CN-121995478-A - Deep coal bed gas containing heterogeneity detection method, storage medium and equipment

CN121995478ACN 121995478 ACN121995478 ACN 121995478ACN-121995478-A

Abstract

The invention discloses a method, a storage medium and equipment for detecting the gas-containing heterogeneity of deep coal bed gas, wherein the method comprises the steps of firstly obtaining post-stack seismic data of a corresponding coal bed gas working area, secondly obtaining a coalbed-to-seismic interpretation horizon marked as T according to the post-stack seismic data, thirdly extracting a plurality of positions for the post-stack seismic data to obtain a plurality of seismic channels, fourthly performing time-frequency analysis on the extracted seismic channels by adopting synchronous extrusion S transformation to obtain a time-frequency distribution map, and comparing the obtained time-frequency analysis result with the traditional time-frequency analysis method, the method has higher time-frequency resolution and better time-frequency energy focusing, can effectively detect transient spectrum abnormal characteristics such as 'high-frequency attenuation' related to a deep coal reservoir in the application of actual seismic data, improves the prediction precision of the deep coal reservoir, and is favorable for accurately describing the gas-containing heterogeneity of the deep coal reservoir.

Inventors

KANG ZHILIANG
LEI TAO
REN GUANGLEI
LI XIAOHUI
YANG JING
YANG SHUAIJIE

Assignees

中国石油化工股份有限公司
中国石油化工股份有限公司华北油气分公司

Dates

Publication Date: 20260508
Application Date: 20241106

Claims (10)

1. A method for detecting the heterogeneity of the gas contained in the deep coal bed gas is characterized by comprising the following steps of Step one, acquiring post-stack seismic data of a corresponding coalbed methane work area; Step two, acquiring a layer of interpretation of the coal seam to the earthquake according to the post-stack earthquake data, and marking the layer as T; step three, extracting a plurality of position pairs of post-stack seismic data to obtain a plurality of seismic channels; Step four, performing time-frequency analysis on the extracted seismic channels by adopting synchronous extrusion S transformation to obtain a time-frequency distribution map; And fifthly, analyzing a time-frequency distribution result below the corresponding time depth of the earthquake interpretation layer T on each earthquake channel, and accordingly obtaining gas content differences of the coal seam to be researched at different positions of the working area.
2. The method for detecting the heterogeneity of deep coal bed methane according to claim 1, wherein the seismic signals in the S transformation are synchronously extruded in the fourth step Is defined in the time domain as B represents time of time-frequency transformation, and f is frequency.
3. The method for detecting the heterogeneity of deep coal bed gas according to claim 2, wherein the expression of the frequency domain is
4. A method for detecting the heterogeneity of coal bed methane in deep coal bed methane as recited in claim 3, wherein Is the x (t) Fourier transform, Is that Fourier transform of (a).
5. A method for detecting the heterogeneity of deep coal bed methane as claimed in claim 4, wherein, Wherein the method comprises the steps of
6. The method for detecting the heterogeneity of deep coal bed methane according to claim 5, wherein the true frequency of the signal at the time b can be extracted through the information of any time frequency point (f, b) according to the formula (3) And then the energy of (f, b) can be "rearranged and extruded" into And obtaining a time-frequency distribution diagram.
7. A method for detecting the heterogeneity of deep coal bed gas according to claim 6, wherein the energy is rearranged and squeezed in the time-frequency domain to obtain synchronous squeezing S transformation, Wherein is a unit pulse function according to A time-frequency distribution diagram is obtained.
8. The method for detecting the heterogeneity of the gas in the deep coal bed methane according to claim 7, wherein in the fifth step, the analysis of the time-frequency distribution result of the seismic interpretation layer T on each seismic trace below the corresponding time depth is to detect the high-frequency attenuation phenomenon of the seismic trace below the coal bed position, and the position of the seismic trace with large high-frequency attenuation corresponds to the gas-containing favorable zone of the coal bed methane.
9.A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon computer program instructions, wherein the computer program instructions, when executed by a processor, are for implementing the steps of the deep coalbed methane gas-containing heterogeneity detection method according to any one of claims 1-8.
10. An electronic device comprising a memory and a processor, and computer instructions stored on the memory and run on the processor, which when executed by the processor, perform the steps of the deep coal bed methane gas-containing heterogeneity-detection method of any one of claims 1-8.

Description

Deep coal bed gas containing heterogeneity detection method, storage medium and equipment Technical Field The invention relates to the technical field of oil and gas exploration and development, in particular to a method for detecting the gas-containing heterogeneity of deep coal bed gas, a storage medium and equipment. Background Coalbed methane is a clean energy which is stored in unconventional oil and gas reservoirs, the coalbed methane resources in China are rich, but the overall exploration development degree, the recognition degree of the coalbed methane enrichment mechanism and the energy production main control factors are low, the majority of domestic coalbed methane resource evaluation targets are limited to stratum with the depth of less than 2000m, and the research of deep coalbed methane is necessary to be enhanced along with the transition from the depth of burial to the depth of the unconventional exploration direction in China. The problem is often encountered in the existing deep coal bed methane exploitation practice that the productivity of production wells at different positions on the same coal reservoir can be obviously different, namely, the gas content of the reservoir has stronger heterogeneity on a plane, and how to predict the local change before drilling is implemented, so that the occurrence and development of a deep coal bed methane reservoir earthquake prediction technology with stronger pertinence are urgently needed. In the prior art, a Chinese patent with publication number CN103412326A discloses a method and a system for predicting coalbed methane by inversion of elastic modulus parameters, the method is based on pre-stack seismic data, utilizes Zoeppritz equation set elastic modulus approximation, and simultaneously inverting the relative variation of the prestack Lame constant, the relative variation of the shear modulus and the relative variation of the density, and predicting the coalbed methane according to the inversion result so as to evaluate the difference of the reservoir in different transverse positions. In particular practice, especially when evaluating deep reservoirs, implementation of the method requires seismic data at wide angles of incidence, which is not applicable to the data of the old area collected by some small offset observation systems. In conventional oil and gas exploration and development, after seismic waves pass through an oil and gas-containing reservoir, energy attenuation occurs, and the high-frequency energy attenuation is fast, and the low-frequency energy attenuation is slow, so that the anomaly can be used for indicating the enrichment condition of oil and gas in the reservoir. Unlike conventional oil gas, coal bed gas exists in a coal bed in two forms of free gas and adsorption gas, and the deep coal bed is controlled by temperature and pressure, and a considerable amount of free gas is still stored in the coal bed trap, so that the prediction mechanism of the conventional oil gas can be used as a reference. Different calculation tools are generally used for carrying out time-frequency analysis on post-stack seismic data, the obtained time-frequency diagram reflects the condition that frequency components change along with time, and whether the high-frequency attenuation abnormality exists or not can be detected. Several commonly used time-frequency analysis tools, such as S-transform (ST), short-time fourier transform (STFT), continuous Wavelet Transform (CWT), have the problem of insufficient time-frequency resolution. They generally use a wavelet mother function of a specific type and estimate the time-frequency energy of the signal in the effective area of the function, resulting in that the time-frequency energy obtained at a certain moment always diverges into a certain time and frequency range around the real instantaneous frequency of the signal, so that the instantaneous frequency energy distribution obtained by conventional time-frequency conversion is blurred, has a pseudo-frequency component, can bring about erroneous interpretation results, and is further unfavorable for reservoir gas-containing analysis. Reservoir prediction for deep coal bed gas, in particular to analysis of gas-containing heterogeneity of coal beds, a time-frequency analysis tool with high time-frequency resolution is needed. Disclosure of Invention The invention aims to provide a method, a storage medium and equipment for detecting the gas-containing heterogeneity of deep coal bed gas, and aims to solve the problems of the background technology. The invention is realized in the following way: According to one aspect of the present invention, there is provided a method for detecting gas-containing heterogeneity of deep coal bed methane, comprising Step one, acquiring post-stack seismic data of a corresponding coalbed methane work area; Step two, acquiring a layer of interpretation of the coal seam to the earthquake according to the post-stack earthqu