CN-122016890-A - Method for measuring conversion coefficient of organic carbon and organic matter

CN122016890ACN 122016890 ACN122016890 ACN 122016890ACN-122016890-A

Abstract

The invention discloses a method for measuring conversion coefficients of organic carbon and organic matters, which comprises the steps of S1, selecting a proper amount of rock sample, crushing the rock sample into a sample A and a sample B, S2, measuring the organic carbon content in the sample A, S3, measuring the organic matter content in the sample B, and S4, calculating the conversion coefficients of the organic carbon and the organic matters according to the organic carbon content and the organic matter content. The invention respectively measures the light hydrocarbon content, the soluble organic matter content and the insoluble organic matter content in the rock by comprehensively using a thermogravimetric method, a extraction method and a chemical separation method, calculates the non-organic matter impurity content in the insoluble organic matter by using an X-ray diffraction method, calculates the total organic matter content, measures the organic carbon content by using a carbon-sulfur analysis method, and finally obtains the conversion coefficient of the organic carbon and the organic matter according to the measured organic matter content and the organic carbon content, thereby solving the problem that the conversion coefficient 1.724 in the existing standard can not meet the requirement of calculating the organic matter content in the stratum rock.

Inventors

TAN JIE
ZHANG BENJIAN
CHEN MANFEI
TAN YAQIAN
DONG BIAN
YU HUAJIE

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20241111

Claims (10)

1. The method for measuring the conversion coefficient of organic carbon and organic matters is characterized by comprising the following steps of: S1, selecting a proper amount of rock samples, and dividing the crushed rock samples into a sample A and a sample B; s2, performing carbon and sulfur analysis on the sample A, and determining the organic carbon content in the sample A; S3, analyzing the sample B, determining the content of soluble organic matters and insoluble organic matters in the sample B, and obtaining the content of the organic matters in the sample B according to the content of the soluble organic matters and the content of the insoluble organic matters; and S4, calculating to obtain conversion coefficients of the organic carbon and the organic matters according to the organic carbon content and the organic matter content.
2. The method for measuring conversion coefficients of organic carbon and organic matters according to claim 1, wherein in the step S2, the content of the organic carbon is measured to meet the technical requirement of GB/T19145-2022 for measuring total organic carbon in sedimentary rock, and the calculation formula of the content of the organic carbon is as follows: wherein: Q TOC -the total organic carbon content in sample A, expressed as a percentage; I-integral of sample A in square millimeters (mm 2 ); m-mass of sample A in grams (g); Qs—the value of the certificate of the total organic carbon content in sample a,%; ms-mass of standard in grams (g); Is-integral value of the standard in square millimeters (mm 2 ).
3. The method for measuring conversion coefficient of organic carbon and organic matter according to claim 1 or 2, wherein in step S3, the method for analyzing the sample B is as follows: S3-1, adding dichloromethane into the sample B by using an extractor, uniformly mixing, extracting soluble organic matters by using a extraction method, and measuring the content of the soluble organic matters; s3-2, drying a sample B after extracting soluble organic matters, extracting insoluble matters by using a kerogen separation method, and measuring the content of the insoluble matters; S3-3, calculating the content of insoluble organic matters in the insoluble matters by using an X-ray diffraction method; And S3-4, adding the content of the soluble organic matters to the content of the insoluble organic matters to obtain the organic matters in the sample B.
4. The method for measuring conversion coefficients of organic carbon and organic matters according to claim 3, wherein in the step S3-1, the extraction of soluble organic matters meets the technical requirement of SY/T5118-2021 for measuring the content of the extracts in rock, and the calculation formula of the content of the soluble organic matters is as follows: wherein: X-the soluble organic matter content in sample B expressed as a percentage; G 1 -weighing the bottle mass, G; G 2 -the mass of soluble organic matters, G, after methylene dichloride is added into a weighing bottle; m 1 -mass of sample B, g.
5. The method for measuring conversion coefficients of organic carbon and organic matters according to claim 3, wherein in the step S3-2, the kerogen separation method meets the technical requirements of the kerogen separation method in sedimentary rock, namely GB/T19144-2010.
6. The method for measuring conversion coefficients of organic carbon and organic matters according to claim 3, wherein in the step S3-3, an X-ray diffraction method meets the technical requirements of SY/T5163-2018, which is an X-ray diffraction analysis method for clay minerals and common non-clay minerals in sedimentary rocks.
7. The method for measuring conversion coefficients of organic carbon and organic matters according to claim 3, wherein in the step S3-3, the content of insoluble organic matters in the insoluble matters is calculated by an X-ray diffraction internal standard method, and the calculation formula is as follows: wherein: y-the insoluble organic matter content of sample B, expressed as a percentage; m 2 -insoluble matter sample mass, g; mcorundum-mass of the pure corundum powder sample of the internal standard substance, g; Icorundum-integral intensity, ° cps of diffraction peak selected by corundum as internal standard; Kcorundum-reference intensity parameter of corundum as internal standard, ° cps; ii-the integrated intensity of the diffraction peak selected for the ith mineral in sample B, ° cps; ki—reference intensity parameter for the i-th mineral in sample B.
8. The method for measuring conversion coefficients of organic carbon and organic matter according to any one of claims 1, 2, and 4 to 7, wherein in step S4, the calculation formula of the conversion coefficients of organic carbon and organic matter is: n=(X+Y)÷Q TOC wherein: n is the conversion coefficient of organic carbon and organic matter; X-the soluble organic matter content in sample B expressed as a percentage; y-the insoluble organic content of sample B, expressed as a percentage.
9. The method for measuring the conversion coefficient of organic carbon and organic matter according to claim 1, wherein in the step S1, the particle size of the crushed rock sample is 0.15mm or less.
10. The method for measuring conversion coefficients of organic carbon and organic matters according to claim 1, wherein in the step S1, the mass of the sample A is not less than 4g and the mass of the sample B is not less than 50g.

Description

Method for measuring conversion coefficient of organic carbon and organic matter Technical Field The invention relates to the technical field of oil and gas reservoir exploration and research, in particular to a method for measuring conversion coefficients of organic carbon and organic matters. Background According to the national agricultural industry Standard, soil detection, section 6, determination of soil organic matter, NY/T1121.6-2006, in soil organic matter determination, the coefficient 1.724 of conversion of organic carbon into organic matter is generally used as a standard value to convert the experimentally measured organic carbon content into organic matter content. The conversion coefficient 1.724 is derived from the Van Bemmelen factor and is an empirical coefficient based on the average value of the organic carbon content of the global soil. Global investigation by scholars at home and abroad shows that the average carbon content of the organic matters in the soil layer of 0-100cm of the global soil is 0.58, which means that the content of the organic matters in the soil is about 1.724 times the content of the organic carbon (namely 1/0.58 approximately equal to 1.724). In addition, xu Jianming, pages 42 of the fourth edition of soil science, which is a common empirical factor used in soil science, is mentioned to estimate the organic matter content of the soil. Since in practice, the direct determination of organic matter is complex and time consuming, it is a relatively simple and widely accepted method to estimate the organic matter content by determining the organic carbon and using this conversion factor. For example, patent document CN104280512a also discloses the use of 1.724 as a conversion factor in the specification. However, this scaling factor may not always be applicable because it does not take into account different types of organic matter and soil conditions. Among them, kerogen is an important component of soil organic matter, and its type and nature can affect the conversion coefficient of organic carbon to organic matter. In addition, the soil contains other types of organic matters such as animal and plant residues, microbial metabolites and the like, and the organic matters of different types have different carbon content, decomposition rate, stability and the like, so that the contribution of the organic matters to the soil is different. For organic matters in stratum rock, the stratum rock is not easily influenced by external environment change after long-time compaction and diagenetic effect, the content of easily decomposed organic matters is low, the carbon content and the stability of the stratum rock are always higher than those of the organic matters in soil, and the stratum rock has great difference in composition and structure with the organic matters in the soil. Therefore, the calculation of organic matter content using the same conversion coefficient for organic carbon in rock and soil is not accurate. Currently, the method for measuring the conversion coefficient of the organic carbon and the organic matter in the soil comprises a thermogravimetric method, a chemical method, a chromatographic method, a CT scanning method and the like. However, each method has its limitations. For example, thermogravimetry may be affected by factors such as heating rate, sample particle size, and mineral composition, chemical methods may be affected by factors such as reagent purity, reaction conditions, and operator skill, chromatography may be affected by factors such as column performance, detector sensitivity, and sample pretreatment, CT scanning may be affected by image resolution, artifacts, and gray scale selection. These limitations may lead to inaccuracy in the results of the organic matter or organic carbon content measurement, which in turn affects the accuracy of the conversion factor. In the oil and gas exploration and development process, the organic matter content and type of the hydrocarbon source rock are important indexes for evaluating hydrocarbon production potential. If an improper conversion coefficient is used, the exploratory staff may make a wrong assessment of the quality of the hydrocarbon source rock and may also cause a misjudgment on the amount of hydrocarbon resources, thereby affecting the formulation of the exploration strategy, and affecting the later development decisions and return on investment. Therefore, a more accurate determination method for conversion coefficients of organic carbon and organic matters is needed to provide a reference for rapidly and accurately determining the content of the organic matters in the rock and accurately evaluating the abundance of the organic matters. Disclosure of Invention The invention aims to solve the problems in the prior art and provide a method for measuring conversion coefficients of organic carbon and organic matters, which is characterized in that the method is used for respectively measuring