Method for indoor measurement of wave velocity confining pressure and dispersion correction in consideration of formation characteristics

Abstract

A method for indoor measurement of wave velocity confining pressure and dispersion correction in consideration of formation characteristics comprises the following steps of (1) collecting geological and logging data, coring data and underground rocks in a research area; (2) making a core sample into multiple standard rock samples, and performing indoor acoustic test to obtain an indoor acoustic time difference value; (3) using 25kHz as a target frequency, correcting the frequency of the indoor test acoustic time difference value, and calculating to obtain an indoor test acoustic time difference value; (5) establishing a relationship changing along with the confining pressure between the acoustic time difference ratios under different confining pressures and 0 confining pressure, and establishing a relationship model between the acoustic time difference ratios and the confining pressures; (4) using the logging data to calculate the mud content and porosity; and (5) using an establishedformula to establish a relation between the corrected acoustic wave and on-site acoustic wave. The invention eliminates the indoor acoustic time difference dispersion phenomenon through the established correction model, and also considers the formation confining pressure conditions, rock porosity, mud content, etc. to obtain a true acoustic time difference value under the actual conditions of theformation.

Description

technical field [0001] The invention belongs to the technical field of well logging, and in particular relates to an indoor measurement wave velocity confining pressure and dispersion correction method considering formation characteristics. Background technique [0002] Acoustic logging is an effective means to obtain various physical parameters of the formation. By means of acoustic logging data, various information of strata continuously distributed along the borehole profile can be obtained. Therefore, acoustic logging data are often used in cementing, drilling, pressure cracking and other oil and gas exploration and development links. A major feature of acoustic logging is to study the propagation characteristics of mechanical waves between acoustic waves and ultrasonic waves. The main range of acoustic wave frequencies is 15-25kHz to obtain accurate measurement results. In the laboratory, the sound wave transmission method is usually used to study the propagation chara...

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Problems solved by technology

[0003] However, in the application process, there is a difference between the laboratory acoustic test frequency and the field logging acoustic wave frequency. The former is generally higher than the latter, resulting in a difference between the laboratory test acoustic wave time difference and the well logging acoustic wave time difference. If the laboratory test results are directly substituted into In the prediction model of rock mechanics parameters, large errors may occur. Therefore, the phenomenon of dispersion needs to be considered, that is, the acoustic time difference under the laboratory measurement conditions needs to be converted to the acoustic time difference under the formation conditions.

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