Method for calculating shear wave velocity of sandstone formation

Abstract

The invention provides a method for calculating shear wave velocity of a sandstone formation, and belongs to the field of rock physics and geophysical logging. The method comprises the following steps: (1) inputting an actually-measured longitudinal wave velocity Vp, density, porosity phi and a shale content Vsh curve of the sandstone formation, and setting an initial value and an interval of a consolidation coefficient c; (2) calculating a dry rock elastic modulus; (3) calculating a saturated rock elastic modulus, and calculating to obtain a calculated longitudinal wave velocity; (4) establishing an error function between the actually-measured longitudinal wave velocity Vp and the calculated longitudinal wave velocity; (5) within the value range of the consolidation coefficient c, changing the value of the consolidation coefficient c by using the interval, repeating the step (2) to the step (4) once when the changing is implemented every time to obtain the error function corresponding to each new consolidation coefficient c, comparing the error functions corresponding to all the consolidation coefficients c to find a consolidation coefficient c' which enables the error function to be minimum, and calculating the obtained shear wave velocity, namely the solved shear wave velocity, by virtue of the consolidation coefficient c' which enables the error function to be minimum.

Description

technical field [0001] The invention belongs to the fields of petrophysics and geophysical well logging, and in particular relates to a method for calculating shear wave velocity in a sandstone formation. Background technique [0002] The target of oil and gas exploration has changed from simply focusing on structural oil and gas reservoirs to focusing on the exploration of complex stratigraphic, lithologic or structural-stratigraphic-lithological composite oil and gas reservoirs, and the difficulty of exploration has greatly increased. The regional scope of oil and gas exploration has shifted from the eastern land plain to the western mountainous area, desert, loess area and offshore sea area. It is difficult and costly to obtain qualified geological and geophysical data in these areas. The burial depth of oil and gas exploration target layers is increasing, some of which exceed 7000m, which belong to deep or ultra-deep exploration, which makes it difficult to apply some ef...

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Problems solved by technology

[0003] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and to provide a calculation method of shear wave velocity in sandstone formations, which is not suitable for measuring the shear wave velocity due to the large regional influence, large calculation error and low operating efficiency of the conventional shear wave velocity calculation method. Real-time interpretation of well data, pre-stack seismic inversion and pre-stack seismic attribute analysis, etc., the application is limited and other shortcomings, the method of the present invention uses the principle of rock physics to calculate the shear wave velocity from the logging data

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