Method, system, equipment and medium for evaluating reservoir capacity of tight gas reservoir

Abstract

The invention discloses a method, a system, equipment and a medium for evaluating the reservoir capacity of a tight gas reservoir, and relates to the technical field of petroleum and natural gas engineering. Comprising the following steps: acquiring actually measured Young modulus of each mineral component in a standard rock sample of a tight gas reservoir to be measured, and calculating theoretical Young modulus of each mineral component in the standard rock sample through a Young modulus calculation formula; combining the theoretical Young modulus with the actually measured Young modulus to obtain the mineral dispersity of each mineral component, and calculating the skeleton brittleness of each mineral component; measuring the total porosity and the effective porosity of the standard rock sample, calculating the effective porosity percentage of the standard rock sample, calculating the pore throat complexity of each mineral component, and calculating the pore throat effectiveness of each mineral component; and calculating a reservoir factor, and comprehensively evaluating the reservoir capacity of the tight gas reservoir to be tested. According to the method, the reservoir capacity of the tight gas reservoir is reflected through the numerical value of the reservoir factor, so that the evaluation result of the reservoir capacity of the tight gas reservoir is more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum and natural gas engineering, and in particular to a method, system, equipment and medium for evaluating the storage capacity of a tight gas reservoir. Background Art

[0002] China is extremely rich in tight oil and gas resources, which are mainly distributed in large basins such as the Ordos, Songliao, Junggar, and Sichuan basins. They have huge development potential and have become the most strategic oil replacement resource in the country's "14th Five-Year Plan" and the main force for China's future oil and gas reserves and production. Finding favorable reservoir quality is the primary goal of exploration and development and the key to achieving a breakthrough in single well production. Rock storage capacity is a core factor that directly affects the potential of oil and gas exploration resources and scale-effective development. Among them, the degree of natural fracture development and pore connectivity are direct indicators for evaluating storage capacity.

[0003] In the prior art, for example, there is the Chinese patent invention application number CN202011140522.3, which is “a method for characterizing shale storage capacity based on shale organic pore morphology”. This method first collects shale samples through cores or field sections, and performs argon ion polishing on the cut samples and observes them under an environmental scanning electron microscope. Secondly, an environmental scanning electron microscope is used to observe and randomly select 50-100 areas with developed organic pores and preserve them. The selected organic pores are quantitatively characterized in morphology, and the morphology of the organic pores is characterized by the deformation index T. The deformation index of all organic pores is calculated using the deformation calculation formula, and the average deformation index T of the sample is calculated; finally, a storage capacity factor is defined to evaluate the final storage capacity of the shale.

[0004] The defects of the above-mentioned prior art are: the core factors affecting the storage capacity of unconventional reservoirs are not taken into account, resulting in inaccurate evaluation results of the storage capacity of tight gas reservoirs. Summary of the invention

[0005] Based on this, it is necessary to provide a method, system, equipment and medium for evaluating the storage capacity of tight gas reservoirs in response to the above technical problems.

[0006] The embodiment of the present invention provides a method for evaluating the storage capacity of a tight gas reservoir, comprising:

[0007] Obtain the measured Young's modulus of each mineral component in the standard rock sample of the tight gas reservoir to be tested, and calculate the theoretical Young's modulus of each mineral component in the standard rock sample by the Young's modulus calculation formula;

[0008] The measured Young's modulus is divided by the theoretical Young's modulus to obtain the mineral dispersion that characterizes the embedding characteristics of each mineral component. The mineral dispersion of each mineral component is substituted into the skeleton brittleness calculation formula to obtain the skeleton brittleness that characterizes the intrinsic stability of each mineral component.

[0009] The total porosity and effective porosity of the standard rock sample are measured, and the porosity and effective porosity of the standard rock sample are substituted into the effective porosity percentage calculation formula to obtain the effective porosity percentage that characterizes the effective space ratio of fluid flow in the standard rock sample;

[0010] Substitute the effective pore percentage and the mineral dispersion of each mineral component into the pore throat complexity calculation formula to obtain the pore throat complexity of each mineral component; substitute the effective pore percentage into the pore throat effectiveness calculation formula to obtain the pore throat effectiveness of each mineral component;

[0011] The reservoir factor is calculated based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and the reservoir capacity of the tight gas reservoir to be tested is evaluated by the reservoir factor.

[0012] In addition, the theoretical Young's modulus of each mineral component in the standard rock sample is calculated by the Young's modulus calculation formula, and the formula is:

[0013]

[0014] Among them, E b is the theoretical Young's modulus, E bi is the standard Young's modulus of a single mineral, i is the number of mineral components, m i is the percentage of each mineral, and n is a positive integer.

[0015] In addition, the measured Young's modulus is divided by the theoretical Young's modulus to obtain the mineral dispersion that characterizes the embedding characteristics of each mineral component, and the formula is:

[0016]

[0017] Among them, E p is the mineral dispersion, E b is the theoretical Young's modulus, E s is the measured Young's modulus.

[0018] In addition, the skeleton brittleness characterizing the intrinsic stability of each mineral component is obtained, and the formula is:

[0019]

[0020] Among them, BI is the skeleton brittleness, m i is the percentage content of each mineral, m min+1 It is the second least abundant brittle mineral. p is the mineral dispersion and i is the number of mineral components.

[0021] In addition, the effective pore percentage characterizing the effective space ratio of fluid flow in the standard rock sample is obtained by the formula:

[0022]

[0023] Among them, L y is the effective porosity percentage, L s is the effective porosity, L z is the total porosity.

[0024] In addition, the pore throat complexity of each mineral component is calculated by the following formula:

[0025]

[0026] Among them, K L is the pore throat complexity, L y is the effective porosity percentage, E p is the mineral dispersion;

[0027] The calculation formula for obtaining the pore throat effectiveness of each mineral component is:

[0028]

[0029] Among them, W y is the pore throat effectiveness, L y is the effective porosity percentage, m t is the percentage of clay minerals, j is the subscript of clay, v j is the percentage of each clay mineral in the total clay minerals, and v4 is the percentage of montmorillonite in the total clay minerals.

[0030] In addition, the reservoir factor is calculated based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and the formula is:

[0031] CI=BI·K L ·W y

[0032] Among them, CI is the reservoir factor, BI is the skeleton brittleness, K L is the pore throat complexity, W y is the pore throat effectiveness;

[0033] The larger the value of the reservoir factor CI is, the stronger the storage capacity of the tight gas reservoir to be tested is; conversely, the smaller the value of the reservoir factor CI is, the weaker the storage capacity of the tight gas reservoir to be tested is.

[0034] In addition, a system for evaluating storage capacity of a tight gas reservoir includes:

[0035] The rock sample measurement module is used to obtain the measured Young's modulus of each mineral component of the standard rock sample in the tight gas reservoir to be measured, and calculate the theoretical Young's modulus of each mineral component in the standard rock sample through the Young's modulus calculation formula;

[0036] The skeleton brittleness module is used to divide the measured Young's modulus by the theoretical Young's modulus to obtain the mineral dispersion that characterizes the embedding characteristics of each mineral component. The mineral dispersion of each mineral component is substituted into the skeleton brittleness calculation formula to obtain the skeleton brittleness that characterizes the intrinsic stability of each mineral component.

[0037] The effective pore module is used to measure the total porosity and effective porosity of the standard rock sample, and substitute the porosity and effective porosity of the standard rock sample into the effective pore percentage calculation formula to obtain the effective pore percentage that characterizes the effective space ratio of the fluid flow in the standard rock sample;

[0038] The pore throat module is used to substitute the effective pore percentage and the mineral dispersion of each mineral component into the pore throat complexity calculation formula to obtain the pore throat complexity of each mineral component; substitute the effective pore percentage into the pore throat effectiveness calculation formula to obtain the pore throat effectiveness of each mineral component;

[0039] The evaluation module is used to calculate the storage factor based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and to evaluate the storage capacity of the tight gas reservoir to be tested with the storage factor.

[0040] In addition, a computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method for evaluating the storage capacity of a tight gas reservoir when executing the computer program.

[0041] In addition, a storage medium stores a computer program thereon, and when the computer program is executed by a processor, the steps of the above-mentioned method for evaluating the storage capacity of a tight gas reservoir are implemented.

[0042] Compared with the prior art, the above-mentioned method, system, device and medium for evaluating the storage capacity of a tight gas reservoir provided by the embodiment of the present invention have the following beneficial effects:

[0043] The present invention obtains a standard rock sample of a tight gas reservoir to be tested, calculates the measured Young's modulus of each mineral component in the standard rock sample; calculates the theoretical Young's modulus of each mineral component through a Young's modulus calculation formula, combines the theoretical Young's modulus with the measured Young's modulus to obtain the mineral dispersion of each mineral component, and calculates the skeleton brittleness of each mineral component; measures the total porosity and effective porosity of the standard rock sample, calculates the effective porosity percentage of the standard rock sample, calculates the pore throat complexity of each mineral component, and calculates the pore throat effectiveness of each mineral component.

[0044] Compared with the existing technology, it takes into account the factors affecting the single well production capacity in unconventional tight gas reservoirs, and calculates the reservoir factor by combining the three factors that conform to the reservoir characteristics, namely skeleton brittleness, pore throat complexity, porosity and pore throat effectiveness. The reservoir factor is used as the core factor affecting the storage capacity of unconventional reservoirs, and the storage capacity of tight gas reservoirs is reflected by the numerical value of the reservoir factor, making the evaluation results of the storage capacity of tight gas reservoirs more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A flowchart of a method for evaluating the storage capacity of a tight gas reservoir provided in an embodiment;

[0046] Figure 2 A comparison diagram of core pore throat complexity of a method for evaluating the storage capacity of a tight gas reservoir provided in an embodiment;

[0047] Figure 3 A core pore throat effectiveness comparison diagram of a method for evaluating the storage capacity of a tight gas reservoir provided in an embodiment;

[0048] Figure 4 A core storage factor comparison diagram of a method for evaluating the storage capacity of a tight gas reservoir provided in an embodiment. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] In one embodiment, a method for evaluating the storage capacity of a tight gas reservoir is provided, such as Figure 1 As shown, the method includes:

[0051] 1. Obtain the measured Young's modulus of each mineral component in the standard rock sample of the tight gas reservoir to be tested, and calculate the theoretical Young's modulus of each mineral component in the standard rock sample through the Young's modulus calculation formula. The specific contents are as follows:

[0052] (1) Rock sample preparation: Three core samples were taken from different locations of the target reservoir section of the horizontal well KZ1 in a tight gas reservoir, numbered G1 to G3. The rocks in the tight gas reservoir section were made into standard rock samples with a diameter of 2.5 cm and a length of 5 cm. The standard rock samples were placed in a 100°C oven and dried to constant weight.

[0053] (2) Mineral content and mechanical parameter testing: The mineral content of the rock sample in step (1) was tested using an X-ray diffractometer, and the measured Young's modulus of the rock sample in step (1) was tested using a triaxial rock mechanics testing system, see Table 1.

[0054] Table 1 Mineral composition content

[0055]

[0056] 2. The measured Young's modulus is divided by the theoretical Young's modulus to obtain the mineral dispersion that characterizes the distribution characteristics of each mineral component. The mineral dispersion of each mineral component is substituted into the skeleton brittleness calculation formula to obtain the skeleton brittleness that characterizes the inherent stability of each mineral component. Specifically including:

[0057] According to the Rock Physics Handbook, the standard values ​​of Young's modulus of each mineral are obtained, among which feldspar is 64839MPa, dolomite is 105309MPa, quartz is 95943MPa, calcite is 78011MPa, pyrite is 283056MPa, and clay minerals are 21914MPa. The theoretical Young's modulus is obtained using formula (1), the mineral dispersion is obtained using formula (2), and the skeleton brittleness is obtained using formula (3), see Table 2.

[0058]

[0059] Where: E b is the theoretical Young's modulus, MPa; E bi is the standard Young's modulus of a single mineral, MPa; i is the number of minerals, pieces; m i is the percentage content of each mineral, %; E s is the measured Young's modulus, MPa; E p is the mineral dispersion, dimensionless; m min+1 It is the second least abundant brittle mineral, called attachment mineral, %; BI is skeleton brittleness, dimensionless.

[0060] Table 2 Skeleton brittleness table

[0061]

[0062] 3. Measure the total porosity and effective porosity of the standard rock sample, substitute the porosity and effective porosity of the standard rock sample into the effective porosity percentage calculation formula, and obtain the effective porosity percentage that characterizes the effective space ratio of fluid flow in the standard rock sample.

[0063] 4. Substitute the effective pore percentage and the mineral dispersion of each mineral component into the pore throat complexity calculation formula to obtain the pore throat complexity of each mineral component; substitute the effective pore percentage into the pore throat effectiveness calculation formula to obtain the pore throat effectiveness of each mineral component.

[0064] The specific contents are as follows:

[0065] (1) Porosity measurement: The total porosity and effective porosity of the rock samples were measured using a helium porosity automatic measuring instrument (see Table 3).

[0066] (2) Pore throat distribution complexity: The effective pore percentage is calculated according to formula (4), and the pore throat complexity is calculated using formula (5), see Table 3.

[0067] (3) Pore throat effectiveness: Considering the influence of different clay mineral contents, the pore throat effectiveness is calculated using formula (6), as shown in Table 3. The percentage of clay minerals is shown in Table 4.

[0068]

[0069] Where: L s is the effective porosity, dimensionless; L z is the total porosity, dimensionless; L y is the effective porosity percentage, %; K L is the pore throat complexity, dimensionless; E p is the mineral dispersion, dimensionless; W y is the pore throat effectiveness, dimensionless; m t is the percentage of clay minerals, %; j is the subscript of clay, pieces; v j is the percentage of each clay mineral in the total clay minerals, %; v4 is the percentage of montmorillonite in the total clay minerals, %.

[0070] Table 3 Pore throat data

[0071]

[0072] Table 4 Clay mineral content

[0073]

[0074] The pore throat complexity of G1, G2, and G3 rock samples is as follows: Figure 2 The pore throat effectiveness of G1, G2, and G3 rock samples is shown in Figure 3 shown.

[0075] 5. Considering the connectivity of natural fractures, the reservoir factor is calculated based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and the reservoir capacity of the tight gas reservoir to be tested is evaluated by the reservoir factor. Using formula (7), the result is that the reservoir factor of the G1 rock sample is 0.2763, the reservoir factor of the G2 rock sample is 0.3086, and the reservoir factor of the G3 rock sample is 0.3759. Therefore, the reservoir capacity is G3>G2>G1. Figure 4 shown.

[0076] CI=BI·K L·W y (7)

[0077] Where: CI is the reservoir factor, dimensionless; BI is the skeleton brittleness, dimensionless; K L is the pore throat complexity, dimensionless; W y It is the pore throat effectiveness and is dimensionless.

[0078] In one embodiment, a system for evaluating the storage capacity of a tight gas reservoir is provided, the system comprising:

[0079] The rock sample determination module is used to obtain the standard rock sample of the tight gas reservoir to be measured, calculate the measured Young's modulus of the standard rock sample, and determine the content of multiple mineral components of the standard rock sample;

[0080] The skeleton brittleness module is used to calculate the theoretical Young's modulus of each mineral component in the standard rock sample through the Young's modulus calculation formula. The measured Young's modulus is divided by the theoretical Young's modulus to obtain the mineral dispersion that characterizes the embedding characteristics of each mineral component; the mineral dispersion of each mineral component is substituted into the skeleton brittleness calculation formula to obtain the skeleton brittleness that characterizes the intrinsic stability of each mineral component;

[0081] The effective pore module is used to measure the total porosity and effective porosity of the standard rock sample, and substitute the porosity and effective porosity of the standard rock sample into the effective pore percentage calculation formula to obtain the effective pore percentage that characterizes the effective space ratio of the fluid flow in the standard rock sample;

[0082] The pore throat module is used to substitute the effective pore percentage and the mineral dispersion of each mineral component into the pore throat complexity calculation formula to obtain the pore throat complexity of each mineral component; substitute the effective pore percentage into the pore throat effectiveness calculation formula to obtain the pore throat effectiveness of each mineral component;

[0083] The evaluation module is used to calculate the storage factor based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and to evaluate the storage capacity of the tight gas reservoir to be tested with the storage factor.

[0084] In one embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the steps of a method for evaluating the storage capacity of a tight gas reservoir are implemented.

[0085] In one embodiment, a storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of a method for evaluating the storage capacity of a tight gas reservoir are implemented.

[0086] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for evaluating the storage capacity of a tight gas reservoir, characterized in that: include: Obtain the measured Young's modulus of each mineral component in the standard rock sample of the tight gas reservoir to be tested, and calculate the theoretical Young's modulus of each mineral component in the standard rock sample by the Young's modulus calculation formula; The measured Young's modulus is divided by the theoretical Young's modulus to obtain the mineral dispersion that characterizes the embedding characteristics of each mineral component. The mineral dispersion of each mineral component is substituted into the skeleton brittleness calculation formula to obtain the skeleton brittleness that characterizes the intrinsic stability of each mineral component. The total porosity and effective porosity of the standard rock sample are measured, and the porosity and effective porosity of the standard rock sample are substituted into the effective porosity percentage calculation formula to obtain the effective porosity percentage that characterizes the effective space ratio of fluid flow in the standard rock sample; Substitute the effective pore percentage and the mineral dispersion of each mineral component into the pore throat complexity calculation formula to obtain the pore throat complexity of each mineral component; substitute the effective pore percentage into the pore throat effectiveness calculation formula to obtain the pore throat effectiveness of each mineral component; The reservoir factor is calculated based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and the reservoir capacity of the tight gas reservoir to be tested is evaluated by the reservoir factor.

2. A method for evaluating the storage capacity of a tight gas reservoir according to claim 1, characterized in that: The theoretical Young's modulus of each mineral component in the standard rock sample is calculated by the Young's modulus calculation formula, and the formula is: Among them, E b is the theoretical Young's modulus, E bi is the standard Young's modulus of a single mineral, i is the number of mineral components, m i is the percentage of each mineral, and n is a positive integer.

3. A method for evaluating the storage capacity of a tight gas reservoir according to claim 1, characterized in that: The measured Young's modulus divided by the theoretical Young's modulus is used to obtain the mineral dispersion that characterizes the embedding characteristics of each mineral component, and the formula is: Among them, E p is the mineral dispersion, E b is the theoretical Young's modulus, E s is the measured Young's modulus.

4. A method for evaluating the storage capacity of a tight gas reservoir according to claim 1, characterized in that: The skeleton brittleness that characterizes the intrinsic stability of each mineral component is obtained, and its formula is: Among them, BI is the skeleton brittleness, m i is the percentage content of each mineral, m min+1 It is the second least abundant brittle mineral. p is the mineral dispersion, i is the number of mineral components, and n is a positive integer.

5. A method for evaluating the storage capacity of a tight gas reservoir according to claim 1, characterized in that: The formula for obtaining the effective pore percentage that characterizes the effective space ratio of fluid flow in the standard rock sample is: Among them, L y is the effective porosity percentage, L s is the effective porosity, L z is the total porosity.

6. A method for evaluating the storage capacity of a tight gas reservoir according to claim 1, characterized in that: The pore throat complexity of each mineral component is calculated by the following formula: Among them, K L is the pore throat complexity, L y is the effective porosity percentage, E p is the mineral dispersion; The calculation formula for obtaining the pore throat effectiveness of each mineral component is: Among them, W y is the pore throat effectiveness, L y is the effective porosity percentage, m t is the percentage of clay minerals, j is the subscript of clay, v j is the percentage of each clay mineral in the total clay minerals, and v4 is the percentage of montmorillonite in the total clay minerals.

7. A method for evaluating the storage capacity of a tight gas reservoir according to claim 1, characterized in that: The reservoir factor is calculated based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and the formula is: CI=BI K L ·IN y Among them, CI is the reservoir factor, BI is the skeleton brittleness, K L is the pore throat complexity, W y is the pore throat effectiveness; The larger the value of the reservoir factor CI is, the stronger the storage capacity of the tight gas reservoir to be tested is; conversely, the smaller the value of the reservoir factor CI is, the weaker the storage capacity of the tight gas reservoir to be tested is.

8. A system for evaluating the storage capacity of a tight gas reservoir, characterized in that: include: The rock sample measurement module is used to obtain the measured Young's modulus of each mineral component of the standard rock sample in the tight gas reservoir to be measured, and calculate the theoretical Young's modulus of each mineral component in the standard rock sample through the Young's modulus calculation formula; The skeleton brittleness module is used to divide the measured Young's modulus by the theoretical Young's modulus to obtain the mineral dispersion that characterizes the embedding characteristics of each mineral component. The mineral dispersion of each mineral component is substituted into the skeleton brittleness calculation formula to obtain the skeleton brittleness that characterizes the intrinsic stability of each mineral component. The effective pore module is used to measure the total porosity and effective porosity of the standard rock sample, and substitute the porosity and effective porosity of the standard rock sample into the effective pore percentage calculation formula to obtain the effective pore percentage that characterizes the effective space ratio of the fluid flow in the standard rock sample; The pore throat module is used to substitute the effective pore percentage and the mineral dispersion of each mineral component into the pore throat complexity calculation formula to obtain the pore throat complexity of each mineral component; substitute the effective pore percentage into the pore throat effectiveness calculation formula to obtain the pore throat effectiveness of each mineral component; The evaluation module is used to calculate the storage factor based on the skeleton brittleness, pore throat complexity and pore throat effectiveness of each mineral component in the standard rock sample, and to evaluate the storage capacity of the tight gas reservoir to be tested with the storage factor.

9. A computer device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the computer program, the steps of the method for evaluating the storage capacity of a tight gas reservoir as described in any one of claims 1 to 7 are implemented.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for evaluating the storage capacity of a tight gas reservoir according to any one of claims 1 to 7 are implemented.

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