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Method for identifying gas reservoir by using frequency-variable seismic reflection coefficient

A technology of seismic reflection and gas reservoir, applied in seismic signal processing and other directions

Inactive Publication Date: 2015-10-28
CHENGDU UNIVERSITY OF TECHNOLOGY
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  • Application Information

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Problems solved by technology

We know that the expression of the reflection coefficient of any incident angle in porous media is extremely complicated (Denneman et al, 2002), but if only the normal incidence of seismic waves is considered, the equation can be greatly simplified

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  • Method for identifying gas reservoir by using frequency-variable seismic reflection coefficient
  • Method for identifying gas reservoir by using frequency-variable seismic reflection coefficient
  • Method for identifying gas reservoir by using frequency-variable seismic reflection coefficient

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Embodiment Construction

[0025] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] Concrete steps of the present invention are as follows:

[0027] (1) The theory and formula of the normal reflection coefficient on the air-water interface

[0028] The change of reflection coefficient with frequency is expressed by formula (1-1):

[0029] R F F ( ω ) = R 0 F F + C 1 ( 1 + i ) ω - - - ( 1 - 1 )

[0030] The coefficient is directly proportional to the fluidity of the reservoir f...

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Abstract

The invention discloses a method for identifying a gas reservoir by using a frequency-variable seismic reflection coefficient. The method is achieved by means of high-resolution seismic survey and seismic frequency band expansion by high-fidelity seismic inverse-Q filtering. The method has beneficial effects that in a southwest certain gas field with a low-permeability ultra-dense sandstone reservoir, a phenomenon that a reflection coefficient on a gas-water interface varies with frequency can be still observed in a seismic frequency band; an attribute C1 generated by seismic inversion may indicate the existence of a gas-bearing characteristic; and a new attribute described in the specifications and generated by weighting the absolute value of the C1 can be used for discriminating a gas reservoir and a water reservoir.

Description

technical field [0001] The invention belongs to the technical field of earth exploration and relates to a method for identifying gas-bearing reservoirs by using frequency-variable seismic reflection coefficients. Background technique [0002] Like other sedimentary rocks, hydrocarbon reservoirs are fluid-saturated porous media, and the elastic properties of reservoirs can be described by the theory of porous media. However, most of the studies on elastic porosity theory focus on the velocity dispersion and attenuation, and only a few scholars have studied the reflection coefficient of plane waves in porous media. In this paper, first, we set up a geophysical model of the gas-water contact using petrophysical data collected from a gas field in southwest China. Then, within the seismic frequency band, the possibility of the normal reflection coefficient varying with frequency is investigated. [0003] As we all know, the classical porous media theory (Biot, 1956a,b, Dvorkin,...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/28
Inventor 李勇朱颜张文璨张秋冬吴哲潇段金亮
Owner CHENGDU UNIVERSITY OF TECHNOLOGY