A system and method for monitoring a wellbore are disclosed herein. A pulse generator comprises a plurality of ports, wherein a first one of the plurality of ports is coupled to a first location of interest and a second one of the plurality of ports is coupled to a second location of interest. An electromagnetic pulse is generated at the first port and the second port. A reflected electromagnetic pulse is received at the first port and the second port. In another embodiment, the pulses are received at a separate pulse receiver with a plurality of receiving ports. A data storage device is coupled to the pulse generator or the pulse receiver, and data relating to the reflected magnetic pulse is stored at the data storage device.

Downhole nuclear magnetic resonance (NMR) methods that utilize oleophilic nanoparticle may allow for differentiation of light oil and oil-based filtrates. For example, a method may involve drilling a wellbore penetrating a subterranean formation using an oil-based drilling fluid that comprises an oil base fluid and a plurality of oleophilic nanoparticles; performing a plurality of NMR measurements at a plurality of depths of investigation (DOI) of a near-wellbore portion of the subterranean formation; and producing an invasion profile of an oil-based drilling fluid filtrate into the near-wellbore portion of the subterranean formation based on the plurality of NMR measurements.

Downhole nuclear magnetic resonance (NMR) methods that utilize oleophilic nanoparticle may allow for differentiation of light oil and oil-based filtrates. For example, a method may involve drilling a wellbore penetrating a subterranean formation using an oil-based drilling fluid that comprises an oil base fluid and a plurality of oleophilic nanoparticles; performing a plurality of NMR measurements at a plurality of depths of investigation (DOI) of a near-wellbore portion of the subterranean formation; and producing an invasion profile of an oil-based drilling fluid filtrate into the near-wellbore portion of the subterranean formation based on the plurality of NMR measurements.

This disclosure includes a current sensor configured to detect a signal current in a drilling system component of a drilling system, a telemetry system, and a method for detecting a signal current. The current sensor includes a magnetic body, at least one field coil positioned on the magnetic body, and at least one drive coil positioned on the magnetic body. The at least one field coil configured to detect a first magnetic field that passes within the magnetic body that is induced by the signal current carried by the drill system component when the current sensor is positioned in proximity to the drilling system component. The at least one drive coil configured to generate a second magnetic field. The current sensor is configured to modulate the second magnetic field such the at least one field coil detects the modulated magnetic field.

This disclosure includes a current sensor configured to detect a signal current in a drilling system component of a drilling system, a telemetry system, and a method for detecting a signal current. The current sensor includes a magnetic body, at least one field coil positioned on the magnetic body, and at least one drive coil positioned on the magnetic body. The at least one field coil configured to detect a first magnetic field that passes within the magnetic body that is induced by the signal current carried by the drill system component when the current sensor is positioned in proximity to the drilling system component. The at least one drive coil configured to generate a second magnetic field. The current sensor is configured to modulate the second magnetic field such the at least one field coil detects the modulated magnetic field.

Acoustic imaging tools and methods use refracted wave amplitudes to generate borehole images, thereby providing a method and tool that is highly sensitive to borehole discontinuities.

Acoustic imaging tools and methods use refracted wave amplitudes to generate borehole images, thereby providing a method and tool that is highly sensitive to borehole discontinuities.

A method for signal communication between a well drilling instrument and the Earth's surface includes generating an electromagnetic field in an instrument disposed in drill string used to drill a wellbore. The electromagnetic field comprises encoded measurements from at least one sensor associated with the instrument. A signal is measured corresponding to an amplitude, phase or frequency of the electromagnetic field. The measurements are decoded from the measured signal. The measured signal comprises at least one of a voltage imparted across a capacitive electrode proximate ground surface and a galvanic electrode in contact with the ground surface, and a voltage imparted across two capacitive electrodes each proximate a ground surface and separated from each other by a known distance.

Examples described herein provide a computer-implemented method for deriving textual properties of a reservoir formation. The method includes acquiring multi-frequency dielectric data (ε.sub.meas). The method further includes applying a dielectric mixing model between different fluid phases to generate an effective fluid permittivity (ε.sub.fluid) by mixing the permittivity of water and hydrocarbon fluids. The method further includes applying the dielectric mixing model between the effective fluid permittivity (ε.sub.fluid) and a matrix permittivity (ε.sub.m). The method further includes minimizing a difference between a measured dielectric response and the dielectric mixing model by optimizing model parameters. The method further includes computing a cementation exponent (m) and a saturation exponent (n) from the multi-frequency dielectric data (ε.sub.meas). The method further includes estimating a formation property based at least in part on the cementation exponent (m) and the saturation exponent (n). A wellbore operation is controlled based at least in part on the formation property.

Examples described herein provide a computer-implemented method for deriving textual properties of a reservoir formation. The method includes acquiring multi-frequency dielectric data (ε.sub.meas). The method further includes applying a dielectric mixing model between different fluid phases to generate an effective fluid permittivity (ε.sub.fluid) by mixing the permittivity of water and hydrocarbon fluids. The method further includes applying the dielectric mixing model between the effective fluid permittivity (ε.sub.fluid) and a matrix permittivity (ε.sub.m). The method further includes minimizing a difference between a measured dielectric response and the dielectric mixing model by optimizing model parameters. The method further includes computing a cementation exponent (m) and a saturation exponent (n) from the multi-frequency dielectric data (ε.sub.meas). The method further includes estimating a formation property based at least in part on the cementation exponent (m) and the saturation exponent (n). A wellbore operation is controlled based at least in part on the formation property.