parameter may include, for instance, the permeability of the subsurface formation and the drilling parameter may include, for instance, a change in the orientation of a directional drilling assembly or the point at which to stop drilling. The invention further involves an apparatus adapted to carry out the inventive method.

Abstract: The present invention discloses a method and apparatus to make a nuclear magnetic resonance measurement on a flowing fluid using varied wait times. In one method, NMR measurements are made by: a) flowing the fluid through a static magnetic field; b) applying a group of oscillating magnetic field pulses to the flowing fluid, wherein the group of pulses is comprised of an initial pulse and one or more refocusing pulses; c) detecting magnetic resonance signals from the flowing fluid; d) after a wait time, repeating (b) and (c) one or more times, wherein at least two of the repetitions have varied wait times; and e) analyzing the detected magnetic resonance signals to extract information about the flowing fluid. Further, varied wait time measurements may be useful in determining the flow rate of the sample.

Abstract: A slotted NMR antenna cover for improved mechanical ruggedness during transmission and reception of NMR signals in a down hole environment during either MWD or wire line operations. A NMR slotted antenna cover is provided comprising an elongated tubular structure with longitudinal gaps or slots filled with a RF transmissive or non-conductive material. The slots can befilled at the slot ends with soft magnetic material to improve efficiency of the antenna. The slots are radial concave to reduce eddy currents induced by alternating magnetic flux entering and leaving the slots surrounding the antenna. In another embodiment, the antenna cover is RF transmissive on only a portion of the antenna, via slots or transmissive material, so that the antenna cover can be used to allow RF transmission from the antenna in a side looking or beam pattern restricted mode only.

Abstract: A method for processing Nuclear magnetic resonance (NMR) well logging data in the presence of coherent transient signals and offsets is disclosed. The method comprises the addition of R and X-Channel transients and offsets to the relaxation model appropriate for a user selected pulse sequence. The effects of the ringing and offsets are automatically compensated for by fitting R and X-Channel spin-echo data to the relaxation model.

Abstract: The subject invention pertains to a method and apparatus for Nuclear Magnetic Resonance (NMR) imaging. The subject method and apparatus are advantageous with respect to the use of RF coils for receiving signals in NMR scanners. The subject invention can utilize multiple coils to, for example, improve the signal to noise, increase the coverage area, and/or reduce the acquisition time. The use of multiple smaller surface or volume coils to receive NMR signals from the sample can increase the signal to noise ratio compared to a larger coil that has the same field of view and coverage area.

Abstract: 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.

Abstract: The present invention provides an improved NMR sequence for detecting small amount of a substance having short NM transversal relaxation in the presence of a large amount of a substance having long NMR relaxation. A sequence of pulses enables the original z-oriented magnetization vector of a substance to experience differing reorientation effects based on the relative transverse relaxation rate of the substance. After said pulse sequence, a substance with long transverse relaxation experiences a substantial inversion of its nuclear magnetization vector, while a substance with short transverse relaxation experiences a nearly zero value of its vector. After a determinable wait time, said vectors can be shown to experience recognizably different behavior under the application of a CPMG sequence of pulses. Appropriate wait time can be determined by zeroing out spin echoes during the CPMG pulse sequence.

Abstract: A method for measuring in situ formation fluid flow utilizing an NMR logging while drilling tool is disposed in the borehole, a modified saturation recovery or time of flight angiography pulse sequence is utilized to tag spins in the formation, at least two measurements are made of the tagged spins as they propagate toward the borehole in the under-balanced environment, allowing a determination of fluid velocity, from which permeability may be determined. Techniques are disclosed to perform the method in both an over-balanced and under-balanced environment.

Abstract: Novel pulse sequences are used to probe the properties of porous media, such as are found in subterranean formations and core samples. This use allows diffusion effects to be uncoupled from the overall T2 relaxation time of the sample. Properties such as internal field gradient and distribution of diffusion coefficients may be determined. A series of pulse sequences are applied to the media to be evaluated. The series of pulse sequences include first and second windows. The first windows include pulse sequences have varying characteristics, such as increasing echo spacing, while the second windows preferably utilize similar pulse sequences which have very small echo spacing. Apparent internal field gradient distribution and apparent diffusion coefficient may be determined as a function of T2 relaxation time.

Abstract: Disclosed are a method and system for developing customized bound water transformations to obtain accurate determinations of non-producible water from nuclear magnetic resonance (NMR) logs. The approaches of this invention can be applied for in situ calibration where laboratory NMR measurements may not be possible or practical. In particular, a transformation model directly linking BVI and capillary pressure is developed by calibrating NMR derived BVI with the core data, the novel transformation model utilizes SBVI and/or CBVI models to directly relate NMR derived BVI and capillary pressure responses through the height of the measurement in a borehole. The derived height-based BVI transformation model is applied to the NMR log of the borehole to quantify non-producible water in the NMR log.

Abstract: An improvement in a magnetic resonance method for determining at least one property of multiple samples, including introducing multiple samples into the interrogation zone simultaneously; applying a gradient magnetic field to the interrogation zone wherein different positions within the interrogation zone are sensitive to different specific frequencies; monitoring energy emitted by the samples in the different positions and generating an output signal having a characteristic which is proportional to the energy emitted corresponding thereto in different frequency bands; and, attributing the signals to specific positions and samples, and comparing the output signal characteristics of the specific positions and samples with like data obtained from at least one similar sample to provide an indication of the corresponding property of the samples.

Abstract: An analytical instrument for analyzing biohazardous specimens is provided. The instrument provides means for exposing only the sample chamber to the containment area. A process for analyzing a biohazardous sample is also provided.

Abstract: A system and method for calculating the lateral velocity of a rotating drilling tool within a borehole, the system comprising: a pair of accelerometers placed oppositely across the drilling tool axis of rotation and two magnetometers. The method comprises: reading tool radial acceleration signals ar1, ar2, and tangential acceleration signals, at1 and at3, obtained with a quadrature accelerometer detection system; reading Bx and By, the tool's magnetic phase data, from two orthogonally placed magnetometers; determining the rotational phase angle of the drilling tool relative to the earth's gravity field by first determining the tool's magnetic phase, and the phase shift between the tool's magnetic phase and gravity phase; and processing the foregoing data to yield a lateral tool velocity which optionally compensates for the effect of gravity on the accelerometers, or converts the lateral tool velocity from the tool reference frame to the borehole reference frame, or does both.

Abstract: A method and apparatus for transferring data from a logging tool to a surface computer that involves attaching a stand-alone data dump device to the logging tool after the logging tool has gathered data about downhole parameters. After attaching the data dump device, data contained in a memory of the logging tool is copied to a memory of the data dump device. In one embodiment, once data copying between the logging tool and data dump device is complete, the data dump device is disconnected from the logging tool and connected to a surface computer which reads the data previously copied to the data dump device. A second embodiment of the data dump device has a radio frequency communication link between the surface computer and the data dump device to allow a wireless communication between the surface computer and the data dump device and/or logging tool.

Abstract: Nuclear magnetic resonance techniques are used in a fluid sampling tool that extracts a fluid from subsurface earth formations into a flow channel within the tool. The magnetic resonance techniques involve applying a static magnetic field and an oscillating magnetic field to the fluid in the flow channel, and magnetic resonance signals are detected from the fluid and analyzed to extract information about the fluid such as composition, viscosity, etc.

Abstract: A method for manufacturing NMR measurement-while-drilling tool having the mechanical strength and measurement sensitivity to perform NMR measurements of an earth formation while drilling a borehole, and a method and apparatus for monitoring the motion of the measuring tool in order to take this motion into account when processing NMR signals from the borehole. The tool has a permanent magnet with a magnetic field direction substantially perpendicular to the axis of the borehole, a steel collar of a non-magnetic material surrounding the magnet, antenna positioned outside the collar, and a soft magnetic material positioned in a predetermined relationship with the collar and the magnet that helps to shape the magnetic field of the tool. Due to the non-magnetic collar, the tool can withstand the extreme conditions in the borehole environment while the borehole is being drilled.

Abstract: A novel method and apparatus is disclosed for the separation of fluid phases in borehole measurements. The method is based on selecting an optimum contrast mechanism and a corresponding set of measurement parameters for a particular borehole environment. The contrast mechanism can be based on, among others, diffusion, relaxation time or hydrogen index differences between different types of fluids. Once an initial measurement is made, the measurement parameters are compared to a predetermined set of values to broadly estimate the types of fluids present in the geologic environment. If necessary, the measurement is repeated to obtain optimal fluid typing for the estimated fluid types.

Abstract: The invention is a method of reducing the effects of non-formation signals in an NMR logging echo signal obtained within a borehole in an earth formation. The method obtains a non-formation signal by the application of at least an excitation pulse, and preferably also at least one refocusing pulse. The obtained signal is used to numerically construct a synthetic ringing signal sequence. The constructed signal can then be subtracted from an NMR echo signal to reduce the effects of ringing.

Abstract: When NMR spin echo measurements are obtained with one or more of (i) different echo intervals, (ii) different static field gradients, (iii) different polarization times, or (iv) noise levels, due to fluid diffusivity, the spin echo measurements cannot be simply combined. However, by applying a correction factor, such a combination is possible, giving an improved interpretation of the formation properties.

Abstract: An NMR instrument for determining formation fluid properties includes a housing adapted to move in a wellbore; a magnet disposed in the housing adapted to induce a static magnetic field; an antenna assembly disposed in the housing adapted to resonate at a first frequency and a second frequency, the first frequency corresponding to a resonance frequency of a first nucleus, the second frequency corresponding to a resonance frequency of a second nucleus, wherein the first nucleus is different from the second nucleus; means for inducing an RF magnetic field; and means for detecting NMR signals at the first frequency. A method of NMR measurement includes inducing a static magnetic field having a selected magnetic field strength in an earth formation sample; acquiring NMR measurements having J coupling information; and deriving the J coupling information from the NMR measurements.

Abstract: Methods and systems for finding a low rank approximation for an m×n matrix A are described. The described embodiments can independently sample and/or quantize the entries of an input matrix A, and can thus speed up computation by reducing the number of non-zero entries and/or their representation length. The embodiments can be used in connection with Singular Value Decomposition techniques to greatly benefit the processing of high-dimensional data sets in terms of storage, transmission and computation.

Abstract: A method and apparatus for the rapid tomographic measurement of conductivity distribution in a sample in which current excitations or voltage excitation is applied to the sample via electrodes or the like and potential differences or magnetic field strengths association with those excitation fields are measured and analyzed, e.g. by a Fourier analysis.

Abstract: An apparatus is disclosed for generating a magnetic field of high field strength, spatial uniformity and minimal drift of magnetic field intensity over a temperature range of about 0° C. to 175° C. This apparatus may be used in a standard modular logging tool for direct downhole NMR measurements of various parameters of fluid samples of geologic formations near the walls of a borehole. In one embodiment, the apparatus is composed of two tubular permanent magnets made of different magnetic materials with different magnetic temperature coefficients to provide temperature compensation. The apparatus preferably also utilizes a pressure barrel that surrounds the magnets and provides a return path for magnetic flux lines, thereby increasing flux density within the measurement volume.

Abstract: An expert system is included in a downhole processor designed to acquire and process NMR data downhole in real time. The downhole processor controls the acquisition of the NMR data based at least in part on instructions transmitted downhole from a surface location and at least in part on evaluation of downhole conditions by the expert system. The downhole conditions include drilling operation conditions (including motion sensors) as well as lithology and fluid content of the formation obtained from other MWD data. The wait time, number of echos, number of repetitions of an echo sequence, interecho time, bandwidth and shape of the tipping and refocusing pulses may be dynamically changed. Data processing is a combination of standard evaluation techniques. Selected data and diagnostics are transmitted uphole. The expert system may be implemented as a two stage neural net. The first stage does the formation evaluation and the second stage controls the NMR pulse sequence.

Abstract: The present invention provides a method for obtaining a multi-dimensional proton density distribution from a system of nuclear spins. A plurality of nuclear magnetic resonance (NMR) data is acquired from a fluid containing porous medium having a system of nuclear spins. A multi-dimensional inversion is performed on the plurality of nuclear magnetic resonance data using an inversion algorithm to solve a mathematical problem employing a single composite kernel to arrive at a multi-dimensional proton density distribution. Ideally, the mathematical problem can be cast in the form of a Fredholm integral of the first kind wherein a two or more kernels can be reduced to a single composite kernel for ease of solution. Preferably, a series of conventional CPMG pulse sequences, using a conventional NMR tool, can be used to excite the system of nuclear spins.

Abstract: Wireline NMR well logging measurements suffer from disadvantages of poor vertical resolution, logging speeds less than 20 ft/min, and power consumption in excess of 200 W. In spite of these disadvantages, NMR well logging is used because it is capable of providing estimates for a number of petrophysical parameters that are difficult to obtain from other wireline data. These include estimates of the bulk volume irreducible (BVI) of fluids in the formation. The present invention targets BVI and clay bound water (CBW) measurements. Logging speeds of up to 60 ft/min are attainable with little or no loss of resolution. In one preferred embodiment, the tool has four sensors circumferentially distributed around the logging tool and in contact with the borehole wall. A horseshoe like magnet is used to generate the static magnetic field.

Abstract: A method and apparatus for determining the oil and water content of a heavy oil and water emulsion includes a low field NMR spectrometer and means for determining the total amplitude of an NMR spectrum at specified T2 values.

Abstract: A nuclear magnetic resonance (NMR) logging system for measuring fluid properties of formation penetrated by a well borehole. The system uses a conductive permanent magnet to generate a field H0. The conductive permanent magnet is disposed within a logging tool so that the H0 field is perpendicular to the axis of the borehole. Soft ferrite elements are disposed on each pole of the permanent conductive magnet and a RF coil is disposed about both the permanent magnet and the ferrite. The resulting H1 field induced by the RF coil is perpendicular to both the H0 and the axis of the borehole. The soft ferrite elements focus the conductive permanent magnetic field and increase the effectiveness of the RF antenna. A two coil embodiment is disclosed that produces a combined RF field which is substantially perpendicular to the static magnetic field external to the conductive permanent magnet, and is contained within the soft ferrite elements in the vicinity of said conductive permanent magnet.

Abstract: An antenna structure is separately and independently formed with respect to a tubular adapted for long-term disposal within a wellbore. The antenna is adapted for easy and rapid deployment on the tubular. An independently formed ‘partial ring section’ (or arcuate shaped member) contains an antenna coil. In one embodiment, one or more of the independently formed partial ring sections is placed on the exterior of the tubular to form a well completion. In another embodiment, a plurality of partial ring sections are coupled to a spooled cable for rapid deployment of the antennas onto a tubular in the field. Another embodiment includes partial ring sections forming an antenna with multiple coils of differing orientation to provide directional sensitivity.

Abstract: A method is disclosed for interpretation of multi-dimensional nuclear magnetic resonance data taken on a sample of an earth formation. Specifically, a set of NMR data is acquired for a fluid sample located either in a borehole or in a laboratory environment. From the set of NMR data, a multi-dimensional distribution is calculated using a mathematical inversion that is independent of prior knowledge of fluid sample properties. The multi-dimensional distribution is graphically displayed on a multi-dimensional map. Each fluid instance or artifact visible on the graph is identified as representing a probable existence of a detected fluid. One or more quantitative formation evaluation answers for one or more fluid instances is computed based on the multi-dimensional distribution associated with the respective fluid instance.

Abstract: The present invention relates to a method and apparatus for determining the presence of magnetic materials in a media, such as an earth formation. More specifically, the method of the present invention correlates a diffusion-relaxation calibration function representative of magnetic materials with a 2-D function developed using diffusion-editing to determine the presence and relative content of magnetic materials in a media.

Abstract: A description is given of a method for determining the content of a first component of a sample, which first component provides a first NMR signal and has a first self-diffusion coefficient D1, the sample additionally containing at least one further component which provides a further NMR signal and has a larger self-diffusion coefficient D2, in particular for determining the fat content of a hydrous sample, with the aid of a low-resolution nuclear magnetic resonance (NMR) pulse spectrometer, the sample being excited by a radio-frequency (RF) excitation pulse and being exposed to a magnetic gradient field and to a sequence of further refocusing RF pulses for generating spin echo signals, the spin echo signals being detected and their amplitude values being determined, from which a value for the content of the first component of the sample is determined. The magnetic gradient field is not switched off during the sequence of further refocusing RF pulses.

Abstract: A high vertical resolution antenna design is provided for use in an NMR measurement apparatus. Multiple coils are situated along the length of a magnet. A primary coil is energized to cause an oscillating magnetic field in a portion of earth formation surrounding a borehole. A secondary coil having smaller dimensions than the primary coil is operated to receive spin echoes from a depth of investigation associated with the secondary coil. A distance sufficient to minimize electrical coupling separates the coils. The separation distance can be reduced by selecting a secondary coil with orthogonal polarization to the primary coil. Alternatively, a cross coil configuration can be implemented where the orthogonal secondary coil at least partially overlaps the primary coil, thereby reducing the overall length necessary for the polarizing magnet.

Abstract: One embodiment of the present invention is a method for nuclear magnetic resonance imaging of an investigation region of formation surrounding a wellbore. The method comprises the steps of applying a series of magnetic field gradients to phase encode nuclear spins within the investigation region, wherein the strength of the magnetic field gradient applied is different from at least one previously applied magnetic field gradient within the series. Nuclear magnetic resonance signals are detected from the investigation region resulting from the series of magnetic field gradients.

Abstract: The present invention discloses a method and apparatus to make a nuclear magnetic resonance measurement on a flowing fluid using varied wait times. In one method, NMR measurements are made by: a) flowing the fluid through a static magnetic field; b) applying a group of oscillating magnetic field pulses to the flowing fluid, wherein the group of pulses is comprised of an initial pulse and one or more refocusing pulses; c) detecting magnetic resonance signals from the flowing fluid; d) after a wait time, repeating (b) and (c) one or more times, wherein at least two of the repetitions have varied wait times; and e) analyzing the detected magnetic resonance signals to extract information about the flowing fluid. Further, varied wait time measurements may be useful in determining the flow rate of the sample.

Abstract: The present invention is method of determining the distribution of shales, sands and water in a reservoir including laminated shaly sands using vertical and horizontal conductivities derived from nuclear, NMR, and multi-component induction data such as from a Transverse Induction Logging Tool (TILT). Making assumptions about the anisotropic properties of the laminated shale component and an assumption that the sand is isotropic, the TILT data are inverted. An estimate of the laminated shale volume from this inversion is compared with an estimate of laminated shale volume from nuclear logs using a Thomas-Stieber and Waxman-Smits model. A difference between the two estimates is an indication that the sands may be anisotropic. A check is made to see if a bulk water volume determined from the inversion is greater than a bulk irreducible water volume from NMR measurements. In one embodiment of the invention, NMR data are then used to obtain sand distribution in the reservoir.

Abstract: A method for determining downhole reservoir wettability includes acquiring a first set of NMR measurements of formation fluids in earth formations at a selected axial depth; inverting the first set of the NMR measurements to produce a first distribution of a spin relaxation parameter for a fluid component in the formation fluids; acquiring a second set of NMR measurements of a formation fluid sample removed by a formation fluid testing tool at the selected axial depth, the formation fluid sample being kept at a substantially same pressure and temperature as those of the formation fluids in the earth formations at the selected axial depth; inverting the second set of NMR measurements to produce a second distribution of the spin relaxation parameter for the fluid component in the formation fluid sample; determining the reservoir wettability from a comparison of the first and second distributions of the spin relaxation parameter.

Abstract: A method and apparatus for performing NMR measurements suppressing contribution to NMR signals from within the borehole. Within the region of examination, the RF magnetic field has a spatially varying intensity. NMR signals (free induction decay or spin echo signals) are inverted to give spin density as a function of field intensity. This inversion is then mapped to spatial positions using the known RF field variation. The effect of signals arising from within the borehole can be suppressed. It is also possible to obtain an azimuthal image of the spin density.

Abstract: A method for manufacturing NMR measurement-while-drilling tool having the mechanical strength and measurement sensitivity to perform NMR measurements of an earth formation while drilling a borehole, and a method and apparatus for monitoring the motion of the measuring tool in order to take this motion into account when processing NMR signals from the borehole. The tool has a permanent magnet with a magnetic field direction substantially perpendicular to the axis of the borehole, a steel collar of a non-magnetic material surrounding the magnet, antenna positioned outside the collar, and a soft magnetic material positioned in a predetermined relationship with the collar and the magnet that helps to shape the magnetic field of the tool. Due to the non-magnetic collar, the tool can withstand the extreme conditions in the borehole environment while the borehole is being drilled.