Method and device for obtaining noise-reducing NMR (Nuclear Magnetic Resonance) logging echo signal

Abstract

The invention provides a method and device for obtaining a noise-reducing NMR (Nuclear Magnetic Resonance) logging echo signal. The method comprises the following steps: a received NMR logging echo signal can be converted into a digital echo signal by an AD (Analog-to-Digital) converting unit; the digital echo signal is subjected to delay processing by a delay module, and thus a delayed digital echo signal can be obtained; the delayed digital echo signal is subjected to filter processing by an FIR (Finite Impulse Response) filter, and thus a filtered echo signal can be obtained; the filtered echo signal is subjected to FFT (Fast Fourier Transform) processing by an FFT unit, and thus a frequency domain filtered echo signal can be obtained; the frequency domain filtered echo signal is subjected to phase correction by a phase correction unit according to the digital echo signal obtained by a counter, and thus a phase correction filtered echo signal can be obtained; and the phase correction filtered echo signal is subjected to IFFT (Inverse Fast Fourier Transform) processing by an IFFT unit, and thus the noise-reducing NMR logging echo signal can be obtained. According to the scheme, the problem of phase drift generated in a filtering process is removed.

Description

technical field [0001] The invention relates to nuclear magnetic resonance logging technology, in particular to a method and device for obtaining noise-reduced nuclear magnetic resonance logging echo signals. Background technique [0002] In the field of oil exploration, low-field NMR (Nuclear Magnetic Resonance, NMR) is often submerged in noise due to the low magnetic field strength and weak spin echo signals. In order to obtain an ideal spin echo signal, the acquired spin echo signal must be de-noised. [0003] At present, a filtering technique is generally used to perform noise reduction processing on the spin echo signal. Adaptive Line Enhancement (ALE) technology based on adaptive filtering is a new and effective noise reduction processing method. In the adaptive filter design of ALE, no external reference signal can be utilized. Due to the obvious period of the narrowband signal and the poor periodicity of the broadband noise, the correlation function of the narrowb...

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Problems solved by technology

[0004] The present invention provides a method and device for obtaining noise-reducing nuclear magnetic resonance logging echo signals, which are used to solve the problem of echo signal phase drift existing in the existing adaptive spectral line enhancement filtering technology

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