Method for measuring dynamic damage degree of rock in confining pressure condition

Abstract

The invention provides a method for measuring the dynamic damage degree of rock in a confining pressure condition. The method comprises: 1) arranging a sound wave emission probe and a sound wave reception probe of a sound wave test system at two fixed pressure heads, and fixing a manufactured stratigraphic rock test piece between the two fixed pressure heads; 2) putting the test piece and fixed pressure heads in a triaxial testing machine, applying the confining pressure to the test piece via the triaxial testing machine and performing axial pre-loading, and starting the sound wave test systemto obtain the initial sound wave speed of the test piece; 3) while performing axial loading on the test piece through the triaxial testing machine, starting the sound wave test system to collect theaxial load and sound wave speed, stopping data collection when the test piece is broken, reducing the axial pressure and confining pressure from the test piece in sequence, and taking the test piece out to finish the test; and 4) treat the experimental data to obtain a dynamic damage degree and stress state curve, and calculating the damage degree of surrounding rock of a target well section according to the sound wave well-logging data of an oil well.

Description

technical field [0001] The invention belongs to the field of petroleum engineering rock mechanics, in particular to a method for measuring the dynamic damage degree of rock under confining pressure conditions. Background technique [0002] Oil drilling engineering refers to the use of special drilling equipment and technology to drill a certain diameter cylindrical wellbore at a predetermined surface position in the oil storage block discovered through exploration, and drill into the underground oil and gas layer. In practice, during the drilling and production process of the rock mass around the wellbore, the surrounding rock of the borehole wall is damaged to varying degrees due to the external load such as the original in-situ stress, and the surrounding rock of the borehole wall has elastic zones and damaged zones at the same time. In addition, in the process of hydraulic fracturing, the pressure of the fracturing fluid will also cause damage to the surrounding rock of t...

AI Technical Summary

Problems solved by technology

At the oilfield site, the longitudinal wave and shear wave velocity of the surrounding rock of the oil well wall are obtained by means of acoustic logging of the oil well, and the elastic parameters of the rock (such as dynamic elastic modulus and dynamic Poisson's ratio) are calculated through the acoustic wave velocity. Well method to directly obtain the damage degree of the surrounding rock of the oil well

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