Recovery method of original hydrogen index and organic carbon of high-over-mature sapropelic marine shale

Abstract

The invention provides a high-over mature decayed mud type marine shale original hydrogen index and organic carbon recovery method, which belongs to the technical field of oil and gas geochemistry research, and realizes the high-over mature decayed mud type marine shale original hydrogen index and organic carbon content recovery under the condition of considering the influence of the paleo-productivity and land source input. The method comprises the steps of selecting the high-over mature rotten mud type marine shale in a research area as a target shale sample, determining the content of organic carbon, the content of free hydrocarbon and the content of pyrolytic hydrocarbon at present, and calculating the potential of hydrocarbon generation; determining the total phosphorus content and the aluminum content, and calculating the autogenous organic phosphorus content; selecting a shale sample in an immature-low mature stage in the same layer system as a target shale sample as a referenceshale sample; and obtaining the lowest hydrogen index and the highest hydrogen index of the reference shale sample, and recovering the original hydrogen index and the original organic carbon contentby taking the lowest hydrogen index and the highest hydrogen index as references and utilizing the ratio of the content of the autogenous organic phosphorus to the content of the total phosphorus.

Description

technical field [0001] The invention belongs to the technical field of oil and gas geochemistry research, and in particular relates to a method for recovering the original hydrogen index and organic carbon of high-over-mature sapropelic marine shale. Background technique [0002] The total organic carbon content (TOC) of shale refers to the percentage of the total mass of organic carbon in shale to the total mass of mud shale, and the hydrogen index (HI) refers to the content of pyrolyzed hydrocarbons (S 2 ) to TOC, which represents the hydrocarbon generation potential of kerogen in shale. Therefore, TOC and HI are important indicators for evaluating shale gas generation and storage. However, due to a large amount of hydrocarbon generation in the shale at the high-over-mature stage, the current organic carbon content and the current hydrogen index are greatly reduced. Therefore, the current indicators cannot reflect the true hydrocarbon generation potential of the shale. ...

AI Technical Summary

Problems solved by technology

Therefore, for the high-over-mature stage, the hydrogen index obtained by rock pyrolysis analysis (Rock-Eval Pyrolysis) is too low to reflect its true hydrogen index characteristics

At the same time, due to the shale hydrogen index has a certain range of variation, previous studies have used the average hydrogen index (HI ave ) has certain limitations, so it cannot effectively restore the original organic carbon content of high-over-mature shale, which affects the evaluation of shale gas.

In addition, the kerogen type of marine shale is controlled by the input and preservation of organic matter, while the existing shale original hydrogen index and organic carbon restoration methods do not take into account the influence of organic matter input and preservation conditions, and cannot effectively restore high-excessive The original hydrogen index and original organic carbon content of mature sapropelic marine shale affect the evaluation of shale gas

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