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: Methods and systems for the extraction of a formation fluid sample using a fluid extraction tool including an elongated body and a sealing pad extending therefrom, the sealing pad having an opening for establishing fluidic communication between an earth formation and the elongated body. The sealing pad communicable with from a container holding a selective permeability agent (SPA) capable of modifying the permeability of one or more fluids within the formation. The container coupled with a device for injecting the SPA into the earth formation and extracting a formation fluid sample therefrom.

Abstract: Methods, devices, and systems for tracking lateral motion of a nuclear magnetic resonance (NMR) tool are disclosed. In some embodiments, a phase shift for one or more spin-echo signals received by the NMR tool is detected during a velocity measurement sequence that corresponds to at least one formation measurement sequence. A lateral velocity of the NMR tool is determined based, at least in part, on the detected phase shift.

Abstract: Pressure coring where the core apparatus drills the core sample and seals the core sample at its native downhole pressure (e.g., several thousand psi) may be expanded to include nuclear magnetic resonance (NMR) imaging components to produce a pressurized NMR core holder that allows for NMR imaging of the core samples having been maintained in a downhole fluid saturation state. NMR imaging performed may include 1H and also 19F imaging depending on the chamber fluid used in the pressurized NMR core holder.

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: 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.

Abstract: Methods, devices, and systems for tracking lateral motion of a nuclear magnetic resonance (NMR) tool are disclosed. In some embodiments, a phase shift for one or more spin-echo signals received by the NMR tool is detected during a velocity measurement sequence that corresponds to at least one formation measurement sequence. A lateral velocity of the NMR tool is determined based, at least in part, on the detected phase shift.

Abstract: A method includes generating a temperature-corrected nuclear magnetic resonance (NMR) measurement-derived value corresponding to a target temperature using at least one of a dimension-reduction operation or a parameter-correlation operation 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 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.

Abstract: Pressure coring where the core apparatus drills the core sample and seals the core sample at its native downhole pressure (e.g., several thousand psi) may be expanded to include nuclear magnetic resonance (NMR) imaging components to produce a pressurized NMR core holder that allows for NMR imaging of the core samples having been maintained in a downhole fluid saturation state. NMR imaging performed may include 1H and also 19F imaging depending on the chamber fluid used in the pressurized NMR core holder.

Abstract: A subterranean characterization and fluid sampling device includes a tool body, a probing module, and a permanent magnet. The tool body includes a fluid testing module configured to retain a fluid sample and an internal radio frequency coil disposed within the tool body and drivable to generate RF magnetic field B2. The probing module is coupled to the tool body and configured to withdraw the fluid sample from a formation and deliver the fluid sample to the fluid testing module. The probing module comprises an external antenna drivable to generate RF magnetic field B1. The permanent magnet induces static magnetic field B0. The permanent magnet is coupled to the tool body and external to the probing module.

Abstract: Nuclear magnetic resonance (NMR) method, system, and sensing device for downhole measurements. The NMR device for characterizing a subterranean zone includes a tool body, a magnetic element, and a radio frequency coil. The tool body includes an uphole end and a downhole end, where a longitudinal axis extends through the uphole end and downhole end. The magnetic element is located within the tool body and generates a static magnetic field (B0) in a longitudinal direction at a region of the subterranean zone. The radio frequency coil is located within the tool body and generates a radio frequency magnetic field (B1). The magnetic element and the radio frequency coil enable a side-looking NMR mode.

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 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: Nuclear magnetic resonance methods may be used to determine the porosity and the pore type of subterranean formations while accounting for fluid infiltration from the drilling mud or mud filtrate thereof into the formation. For example, the apparent porosity of (1) a shallow sensitive volume (?sh) and (2) a deep sensitive volume (?deep) may be measured. Then, a comparison of the ?sh and the ?deep may be performed, and the porosity (?) of a portion of the subterranean formation may be calculated based on the comparison of the ?sh and the ?deep.

Abstract: A formation evaluation system reduces inversion matrixes used to determine formation properties, thereby increasing the memory management and processing efficiency of the evaluation system. NMR data is acquired from a wellbore and expressed mathematically by the system as a least squares solution to a linear system. The least squares solution is approximated using a numerical decomposition method and the evaluation system determines a formation property using the approximated least squares solution. Thereafter, a downhole operation may be planned, analyzed or conducted using the determined formation property.

Abstract: A nuclear magnetic resonance device for subterranean characterization includes a tool body, a peripheral measurement device, and a controller. The tool body includes a permanent magnet located therein, permanent magnet inducing a static magnetic field (B0) in a region of interest. The peripheral measurement device is coupled to the tool body. The measurement device includes a radio frequency coil controllable to generate a radio frequency magnetic field (B1) in the region of interest, receive a response signal, or both. The controller is communicatively coupled to the radio frequency coil and controllable to drive the radio frequency coil, process the response signal, or both.

Abstract: Various embodiments include a method for generating a pulse for use in nuclear magnetic resonance (NMR) logging. One such method generates the pulse by adjusting one or more of pulse parameters including a pulse shape, a pulse amplitude, a pulse phase, and/or a pulse frequency. The generated pulse produces a substantially uniform nuclear spin saturation or nuclear spin inversion response from a fluid. A wait time between the pulse transmission and an echo that indicates spin equilibrium has been achieved is substantially equal to a T1 time indicating characteristics of the fluid.

Abstract: A subterranean characterization and fluid sampling device includes a tool body, a probing module, and a permanent magnet. The tool body includes a fluid testing module configured to retain a fluid sample and an internal radio frequency coil disposed within the tool body and drivable to generate RF magnetic field B2. The probing module is coupled to the tool body and configured to withdraw the fluid sample from a formation and deliver the fluid sample to the fluid testing module. The probing module comprises an external antenna drivable to generate RF magnetic field B1. The permanent magnet induces static magnetic field B0. The permanent magnet is coupled to the tool body and external to the probing module.