Method for dynamically judging origin type of deep marine gas

Abstract

The invention provides a method for dynamically judging an origin type of deep marine gas. The method comprises: developing a hydrocarbon generation simulation experiment of marine hydrocarbon source rock, and establishing a three-dimensional reference judging plate; determining a to-be-judged main gas production layer, and collecting a gas sample from the production layer; measuring the characteristics, of gas component and monomer hydrocarbon carbon isotope, of the collected gas sample; according to the obtained characteristic of monomer hydrocarbon carbon isotope of the gas sample, calculating maturity of gas based on a formula; and putting the obtained characteristic of gas component, the obtained characteristic of monomer hydrocarbon carbon isotope, and the obtained maturity into the three-dimensional reference judging plate to identify the origin type of the gas. According to the method for dynamically judging the origin type of deep marine gas, the origin type of gas in different evaluation stages can be judged, and gas from kerogen degradation and gas from crude oil cracking can be effectively judged. The method is suitable for judging over-matured deep gas, and the influence of geological environment on a fluid medium can be truly reflected.

Description

technical field [0001] The invention relates to a method for dynamically identifying the genetic type of deep marine natural gas, and belongs to the technical field of petroleum and natural gas exploration geology-geochemistry. Background technique [0002] In China, marine strata have become an important successor field for oil and gas exploration after continental basins, and are receiving more and more attention. The oil and gas-bearing basins developed on land in China are all superimposed basins, and the facies are generally located in the middle and lower parts of the superimposed basins, with thick deposits, deep burials, and long evolution history, and the organic matter in them generally reaches a high-to-mature stage (et al. The effective vitrinite reflectance Ro is generally greater than 2%). In this way, two results are produced. One is that the source rock kerogen has entered the thermal degradation gas stage, and the other is that the liquid hydrocarbons forme...

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Problems solved by technology

However, as the scale of deep natural gas exploration increases and the geochemical characteristics of natural gas become richer and more diverse, the use of the above indicators and charts increasingly shows its limitations

[0006] The reason is that the indicators and charts proposed by the predecessors are based on the data obtained from the simulation experiment, and the experimental conditions have two deficiencies: first, the experimental temperature is relatively low (<500°C), which fails to reflect the gas characteristics of the mature stage ; Second, the sample boundary conditions are single, and the influence of the fluid medium in the real geological environment on the hydrocarbon generation of organic matter is not considered

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