A system for imaging material, typically in an underground scenario, comprising of a plurality of conductive electrodes supported on a conductive substrate positionable in an environment to be imaged, a signal generator connected to at least two of the electrodes, and a signal detector connected to at least two of the electrodes, and wherein an impedance compensator is arranged between each electrode and its substrate to counter parasitic impedance between the two. Typically the impedance compensator may be arranged to act as a negative capacitance, which may be approximately equal to any capacitance between the electrode and the substrate. An electrode may be a drive electrode coupled to a signal generator, or a detector electrode coupled to a detector, or may be reconfigurable to act as either one.

A system for imaging material, typically in an underground scenario, comprising of a plurality of conductive electrodes supported on a conductive substrate positionable in an environment to be imaged, a signal generator connected to at least two of the electrodes, and a signal detector connected to at least two of the electrodes, and wherein an impedance compensator is arranged between each electrode and its substrate to counter parasitic impedance between the two. Typically the impedance compensator may be arranged to act as a negative capacitance, which may be approximately equal to any capacitance between the electrode and the substrate. An electrode may be a drive electrode coupled to a signal generator, or a detector electrode coupled to a detector, or may be reconfigurable to act as either one.

A method for magnetic ranging includes switching an electromagnet deployed in a target wellbore between at least first and second states and acquiring a plurality of magnetic field measurements at a magnetic field sensor deployed on a drill string in a drilling wellbore while the electromagnet is switching. The magnetic field measurements may be sorted into at least first and second sets corresponding to the first and second states of the electromagnet. The first and second sets of magnetic field measurements are then processed to compute at least one of a distance and a direction from the drilling well to the target. The electromagnet may be automatically switched back and forth between the first and second states independently from the acquiring and sorting of the magnetic field measurements.

A method for magnetic ranging includes switching an electromagnet deployed in a target wellbore between at least first and second states and acquiring a plurality of magnetic field measurements at a magnetic field sensor deployed on a drill string in a drilling wellbore while the electromagnet is switching. The magnetic field measurements may be sorted into at least first and second sets corresponding to the first and second states of the electromagnet. The first and second sets of magnetic field measurements are then processed to compute at least one of a distance and a direction from the drilling well to the target. The electromagnet may be automatically switched back and forth between the first and second states independently from the acquiring and sorting of the magnetic field measurements.

Some examples of transferring data from a subsurface of a wellbore using well fluids include positioning multiple data recording devices at a subsurface location in a wellbore. When a well fluid flows through the wellbore past the subsurface location to a surface, each data recording device is configured to receive and store data describing subsurface wellbore conditions at or near the subsurface location. At least a portion of the data describing the subsurface wellbore conditions are stored on each data recording device. Each data recording device is released from the subsurface location. The well fluid flows each data recording device to the surface.

Some examples of transferring data from a subsurface of a wellbore using well fluids include positioning multiple data recording devices at a subsurface location in a wellbore. When a well fluid flows through the wellbore past the subsurface location to a surface, each data recording device is configured to receive and store data describing subsurface wellbore conditions at or near the subsurface location. At least a portion of the data describing the subsurface wellbore conditions are stored on each data recording device. Each data recording device is released from the subsurface location. The well fluid flows each data recording device to the surface.

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.

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.

A method for sensing a condition of a hydrocarbon reservoir from a subterranean well having a lined section with a liner and an unlined section includes attaching an electric current sensor to the liner proximate to a lower end of the lined section and a plurality of electromagnetic sources located along the unlined section. The electromagnetic sources are activated independently and the resulting current induced in the liner by each electromagnetic source is measured with the electric current sensor. These measurements can be inverted to determine the spatial distribution of the electric conductivity within the reservoir and its changes in time due to fluid substitution during production. Alternatively, a fast and robust method for interpretation of the data is presented for early detection and location of a possible water front approaching the production well.

A system to measure a streaming potential of a core plug includes a measurement cell having a chamber to hold the core plug and an inlet fluid line connected to an inlet port of the measurement cell. A filtration device is arranged to control a salinity and ionic strength of a liquid medium received in the chamber through the inlet fluid line. The filtration device has membrane filters with different ion rejection rates and is controllable to selectively dispose each of the membrane filters in the inlet fluid line.