Method and system for measuring rock attenuation coefficient

Abstract

The embodiment of the invention provides a method and a system for measuring a rock attenuation coefficient. The system comprises an opening container, a vibration source, a resonance chamber, a hydrophone, a phase-lock amplifier and an upper computer, wherein the opening container is used for containing a solution used as a sound bearing medium; the vibration source is used for generating a sound wave signal for driving the system to resonate; the resonance chamber is immersed in the solution and is used for outputting resonance sound pressure field signals generated in the resonance process of the system; the resonance sound pressure field signals comprise the resonance sound pressure field signals under the states of loading no sample, singly loading a first sample, singly loading a second sample and singly loading a rock sample in the resonance chamber; the hydrophone is arranged in the resonance chamber and is used for collecting the resonance sound pressure field signals; the phase-lock amplifier is used for outputting a vibration source stimulating signal to the seismic source, performing phase-lock treatment on the seismic source stimulating signal and the resonance sound pressure field signals collected by the hydrophone and then supplying to the upper computer; the upper computer is used for acquiring a quality factor of the rock sample according to the signal supplied by the phase-lock amplifier. According to the method and the system, the measuring practicability and the measuring efficiency of the rock attenuation coefficient can be improved.

Description

technical field [0001] The present application relates to the technical field of research on rock physical properties of reservoirs, in particular to a method and system for measuring rock attenuation coefficients. Background technique [0002] The laboratory measurement of petrophysical properties is a basic research work in geophysical applied research. Due to the complexity of underground rocks, it is generally believed that the petrophysical properties of rocks change with the frequency. Accurately measuring the petrophysical properties in the field application frequency range in the laboratory is very important for using seismic exploration and acoustic logging data to understand underground rocks. It is of great significance to study the change characteristics of seismic phase and logging phase with frequency. The change of seismic wave attenuation in rocks and its generation mechanism are one of the objects that have been extensively studied. [0003] At present, th...

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Problems solved by technology

Under the resonant rod method, the cylindrical or parallelepiped sample is forced to move into or through the resonance state, and the resonance peak fmax and half-power bandwidth Δf are obtained by using the spectrum scanning method, and then the quality factor is determined accordingly; the measurement frequency band is kilohertz, Close to the acoustic logging frequency band; when the measurement frequency is low, a long, durable and uniform sample is required, but such samples are not easy to obtain, and the sample preparation takes a long time

Under the stress-strain method, the periodic application of force causes the object to deform, and the rate of deformation change is lower than the natural resonance frequency of the sample. The attenuation of the sample is calculated from the phase difference obtained by the applied stress and the corresponding strain; the measurement frequency band is lower, ranging from a few Hz to Several kilohertz, including the seismic exploration frequency band, can measure relatively accurate and continuous attenuation parameters in a wide range of low frequency bands, but it takes a long time to prepare rock samples

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