Systems and methods of the present disclosure relate to processing nuclear magnetic resonance (NMR) data. An NMR downhole tool may include a housing, magnets disposed within the housing, an antenna extending along a circumference of the housing, and an information handling system configured to receive NMR signals via the antenna, wherein the NMR signals are based on an operating frequency, a static magnetic field B.sub.0, and a radio frequency (RF) field B.sub.1, which are defined by the antenna and the magnets. The information handling system may be further configured to project the NMR signals to a forward modeling space, and transmit vectors resulting from projecting the NMR signals to the forward modeling space.

A system for acquiring directional information about a geologic formation includes at least one directionally sensitive nuclear magnetic resonance (NMR) assembly disposed at a borehole string including the downhole component. The at least one NMR assembly includes at least one magnet configured to generate a static magnetic field and at least one coil configured to generate an oscillating magnetic field, the at least one NMR assembly configured to perform an NMR measurement of at least one sector of a formation region. The system also includes a processing device configured to receive NMR measurement data from the at least one NMR assembly. The processing device is configured to analyze the NMR measurement data to estimate a parameter of the sector, determine a direction of the downhole component based on the estimated parameter; and steer the downhole component according to the determined direction.

A distributed device and method for detecting groundwater based on nuclear magnetic resonance are provided. The device includes an excitation apparatus, multiple polarization apparatuses, an aerial reception apparatus, and a control apparatus. The aerial reception apparatus includes an array cooled coil sensor. For each of the multiple polarization apparatuses, a position analysis module determines, together with a second position analysis module of the polarization apparatus, a position of the array cooled coil sensor relative to a polarization coil in the polarization apparatus. A polarization transmitter in the polarization apparatus switches to a mode of waiting for output in a case that the array cooled coil sensor is in coverage of the polarization coil. The polarization transmitter in the polarization apparatus remains in a standby mode in a case that the array cooled coil sensor is beyond coverage of the polarization coil.

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.

An NMR logging system is disclosed which continues logging without interruption despite switching activation sets to adapt to changes in formation properties. Based on detection of an approaching or encountered geological boundary, an appropriate activation set is transmitted to the downhole NMR tool while the NMR tool continues logging. This system optimizes NMR data collection for each formation and associated formation fluid properties while reducing the need to stop the tool string movement while switching the activation set, and reduces incomplete collection of NMR and non-NMR logging tool data.

An NMR measurement apparatus includes a transmitting antenna including a transmitter coil, a capacitor, a dissipating component and a restricting component, and a receiving antenna physically separated from the transmitting antenna. A processor is configured to apply a drive signal at a first voltage level to generate a transmission signal having a selected transmission frequency, where the receiving antenna is deactivated during generation, connect the dissipating component to the transmitter coil to dissipate stored energy in the transmitter coil, connect the restricting component to the transmitter coil to restrict the transmitting antenna to a second voltage level smaller than the first voltage level and based on a voltage of NMR signals from the sensitive volume, activate the receiving antenna and detect a NMR signal, where the restricting component is connected to the transmitter coil and restricts the transmitting antenna during the activating and the detecting.

Techniques for analyzing a sample include preparing a sample; circulating a gel solution through the sample to saturate the sample; scanning the saturated sample with a nuclear magnetic resonance (NMR) system to determine two or more NMR values of the saturated sample; determining a permeability of the saturated sample based, at least in part, on the two or more NMR values of the saturated sample; aging the saturated sample; scanning the aged sample with the NMR system to determine two or more NMR values of the aged sample; determining a permeability of the aged sample based, at least in part, on the two or more NMR values of the aged sample; comparing the determined permeability of the saturated sample against the determined permeability of the aged sample; and based on the compared permeabilities, determining a gel solution syneresis rate.

A method may include obtaining first nuclear magnetic resonance (NMR) data for a saturated core sample regarding a geological region of interest. The method may further include determining, using the first NMR data, spatial porosity data based on the saturated core sample. The spatial porosity data may describe various porosity values as a function of a sampling position of the saturated core sample. The method may further include obtaining second NMR data for a desaturated core sample regarding the geological region of interest. The method may further include determining, using the second NMR data, spatial permeability data based on the desaturated core sample. The method may further include determining a geological model for the geological region of interest using the spatial porosity data, the spatial permeability data, and a fitting process.

Disclosed is a characterization method of closed pores and connectivity of coal measure composite reservoirs, including collecting samples of coal seams and shales reservoirs, carrying out low-field NMR experiments and NMR freeze-thaw experiments on plunger samples and crushed samples with different particle sizes to obtain cumulative pore volume distribution and differential pore size distribution of the crushed samples, comparing crushed samples with plunger samples for optimal crushed particle sizes, and preliminarily determining a distribution range of closed pores; carrying out SAXS experiments on crushed samples to obtain size distribution and volume of total pores of 1-100 nanometers; calculating pore volume of total pores and closed pore volume in composite reservoirs by low-field NMR experiments results; carrying out non-steady overburden permeability experiments and variable factors on plunger samples of coal seams, shales and tight sandstone to characterize the connectivity under influence of pores development and lithologic combinations.

A method for estimating an effect on nuclear magnetic resonance (NMR) measurements of an invasion of solid particles into pores of an earth formation penetrated by a borehole includes conveying a carrier through the borehole and performing an NMR measurement on a volume of interest in the formation to provide a relaxation time constant using an NMR tool disposed at the carrier. The method further includes receiving information describing the solid particles in the pores and quantifying, using a processor, an effect on the measured relaxation time constant due to the invasion of solid particles using the received information.