Converted wave extreme attribute hydrocarbon detection method

Abstract

The invention provides a converted wave extreme attribute hydrocarbon detection method, which belongs to the field of hydrocarbon geophysics. The method includes the following steps: (1) a converted wave common conversion point gather is inputted; (2) velocity analysis and dynamic correction are carried out for the common conversion point gather, so that a dynamically corrected gather is formed; (3) longitudinal wave and transverse wave velocity fields are inputted, the angles of converted wave incidence are tracked by a ray, and a converted wave angle gather is formed; (4) the power function y equal to ax plus cx fitting of amplitude versus angle is carried out for a converted wave amplitude sequence at the same time sampling point and different angles of incidence point by point, and an extreme position and extreme amplitude are outputted; (5) a velocity ratio Gamma is obtained by inversion; (6) a transverse wave reflection coefficient Rss0 is inverted; (7) according to a reservoir gas-bearing velocity ratio decrease principle, the gas-bearing property of a reservoir is predicted by means of the velocity ratio Gamma obtained by inversion. The method utilizes high-signal-to-noise-ratio data within an offset range nearby the extreme amplitude, and increases the precision of converted wave AVO (Amplitude Variation with Offset) inversion.

Description

technical field [0001] The invention belongs to the field of oil and gas geophysics, and in particular relates to a method for detecting oil and gas with converted wave extreme value attributes. Background technique [0002] In recent years, the relationship between seismic reflection amplitude and offset variation (AVO) has become a hot spot in the research of geophysical prospecting technology. With the development of multi-component seismic exploration technology, the research on converted wave AVO technology has attracted more attention. The change of reflection coefficient with incident angle itself implies the information of elastic parameters, and the density, P-wave velocity and S-wave velocity of rock can be directly inverted by using AVO characteristics, and seismic reservoir description can be quantitatively carried out. Zoeppritz (1919) derived the Zoeppritz equation describing the displacement-amplitude relationship between the incident wave, reflected wave, and...

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Problems solved by technology

[0004] When the longitudinal wave is vertically incident, the reflection coefficient of the converted wave is zero. As the incident angle increases, the reflection coefficient increases. Therefore, the signal-to-noise ratio of the converted wave data in the range of close offset (small incident angle) is low, and the accuracy of AVO inversion is low. low, poor stability

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