CN-122016592-A - Natural gas migration path identification method and system

Abstract

The application discloses a natural gas migration path identification method and a natural gas migration path identification system, which belong to the technical field of oil-gas geology and exploration and evaluation, and comprise the steps of taking fractionation of carbon isotopes in a natural gas migration process as a research object, and constructing a migration fractionation model by coupling diffusion and adsorption; the method comprises the steps of selecting a calibration well, fitting measured carbon isotope concentration value data of the calibration well to determine optimal parameters of an migration fractionation model, inputting measured carbon isotope concentration value data of different well positions in an actual identification process, substituting the measured carbon isotope concentration value data of different well positions into the migration fractionation model to calculate natural gas migration distances of different well positions, comparing the natural gas migration distances of different well positions, combining a regional structure and well position, and deducing migration direction and migration path of natural gas from a starting place. The application uses the carbon isotope migration fractionation model to invert the natural gas migration distance and migration path and is used for constructing a reservoir mode.

Inventors

• YUAN SHENGBIN
• GENG HENG
• MAO MIN
• ZHANG HUANXU
• YI BIN
• SONG TING

Assignees

• 中法渤海地质服务有限公司

Dates

Publication Date

20260512

Application Date

20251209

Claims (10)

1. 1. A natural gas migration path identification method is characterized by comprising the following steps of, The fractionation of carbon isotopes in the natural gas migration process is taken as a research object, and a migration fractionation model is constructed through coupling diffusion and adsorption; Selecting a calibration well, and fitting actual measurement data of a carbon isotope concentration value of the calibration well to determine optimal parameters of the migration fractionation model; In the actual identification process, inputting measured data of carbon isotope concentration values of different well positions, substituting the measured data into an migration fractionation model to calculate natural gas migration distances of different well positions; and comparing the natural gas migration distances of different well sites, and deducing the migration direction and the migration path of the natural gas from the starting place by combining the regional structure and the well site position.
2. 2. The method of claim 1, wherein comparing the natural gas migration distances at different well locations, combining the zone configuration and the well location, and after deducing the migration direction and the migration path of the natural gas from the origin, further comprises combining the migration path with the gas reservoir distribution characteristics to construct a natural gas reservoir pattern.
3. 3. The method for identifying a natural gas migration path according to claim 1, wherein the constructing of the migration fractionation model by coupling diffusion and adsorption comprises constructing a carbon isotope diffusion model and a carbon isotope adsorption model, and constructing the migration fractionation model by coupling the carbon isotope diffusion model and the carbon isotope adsorption model.
4. 4. The method of claim 3, wherein modeling the carbon isotope diffusion comprises combining the error function with a one-dimensional Fick's second law to obtain the carbon isotope diffusion model.
5. 5. The method for identifying a path of transportation of natural gas according to claim 3, wherein establishing the model of carbon isotope adsorption comprises obtaining the model of carbon isotope adsorption by combining the simplified adsorption capacity of the langmuir adsorption model.
6. 6. The method of claim 1, wherein the determined optimal parameters of the migration fractionation model include a maximum fractionation magnitude, an adsorption compensation term, and an adsorption compensation characteristic distance.
7. 7. The method for identifying natural gas migration paths according to claim 6, wherein in the actual identification process, actual measurement data of carbon isotope concentration values of different well locations are input, and the actual measurement data of carbon isotope concentration values of different well locations are substituted into the migration fractionation model to calculate natural gas migration distances of different well locations.
8. 8. The method of claim 2, wherein the combining the migration path with the reservoir distribution characteristics to construct the natural gas reservoir pattern further comprises quantitatively interpreting the complex migration process based on the natural gas reservoir pattern.
9. 9. The method of claim 8, wherein quantitatively interpreting complex migration processes based on natural gas sequestration patterns, comprising: the determination is based on the difference in isotope fractionation of different migration processes, whether it is gas chimney or lateral migration.
10. 10. A natural gas migration path identification system comprising one or more processors and storage means for storing one or more programs which, when executed by the one or more processors, cause the one or more processors to implement the natural gas migration path identification method of any one of claims 1-9 and to identify a natural gas migration path in accordance with the natural gas migration path identification method.

Description

Natural gas migration path identification method and system Technical Field The application relates to the technical field of oil-gas geology and exploration and evaluation, in particular to a natural gas migration path identification method and a natural gas migration path identification system. Background The natural gas reservoir process is controlled by multiple links such as hydrocarbon production, reservoir, cap layer and migration. The migration path and the reservoir forming mode are important links of oil and gas geological evaluation, and directly influence resource exploration deployment and reservoir prediction. The conventional natural gas migration research mainly depends on structural interpretation, fluid inclusion and gas reservoir distribution characteristics, and has the defects that the conventional structural interpretation often cannot accurately describe a specific migration path of natural gas, the migration path is not clear, the conventional natural gas migration distance and path discrimination is mainly dependent on seismic attribute or analogy research, a calculation model driven by physical parameters is lacking, a quantification tool is lacking, and the quantitative migration calculation and the reservoir forming process are difficult to directly link due to the fact that the quantitative migration path cannot be quantitatively calculated, so that the construction and prediction accuracy of a reservoir forming mode is affected. Disclosure of Invention The application aims to provide a natural gas migration path identification method and a natural gas migration path identification system for inverting a natural gas migration distance and a natural gas migration path by using a carbon isotope migration fractionation model and constructing a reservoir mode. In order to achieve the above purpose, the technical scheme of the application is as follows: A natural gas migration path identification method comprises the steps of, The fractionation of carbon isotopes in the natural gas migration process is taken as a research object, and a migration fractionation model is constructed through coupling diffusion and adsorption; Selecting a calibration well, and fitting actual measurement data of a carbon isotope concentration value of the calibration well to determine optimal parameters of the migration fractionation model; In the actual identification process, inputting measured data of carbon isotope concentration values of different well positions, substituting the measured data into an migration fractionation model to calculate natural gas migration distances of different well positions; and comparing the natural gas migration distances of different well sites, and deducing the migration direction and the migration path of the natural gas from the starting place by combining the regional structure and the well site position. Optionally, after comparing the natural gas migration distances of different well sites, combining the region structure and the well site positions and deducing the migration direction and the migration path of the natural gas from the starting place, the method further comprises combining the migration path with the gas reservoir distribution characteristics to construct a natural gas reservoir mode. Optionally, the coupling diffusion and adsorption construct the migration fractionation model comprises establishing a carbon isotope diffusion model and a carbon isotope adsorption model, and coupling the carbon isotope diffusion model and the carbon isotope adsorption model to construct the migration fractionation model. Optionally, establishing the carbon isotope diffusion model includes combining the error function with a one-dimensional Fick second law to obtain the carbon isotope diffusion model. Optionally, establishing the carbon isotope adsorption model comprises combining the Langmuir adsorption model to simplify the adsorption capacity to obtain the carbon isotope adsorption model. Optionally, the determined optimal parameters of the migration fractionation model include a maximum fractionation amplitude, an adsorption compensation term and an adsorption compensation characteristic distance. Optionally, in the actual identification process, inputting the measured carbon isotope concentration value data of different well positions, substituting the measured carbon isotope concentration value data into an migration fractionation model to calculate the natural gas migration distances of different well positions, wherein when the starting place of the natural gas of the gas field to be identified is known, the migration time and the effective diffusion coefficient are set according to geological events, and the measured carbon isotope concentration value data of different well positions are input into the calibrated migration fractionation model to calculate the natural gas migration distances of different well positions. Optionally, after the natural gas reser