Abstract: This method for analysis processing by using measured impedance spectrum data includes: a step for determining whether to reset the maximum value and/or the minimum value of logarithmic relaxation time corresponding to a measured logarithmic frequency on the basis of the measured impedance spectrum data; a step for setting the number of equal-interval divisions within the range of the logarithmic relaxation time set in the determination step; and a step for analyzing parameters R?, T, L, and Rl for the range of the set logarithmic relaxation time so as to satisfy a prescribed expression (A) by applying a regularized least-squares method.

Abstract: A method for evaluating saturation of a kerogen bearing subterranean formation includes obtaining conductivity and permittivity values of the formation and providing an effective medium model relating the conductivity and the permittivity to a water filled porosity of the formation and an effective aspect ratio of graphitic kerogen particulate in the formation. The obtained conductivity and the permittivity values are input into the model which is in turn processed to compute the water filled porosity. The method may further optionally include evaluating the water filled porosity to estimate a hydrocarbon producibility of the formation.

Abstract: Examples relate to a concept for anonymous re-identification, more specifically, but not exclusively, to systems, apparatuses, methods and computer programs for performing anonymous re-identification and for training a machine-learning model for use in anonymous re-identification. An apparatus for re-identification comprises processing circuitry configured to obtain media data via an interface. the processing circuitry is configured to generate a re-identification code representing at least a portion of the media data using a hashing algorithm. The processing circuitry is configured to transform the re-identification code using a transformation functionality to obtain a transformed re-identification code.

Abstract: A system and method for MRI are provided. An initial spatial factor may be based on first MRI signals collected in a first imaging stage of an MRI scan of a subject. Second MRI signals collected during a second imaging stage of the MRI scan after the first imaging stage may be obtained. Temporal factors or/and updated spatial factors may be determined. Each of the temporal factors may be determined based on the second MRI signals collected before the determination of the temporal factor. Each of the updated spatial factors may be determined based on the second MRI signals collected before the determination of the updated spatial factor. Real-time MRI images within the second imaging stage may be generated. Each of the real-time MRI images may be generated based on the latest determined temporal factor and one of the initial spatial factor or the latest determined spatial factor.

Abstract: Disclosed herein is a polymer prediction system, comprising a deep learning neural network and a training dataset. The deep learning neural network can comprise: a property branch comprising two or more layers, each layer having a plurality of neurons; a polymer branch comprising two or more layers, each layer having a plurality neurons; and a merged layer including a concatenation operation, the concatenation operation configured to concatenate the property branch and the polymer branch. The training dataset can include a plurality of known polymers and a plurality of descriptors for each of the plurality of known polymers. Also disclosed herein are methods of using the same.

Abstract: Tools and methods are used to determine the oil, water, and solids volume fractions in a drilling fluid at the rig site. The volume fractions can be determined in-line with returned drilling fluid by using an NMR magnet and a flow line or sample chamber that receives a fluid sample and loads it into the NMR magnet. Using an RF probe, spectrometer, and computing device, data processing and interpretation of NMR data from the spectrometer is performed, while also raising a flag when iron contamination exceeds a predefined threshold.

Abstract: The present invention provides a device and a method for measuring fluid saturation in nuclear magnetic resonance (NMR) on-line displacement, the method comprising: measuring a nuclear magnetic resonance (NMR) T2 spectrum under the dead volume filling of the on-line displacement system as displacing phase fluid and the core to be measured as saturated nuclear magnetic detection phase fluid to generate a calibrated T2 spectrum; measuring a nuclear magnetic resonance (NMR) T2 spectrum of a process in which the core to be measured is converted from a saturated displaced phase fluid into a displacing phase fluid to generate a displacement process T2 spectrum; generating the fluid saturation of the on-line displacement system in real time according to the generated calibrated T2 spectrum and the displacement process T2 spectrum. The present invention achieves the purpose of improving measurement precision of fluid saturation in the on-line displacement process.

Abstract: A method (and corresponding system) that characterizes a porous rock sample is provided, which involves subjecting the porous rock sample to an applied experimental pressure where a first fluid that saturates the porous rock sample is displaced by a second fluid, and subsequently applying an NMR pulse sequence to the rock sample, detecting resulting NMR signals, and generating and storing NMR data representative of the detected NMR signals. The application of experimental pressure and NMR measurements can be repeated over varying applied experimental pressure to obtain NMR data associated with varying applied experimental pressure values. The NMR data can be processed using inversion to obtain a probability distribution function of capillary pressure values as a function of NMR property values. The probability distribution function of capillary pressure values as a function of NMR property values can be processed to determine at least one parameter indicative of the porous rock sample.

Abstract: Apparatuses and methods for MRI take advantage of properties of electropermanent magnet module arrays to change the magnetic state of their magnetizable material during a spin echo.

Abstract: A method can include accessing a measurement model in memory of a downhole tool; determining an optimal parameter set using a processor of the downhole tool and the measurement model; and performing at least one measurement using at least one sensor of the downhole tool operated according to the optimal parameter set.

Abstract: Methods and systems are provided for clay detection, clay typing, and clay volume quantification using downhole electromagnetic measurements conducted by a downhole logging tool on a formation at a low frequency less than 5000 Hz. The downhole electromagnetic measurements are used to determine permittivity data that characterizes permittivity of the formation at the low frequency less than 5000 Hz. The downhole low frequency electromagnetic measurements are nondestructive, and the results indicate it is with high sensitivity to the existence of clays.

Abstract: This invention is useful for determining the permeability of a geological formation using 1H NMR diffusion measurements acquired in the laboratory and using downhole 1H NMR well logging. The current technology for obtaining formation permeability downhole using NMR is not adequate for low-permeability, unconventional source rock formations with high organic content. This new method uses laboratory 1H NMR diffusion measurements for creating continuous downhole well logs of the mobile-hydrocarbon permeability of the hydrocarbon-filled pore space of downhole geological formations.

Abstract: A method, a device and a medium for acquiring logging parameters are provided, wherein the logging parameters include gas-bearing porosities, and the method includes: acquiring a two-dimensional nuclear magnetic logging analysis graph; determining a gas-bearing region from the two-dimensional nuclear magnetic logging analysis graph; and summing contour values of the gas-bearing region as a gas-bearing porosity. The device for acquiring logging parameters includes a processor and a computer readable storage medium, wherein instructions are stored in the computer readable storage medium, and the processor executes the instructions to perform the foregoing method for acquiring logging parameters. The medium for acquiring logging parameters stores computer executable instructions, which are used for executing the foregoing method for acquiring logging parameters.

Abstract: A system of field cycled magnetic resonance system and a method of operating a field cycled magnetic resonance system are described. In accordance with various embodiments, the disclosed system includes a static field magnet, wherein the magnet is configured to provide a low static external magnetic field to a given field of view, a radio frequency coil, and a field cycling magnet. In accordance with various embodiments, the method includes providing a static field magnet configured to image a tissue sample within a given field of view, applying a low static external magnetic field to the given field of view, providing a radio frequency coil configured to produce cycling radio frequency field, providing a field cycling magnet, altering the low static external magnetic field within the given field of view, and collecting images from the system.

Abstract: A well sampling apparatus is described herein. The well sampling apparatus includes one or more pressure-activated samplers in a sampling assembly. The samplers are coupled to an activating mechanism that includes a remotely activated local actuator. The remotely activated local actuator is coupled to a pressure source that, when released by the remotely activated local actuator, operates the pressure-activated sample to obtain a sample fluid.

Abstract: Embodiments of the present disclosure are directed towards a method for improving neutron interpretations in a subsurface formation. Embodiments may include estimating mineral concentrations and kerogen concentrations at one or more depths in the subsurface formation and determining kerogen properties at one or more depths in the subsurface formation. Embodiments may further include calculating mineral properties at one or more depths in the subsurface formation and calculating a neutron-based log response to a rock matrix based upon, at least in part, the kerogen properties and the mineral properties at one or more depths in the subsurface formation by subtracting.

Abstract: In some embodiments, a method includes generating at least a first pulse sub-sequence comprising a number of refocusing pulses at a first flip angle and generating at least a second pulse sub-sequence comprising a number of refocusing pulses at a second, lower flip angle. The method further includes detecting, by a nuclear magnetic resonance (NMR) sensor of a logging tool positioned in a wellbore formed in a subsurface formation, NMR spin-echo signals generated in response to at least the first pulse sub-sequence to acquire a first dataset of transversal NMR relaxation data, detecting, by the NMR sensor, NMR spin-echo signals generated in response to at least the second pulse sub-sequence to acquire a second dataset of transversal NMR relaxation data, and determining a property of the subsurface formation based on the first and second datasets of transversal NMR relaxation data.

Abstract: A computer-implemented method for modeling fabrication constraints of a fabrication process is described. The method includes receiving training data including pre-fabrication structures and post-fabrication, training a fabrication constraint model by optimizing parameters of the fabrication constraint model based on the training data to model the fabrication constraints of the fabrication process, receiving an input design corresponding to a physical device, and generating a fabricability metric of the input design via the fabrication constraint model. The fabricability metric is related to a probabilistic certainty that the input design is fabricable by the fabrication process determined by the fabrication constraint model.

Abstract: Systems and methods include a computer-implemented method: Total clay, effective porosity (PHIE) values, and gas volume are determined for a tight gas sandstone reservoir characterization using petrophysical evaluation results. Regions of the tight gas sandstone reservoir are characterized, including performing diagenetic rock typing for the regions using the total clay and PHIE values, where the diagenetic rock typing reflects porosity/permeability and clay content change. Sweet spots are determined based on the diagenetic rock typing and gas volume variation. Ranked sweet spots are determined by indexing and ranking the sweet spots by category. Optimized infill drilling locations and target zones are determined, and well placements in the tight gas sandstone reservoir are assisted using the diagenetic rock typing and the ranked sweet spots.

Abstract: Methods for detection of web application anomalies include receiving, by processors of a web server, web application logs and database logs. A machine learning algorithm is executed by the processors to segment the web application logs and the database logs into clusters based on probability density modeling, such that a variance of features within each cluster is less than a threshold variance. Each cluster corresponds to authorized access of backend databases or unauthorized access of the backend databases. The processors compare each cluster to baseline clusters corresponding to the authorized access of the backend databases. The processors determine that a particular cluster corresponds to the unauthorized access of the backend databases based on the comparison. Responsive to determining that the particular cluster corresponds to the unauthorized access of the backend databases, a display device of the web server generates a graphical user interface representing the particular cluster.

Abstract: System and methods for nuclear magnetic resonance (NMR) fluid substitution are provided. NMR logging measurements of a reservoir rock formation are acquired. Fluid zones within the reservoir rock formation are identified based on the acquired measurements. The fluid zones include water zones comprising water-saturated rock and at least one oil zone comprising rock saturated with multiphase fluids. Water zones having petrophysical characteristics matching those of the oil zone(s) within the formation are selected. NMR responses to multiphase fluids resulting from a displacement of water by hydrocarbon in the selected water zones are simulated. A synthetic dataset including NMR T2 distributions of multiphase fluids is generated based on the simulation. The synthetic dataset is used to train a machine learning (ML) model to substitute NMR T2 distributions of multiphase fluids with those of water. The trained ML model is applied to the NMR logging measurements acquired for the oil zone(s).

Abstract: A method includes generating a temperature-corrected nuclear magnetic resonance (NMR) measurement-derived value corresponding to a target temperature using a correlation model that is based on a difference between the target temperature and a sample temperature. The method also includes determining a formation property based on the temperature-corrected NMR measurement-derived value corresponding to the target temperature.

Abstract: A method and system for resistivity imaging. A method may comprise disposing a downhole tool into a borehole, applying a voltage difference between the array of injector electrodes, constructing a first set of formation images for each of the plurality of frequencies, applying a mud effect removal algorithm to produce a second set of formation images for each of the plurality of frequencies, applying a dielectric correction algorithm to each of the plurality of frequencies to produce a third set of formation images for each of the plurality of frequencies, and combining the first set of formation images, the second set of formation images, and the third set of formation images to obtain a blended image. A system for resistivity imaging may comprise a downhole tool. The downhole tool may comprises a pad, an array of injector electrodes, and one or more return electrodes.

Abstract: A method and a device for performing homonuclear J-coupling spectroscopy on a sample, the method including: a) producing transverse magnetization in the sample by applying an RF excitation pulse at a nuclear magnetic resonance (NMR) frequency; b) after a delay ?, applying a refocusing pulse to the sample; c) performing a step of, applying another refocusing pulse to the sample after a delay 2?, N times, where N ranges from Nmin to Nmax; d) following a final one of the refocusing pulses, acquiring an NMR signal from the sample; and repeating steps a)-c) for different values of N, adjusting ? so that a total time T=2(N+1)? remains constant, where T is a time between a start of the RF excitation pulse and a center or a start of a final one of the NMR signals.

Abstract: A method for calculating a magnetic influence factor (MIF) between an atom and a resonant atom of a molecule of a material includes determining a current magnetic field strength at a test location above a quantity of material buried at the test location, transmitting a test signal from an antenna at the test location, the test signal comprising a test fundamental frequency, and detecting, at the test location, a reflected wave comprising the test fundamental frequency on the antenna. The method includes varying the test fundamental frequency while retransmitting the test signal and detecting a reflected wave until reflected waves of various test frequencies are detected and identifying from the detected reflected waves a resonant frequency corresponding to a maximum magnitude of the detected reflected waves. The material includes molecules with a resonant atom and at least one atom different than the resonant atom.

Abstract: Techniques including methods, apparatus and computer program products are disclosed. These techniques include computer instructions that are encoded on computer storage media for determining wettability. The techniques use a numerical aging computation process to provide a representation of a wettability alteration of a physical rock sample in the presence of at least two fluids is disclosed. The techniques include retrieving a representation of a physical rock sample, the representation including pore space and grain space data corresponding to the physical rock sample, calculating local curvature for each surface in the pore space, determining from the calculated local curvature whether water-film breakage will occur, and classifying the wettability of the physical rock based on the determination of water-film breakage.

Abstract: Sonde devices for providing magnetic field signals for use with utility locators or other devices are disclosed. In one embodiment a sonde device includes a housing, a core comprising a plurality of core sections, and one or more support structures, which may include windings. Circuit and/or power supply elements may be disposed fully or partially within the core to control generation of predefined magnetic field frequencies and waveforms.

Abstract: A method for determining the degree of cure in forages using a nuclear magnetic resonance (NMR) technique. An NMR instrument is used to determine the amount of bound moisture (typically called stem moisture) and free moisture (typically called dew moisture) the degree of which can be used to determine how cured the forage is. This method represents an improvement on the traditional ways of determining how cured a forage is. The traditional ways have been by twisting a bunch of forage in ones hands or using a mechanical method (Hammer of fingernail) to determine if there is too much stem moisture in the stem nodes. The method can be applied using a portable instrument or building the instrument into a forage harvesting machine such as a hay baler.

Abstract: An apparatus (and method) for automated NMR relaxation measurements on borehole materials (e.g., drill cuttings, sidewall cores and whole cores) includes a sample cassette and a sample transfer system operating synchronized with the NMR experiment. The apparatus implements an automatic calibration, adaptive data stacking and automated measurements of the sample volume for irregular shaped samples. The measurements throughput may be increased by creating more than one excitation/detection volume during a measurement cycle. The NMR surface data may be interpreted together with other bulk sensitive measurement data (e.g. natural gamma ray spectroscopy) or/and downhole data to evaluate earth formations while drilling an oil well.

Abstract: A method for measuring a gradient field of a nuclear magnetic resonance (NMR) system based on a diffusion effect uses a non-uniform field magnet, an NMR spectrometer, a radio frequency (RF) power amplifier, an RF coil, and a standard quantitative phantom with known apparent diffusion coefficient (ADC) and time constant for decay of transverse magnetization after RF-pulse (T2). A plurality of sets of signals are acquired by an NMR sequence with different diffusion-sensitive gradient durations or different echo spacings and the magnitude of the gradient field is calculated by fitting based on the plurality of sets of signals. The method does not require an additional dedicated magnetic field detection device, has a short measurement time, is easy to use with the NMR system, and is convenient to complete gradient field measurement at the installation site, thereby improving the installation and service efficiency of the NMR system.

Abstract: A porosity model of a core sample obtained from a subterranean formation is determined. The porosity model includes a macroporosity group and a microporosity group. A nuclear magnetic resonance (NMR) measurement is performed to obtain an NMR T2 distribution of the core sample at 100% water saturation. A desaturation step is performed on the core sample. An NMR measurement is performed for the desaturation step to obtain an NMR T2 distribution of the core sample. A resistivity index of the subterranean formation is determined at least based on the porosity model and each of the NMR T2 distributions.

Abstract: In a method for reducing the amount of ambient radio frequency electromagnetic and pulsating magnetic fields (“electrosmog”), resonance circuit units placed in a predetermined environment are energized by radio frequency electromagnetic and pulsating magnetic field energy transmitted to the resonance circuits by an electromagnetically connected antenna, at least a portion of energy is consumed as resonance circuit loss, reducing the amount of the ambient fields. An apparatus implementing the method comprises passive resonance circuits formed by an antenna comprising logarithmic spiral coils with identical or different pitches and passive resonance circuits formed by opposite logarithmic spiral coil panels, the resonance circuits are connected to each other and to the antenna by electrically conductive spacers, a shielding metal plate connected to ground potential is arranged adjacent to the antenna, latter is coaxial with the resonance circuit panels, which are also connected to each other via a supply line.

Abstract: Methods and systems are disclosed for determining a material property transition within a wellbore. In some embodiments, a method includes determining a material transition profile for each of a plurality of test points within a linear measurement path including, for each test point, determining an acoustic response for a first location within the linear measurement path, and determining an acoustic response for a second location within the linear measurement path. The test point is between the first and second locations. The method further includes generating a material transition profile for the test point based, at least in part, on a difference between the acoustic response at the first location and the acoustic response at the second location.

Abstract: A rock fabric classification for modeling subterranean formation includes receiving petrophysical properties from a core analysis of a core sample from a wellbore, receiving a core description of the core sample, the core description comprising sedimentological properties of the core sample, determining one or more groups of core samples with similar sedimentological properties and similar core descriptions, determining bounds for each of the one or more groups, providing the bounds and an identifier of each of the one or more groups, as input to a model for petrophysical rock typing or saturation modeling.

Abstract: A nuclear magnetic resonance (NMR) logging system and method is disclosed. The method may include obtaining an NMR well log, a measured downhole temperature, and at least one rock sample for a formation in a subsurface region. The method may further include determining an NMR distribution for each sample and selecting a set of samples based on the determined NMR distribution. For each selected sample, the method may further include determining a first parameter of the NMR distribution, a regression parameter of a relationship, and a first and second fractal parameters of the NMR distribution. The method may further include determining a second parameter of the NMR distribution based on the first and second fractal parameters, the regression parameter, and the downhole temperature. The method may still further include determining a parameter of the formation based on the second parameter of the NMR distributions of the set of samples.

Abstract: A method for predicting formation permeability by measuring diffusional tortuosity in several directions by pulse gradient NMR. The method comprises evaluating an anisotropic diffusion coefficient by pulsed gradient NMR, determining diffusional tortuosity from the restricted diffusion data, supplementing the NMR results with resistivity and sonic logging data, measuring anisotropic tortuosity and porosity by resistivity and sonic data and combining all components in a single fitting model. The 11-coefficient model is trained to recognize the true values of permeability by comparing the real oil permeabilities measured in a library of oil-carrying rock cores with the NMR, resistivity and sonic correlates. The fitting coefficients are extracted by minimizing the discrepancy between the laboratory measured permeabilities and the predicted values combining all rapid logging information components with the agreement-maximizing weights.

Abstract: A method for evaluating drilling fluid includes making an NMR measurement of a sample of the drilling fluid and inverting the measurements to compute a corresponding T1T2 plot. The T1T2 plot is in turn evaluated to characterize the drilling fluid. In one embodiment, a stability index of the fluid may be computed from multiple NMR measurements made while aging the sample.

Abstract: A nuclear magnetic resonance (NMR) sensor and methods and systems for use are provided. The method comprises disposing a nuclear magnetic resonance (NMR) sensor into a borehole, the NMR sensor comprising a magnet assembly to create a static magnetic field and a first transversal-dipole antenna having an azimuthally selective response function. The method further comprises, while rotating the NMR sensor, initiating azimuthally selective NMR excitation in at least one sensitivity region at a first frequency using the first transversal-dipole antenna and the magnet assembly, wherein the at least one sensitivity region is determined by the static magnetic field and the RF magnetic field. The method then comprises acquiring one or more azimuthally selective NMR signals at the first frequency using the first transversal-dipole antenna.

Abstract: A non-transitory computer-readable recording medium stores a learning program that causes a computer to execute a process including: extracting, from a plurality of data groups, a plurality of first data groups having an order; generating, for each data element corresponding to each of the first data groups, an ordered data matrix in which data elements having same order have value corresponding to relationship among the data elements and data elements having different orders have values corresponding to the different orders; and obtaining input tensor data by performing tensor decomposition with the ordered data matrix, inputting the input tensor data to a neural network at time of performing deep machine learning, performing deep machine learning of the neural network, and learning about method for the tensor decomposition.

Abstract: 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.

Abstract: Systems and methods include a computer-implemented method for characterizing low-permeability reservoirs by using numerical models. A numerical model modeling production of a well is prepared using reservoir data and well data. The numerical model is updated, including adjusting numerical model properties, until results of performing a quality assurance/quality control check indicate that the numerical model is within acceptable limits. Pressure derivatives are extracted from a transient test to create a functional numerical model. Simulations are run on the functional numerical model and reservoir features and properties are adjusted until acceptable results are achieved on: 1) a pressure match between pressures modeled in the functional numerical model and transient pressures of the well, and 2) a log-log plot derivative match between a pressure derivative of the functional numerical model and a pressure derivative of the transient pressures of the well.

Abstract: An apparatus for performing a nuclear magnetic resonance (NMR) measurement in a borehole penetrating a subsurface formation includes an NMR tool having an outside diameter that is less than an inside diameter of a drill tubular disposed in the borehole, the drill tubular having an opening at the distal end of the drill tubular leading into the borehole, and a retaining device configured to allow at least a section of the NMR tool to protrude through the opening of the drill tubular and prevent an unrestrained release of the NMR tool through the opening. The apparatus also includes a transmitter antenna and a receiver antenna coupled to the NMR tool, wherein the transmitter antenna and/or the receiver antenna are extendable from the NMR tool.

Abstract: In an embodiment is provided a method of determining at least one property of a fluid that includes inducing a paramagnetic response from at least one diamagnetic species flowing through a system, the fluid including the at least one diamagnetic species; performing electron paramagnetic resonance (EPR) spectroscopy on at least a portion of the fluid to generate an EPR spectrum; and determining at least one property of the fluid based on the EPR spectrum. In another embodiment is provided a method of determining at least one property of a first fluid that includes introducing an inhibitor composition to a first fluid flowing through a system to form a second fluid; performing EPR spectroscopy on at least a portion of the second fluid to generate an EPR spectrum; and determining at least one property of the second fluid based on the EPR spectrum. Apparatus for determining fluid properties are also provided.

Abstract: A nuclear magnetic resonance (NMR) tool includes an antenna assembly and a magnet assembly. The NMR tool also includes a motional sensor comprising at least one radio frequency (RF) antenna disposed about a tool axis and about at least a portion of the magnet assembly, in which the motional sensor is operable to generate readings for lateral motion of the antenna assembly and the magnet assembly. The at least one RF antenna has a soft magnetic core and a coil winding disposed around the soft magnetic core. The motional sensor can determine a one-dimensional NMR image indicating a lateral displacement of the NMR tool based on one or more spatial positions of NMR excitation volumes in the region of interest that correspond to respective excitation frequencies in the at least one RF antenna.

Abstract: Echo signals are acquired from operation of a nuclear magnetic resonance logging (NMR) tool in a borehole. A multi-inversion process is performed on the echo signals. The multi-inversion process includes a downhole processor performing a downhole inversion. The multi-inversion process includes reconstructing echoes from coefficients in the downhole inversion. Reconstructing echoes is performed by one of the downhole processor or an uphole processor. The multi-inversion process includes transmitting one of: (a) the coefficients in the downhole inversion or (b) the reconstructed echoes to the uphole processor. The multi-inversion process includes the uphole processor performing an uphole inversion on the reconstructed echoes to produce final coefficients used in a spectrum.

Abstract: Echo signals are acquired from operation of a nuclear magnetic resonance logging (NMR) tool in a borehole. The acquired echo signals are processed with respect to an inversion of each matrix in a plurality of matrices, wherein each matrix in the plurality of matrices accounts for motion of the NMR tool at a respective rate of penetration (ROP) of the NMR tool in the borehole, to produce respective spectrum coefficients for each ROP. Each spectrum is processed with respect to the respective matrices in the plurality of matrices to produce a test echo signal for each ROP. The acquired echo signals and the test echo signal for each ROP are processed to produce an error for each ROP. The ROP for the minimum of the errors is identified as the ROP of the NMR tool.

Abstract: A nuclear magnetic resonance (NMR) tool for use in a subterranean region, the NMR tool comprising a magnet assembly to produce a magnetic field in a volume in the region, an antenna assembly to produce an excitation in the volume, and to receive NMR signals from the volume, and an acquisition system coupled to the antenna assembly and configured to acquire a first NMR signal using a first acquisition window having a first duration, and acquire a second NMR signal using a second acquisition window having a second duration, wherein the second duration is different than the first duration, and a processor coupled to the acquisition system and configured to determine a lateral displacement of the NMR tool as a function of time based on the first and second NMR signals, and apply the lateral displacement to the first NMR signal to generate NMR relaxation data with reduced motion effects.

Abstract: A method and system for interspersing different wait times in trainlet and partial recovery sequences is provided. The method includes introducing a nuclear magnetic resonance (NMR) tool into a wellbore penetrating a subterranean formation. The method also includes applying an NMR pulse sequence to the subterranean formation using the NMR tool, in which the NMR pulse sequence includes at least two different wait times interspersed between successive sequences of radio frequency (RF) pulses. The method also includes measuring one or more echo signals corresponding to a substance in the subterranean formation based on the applied NMR pulse sequence. The method also includes determining a distribution of a characteristic of the substance based on the measured one or more echo signals.

Abstract: A system having an NMR measurement device make measurements on a region of investigation in which an NMR-active fluid has been injected. A source of the NMR-active fluid (e.g., methane) is provided, and the pressure of the region of investigation may be monitored. A sealing apparatus serves to isolate the region of investigation. A parameter is estimating using the obtained measurement. The parameter estimated may include the inter-granular porosity, intra-kerogen porosity, kerogen maturity, free gas volume, and/or adsorbed gas volume. A baseline measurement may be made prior to injecting the NMR-active fluid, and the region of investigation may be evacuated before injecting the NMR-active fluid. The obtained T2 distribution can be resolved and each peak attributed to different constituent sources of the signal. The system can be conveyed into a wellbore using a drillstring, a wireline, a slickline, or a coil tubing.

Abstract: A method for determining pore size distribution of rocks is provided. Capillary pressure measurements on rock cores are analyzed to determine a pore size distribution, with smaller pores requiring greater capillary pressure to relinquish contained fluid. Large pores with rough surfaces introduce inaccuracies in determining the pore size distribution. Embodiments of the invention correct the rough surface induced inaccuracies by measuring the shift in NMR T2 distribution from full saturation to the current state of desaturation and subtracting the T2 contributions in the desaturated state that have smaller T2 values (i.e., smaller transverse relaxation time) than the smallest T2 values (i.e., shortest transverse relaxation time) in the saturated distribution.