A method for a multichannel geophysical data acquisition system is provided in the field of electrical resistivity tomography. Individual and autonomous node operating systems are provided. Separate communication channels for upstream and downstream data transfer, high voltage transfer and synchronization signals are provided. A novel use of high voltage isolation barriers is also provided. A direct memory access data transfer process is provided.

Described are systems, devices, and methods for processing Eddy-current response signals acquired in a set of multiple nested pipes, such as, e.g., nested casing strings within a completed wellbore. In various embodiments, time boundaries between time slots within the Eddy-current response signals are determined adaptively based on an input response signal specific to the nested pipes (e.g., one of the measured signals itself). Additional embodiments are disclosed.

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 a multichannel geophysical data acquisition system is provided in the field of electrical resistivity tomography. Individual and autonomous node operating systems are provided. Separate communication channels for upstream and downstream data transfer, high voltage transfer and synchronization signals are provided. A novel use of high voltage isolation barriers is also provided. A direct memory access data transfer process is provided.

A method for a multichannel geophysical data acquisition system is provided in the field of electrical resistivity tomography. Individual and autonomous node operating systems are provided. Separate communication channels for upstream and downstream data transfer, high voltage transfer and synchronization signals are provided. A novel use of high voltage isolation barriers is also provided. A direct memory access data transfer process is provided.

The invention relates to a system for monitoring a substratum (1) with regard to damage and/or for protecting a substratum (1) from damage. The system comprises: an electrolytically active layer (4), which has a moisture-dependent electrical resistance; at least one electrode pair, the spaced-apart electrodes (3a, 3b) of which are connected to each other by means of the electrolytically active layer (4); and a measuring device, by means of which a property, in particular an electrical quantity of the electrolytically active layer (4) or of the electrodes (3a, 3b), can be measured by using electrodes (3a, 3b) of at least one electrode pair, in particular of each electrode pair, and/or a control device, by means of which a voltage can be applied to the electrodes (3a, 3b) of at least one electrode pair, in particular of each electrode pair. At least one of the electrodes (3a, 3b) of the at least one electrode pair is designed as a planar electrode in the electrolytically active layer (4), in particular the plane of said at least one electrode is oriented parallel to the surface of the substratum (1). The invention further relates to a method for producing a system for monitoring and/or for protecting a substratum, to a method for monitoring a substratum with regard to damage, and to a method for protecting a substratum from damage, in particular moisture damage and/or damage as a result of the penetration of harmful substances.

Methods, systems, and computer program products use current leakage rates to evaluate the resistivity of a subterranean formation around a drilling well in conjunction with a ranging operation. The evaluation entails obtaining a current distribution along a section of the drilling well as part of a ranging measurement. The current distribution allows the current leakage rate to be determined along that section of the drilling well. Multiple current leakage rates may then be determined along the drilling well to produce a leakage rate curve that may be matched with modeled or known leakage rate curves to estimate the formation resistivity around the drilling well. Formation resistivity may also be calculated from the current distribution using an appropriate equation. The ability to obtain a current distribution along a section of the drilling well as part of a ranging measurement allows formation resistivity to be evaluated in conjunction with ranging operations.

Methods, systems, and computer program products use current leakage rates to evaluate the resistivity of a subterranean formation around a drilling well in conjunction with a ranging operation. The evaluation entails obtaining a current distribution along a section of the drilling well as part of a ranging measurement. The current distribution allows the current leakage rate to be determined along that section of the drilling well. Multiple current leakage rates may then be determined along the drilling well to produce a leakage rate curve that may be matched with modeled or known leakage rate curves to estimate the formation resistivity around the drilling well. Formation resistivity may also be calculated from the current distribution using an appropriate equation. The ability to obtain a current distribution along a section of the drilling well as part of a ranging measurement allows formation resistivity to be evaluated in conjunction with ranging operations.

A magnetic flux measurement apparatus and method for nondestructive thickness imaging of metallic objects. The apparatus can primarily be used for thickness imaging of concentric metallic pipes, such as inner tubing and outer casing pipes in downhole applications. The magnetic flux measurement apparatus includes a transducer that includes a magnetic field source, magnetic flux sensor rings and a magnetic flux guide lens both positioned in alignment with a lateral axis of the magnetic field source. The magnetic flux guide lens is made of ferromagnetic material with high magnetic permeability that can direct flux lines into a predetermined sensor area for higher sensitivity and signal to noise ratio.