The invention relates to the technical field of oilfield exploration, and discloses a 4D quantitative and intelligent diagnosis method and system for spatio-temporal evolution of oil-gas reservoir damage types and extent. The method includes: determining a characteristic parameter characterizing reservoir damage by each of a plurality of factors based on a spatio-temporal evolution simulation equation of reservoir damage by each of the plurality of factors; and determining an effective characteristic parameter characterizing the damage extent of the reservoir based on the characteristic parameter characterizing reservoir damage rby each of the plurality of factors. The invention can quantitatively simulate the characteristic parameters of reservoir damage caused by the various factors and a total characteristic parameter of the reservoir damage. Therefore for a well without reservoir damage, performing quantitative prediction of reservoir damage and spatio-temporal deduction of damage laws is of scientific guidance significance for preventing reservoir damage, and formulating development plans for oil pools and subsequent well stimulation measures, and for a well with reservoir damage, also performing quantitative diagnosis of reservoir damage and spatio-temporal deduction of damage laws achieves optimal design of a declogging measure and improvement or restoration of oil-gas well production and water well injection capacity.

A computer-implemented method includes receiving a plurality of sensor signals, each signal of the plurality of sensor signals being tagged with an associated time and depth. The method also includes selecting a baseline signal. The method further includes comparing a selected sensor signal, of the plurality of sensor signals, to the baseline signal. The method also includes determining a difference between the baseline signal and the selected sensor signal exceeds a threshold. The method includes identifying, based at least in part on the difference, a feature of interest associated with the selected sensor signal.

Downhole monitoring systems are described. The systems include a downhole string disposed in a borehole, the string having a downhole tool and the borehole has fluid therein. A sacrificial electrical sensor element is arranged in or on the string. The sacrificial electrical sensor element includes magnetic material at least partially exposed to the fluid and at least one coil arranged in magnetic communication with the magnetic material. A controller is configured to provide an electrical current into the coil, measure an electrical property of the coil that is based on the magnetic material in magnetic communication with the coil, and determine a wear state of the downhole tool based on the measured electrical property.

A method can include energizing a tube with a longitudinally extending magnetic field generated inside the tube, using a magnetic field-detecting logging tool to generate magnetic flux signals generated inside the tube externally of the material of the tube wall resulting from such energizing at circumferential locations on the inner surface of the tube and at distances along the tube, iteratively using a model of the relationship between the generated magnetic flux signals and the thickness of the tube wall to derive a thickness profile of the tube wall by using (i) the magnetic permeability of the tube material deduced from the magnetic flux signals and (ii) a defect-free flux parameter representative of any non-linearity between the magnetic field strength and flux density in the tube, the iteration including using the model to calculate an initial approximate wall thickness profile using an initial estimate of the defect-free flux parameter.

A tool including a dispersive spectrometer deployable within a wellbore is provided. The dispersive spectrometer includes a waveguide layer to detect electromagnetic radiation according to wavelength. The dispersive spectrometer also includes a plurality of detector elements disposed along the waveguide layer to detect electromagnetic radiation associated with a portion of the wavelength of the electromagnetic radiation. A method for using the tool in a subterranean application is also provided.

A system may include an electromagnetic (EM) logging tool for inspecting downhole tubulars. The EM logging tool may include a mandrel, at least one low-frequency transmitter coil disposed on the mandrel, at least one-low frequency receiver coil disposed on the mandrel, and at least one-high frequency sensor configured to measure one or more electromagnetic properties of a tubular.

A method may include obtaining caliper log data regarding a well. The method may further include determining, using a descaling model and the caliper log data, various predicted caliper log values for a descaled well. The descaled well may correspond to the well following a scale treatment. The method may further include determining whether the descaled well satisfies a predetermined criterion based on the predicted caliper log values. The method may further include determining, in response to determining that the descaled well fails to satisfy the predetermined criterion, a tubular replacement for the well. The method may further include transmitting, to a control system, a command that implements the tubular replacement.

A system may include an electromagnetic (EM) logging tool for inspecting downhole tubulars. The EM logging tool may include a mandrel, at least one low-frequency transmitter coil disposed on the mandrel, at least one-low frequency receiver coil disposed on the mandrel, and at least one-high frequency sensor configured to measure one or more electromagnetic properties of a tubular.

A system for inspecting a tubular may comprise an electromagnetic (EM) logging tool and information handling system. The EM logging tool may further include a mandrel, one or more sensor pads attached to the mandrel by one or more extendable arms, and one or more partial saturation eddy current sensors disposed on each of the one or more sensor pads.

A method and system for estimating parameters of pipes. The method may comprise disposing an electromagnetic (EM) logging tool into a pipe string, creating a log from a first set of one or more measurements, and creating a synthetic model of one or more nested pipes based at least in part on a well plan. The method may further comprise adding a modeled pipe to the synthetic model, estimating one or more parameters of the modeled pipe through model calibration to form a calibrated model, and performing an inversion with the calibrated model to estimate one or more pipe parameters of the pipe string. The system may comprise an electromagnetic logging tool that may comprise a transmitter, wherein the transmitter is a first coil and is operable to transmit an electromagnetic field, and a receiver, wherein the receiver is a second coil and is operable to measure the electromagnetic field.