A Method for Indoor Wave Velocity Measurement Confining Pressure and Dispersion Correction Considering Formation Characteristics

Abstract

A method for indoor measurement of wave velocity confining pressure and dispersion correction considering formation characteristics, comprising the following steps: (1) collecting geology, logging data, coring data and downhole rocks in the research area; (2) making core samples into multiple standard Rock sample, and conduct indoor acoustic wave test to obtain indoor acoustic wave time difference; (3) take 25kHz as the target frequency, correct the indoor test acoustic wave time difference frequency, and calculate the indoor test acoustic wave time difference; (5) establish different confining pressure and Establish the relationship model between the acoustic transit time ratio and the confining pressure under 0 confining pressure; (4) calculate the shale content and porosity by using the logging data; (5) use the established formula to establish the correction Relational formula of back sound wave and live sound wave. The invention eliminates the phenomenon of indoor acoustic time difference dispersion through the established correction model; also considers the formation confining pressure condition, rock porosity, mud content, etc., and obtains the real acoustic time difference value under the actual situation of the formation.

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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