807 results about "Transient electromagnetics" patented technology

A transmitter antenna assembly for transient electromagnetic well logging instrument comprises an antenna coil coupled with a current source and a magnetic core having residual magnetization. Switching current in the antenna coil results in magnetization reversal in the magnetic core and change in magnetic dipole moment of the antenna. After the magnetization reversal is complete the current is removed and the new vector of magnetic dipole of the antenna maintains constant (steady-state phase of the antenna dipole) due to magnetic hysteresis of magnetic material employed for the magnetic core. No power expenditure during the steady-state phase of the magnetic dipole facilitates highly effective generation and fast switching of a large magnetic dipole. The magnetic core also serves as a shield between the antenna coil and any conductive part of the antenna assembly. Embodiments suitable for measurement-while-drilling or measurements through casing make use of residual magnetization of magnetic drill collar or magnetic casing respectively.

A transmitter system for inducing a transient electromagnetic field in an earth formation comprises an inductive element to generate an electromagnetic field in response to a flow of electric current through the inductive element. Furthermore, switching means arranged to interrupt the flow of electric current through the inductive element, which switching means comprises a primary switch and an auxiliary switch arranged in series connection with each other. The auxiliary switch has a lower breakdown voltage than the primary switch. This induces a transient electromagnetic field in the earth formation. Delay circuitry may impose a time delay between switching of the auxiliary switch relative to switching of the primary switch. A transient electromagnetic response signal may be recorded, and used in a method of producing a mineral hydrocarbon fluid.

A pulsed eddy current sensor probe includes a sensor array board. A number of sensors are arranged on the sensor array board and are operable to sense and generate output signals from the transient electromagnetic flux in a part being inspected. Each of the sensors has a differential output with a positive and a negative output. At least one drive coil is disposed adjacent to the sensors and is operable to transmit transient electromagnetic flux into the part. A first and a second multiplexer are arranged on the sensor array board and are operable to switch between the sensors. The first and second multiplexers are connected to the positive and negative outputs of the sensors, respectively.

A method, apparatus and system that employs particles, e.g., nanoparticles, and an electric or electro-magnetic field, to cause electroporation in target cells at reduced fields. Electroporation may be irreversible, leading to targeted cell death, or reversible, allowing species to be introduced into the target cell. The method introduces a particle to a position adjacent to the cell membrane of a target cell and exposes the target cell to a transient electromagnetic field for a time interval to cause targeted electroporation. A smaller electric field is applied, thereby surmounting similar methods. The particle enhances the effect of the electric field in its immediate vicinity, so reducing the field strength needed to achieve electroporation and thereby reducing the risk of damage to cells through high field exposure. Electroporation can be targeted to a subset of target cells by targeting the particles to surface markers on the target cell membrane.

A transmitter on a bottomhole assembly (BHA) is used for generating a transient electromagnetic signal in an earth formation. A receiver on the BHA receives signals that are indicative of formation resistivity and distances to bed boundaries. A combination of electromagnetic shielding and magnetostatic shielding enables determination of distance to an interface ahead of the drillbit.

Structure for deep MWD resistivity measurements suitable for both geo-steering and measurements ahead of the drill bit is disclosed. The structure is capable of extracting information about resistivity of formation in the presence of conductive drill. In one embodiment, ahead-of-bit sensing is achieved via transient electromagnetic measurements when current is switched off in the transmitter loop and the transient signal is measured in the receiver loops placed at some distances from the receiver. To reduce a parasitic effect of the currents in the drill three-coil bucking system with magnetic nonconductive shield in combination with a highly conductive copper shield are applied. Specifically, a short (less than 1 m) copper cover and short (less than 0.2 m) ferrite cover are placed in the vicinity of transmitting and receiving coils. A bucking operation followed by an inversion is performed on received signals to obtain data reflecting parameters of the surrounding subsurface formations.

A transmitter on a bottomhole assembly (BHA) is used for generating a transient electromagnetic signal in an earth formation. A pair of receivers on the BHA receive signals that are indicative of formation resistivity and distances to bed boundaries. A time dependent calibration factor or a time-independent calibration factor may be used to combine the two received signals and estimate the distance to bed boundaries that are unaffected by the drill conductive body. Further improvement can be obtained by using copper shielding.

The invention discloses a transformer electromagnetic vibration noise calculating method based on the finite element method. The transformer electromagnetic vibration noise calculating method comprises the steps of 1, establishing a structured grid model and an acoustics grid model according to a three-dimensional geometrical model of a transformer; 2, conducting transient electromagnetic simulation on the structured grid model to obtain transient electromagnetic force waves borne by each phase winding and an iron core; 3, conducting FFT on the transient electromagnetic force waves borne by each phase winding and the iron core to obtain the frequency domain distribution of electromagnetic force borne by each phase winding and the iron core; 4, conducting harmonic response analysis on the structured grid model to obtain the vibration displacement data of nodes on the surfaces of the windings and the iron core; 5, conducting sound field calculation on the acoustics grid model to obtain the radiation noise distribution of the transformer. According to the transformer electromagnetic vibration noise calculating method, all noise influence factors are considered, and calculation results are accurate and reliable. The transformer electromagnetic vibration noise calculating method can be used for winding short circuit vibration deformation analysis and the like and can also provide method and basis for motor noise analysis.

A transient electromagnetic borehole system uses an arrangement of sensors deployed in a borehole for reservoir monitoring. Non-conductive casing sections may be used along with an efficient transmitter configured to provide measurements up to 300 m from the borehole. By using multiple receivers, the method can also be used without nonconductive casing.

A three-coil bucking system is used for determination of a formation resistivity property ahead of the drill bit. The conductive drill pipe is provided with non-conductive inserts in the proximity of at least one transmitter and at least two receivers. Transient electromagnetic signals are processed to give the estimate of the resistivity property and for geosteering.

A transverse induction transmitter on an instrument induces currents in an earth formation when it is pulsed. Transient measurements made at transverse and axial receivers are used for determination of a distance to a bed boundary. This may be used to control the drilling direction. Alternatively, a transmitter on an instrument having a conductive body induces currents in the earth formation. Transient signals are measured and the effect of the conductive body is removed by using a reference signal measured in a homogenous space.

The invention provides a long-lead source transient electromagnetic ground-air detecting method which comprises the following steps of: detecting a deep geologic target body by a working device adopting a long-lead source transient electromagnetic terra-air detecting method to obtain transient electromagnetic observing data; converting the transient electromagnetic observing data into transient electromagnetic virtual wave data and obtaining a transient electromagnetic synthetic aperture data volume by adopting a multipoint data synthesis method to finish data reserve for carrying out fine explanation on the deep geologic target body; and obtaining a transient electromagnetic synthetic aperture imaging profile by adopting a Kirchhoff offset imaging method and a speed modeling method and processing and explaining the transient electromagnetic synthetic aperture data volume to finish fine detection on the deep geologic target body and obtain the information of the deep geologic target body. The long-lead source transient electromagnetic ground-air detecting method can be used for carrying out accurate exploration on the deep geologic target body, thereby obtaining the accurate and detailed geologic information of the deep geologic target body so as to achieve the aim of searching various deep geologic target bodies.

The invention discloses a geophysical exploration device and the method which combines the nuclear magnetic resonance and the transient electromagnetism. First to select the coupled device in the transient electromagnetism mode, and it lays the emission loop and the receiving loop to detect every measuring point in the detecting section and treat the transient electromagnetism data to find the low electrical resistivity point; then it changes to the nuclear magnetic resonance mode and lays the emission loop using the demarcated abnormal detecting point as the center, so it compares the detected data or the figure with the resistivity detected by the transient electromagnetism to judge the true or false of the detected resistivity. The invention can decrease the device cost and improve the detecting efficient and the precision.

The invention relates to an electrical source transient electromagnet ground-air detection method. The electrical source transient electromagnet ground-air detection method comprises the steps that a long grounding wire is adopted as an emitting source, and a helicopter or an unmanned aerial vehicle carries a receiving coil for data collection; observation data are processed according to a full-domain apparent resistivity method, qualitative interpretation on deep geological targets is finished, and profile information such as the attitude, extending direction and scale of the geological targets is obtained; ground-air data are interpreted and processed according to a transient electromagnetic wave field transform method, a three-dimensional migration imaging technology and an inverse synthetic aperture method, fine detection of the deep targets is finished, and detailed information such as the depth, shape and electrical structures of the deep geological structure is obtained. The electrical source transient electromagnet ground-air detection method can achieve electromagnetic detection rapidly on a large scale, the deep geological targets can be detected in a detailed mode, and the accurate and detailed geological information of the deep geological targets can be obtained.

An array of induction magnetometers for use in airborne transient electromagnetic (ATEM) geophysical exploration is disclosed, having similar weight and external dimensions of prior art induction magnetometers but with improved signal strength, signal-to-noise ratio, higher frequency, self-resonance and bandwidth, and providing accurate and well monitored calibration.

The present invention belongs to the coal mining geophysical prospecting technical field, relates to a transient electromagnetic stack advanced detection device and method, in particular, a coal mine underground roadway transient electromagnetic stack advanced detection device and method. According to the device and method of the invention, a probe is arranged in a borehole, so that the probe can be far away from interference sources such as metal machineries in a roadway, and therefore, the influence of the interference sources can be avoided; the hole drilling conditions of a coal mine tunneling face are fully utilized, so that inside-roadway coil emission and inside-borehole three-component receiving can be realized; and a receiving device can move towards a direction before the tunneling face, and therefore, various kinds of the interference of the metal machineries at the tunneling face can be avoided without affecting the tunneling work of a mine party, and the advanced detection data of a plurality of positions in the borehole can be subjected to stack processing, and processing results can be displayed, and thus, hidden water damage geological bodies before the tunneling face can be predicted at an extra long distance.

The invention relates to a transient electromagnetic logging instrument which comprises a shell, a circuit module and an electromagnetic probe system, wherein the circuit module is arranged in the shell, and the electromagnetic probe system is connected with the circuit module. The circuit module is sequentially connected with a power voltage regulator module, a PWM (pulse width modulation) module, a high-power isolating transformer bank and a power conversion module through a direct-current power supply to form a direct-current power supply circuit and a main control circuit taking a digital signal processor as a core, and a communication bus, a power bus, a control bus and a data bus are arranged on the periphery of the main control circuit. The electromagnetic probe system comprises a transmitting coil and a plurality of receiving coils, wherein the transmitting coil is provided with a magnetic core. The instrument detects casing damage and effectively measures the formation resistivity of an open hole well and a cased well in a non-contact mode. High-power transient excitation is realized by the aid of internal iron cores of the coils, the excitation intensity of a transient electromagnetic field is improved, and the formation resistivity is finally obtained by necessarily graduating and processing measured original signals.

A pulsed eddy current two-dimensional sensor array probe for electrically conducting component inspection includes a drive coil disposed adjacent to a structure under inspection, a pulse generator connected to the drive coil and operable to energize in a pulsed manner the drive coil to transmit transient electromagnetic flux into the structure under inspection, and an array of sensors arranged in a two-dimensional array and substantially surrounded by the drive coil and operable to sense and generate output signals from the transient electromagnetic flux in the structure under inspection.

The invention provides a method for detecting a whole field with an electrical source transient electromagnetic method. The method concretely comprises the following steps of: carrying out deep exploration on a deep geologic target body by adopting a detecting method of an electrical source transient electromagnetic method under the condition of a near field source to obtain observation data; andprocessing and explaining the observation data by adopting a transient electromagnetic whole field theory to finish the fine exploration for the deep geologic target body and obtain the information of the deep geologic target body. The method for detecting the whole field with the electrical source transient electromagnetic method can be used for rapidly, efficiently and accurately realizing the three-dimensional exploration for the deep geologic target body, thereby obtaining the information of the finer deep geologic target body.