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Method for identifying porous natural gas hydrate by utilizing AVO attribute analysis

A natural gas and hydrate technology, applied in the field of geological exploration and energy exploration, can solve the problems of accuracy, increase of compressional and shear wave velocity, and low reliability of natural gas hydrate, so as to improve reliability, high drilling cost and save The effect of drilling costs

Pending Publication Date: 2021-12-24
GUANGDONG LAB OF SOUTHERN OCEAN SCI & ENG GUANGZHOU
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  • Claims
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Problems solved by technology

[0010] The purpose of the present invention is to provide a method for identifying pore-type natural gas hydrates by using AVO (amplitude varies with offset) attribute analysis, clarify the intrinsic relationship between AVO attributes and pore-type natural gas hydrates, and use AVO technology to identify and judge Whether the high-velocity characteristics of the formation is caused by the pore-containing gas hydrate formation or the non-gas hydrate-containing pore-type hydrate formation, so as to improve the reliability of the identification of pore-containing gas hydrate, and solve the problem of using BSR accuracy and P-s wave velocity. Anomaly Elevation to Identify Gas Hydrate Issues with Low Confidence

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  • Method for identifying porous natural gas hydrate by utilizing AVO attribute analysis
  • Method for identifying porous natural gas hydrate by utilizing AVO attribute analysis
  • Method for identifying porous natural gas hydrate by utilizing AVO attribute analysis

Examples

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Embodiment 1

[0042] The method of using AVO analysis to identify pore-type gas hydrates includes the following steps:

[0043] (1) Use seismic data to invert the actual P-wave velocity Vp or S-wave velocity Vs of the formation. According to the GMGS2-08 site logging curve, the high-velocity anomaly area is determined, and the reflective interface is selected as the research location①, as shown in figure 1 shown;

[0044] (2) Extract the reflection amplitude values ​​of the adjacent CRP gathers (CRP584-CRP587) at the GMGS2-08 station at the selected reflection interface position ① from the pre-stack seismic data;

[0045] (3) Calculate the relationship between the reflection coefficient and the incident angle according to the reflection amplitude value, corresponding to the CRP gathers from 584 to 587, which are represented by asterisks, plus signs, crosses and dots respectively, using the Shuey approximate equation (R(θ) =A+Bsin 2 θ) to fit the data to obtain a fitted curve, represented...

Embodiment 2

[0053] The method of using AVO analysis to identify pore-type gas hydrates includes the following steps:

[0054] (1) Use seismic data to invert the actual P-wave velocity Vp or S-wave velocity Vs of the formation. According to the GMGS2-16 site logging curve, the high-velocity anomaly area is determined, and the reflective interface position ① is selected as the research position, as shown in Figure 4 shown;

[0055] (2) Extract the reflection amplitude values ​​of the adjacent CRP gathers (CRP900-CRP903) at the GMGS2-08 station at the selected reflection interface position ① from the pre-stack seismic data;

[0056] (3) Calculate the relationship between the reflection coefficient and the incident angle according to the reflection amplitude value, corresponding to the CRP gathers from 900 to 903, which are represented by asterisks, plus signs, crosses and dots respectively, using the Shuey approximate equation (R(θ) =A+Bsin 2 θ) to fit the data to obtain a fitted curve, ...

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Abstract

The invention discloses a method for identifying porous natural gas hydrates by using AVO attribute analysis. The method comprises the following steps of: (1) inverting actual longitudinal wave velocity or transverse wave velocity of a stratum by using seismic data; (2) determining the position of a high-speed abnormal region on a seismic section according to existing velocity information data, and selecting the position of a reflection interface; (3) extracting a reflection amplitude value on a CRP gather adjacent to the selected reflection interface position from the pre-stack seismic data, calculating a reflection coefficient, and drawing a change relation of the reflection coefficient along with an incident angle; (4) using a Shuey approximation equation to obtain a fitting curve of the reflection coefficient of the adjacent CRP gather changing along with the incident angle; and (5) determining the response characteristic type of reflection interface AVO according to the fitted curve so as to judge whether the porous natural gas hydrate is contained in the stratum or not. According to the method, the reliability of identifying the porous natural gas hydrate is contained in the stratum is improved.

Description

Technical field: [0001] The invention relates to the technical fields of geological exploration and energy exploration, in particular to a method for identifying pore-type natural gas hydrates by using AVO attribute analysis. Background technique: [0002] Natural gas hydrate is a solid ice-like mixture formed by natural gas gas molecules and water molecules under certain conditions (temperature, pressure, etc.). It is flammable, so it is also called combustible ice. The energy produced by the combustion of natural gas hydrate per unit volume is equivalent to the energy produced by the combustion of about 164 volumes of natural gas. It is currently estimated that the storage of combustible ice is twice the total storage of known fossil energy (natural gas, coal and oil). It is mainly Distributed under the deep seabed or under the permafrost. The currently widely accepted types of gas hydrate occurrences are mainly pore-type hydrates and fracture-type hydrates. Fracture-typ...

Claims

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Application Information

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IPC IPC(8): G01V1/30
CPCG01V1/301G01V1/306
Inventor 田冬梅杨胜雄邓雨恬曹荆亚李沅衡胡广曾新阳
Owner GUANGDONG LAB OF SOUTHERN OCEAN SCI & ENG GUANGZHOU
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