摘要:
A multicoil NMR detection and imaging apparatus allows multicoil NMR detection and imaging to be performed efficiently at low operating frequencies. The apparatus comprises an AC voltage generator, a transmit switching circuit, a coil switching network, an array of two or more detection coils, a set of receive switching circuits with one switching circuit for each detection coil, and a set of preamplifier circuits with input impedance substantially greater than the impedance of each respective detection coil at the intended operating frequency. The AC generator produces an alternating current waveform that is routed through one of more detection coils during transmit mode while the preamplifier circuits are isolated from the detection coil(s). During receive mode the AC generator is isolated from the detection coils to prevent noise from the transmitter from degrading the quality of received signals.
摘要:
Technologies applicable to noise canceling in-situ NMR detection and imaging are disclosed. An example noise canceling in-situ NMR detection apparatus may comprise one or more of a static magnetic field generator, an alternating magnetic field generator, an in-situ NMR detection device, an auxiliary noise detection device, and a computer.
摘要:
Technologies including NMR logging apparatus and methods are disclosed. Example NMR logging apparatus may include surface instrumentation and one or more downhole probes configured to fit within an earth borehole. The surface instrumentation may comprise a power amplifier, which may be coupled to the downhole probes via one or more transmission lines, and a controller configured to cause the power amplifier to generate a NMR activating pulse or sequence of pulses. Impedance matching means may be configured to match an output impedance of the power amplifier through a transmission line to a load impedance of a downhole probe. Methods may include deploying the various elements of disclosed NMR logging apparatus and using the apparatus to perform NMR measurements.
摘要:
NMR relaxation time estimation methods and corresponding apparatus generate two or more alternating current transmit pulses with arbitrary amplitudes, time delays, and relative phases; apply a surface NMR acquisition scheme in which initial preparatory pulses, the properties of which may be fixed across a set of multiple acquisition sequence, are transmitted at the start of each acquisition sequence and are followed by one or more depth sensitive pulses, the pulse moments of which are varied across the set of multiple acquisition sequences; and apply processing techniques in which recorded NMR response data are used to estimate NMR properties and the relaxation times T1 and T2* as a function of position as well as one-dimensional and two-dimension distributions of T1 versus T2* as a function of subsurface position.
摘要:
Technologies applicable to detection and characterization of subsurface contaminants by NMR and dielectric measurements are disclosed. The disclosed technologies include methods for obtaining and combining data from NMR and dielectric measurements to detect, quantify, and characterize non-native non-aqueous phase liquid (NAPL) contaminants located in geologic materials.
摘要:
Technologies applicable to NMR detection of water and hydrocarbons during induced alteration processes are disclosed. NMR measurements may be used to monitor properties of subsurface fluids within a subsurface formation. NMR measurement devices may be deployed proximal to or within a subsurface formation that contains hydrocarbons. Multiple NMR measurements may be performed during an induced alteration process applied to the subsurface formation to determine properties of the subsurface formation or fluid as the induced alteration process progresses. Changes in properties of the subsurface formation or fluid may be determined and may be used to determine efficacy of, optimize, or otherwise modify the induced alteration process.
摘要:
Technologies applicable to noise canceling in-situ NMR detection and imaging are disclosed. An example noise canceling in-situ NMR detection apparatus may comprise one or more of a static magnetic field generator, an alternating magnetic field generator, an in-situ NMR detection device, an auxiliary noise detection device, and a computer.
摘要:
Technologies applicable to detection and characterization of subsurface contaminants by NMR and dielectric measurements are disclosed. The disclosed technologies include methods for obtaining and combining data from NMR and dielectric measurements to detect, quantify, and characterize non-native non-aqueous phase liquid (NAPL) contaminants located in geologic materials.
摘要:
Nuclear Magnetic Resonance (NMR) measurement apparatus, NMR sensors, NMR measurement methods are disclosed to determine NMR properties of engineered flow management structures, and to estimate engineering properties using determined NMR properties. Example engineered flow management structures include engineered water storage, water management, water production, water sampling structures, and/or structures that serve as conduits or barriers to water movement. Technologies disclosed herein are also applicable to measuring properties relating to other fluid and/or gas flow in engineered flow management structures.
摘要:
Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety of phase cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and undesired signals are canceled.