A method for combining nuclear magnetic resonance (NMR) analysis and digital rock physics (DRP) analysis based on drilling cuttings or other rock samples for improved downhole nuclear magnetic resonance validation and characterisation. A system for performing the method also is provided.

A method includes disposing a downhole tool having a magnet assembly into a wellbore. The method includes generating, using the magnet assembly, a magnetic polarization in a volume into a subterranean region about the wellbore. The method also includes emitting an excitation in the magnetic polarization in the volume in the subterranean region. The method includes detecting, by at least one antenna, a nuclear magnetic resonance response to the excitation of the volume in the subterranean region. The method also includes determining a property of the subterranean region based on the nuclear magnetic resonance response.

A method includes disposing a downhole tool having a magnet assembly into a wellbore. The method includes generating, using the magnet assembly, a magnetic polarization in a volume into a subterranean region about the wellbore. The method also includes emitting an excitation in the magnetic polarization in the volume in the subterranean region. The method includes detecting, by at least one antenna, a nuclear magnetic resonance response to the excitation of the volume in the subterranean region. The method also includes determining a property of the subterranean region based on the nuclear magnetic resonance response.

A method for detecting net relative motion between a nuclear magnetic resonance (NMR) tool and a specimen includes disposing the NMR tool and the specimen in sensory range of one another, causing the NMR tool to make NMR measurements of the specimen, and processing the NMR measurements to detect net relative motion between the NMR tool and the specimen.

A method for detecting net relative motion between a nuclear magnetic resonance (NMR) tool and a specimen includes disposing the NMR tool and the specimen in sensory range of one another, causing the NMR tool to make NMR measurements of the specimen, and processing the NMR measurements to detect net relative motion between the NMR tool and the specimen.

Systems and method for nuclear magnetic resonance (NMR) well logging use an inversion pulse sequence with a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence to improve spin magnetization calculations. Improved Bloch equation-based calculations consider conditions where a longitudinal relaxation time and a transverse relaxation time of the hydrogen nuclei (e.g., of a subterranean hydrocarbon pool and/or water) are within an order of magnitude of pulse durations for the inversion pulse sequence and the CPMG pulse sequence. Accordingly, an NMR response to the inversion pulse sequence and the CPMG pulse can be detected and used to calculate one or more spin magnetization values with higher accuracy amplitudes. Reservoir characteristics are determined based on the one or more spin magnetization values. As such, improved well operations (e.g., selecting a drilling site, determining a drilling depth, and the like) can be performed.

Systems and method for nuclear magnetic resonance (NMR) well logging use an inversion pulse sequence with a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence to improve spin magnetization calculations. Improved Bloch equation-based calculations consider conditions where a longitudinal relaxation time and a transverse relaxation time of the hydrogen nuclei (e.g., of a subterranean hydrocarbon pool and/or water) are within an order of magnitude of pulse durations for the inversion pulse sequence and the CPMG pulse sequence. Accordingly, an NMR response to the inversion pulse sequence and the CPMG pulse can be detected and used to calculate one or more spin magnetization values with higher accuracy amplitudes. Reservoir characteristics are determined based on the one or more spin magnetization values. As such, improved well operations (e.g., selecting a drilling site, determining a drilling depth, and the like) can be performed.

A vibration detection apparatus applied to a nuclear magnetic resonance while drilling instrument, including a vibration table. The vibration table is configured to horizontally clamp the nuclear magnetic resonance while drilling instrument and further includes a graduated barrel that contains a detection liquid; the graduated barrel is configured to be suspended at the upper side of the vibration table and be spaced apart from the nuclear magnetic resonance while drilling instrument; when the vibration table performs vibration, the graduated barrel keeps stationary, and the nuclear magnetic resonance while drilling instrument preforms high-pressure emission and measurement by means of the graduated barrel. Therefore, the nuclear magnetic resonance while drilling instrument can obtain the echo signal of the graduated barrel during vibration, thereby more accurately detecting the performance thereof and shortening a detection time length.

A vibration detection apparatus applied to a nuclear magnetic resonance while drilling instrument, including a vibration table. The vibration table is configured to horizontally clamp the nuclear magnetic resonance while drilling instrument and further includes a graduated barrel that contains a detection liquid; the graduated barrel is configured to be suspended at the upper side of the vibration table and be spaced apart from the nuclear magnetic resonance while drilling instrument; when the vibration table performs vibration, the graduated barrel keeps stationary, and the nuclear magnetic resonance while drilling instrument preforms high-pressure emission and measurement by means of the graduated barrel. Therefore, the nuclear magnetic resonance while drilling instrument can obtain the echo signal of the graduated barrel during vibration, thereby more accurately detecting the performance thereof and shortening a detection time length.

Methods to operate an NMR tool, methods to simulate a numerically-controlled oscillator of an NMR tool in real time, and downhole NMR tools are presented. A method to operate an NMR tool includes determining a phase shift of a sinusoidal wave, determining a number of look-up tables and a number of terms of Taylor Expansions performed to obtain a value corresponding to a phase angle of the phase shift, and separating the phase angle into a first component and a second component. The method also includes obtaining a first value corresponding to the first component from the number of look-up tables, performing the number of terms of Taylor Expansions on the second component to obtain a second value corresponding to the second component, combining the first value and the second value to obtain the value of the phase angle, and generating the sinusoidal wave having the phase shift.