Method and apparatus for predicting tight gas layer based on frequency-variable reflection amplitude attenuation

Abstract

The embodiment of the invention provides a method and apparatus for predicting a tight gas layer based on frequency-variable reflection amplitude attenuation. The method comprises the following steps:analyzing the range and characteristic frequency of oil and gas reservoir attenuation along with frequency changes; determining pore elastic parameters of a cover layer, an oil and gas reservoir anda water layer; forward modeling attenuation characteristics of the reflection amplitude of the oil and gas reservoir or the water layer along with the offset or the incident angle under different frequency conditions; performing calculation to obtain a pre-stack time-frequency data volume in an effective frequency range; determining an offset range in which the amplitude frequency change of the oil and gas reservoir changes drastically; calculating a pre-stack reflection amplitude attribute parameter AMO according to the offset distance or incident angle determined by a cross plot in combination with a frequency-varying reflection amplitude forward modeling result; and according to a low-frequency attenuation attribute parameter AAI and a high-frequency attenuation attribute parameter AAI,calculating a pre-stack reflection amplitude attenuation index parameter FDAAI depending on frequency changes, determining an FDAAI profile, and carrying out position identification on the oil and gas reservoir, so that the tight gas reservoir can be accurately identified.

Description

technical field [0001] Embodiments of the present invention relate to the field of seismic oil and gas exploration, in particular to a method and equipment for predicting tight gas layers based on frequency-variable reflection amplitude attenuation. Background technique [0002] As a widely used technique, AVO (Amplitude Variation with Offset) can also be used for the analysis of pore fluid attenuation. In the 1960s, Bortfeld proposed the AVO analysis technique. Since then, many experts and scholars have conducted research on this theory, gradually making it an important technique for studying reservoir properties. [0003] Obtaining rock characteristics from seismic data is a challenging task that needs to be described by accurate constitutive equations (mathematical models reflecting the macroscopic properties of matter). Current frequency-dependent AVO processing and inversion algorithms use simplified rheological models and are mainly based on travel-time information to...

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Problems solved by technology

[0004] However, in addition to travel time information, seismic data also contain other useful information, such as seismic wave propagation energy attenuation and relaxation mechanism; and because idealized rheological models are difficult to apply to inversion techniques, frequency-dependent AVO is difficult It is difficult to accurately and effectively identify tight gas layers

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