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: Measurements of a core sample at scales of measurement that differ by multiple orders of magnitude can be used to calculate a value that fairly represents surface roughness of the core sample. This surface roughness value can be used to determine petrophysical properties of the subsurface formation from which the core sample was obtained. The measurements can be nuclear magnetic resonance (NMR) diffusion-relaxation and gas-adsorption measurements. Surface relaxivities at the different scales are determined from the measurements and a ratio those surface relaxivities can be used to calculate the surface roughness value.

Abstract: The present disclosure is directed to a method of determining wettability characteristics of a sub-surface formation within a wellbore utilizing nuclear magnetic resonance (NMR) and bulk fluid measurements at various stages of fluid saturation at that wellbore location. In another aspect, the pumping pressure is incrementally changed within the wellbore, measuring injection fluid and hydrocarbon saturation data values between the incremental pump pressure changes. In another aspect, a measuring and sampling tool is disclosed to execute the method and produce wettability characteristics. In another aspect, a system is disclosed that can operate NMR devices, bulk fluid equipment, pump systems, and other devices to collect data and to determine wettability characteristics on the collected data.

Abstract: Measurements of a core sample at scales of measurement that differ by multiple orders of magnitude can be used to calculate a value that fairly represents surface roughness of the core sample. This surface roughness value can be used to determine petrophysical properties of the subsurface formation from which the core sample was obtained. The measurements can be nuclear magnetic resonance (NMR) diffusion-relaxation and gas-adsorption measurements. Surface relaxivities at the different scales are determined from the measurements and a ratio those surface relaxivities can be used to calculate the surface roughness value.

Abstract: The present disclosure is directed to a method of determining wettability characteristics of a sub-surface formation within a wellbore utilizing nuclear magnetic resonance (NMR) and bulk fluid measurements at various stages of fluid saturation at that wellbore location. In another aspect, the pumping pressure is incrementally changed within the wellbore, measuring injection fluid and hydrocarbon saturation data values between the incremental pump pressure changes. In another aspect, a measuring and sampling tool is disclosed to execute the method and produce wettability characteristics. In another aspect, a system is disclosed that can operate NMR devices, bulk fluid equipment, pump systems, and other devices to collect data and to determine wettability characteristics on the collected data.

Abstract: Disclosed are NMR logging methods and antenna arrangements for fast moving NMR logging tools. The NMR logging tool includes a permanent magnet for inducing a static magnetic field in a formation within a borehole and a transmitter antenna for transmitting a RF pulse sequence into the formation. Two receiver antennae are configured to receive NMR response signals from the formation, the two receiver antennae including a first receiver antenna arranged axially below a second receiver antenna. The first receiver antenna and the second receiver antenna are disposed within a surface area of the transmitter antenna, and the transmitter axial length is substantially the same as an axial length of the two receiver antennae.

Abstract: An electromagnet model or models are created to generate the static and radio frequency magnetic fields of an NMR downhole logging tool. The magnetic field distributions are then used in spin dynamics (SD) simulations to model the impacts of various effects on NMR logging data, effects that cannot be accurately describe by theoretical formulation alone. The accuracy of the electromagnetic model and the SD simulation may be verified against experimental observations or trial logging runs. Simulation of electronic circuit, molecular diffusion, tool motion can all be incorporated in the SD simulation. The NMR data inversion process can be modified according to echoes obtained from SD simulation to obtain more accurate petrophysical parameters.

Abstract: A method and system for nuclear magnetic resonance (NMR) sequence for partially polarized echo trains is provided. An NMR pulse sequence is applied into a wellbore penetrating a subterranean formation using a NMR tool. The NMR pulse sequence includes a first cycle and a second cycle. The first cycle includes a first sequence of radio frequency (RF) pulses of a first duration and a first trainlet sequence of a second duration different from the first duration. The second cycle includes a second sequence of RF pulses of the first duration and a second trainlet sequence of the second duration. The second sequence of RF pulses forms a phase alternated pair with the first sequence of RF pulses. Echo signals corresponding to a substance in the subterranean formation are measured based on the NMR pulse sequence. A distribution of a characteristic of the substance is determined based on the echo signals.

Abstract: Disclosed are NMR logging methods and antenna arrangements for fast moving NMR logging tools. The NMR logging tool includes a permanent magnet for inducing a static magnetic field in a formation within a borehole and a transmitter antenna for transmitting a RF pulse sequence into the formation. Two receiver antennae are configured to receive NMR response signals from the formation, the two receiver antennae including a first receiver antenna arranged axially below a second receiver antenna. The first receiver antenna and the second receiver antenna are disposed within a surface area of the transmitter antenna, and the transmitter axial length is substantially the same as an axial length of the two receiver antennae.

Abstract: A nuclear magnetic resonance (NMR) logging tool configured to be positioned in a borehole created in a subsurface formation. The NMR logging tool includes a magnet to induce a magnetic field in the subsurface formation, a transmission line, and a first shield positioned between the magnet and the transmission line. The NMR logging tool includes a transmitter and an antenna coupled to the transmitter by the transmission line. The antenna is to transmit a radio frequency (RF) magnetic field into the subsurface formation in response to the transmitter supplying power by the transmission line.

Abstract: A logging instrument for estimating a property of a formation is provided. The instrument includes a magnet to generate a magnetic field. The instrument also includes pulse sequencer circuitry that supplies radio frequency (RF) signals. The instrument additionally includes an antenna system configured to transmit the RF signals and to obtain nuclear magnetic resonance (NMR) measurements of the formation in response to the transmitted RF signals. In one aspect, the logging tool contains a temperature sensor configured to obtain temperature measurements of the magnet. The instrument additionally includes a control unit communicatively coupled to the temperature sensor, the antenna system and the pulse sequencer circuitry and configured to receive the temperature measurements and selectively adjust operating parameters of the pulse sequencer circuitry based on the received temperature measurements in order to maintain optimal intensity of the magnetic field.

Abstract: A subterranean characterization and fluid sampling device for analyzing a fluid from a subterranean formation includes a controller, a tool body, and a probing module. The tool body includes a fluid testing module configured to receive a sample of the fluid from the subterranean formation and a permanent magnet configured to induce a static magnetic field (B0). The probing module is coupled to the tool body and separate from the permanent magnet, and configured to withdraw the fluid from the formation and deliver the fluid to the testing module. The probing module comprises an antenna that generates a radio frequency magnetic field (B1) in response to a signal from the controller.

Abstract: NMR tools are described having unidirectional magnetization throughout the magnet assembly. An antenna assembly is positioned around the magnet assembly in order to excite a volume in the surrounding subterranean formation. A layer of soft magnetic core material is positioned under the antenna assembly in order to shield all or most of the RF field generated by the RF antenna away from the conductive components inside the NMR tool. The conductive components may be conductive structural members or a conductive magnet assembly. The soft magnetic core material also shapes the static magnetic field by smoothing out the longitudinal magnetic field variation.

Abstract: A side-looking Nuclear Magnetic Resonance (“NMR”) logging tool is designed to reduce and/or eliminate a borehole signal. The logging tool includes a magnet assembly having at least two magnets with magnetizations in different directions, thus resulting in a net magnetization that reduces the borehole signal.

Abstract: An electromagnet model or models are created to generate the static and radio frequency magnetic fields of an NMR down-hole logging tool. The magnetic field distributions are then used in spin dynamics (SD) simulations to model the impacts of various effects on NMR logging data, effects that cannot be accurately describe by theoretical formulation alone. The accuracy of the electromagnetic model and the SD simulation may be verified against experimental observations or trial logging runs. Simulation of electronic circuit, molecular diffusion, tool motion can all be incorporated in the SD simulation. The NMR data inversion process can be modified according to echoes obtained from SD simulation to obtain more accurate petrophysical parameters.

Abstract: A method and system for nuclear magnetic resonance (NMR) sequence for partially polarized echo trains is provided. An NMR pulse sequence is applied into a wellbore penetrating a subterranean formation using a NMR tool. The NMR pulse sequence includes a first cycle and a second cycle. The first cycle includes a first sequence of radio frequency (RF) pulses of a first duration and a first trainlet sequence of a second duration different from the first duration. The second cycle includes a second sequence of RF pulses of the first duration and a second trainlet sequence of the second duration. The second sequence of RF pulses forms a phase alternated pair with the first sequence of RF pulses. Echo signals corresponding to a substance in the subterranean formation are measured based on the NMR pulse sequence. A distribution of a characteristic of the substance is determined based on the echo signals.

Abstract: A nuclear magnetic resonance (NMR) sensor including a magnet that generates a static magnetic field, a soft magnetic core secured to the magnet, and an antenna extending at least partially about the soft magnetic core and generating a radio frequency (RF) magnetic field. A magnetic permeability of the soft magnetic core in a direction of the static magnetic field is less than the magnetic permeability of the soft magnetic core in a direction of the RF magnetic field.

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 method and system for downhole, real-time determination of relative permeability with nuclear magnetic resonance and formation testing measurements is provided. The method includes introducing a nuclear magnetic (NMR) tool and a formation testing tool into a well bore penetrating a subterranean formation. The method also includes measuring a saturation of a fluid in the subterranean formation from the NMR tool, measuring a mobility of the fluid from the formation testing tool, and measuring a viscosity of the fluid. The method includes calculating a relative permeability of the subterranean formation based on the measured saturation, the measured viscosity and the measured mobility. The method also includes providing a reservoir production prediction metric based on the calculated relative permeability of the subterranean formation for facilitating a well completion operation in the wellbore.

Abstract: Logging-while-drilling (LWD) tools may include multiple instruments interleaved into a compact configuration in a single drill string section that may be capable of nuclear magnetic resonance, resistivity, porosity, gamma density measurements, or any combination thereof. For example, a LWD tool may include a drill collar section containing: a nuclear magnetic resonance (NMR) electronics module and an NMR sensor module interleaved with a nuclear source and at least one nuclear detector.