A method and system for calculating the contribution rate of marine shale organic pores

Abstract

This invention discloses a method and system for calculating the contribution rate of organic matter porosity in marine shale. The calculation method includes the following steps: obtaining a marine shale sample; obtaining the organic carbon content of the marine shale sample using a carbon-sulfur analyzer, and separating the organic matter from the kerogen in the marine shale sample; conducting nitrogen adsorption tests on the marine shale and organic matter separately to obtain the pore surface area, pore volume, pore size-pore volume distribution curves, and pore radius of the marine shale and organic matter; and calculating the pore volume contribution rate and surface area contribution rate of organic matter based on the pore surface area and pore volume of the marine shale and organic matter. This calculation method solves the problem of the strong heterogeneity of organic matter in shale, which makes it difficult to quantify. It can accurately evaluate the contribution of organic matter porosity to the shale pore system, and the experimental principle is simple, efficient, rapid, and the experimental results are accurate and reliable. It provides a new approach and a feasible method for shale gas reservoir evaluation.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to a method and system for calculating the contribution rate of organic matter porosity in marine shale. Background Technology

[0002] In shale gas reservoirs, organic matter pores are considered the most important pore type. Organic matter pores not only provide the conditions necessary for hydrocarbon generation but also provide a site for shale gas preservation, determining the amount of gas produced and adsorbed by the shale, making them a key focus of shale gas research.

[0003] Currently, the evaluation of organic matter porosity is divided into two types: qualitative and quantitative. (1) Qualitative analysis of organic matter porosity characteristics is performed using field emission scanning electron microscopy (FET). (2) Quantitative analysis of shale reservoir and organic matter porosity is performed using techniques such as low-temperature gas (carbon dioxide and nitrogen) adsorption and mercury intrusion porosimetry. However, the characteristics of organic matter porosity structure are not yet clear. Although FET can obtain the porosity of organic matter through microscopic observation, the accuracy of organic matter porosity is reduced due to the limitations of the resolution of the scanning electron microscope and the heterogeneity of organic matter. Low-temperature gas (carbon dioxide and nitrogen) adsorption and mercury intrusion porosimetry can characterize the full-size porosity of shale, but they only quantitatively characterize the pore structure of shale and organic matter, and only evaluate the influence of organic matter on the porosity complexity of shale. There are no reports on the treatment and analysis of the relationship between shale and organic matter. The present invention provides a method for calculating the contribution rate of organic pores in marine shale, which can accurately calculate the contribution rate of organic matter to the specific surface area and pore volume of pores in the shale pore system, providing an effective basis for evaluating the structural characteristics of organic matter and strengthening the shale gas reservoir assessment system. Summary of the Invention

[0004] This solution addresses the problems and needs raised above by proposing a method and system for calculating the contribution rate of organic matter porosity in marine shale. The above-mentioned technical objectives are achieved by adopting the following technical features, and several other technical benefits are also brought about.

[0005] One object of this invention is to provide a method for calculating the contribution rate of organic matter porosity in marine shale, comprising the following steps:

[0006] S10: Obtain samples of marine shale;

[0007] S20: The organic carbon content of marine shale samples was obtained by a carbon-sulfur analyzer, and organic matter kerogen was separated from the marine shale samples.

[0008] S30: Marine shale and organic matter were tested by nitrogen adsorption test to obtain the pore surface area, pore volume, pore size-pore volume distribution curve and pore radius of marine shale and organic matter respectively.

[0009] S40: Calculate the pore volume contribution rate and surface area contribution rate of organic matter based on the pore surface area and pore volume of marine shale and organic matter.

[0010] Furthermore, the method for calculating the contribution rate of organic matter porosity in marine shale according to the present invention may also have the following technical features:

[0011] In one example of the present invention, in step S10, the organic carbon content of the marine shale sample obtained is greater than 2%.

[0012] In one example of the present invention, in step S40, the expression for the organic matter pore volume contribution rate is:

[0013]

[0014] Among them, V org V is the pore volume of 1.0 g of organic matter in a gas adsorption experiment. shl 1.0g of shale pore volume under gas adsorption experiment, TOC is the total organic carbon content of shale, and C1 is a constant determined by the contribution of organic pore volume in different regions of the same target shale.

[0015] In one example of the present invention, the constant C1 determined by the organic pore volume contribution of the same target shale in different regions is determined by collecting the average organic carbon content, average shale pore volume, average organic matter pore volume fraction, and average organic pore volume of the same target shale and organic matter in different regions.

[0016] In one example of the present invention, the expression for the constant C1 determined by the organic pore volume contribution of different regions of the same target shale is as follows:

[0017]

[0018] in, It is the average shale pore volume. It is the average organic matter pore volume fraction. It is the average organic pore volume.

[0019] In one example of the present invention, in step S40, the expression for the contribution rate of the organic matter pore surface area is:

[0020]

[0021] Among them, S org V is the pore surface area of ​​1.0g of organic matter under gas adsorption experiments. shl1 is the pore surface area of ​​1.0g shale under gas adsorption experiments, TOC is the total organic carbon content of shale, and C2 is a constant determined by the contribution of organic matter pore surface area in different regions of the same target shale.

[0022] In one example of the present invention, the constant C2 determined by the contribution of the organic matter pore surface area in different regions of the same target shale is determined by collecting the average organic carbon content, average shale surface area, average organic matter surface area ratio, and average organic matter surface area of ​​the same target shale and organic matter in different regions.

[0023] In one example of the present invention, the expression for the constant C2 determined by the contribution of organic matter pore surface area in different regions of the same target shale is as follows:

[0024]

[0025] in, It is the average specific surface area of ​​shale. It is the average organic matter specific surface area ratio. It is the average specific surface area of ​​organic matter.

[0026] Another object of the present invention is to provide a calculation system for the contribution rate of organic matter porosity in marine shale, comprising:

[0027] The sample acquisition unit is used to acquire samples of marine shale.

[0028] The analysis unit is used to obtain the organic carbon content of marine shale samples by carbon-sulfur analyzer and to separate organic matter kerogen from marine shale samples.

[0029] The testing unit is used to test marine shale and organic matter through nitrogen adsorption experiments, and to obtain the pore surface area, pore volume, pore size-pore volume distribution curve and pore radius of marine shale and organic matter respectively.

[0030] The test unit is used to calculate the pore volume contribution rate and surface area contribution rate of organic matter based on the pore surface area and pore volume of marine shale and organic matter.

[0031] In one example of the present invention, the expression for the organic matter pore volume contribution rate in the test unit is:

[0032]

[0033] Among them, V org V is the pore volume of 1.0 g of organic matter in a gas adsorption experiment. shl 1.0g of shale pore volume under gas adsorption experiment, TOC is the total organic carbon content of shale, and C1 is a constant determined by the contribution of organic pore volume in different regions of the same target shale.

[0034] The preferred embodiments of the invention will be described in more detail below with reference to the accompanying drawings, so as to facilitate an understanding of the features and advantages of the invention. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. The drawings are merely illustrative of some embodiments of the present invention and are not intended to limit the scope of the present invention to all embodiments.

[0036] Figure 1 This is a flowchart of a method for calculating the contribution rate of organic pores according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the pore size-pore volume distribution results of shale according to a specific embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the pore size-pore volume distribution of organic matter according to a specific embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram illustrating the contribution rate of organic matter pore volume according to a specific embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram illustrating the contribution rate of organic matter pore surface area according to a specific embodiment of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, “an” or “a” and similar terms do not necessarily indicate a quantity limitation. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0043] According to a first aspect of the present invention, a method for calculating the contribution rate of organic matter porosity in marine shale is provided, such as... Figure 1 As shown, it includes the following steps:

[0044] S10: Obtain samples of marine shale;

[0045] S20: Obtain the organic carbon content of marine shale samples using a carbon-sulfur analyzer, and separate organic matter and kerogen from the marine shale samples; separate organic matter and kerogen from the obtained shale samples according to the requirements of the national standard "Method for Separation of Kerogen in Sedimentary Rocks (GB / T19144-2010)".

[0046] S30: Marine shale and organic matter were tested by nitrogen adsorption test to obtain the pore surface area, pore volume, pore size-pore volume distribution curve and pore radius of marine shale and organic matter respectively.

[0047] S40: Calculate the pore volume contribution rate and surface area contribution rate of organic matter based on the pore surface area and pore volume of marine shale and organic matter.

[0048] The method described above for calculating the contribution of organic matter porosity in marine shale solves the problem of the inability to quantify the strong heterogeneity of organic matter in shale. It accurately evaluates the contribution of organic matter porosity to the shale pore system. Furthermore, combining this method with nitrogen adsorption experiments allows for the analysis of the organic porosity contribution. The experimental principle is simple, efficient, rapid, and the results are accurate and reliable. This provides a new approach and a practical method for shale gas reservoir evaluation.

[0049] In one example of the present invention, in step S10, the organic carbon content of the marine shale sample obtained is greater than 2%.

[0050] In one example of the present invention, in step S40, the expression for the organic matter pore volume contribution rate is:

[0051]

[0052] Among them, V org V is the pore volume of 1.0 g of organic matter in a gas adsorption experiment. shl 1.0g of shale pore volume under gas adsorption experiment, TOC is the total organic carbon content of shale, and C1 is a constant determined by the contribution of organic pore volume in different regions of the same target shale.

[0053] In one example of the present invention, the constant C1 determined by the organic pore volume contribution of the same target shale in different regions is determined by collecting the average organic carbon content, average shale pore volume, average organic matter pore volume fraction, and average organic pore volume of the same target shale and organic matter in different regions.

[0054] In one example of the present invention, the expression for the constant C1 determined by the organic pore volume contribution of different regions of the same target shale is as follows:

[0055]

[0056] in, It is the average shale pore volume. It is the average organic matter pore volume fraction. It is the average organic pore volume.

[0057] In one example of the present invention, in step S40, the expression for the contribution rate of the organic matter pore surface area is:

[0058]

[0059] Among them, S org V is the pore surface area of ​​1.0g of organic matter under gas adsorption experiments. shl 1 is the pore surface area of ​​1.0g shale under gas adsorption experiments, TOC is the total organic carbon content of shale, and C2 is a constant determined by the contribution of organic matter pore surface area in different regions of the same target shale.

[0060] In one example of the present invention, the constant C2 determined by the contribution of the organic matter pore surface area in different regions of the same target shale is determined by collecting the average organic carbon content, average shale surface area, average organic matter surface area ratio, and average organic matter surface area of ​​the same target shale and organic matter in different regions.

[0061] In one example of the present invention, the expression for the constant C2 determined by the contribution of organic matter pore surface area in different regions of the same target shale is as follows:

[0062]

[0063] in, It is the average specific surface area of ​​shale. It is the average organic matter specific surface area ratio. It is the average specific surface area of ​​organic matter.

[0064] According to a preferred embodiment of the present invention, the prerequisite experimental conditions for testing the nitrogen adsorption curves of shale samples and organic matter are: the test is conducted at a temperature of -196°C.

[0065] A system for calculating the contribution rate of organic matter porosity in marine shale according to a second aspect of the present invention includes:

[0066] The sample acquisition unit is used to acquire samples of marine shale.

[0067] The analysis unit is used to obtain the organic carbon content of marine shale samples by carbon-sulfur analyzer and to separate organic matter kerogen from marine shale samples.

[0068] The testing unit is used to test marine shale and organic matter through nitrogen adsorption experiments, and to obtain the pore surface area, pore volume, pore size-pore volume distribution curve and pore radius of marine shale and organic matter respectively.

[0069] The test unit is used to calculate the pore volume contribution rate and surface area contribution rate of organic matter based on the pore surface area and pore volume of marine shale and organic matter.

[0070] The aforementioned calculation system for the contribution rate of organic matter porosity in marine shale solves the problem of quantifying the strong heterogeneity of organic matter in shale. It accurately evaluates the contribution of organic matter porosity to the shale pore system. Furthermore, combining this with nitrogen adsorption experiments allows for analysis of the organic porosity contribution. The experimental principle is simple, efficient, rapid, and the results are accurate and reliable. This provides a new approach and a practical method for shale gas reservoir evaluation.

[0071] In one example of the present invention, the expression for the organic matter pore volume contribution rate in the test unit is:

[0072]

[0073] Among them, V org V is the pore volume of 1.0 g of organic matter in a gas adsorption experiment. shl 1.0g of shale pore volume under gas adsorption experiment, TOC is the total organic carbon content of shale, and C1 is a constant determined by the contribution of organic pore volume in different regions of the same target shale. Specific Implementation

[0075] Taking the calculation of the contribution rate of organic porosity in the black shale of the Niutitang Formation in northern Guizhou as an example:

[0076] (1) By collecting the average TOC and average pore volume of the same target shale and organic matter from different regions, the constant C1 value can be determined by multiplying the ratio of the average shale pore volume to the average organic matter pore volume by the average organic matter pore volume fraction. The obtained average shale pore volume is 0.0180039 cm³. 3 / g, the average TOC of shale is 4.7%, and the average organic matter pore volume is 0.103133818 cm³. 3 / g, the average pore volume fraction of organic matter is 24.8%.

[0077] (2) By collecting the average TOC and average specific surface area of ​​the same target shale and organic matter from different regions, the constant C2 value can be determined by multiplying the ratio of shale pore specific surface area to average organic matter pore specific surface area by the average organic matter pore specific surface area ratio. The obtained average shale pore specific surface area is 9.456627273 (m²). 2 The average TOC of the shale is 4.70%, and the average organic matter pore surface area is 51.46290273 m². 2 ( / g), average organic matter porosity specific surface area is 23.60%.

[0078] (3) The TOC content of the black shale of the Niutitang Formation was obtained by carbon-sulfur analyzer, and the results are shown in Table 1.

[0079] Table 1 shows the TOC content of the black shale in the Niutitang Formation.

[0080]

[0081] (4) Nitrogen adsorption experiments were conducted on shale and organic matter to obtain pore surface area, pore volume, pore size-pore volume distribution curves, and pore radius. The results are as follows: Figure 2 and Figure 3 As shown.

[0082] (5) Based on the TOC content of shale and the data from nitrogen adsorption experiments, the algorithm invented in this patent is used:

[0083] (6) Figure 4 As shown, according to the calculation method The volume contribution rate (CRV) of microporous organic pores was determined to be 1.22%, that of mesoporous organic pores was 15.83%, that of macroporous organic pores was 27.37%, and that of total organic pores was 44.42%.

[0084] (7) Figure 5 As shown, according to the algorithm The contribution rates of microporous organic specific surface area (CRA) were determined to be 5.74%, mesoporous organic specific surface area (CRA) to be 12.79%, macroporous organic specific surface area (CRA) to be 3.81%, and total organic specific surface area (CRA) to be 22.34%.

[0085] The foregoing description, with reference to preferred embodiments, details an exemplary implementation of the method and system for calculating the contribution rate of organic matter porosity in marine shale proposed in this invention. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of this invention, and various combinations can be made to the various technical features and structures proposed in this invention without exceeding the protection scope of this invention, which is determined by the appended claims.

Claims

1. A method for calculating the contribution rate of organic matter porosity in marine shale, characterized in that, Includes the following steps: S10: Obtain samples of marine shale; S20: The organic carbon content of marine shale samples was obtained by a carbon-sulfur analyzer, and organic matter kerogen was separated from the marine shale samples. S30: Marine shale and organic matter were tested by nitrogen adsorption test to obtain the pore surface area, pore volume, pore size-pore volume distribution curve and pore radius of marine shale and organic matter respectively. S40: Calculate the pore volume contribution rate and surface area contribution rate of organic matter based on the pore surface area and pore volume of marine shale and organic matter; The expression for the contribution rate of organic matter pore volume is as follows: in, V org It is under gas adsorption experiment 1.0 g Organic matter pore volume, V shl It is under gas adsorption experiment 1.0 g Shale pore volume, TOC It refers to the total organic carbon content of shale. C 1 It is a constant determined by the organic pore volume contribution of different regions of the same target shale; constant C 1 The expression is: in, It is the average shale pore volume. It is the average organic matter pore volume fraction. It is the average organic pore volume; The expression for the contribution rate of organic matter pore specific surface area is: in, S org It is under gas adsorption experiment 1.0 g Organic matter pore surface area, V shl It is under gas adsorption experiment 1.0 g Shale pore surface area TOC It refers to the total organic carbon content of shale. C 2 It is a constant determined by the contribution of the organic matter pore surface area in different regions of the same target shale; The expression for constant C2 is: in, It is the average specific surface area of ​​shale. It is the average organic matter specific surface area ratio. It is the average specific surface area of ​​organic matter.

2. The method for calculating the contribution rate of organic matter porosity in marine shale according to claim 1, characterized in that, In step S10, the organic carbon content of the obtained marine shale sample is greater than 2%.

3. The method for calculating the contribution rate of organic matter porosity in marine shale according to claim 1, characterized in that, The constant determined by the organic pore volume contribution of different regions of the same target shale. C 1 The data was determined by collecting data on the average organic carbon content, average shale pore volume, average organic matter pore volume fraction, and average organic pore volume of the same target shale and organic matter in different regions.

4. The method for calculating the contribution rate of organic matter porosity in marine shale according to claim 1, characterized in that, The constant determined by the contribution of organic matter pore surface area to different regions of the same target shale. C 2 The data were determined by collecting data on the average organic carbon content, average shale specific surface area, average organic matter specific surface area ratio, and average organic matter specific surface area of ​​the same target shale and organic matter in different regions.

5. A system for calculating the contribution rate of organic matter porosity in marine shale, characterized in that, include: The sample acquisition unit is used to acquire samples of marine shale. The analysis unit is used to obtain the organic carbon content of marine shale samples by carbon-sulfur analyzer and to separate organic matter kerogen from marine shale samples. The testing unit is used to test marine shale and organic matter through nitrogen adsorption experiments, and to obtain the pore surface area, pore volume, pore size-pore volume distribution curve and pore radius of marine shale and organic matter respectively. The test unit is used to calculate the pore volume contribution rate and surface area contribution rate of organic matter based on the pore surface area and pore volume of marine shale and organic matter. The expression for the contribution rate of organic matter pore volume is as follows: in, V org It is under gas adsorption experiment 1.0 g Organic matter pore volume, V shl It is under gas adsorption experiment 1.0 g Shale pore volume, TOC It refers to the total organic carbon content of shale. C 1 It is a constant determined by the organic pore volume contribution of different regions of the same target shale; constant C 1 The expression is: in, It is the average shale pore volume. It is the average organic matter pore volume fraction. It is the average organic pore volume; The expression for the contribution rate of organic matter pore specific surface area is: in, S org It is under gas adsorption experiment 1.0 g Organic matter pore surface area, V shl It is under gas adsorption experiment 1.0 g Shale pore surface area TOC It refers to the total organic carbon content of shale. C 2 It is a constant determined by the contribution of the organic matter pore surface area in different regions of the same target shale; The expression for constant C2 is: in, It is the average specific surface area of ​​shale. It is the average organic matter specific surface area ratio. It is the average specific surface area of ​​organic matter.

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