Method and system for simultaneously measuring ultrasonic wave speed and quality factor of rock

Abstract

The invention discloses a method and system for simultaneously measuring the ultrasonic wave speed and quality factor of a rock. The method comprises the following steps: selecting a reference sample, obtaining a standard signal of the reference sample by use of an ultrasonic save pulse transmitting measurement system and picking a standard take-off time; selecting a to-be-measured rock sample, obtaining a measuring signal of the to-be-measured rock sample and determining the initial take-off time of the measuring signal; time-shifting the measuring signal according to a time difference to obtain a time shift signal; setting an initial quality factor value and a remained relative time shift initial value of the to-be-measured rock sample and acting the initial quality factor value and the remained relative time shift initial value onto the standard signal to perform forward calculation, so as to obtain a forward calculating signal; comparing the time shift signal and the forward calculating signal within a valid time window to establish a target function; searching the minimum value of the target function by virtue of an optimized algorithm starting from the initial quality factor value and the remained relative time shift initial value, so as to obtain an optimal quality factor value and an optimal remained relative time shift value of the to-be-measured rock sample; calculating to obtain the elapsed time and the ultrasonic wave speed of the to-be-measured rock sample.

Description

technical field [0001] The invention relates to the field of velocity and attenuation measurement based on ultrasonic pulse transmission technology, in particular to a method and system for simultaneous measurement of rock ultrasonic velocity and quality factor. Background technique [0002] Nowadays, with the development of seismic and logging technology, in order to improve the accuracy of reservoir prediction and fluid detection, people urgently need to understand the elastic wave properties of reservoir fluid and rock in more detail, including velocity, attenuation, anisotropy, etc. aspect. [0003] Ultrasonic pulse transmission technology (Birch, 1960) is a commonly used experimental measurement method for studying the wave propagation characteristics of rocks. The collected cores are usually processed into samples of a certain shape and size (such as cylinders). The porosity, permeability, density, and even fabric characteristics of the samples can be obtained through...

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Problems solved by technology

[0013] Because in the prior art, the pick-up of the signal take-off time in speed measurement is affected by attenuation, and the speed is an important input parameter in the Q value calculation method, it is difficult to accurately measure the speed and attenuation alone. The present invention proposes a simultaneous The method and system for obtaining rock ultrasonic velocity and quality factor solves the problem that the existing ultrasonic experimental technology cannot accurately obtain rock velocity and attenuation

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