A method, medium and apparatus for determining gas content of deep shale

Abstract

The application provides a method, medium and device for determining gas content of deep shale, the method comprising: (1) obtaining experimental data; (2) collecting logging data; (3) correlating and fitting the logging data with core test analysis organic carbon content data; (4) obtaining a calculation method of shale porosity POR through multi-curve correlation fitting; (5) combining resistivity with rock electricity parameters and core water saturation to calculate water saturation of deep shale; (6) determining a calculation relationship of adsorbed gas content of deep shale; (7) obtaining a relationship of free gas content of deep shale from step (4) and step (5); (8) obtaining a relationship of total gas content of deep shale from step (6) and step (7); (9) calculating the adsorbed gas content and total gas content of deep shale from the relationships obtained in step (6) and step (8). The application has the beneficial effect of better evaluating the gas content of deep shale.

Description

Technical Field

[0001] This invention relates to the field of marine shale gas logging evaluation technology in oil exploration and development, and more specifically, to a method, medium, and apparatus for determining the gas content of deep shale formations. Background Technology

[0002] In recent years, as oil and gas exploration and development has shifted from conventional to unconventional reservoirs, shale gas has gradually become an important area of ​​exploration and development. Simultaneously, the shift from shallow to deep shale gas formations in exploration and development has led to the inadequacy of existing shale gas evaluation technologies for shallow and medium-depth formations. Shale gas content is a key parameter for controlling shale gas production capacity and selecting optimal core areas, and it also forms the basis for shale gas production capacity. After ten years of arduous research, my country has achieved significant results in shale gas exploration and development in the Sichuan Basin, establishing three national-level shale gas demonstration zones, which have served as models and guides for shale gas exploration and development nationwide.

[0003] Source rocks are rocks rich in organic matter that may or have already generated or released a large amount of oil and gas. Scholars at home and abroad have conducted extensive research on the gas content of shale and proposed a variety of methods to evaluate the gas content of shale using well logging curves. However, the previous methods for evaluating the gas content of shallow and medium-depth shale did not consider the influence of temperature, and the calculated adsorbed gas content of deep shale was too high. Summary of the Invention

[0004] The present invention aims to provide a method, medium, and apparatus for determining the gas content of deep shale, so as to better evaluate the gas content of deep shale.

[0005] This invention provides a method for determining the gas content of deep shale, comprising the following steps:

[0006] (1) Obtain and analyze the porosity, water saturation, rock electrical parameters, high temperature and high pressure isothermal adsorption experimental data and core gas content experimental data of single well core test;

[0007] (2) Collect single-well logging data, including logging data of uranium content from acoustic, density, resistivity and energy spectrum logging;

[0008] (3) Correlation fitting was performed between the uranium content logging data from energy spectrum logging and the organic carbon content data from core test analysis;

[0009] (4) The uranium content logging data from acoustic, density and energy spectrum logging were fitted with the porosity from core test analysis using a multi-curve correlation fitting method to obtain the calculation method for shale porosity POR.

[0010] (5) Combine resistivity logging data with rock electrical parameters and core water saturation to calculate the water saturation of deep shale;

[0011] (6) Using the high temperature and high pressure isothermal adsorption experimental data and combined with step (3), determine the calculation formula for the adsorbed gas content in deep shale;

[0012] (7) The relationship between the free gas content of deep shale is obtained from steps (4) and (5);

[0013] (8) Obtain the relationship between the total gas content of deep shale from steps (6) and (7);

[0014] (9) Calculate the adsorbed gas content and total gas content of deep shale using the relationship obtained from steps (6) and (8).

[0015] Furthermore, the calculation method for shale porosity (POR) in step (4) is as follows:

[0016] POR= a 0 +a 1 ×AC+a 2 ×DEN+a 3 ×logU ;

[0017] in, a 0、 a 1. a 2. a 3 is the calculation coefficient; AC Represents sound waves; DEN Indicates density; U This indicates the uranium content in the well logging data.

[0018] Furthermore, in step (5), resistivity logging data is combined with rock electrical parameters and core water saturation to calculate the water saturation of deep shale using the Archie model; the calculation formula is as follows:

[0019] ;

[0020] in, R t The resistivity of deep shale is given in Ω·m. R w The resistivity of formation water is given in Ω·m. S w To calculate the water saturation of shale using well logging, % . This represents the porosity of deep shale, in percentages (%). a , b、 m and n are both experimental parameters of deep shale rock electrical properties, and are decimals.

[0021] Furthermore, step (6) includes:

[0022] (6.1) Through high-temperature and high-pressure isothermal adsorption experiments and step (5), the calculation models for the Langmuir volume and Langmuir pressure of the Langmuir isothermal adsorption equation were determined:

[0023] ;

[0024] ;

[0025] in, TOC This indicates the percentage of organic carbon, expressed as % . T This indicates the temperature of deep shale formations, in °C. V L Denotes the Langmuir volume, m 3 / T; P L Langmuir pressure, MPa;

[0026] (6.2) Using the calculation model of Langmuir volume and Langmuir pressure in the Langmuir isotherm adsorption equation, the calculation relationship of adsorbed gas content in deep shale is determined:

[0027] ;

[0028] in, V s Indicates the adsorbed gas content in deep shale; P This represents the pressure in deep shale formations, expressed in MPa.

[0029] Furthermore, step (7) includes:

[0030] (7.1) Calculation model and steps (6.1) for calculating the porosity of the pore surface occupied by the adsorbed gas based on the pore space occupied by the adsorbed gas:

[0031] ;

[0032] in, The porosity of the pore surface occupied by adsorbed gas; M CH4 This represents the amount of methane. V CH4 This represents the molar volume of methane under standard conditions. ρ s The adsorption state density of methane;

[0033] (7.2) From steps (4), (5) and (7.1), the calculation model for the content of free gas in the underground state is obtained:

[0034] ;

[0035] in, Q f The content of free gas in the underground state; Porosity;

[0036] (7.3) The free gas content in the underground state obtained from step (7.2) is converted to the free gas content in deep shale under standard conditions of 1 atmosphere and 25°C. The following conversion formula is obtained from the gas mass balance equation:

[0037] ;

[0038] in, V f Indicates the free gas content in deep shale; P 0 represents atmospheric pressure; P This represents the pressure in deep shale formations, in MPa. T The value represents the temperature of the deep shale formation, in °C; Z is the deviation coefficient of the original natural gas in the gas reservoir, which is obtained based on the actual high-pressure physical properties or natural gas composition analysis of each well.

[0039] Furthermore, the relationship between the total gas content of deep shale in step (8) is as follows:

[0040] V t = V s + V f ;

[0041] in, V t This indicates the total gas content of deep shale.

[0042] The present invention also provides a computer terminal storage medium storing computer terminal executable instructions, which are used to execute the method described above for determining the gas content of deep shale.

[0043] The present invention also provides a computing device, comprising:

[0044] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method described above for determining the gas content of deep shale.

[0045] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0046] The calculation of adsorbed gas content and total gas content in deep shale using this invention shows good consistency. By finely evaluating the gas content of shale sections, it can provide a reliable basis for selecting the optimal target and sweet spot in different shale blocks, strongly supporting the capacity construction of shale gas production areas, and has broad application prospects. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a flowchart illustrating a method for determining the gas content of deep shale in an embodiment of the present invention.

[0049] Figure 2 Uranium content in embodiments of the present invention U Data on organic carbon content TOC Relationship diagram.

[0050] Figure 3 Density in the embodiments of the present invention DEN Data on organic carbon content TOC Relationship diagram.

[0051] Figure 4 For the sound waves in the embodiments of the present invention AC Relationship between porosity and core test analysis.

[0052] Figure 5 Uranium content in embodiments of the present invention U Relationship between porosity and core test analysis.

[0053] Figure 6 Density in the embodiments of the present invention DEN Relationship between porosity and core test analysis.

[0054] Figure 7 This is a diagram illustrating the effect of calculating the adsorbed gas content and total gas content of deep shale in an embodiment of the present invention. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments 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. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0057] Example

[0058] like Figure 1 As shown in the figure, this embodiment proposes a method for determining the gas content of deep shale, including the following steps:

[0059] (1) This embodiment is based on the data of more than 30 appraisal wells that have been put into production in the national-level shale gas industry demonstration zone in southern Sichuan. The core test analysis of single wells is used to obtain data on porosity, water saturation, rock electrical parameters, high temperature and high pressure isothermal adsorption test data and core gas content test data.

[0060] (2) Corresponding to step (1), collect single-well logging data, including sonic logging, density logging, resistivity logging, and energy spectrum logging of uranium content. U Well logging data;

[0061] (3) Spectroscopic logging of uranium content U Well logging data and core test analysis of organic carbon content data TOC By performing correlation fitting, we obtain the following: Figure 2 The uranium content shown U Data on organic carbon content TOC Relationship diagram;

[0062] (4) By performing multi-curve correlation fitting between acoustic, density, and energy spectrum logging data of uranium content and core test analysis of porosity, a method for calculating shale porosity (POR) was obtained:

[0063] (4.1) Density DEN Well logging data and organic carbon content data from core test analysis TOC By performing correlation fitting, we obtain the following: Figure 3 The density shown DEN Data on organic carbon content TOC Relationship diagram;

[0064] (4.2) The uranium content is obtained by performing multi-curve fitting on the relationship obtained from steps (3) and (4.1). U and density DEN Calculate organic carbon content data TOC Relationship:

[0065] TOC=a 0 +a 1 ×U – a 2 ×DEN ;

[0066] in, a 0、 a 1. a 2 represents the calculation coefficient;

[0067] (4.3) Sound waves AC Correlation fitting was performed between well logging data and core test analysis porosity to obtain the following results: Figure 4 The sound waves shown AC Relationship between porosity and core test analysis;

[0068] (4.4) Uranium content U Correlation fitting was performed between well logging data and core test analysis porosity to obtain the following results: Figure 5 The uranium content shown U Relationship between porosity and core test analysis;

[0069] (4.5) Density DEN Correlation fitting was performed between well logging data and core test analysis porosity to obtain the following results: Figure 6 The density shown DEN Relationship between porosity and core test analysis;

[0070] The sound waves from steps (4.3), (4.4), and (4.5) AC uranium content U and density DEN By performing multi-curve correlation fitting between well logging data and core test analysis of porosity, a method for calculating shale porosity (POR) was obtained:

[0071] POR= a 0 +a 1 ×AC+a 2 ×DEN+a 3 ×logU ;

[0072] in, a 0、 a 1. a 2. a 3 is the calculation coefficient; AC Represents sound waves; DEN Indicates density; U This indicates the uranium content in the well logging data.

[0073] (5) Combining resistivity logging data with rock electrical parameters and core water saturation, the water saturation of deep shale is calculated using the Archie model:

[0074] ;

[0075] in, R t The resistivity of deep shale is given in Ω·m. R w The resistivity of formation water is given in Ω·m. S w To calculate the water saturation of shale using well logging, % . This represents the porosity of deep shale, in percentages (%). a , b、 m and n are both experimental parameters of deep shale rock electrical properties, and are decimals.

[0076] (6) Using high-temperature and high-pressure isothermal adsorption experimental data and in conjunction with step (3), determine the formula for calculating the adsorbed gas content in deep shale:

[0077] (6.1) Through high-temperature and high-pressure isothermal adsorption experiments and step (5), the calculation models for the Langmuir volume and Langmuir pressure of the Langmuir isothermal adsorption equation were determined:

[0078] ;

[0079] ;

[0080] in, TOC This indicates the percentage of organic carbon, expressed as % . T This indicates the temperature of deep shale formations, in °C. V L Denotes the Langmuir volume, m 3 / T, P L Langmuir pressure, MPa;

[0081] (6.2) Using the calculation model of Langmuir volume and Langmuir pressure in the Langmuir isotherm adsorption equation, the calculation relationship of adsorbed gas content in deep shale is determined:

[0082] ;

[0083] in, V s Indicates the adsorbed gas content in deep shale; P This represents the pressure in deep shale formations, expressed in MPa.

[0084] (7) The relationship between the free gas content of deep shale is obtained from steps (4) and (5):

[0085] (7.1) Calculation model and steps (6.1) for calculating the porosity of the pore surface occupied by the adsorbed gas based on the pore space occupied by the adsorbed gas:

[0086] ;

[0087] in, The porosity of the pore surface occupied by adsorbed gas; M CH4 This represents the amount of methane. V CH4 This represents the molar volume of methane under standard conditions. ρ sThe adsorption state density of methane;

[0088] (7.2) From steps (4), (5) and (7.1), the calculation model for the content of free gas in the underground state is obtained:

[0089] ;

[0090] in, Q f The content of free gas in the underground state; Porosity;

[0091] (7.3) The free gas content in the underground state obtained from step (7.2) is converted to the free gas content in deep shale under standard conditions of 1 atmosphere and 25°C. The following conversion formula is obtained from the gas mass balance equation:

[0092] ;

[0093] in, V f Indicates the free gas content in deep shale; P 0 represents atmospheric pressure; P This represents the pressure in deep shale formations, in MPa. T The value represents the temperature of the deep shale formation, in °C; Z is the deviation coefficient of the original natural gas in the gas reservoir, which is obtained based on the actual high-pressure physical properties or natural gas composition analysis of each well.

[0094] (8) The relationship between the total gas content of deep shale and steps (6) and (7) is obtained:

[0095] V t = V s + V f ;

[0096] in, V t This indicates the total gas content of deep shale.

[0097] (9) Calculate the adsorbed gas content and total gas content of deep shale using the relationship obtained from steps (6) and (8).

[0098] Currently, the gas content of deep shale is mainly determined by conventional well logging sonic logging. AC ,density DEN uranium content U The total gas content is calculated by combining the resistivity at varying depths with core analysis. The calculation of adsorbed gas content and total gas content in deep shale using this invention shows good consistency. Figure 7As shown, by accurately evaluating the gas content of shale sections, a reliable basis can be provided for the selection of optimal targets and sweet spots in different shale blocks, which strongly supports the capacity building of shale gas production areas and has broad application prospects.

[0099] Furthermore, in some embodiments, a computer terminal storage medium is proposed, storing computer terminal executable instructions for performing the method for determining the gas content of deep shale as described in the preceding embodiments. Examples of computer storage media include magnetic storage media (e.g., floppy disks, hard disks, etc.), optical recording media (e.g., CD-ROMs, DVDs, etc.), or memory such as memory cards, ROMs, or RAMs. The computer storage medium may also be distributed across a network-connected computer system, for example, as an application store.

[0100] Furthermore, in some embodiments, a computing device is proposed, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method for determining the gas content of deep shale as described in the foregoing embodiments. Examples of computing devices include PCs, tablets, smartphones, or PDAs.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining the gas content of deep shale, characterized in that, Includes the following steps: (1) Obtain and analyze the porosity, water saturation, rock electrical parameters, high temperature and high pressure isothermal adsorption experimental data and core gas content experimental data of single well core test; (2) Collect single-well logging data, including logging data of uranium content from acoustic, density, resistivity and energy spectrum logging; (3) Correlation fitting was performed between the uranium content logging data from energy spectrum logging and the organic carbon content data from core test analysis; (4) The uranium content logging data from acoustic, density and energy spectrum logging were fitted with the porosity from core test analysis using a multi-curve correlation fitting method to obtain the calculation method for shale porosity POR. (5) Combine resistivity logging data with rock electrical parameters and core water saturation to calculate the water saturation of deep shale; (6) Using the high temperature and high pressure isothermal adsorption experimental data and combined with step (3), determine the calculation formula for the adsorbed gas content in deep shale; (7) The relationship between the free gas content of deep shale is obtained from steps (4) and (5); (8) Obtain the relationship between the total gas content of deep shale from steps (6) and (7); (9) Calculate the adsorbed gas content and total gas content of deep shale using the relationship obtained from steps (6) and (8); The calculation method for shale porosity (POR) in step (4) is as follows: BY= a 0 +a 1 ×AC+a 2 ×DEN+a 3 ×logU ; in, a 0、 a 1. a 2. a 3 is the calculation coefficient; AC Represents sound waves; DEN Indicates density; U Indicates the uranium content in well logging using energy dispersive spectroscopy; In step (5), resistivity logging data are combined with rock electrical parameters and core water saturation to calculate the water saturation of deep shale using the Archie model; the calculation formula is as follows: ； in, R t The resistivity of deep shale is given in Ω·m. R w The resistivity of formation water is given in Ω·m. S w To calculate the water saturation of shale using well logging, % . This represents the porosity of deep shale, in percentages (%). a , b、 m and n are both experimental parameters of deep shale rock electrical properties, and are decimals. Step (6) includes: (6.1) Through high-temperature and high-pressure isothermal adsorption experiments and step (5), the calculation models for the Langmuir volume and Langmuir pressure of the Langmuir isothermal adsorption equation were determined: ； ； in, TOC This indicates the percentage of organic carbon, expressed as % . T This indicates the temperature of deep shale formations, in °C. V L Denotes the Langmuir volume, m 3 / T, P L Langmuir pressure, MPa; (6.2) Using the calculation model of Langmuir volume and Langmuir pressure in the Langmuir isotherm adsorption equation, the calculation relationship of adsorbed gas content in deep shale is determined: ； in, V s Indicates the adsorbed gas content in deep shale; P This represents the pressure in deep shale formations, expressed in MPa. Step (7) includes: (7.1) Calculation model and steps (6.1) for calculating the porosity of the pore surface occupied by the adsorbed gas based on the pore space occupied by the adsorbed gas: ； in, The porosity of the pore surface occupied by adsorbed gas; M CH4 This represents the amount of methane. V CH4 This represents the molar volume of methane under standard conditions. ρ s The adsorption state density of methane; (7.2) From steps (4), (5) and (7.1), the calculation model for the content of free gas in the underground state is obtained: ； in, Q f The content of free gas in the underground state; Porosity; (7.3) The free gas content in the underground state obtained from step (7.2) is converted to the free gas content in deep shale under standard conditions of 1 atmosphere and 25°C. The following conversion formula is obtained from the gas mass balance equation: ； in, V f Indicates the free gas content in deep shale; P 0 represents atmospheric pressure; P This represents the pressure in deep shale formations, in MPa. T The value represents the temperature of the deep shale formation, in °C; Z is the deviation coefficient of the original natural gas in the gas reservoir, which is obtained based on the actual high-pressure physical properties or natural gas composition analysis of each well.

2. The method for determining the gas content of deep shale according to claim 1, characterized in that, The relationship between the total gas content of deep shale in step (8) is as follows: V t = V s + V f ； in, V t This indicates the total gas content of deep shale.

3. A computer terminal storage medium storing computer terminal executable instructions, characterized in that, The computer terminal can execute instructions for performing the method for determining the gas content of deep shale as described in any one of claims 1-2.

4. A computing device, characterized in that, include: At least one processor; The at least one processor is also connected in communication with a memory, wherein the memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the method for determining the gas content of deep shale as described in any one of claims 1-2.

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