Shale gas dessert layer evaluation method, electronic equipment and medium

Abstract

The invention discloses a shale gas dessert layer evaluation method, electronic equipment and a medium. The method comprises the following steps: acquiring an inlet temperature and an outlet temperature of drilling fluid slurry of a coring well, and calculating an average temperature; taking out the rock core, weighing the weight of the rock core and carrying out field analysis; acquiring lost gas volume and analytic gas volume, and further calculating the total gas content of the sample; vertically sectioning the analyzed sample, cleaning and airing to obtain microscopic bedding seam data of the sample; constructing an escape speed index; and establishing a two-factor evaluation model of the total gas content and the escape speed index, and evaluating the shale gas dessert layer. According to the method, the two-factor evaluation parameters are established through the total gas content and the escape speed index, the shale gas dessert layer can be quickly and conveniently identified, and the risk possibly occurring when the dessert layer is evaluated by only using the total gas content is overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas exploration and development evaluation, and more specifically, to a shale gas sweet spot layer evaluation method, electronic equipment and medium. Background Art

[0002] Shale gas refers to the natural gas accumulation in the shale formation system in the form of adsorbed and free states, which is stored in the organic-rich shale and its interlayered muddy siltstone. It is an unconventional natural gas. When judging the gas content of shale gas based on the shale gas content determination method (SY / T 6940-2013) and the shale gas reservoir description technical specification (NB / T 1400-2015), the gas content is ≤1.50m 3 / t, the evaluation category is poor (Class III), 1.50m 3 / t≤gas content≤2.50m 3 / t is medium (Class II), gas content ≥2.5m 3 / t is good (Class I). In recent years, many factors have been involved in the prediction and evaluation of shale gas sweet spots at home and abroad, mainly including burial depth, shale thickness and distribution, total organic carbon content, vitrinite reflectance, porosity, permeability, brittleness index, total gas content, free gas, adsorbed gas, desorption rate and pore pressure.

[0003] Existing technologies include:

[0004] Hu Dongfeng proposed to determine the geological sensitivity sweet spot parameters and engineering sweet spot parameters based on basic geological data, logging data and seismic data, carry out geophysical prediction based on the confirmed geological sensitivity sweet spot parameters and engineering sweet spot parameters, obtain prediction results, establish a shale gas sweet spot quantitative evaluation model Q, and determine the shale gas sweet spot quantitative evaluation factor Q sweet ; According to the evaluation factor Q sweet The numerical range of is used to determine favorable shale gas exploration areas.

[0005] Yang Zhenheng proposed to first determine the average temperature of the shale gas well, obtain the quality, gas volume and time of the core of the target layer of the shale gas well, determine the initial diffusion coefficient of the target layer of the shale gas well, and identify the sweet spot layer of the shale gas well based on the initial diffusion coefficient of the shale gas well. 总含气量 The combined application of ) and initial diffusion coefficient (IDC) can better identify shale gas sweet spots and avoid the risk of single-factor identification of gas content.

[0006] Zhao Ankun et al. proposed to obtain various geological parameters in reservoir sweet spots, preservation sweet spots and pressure coefficient sweet spots, evaluate geological characteristic parameters related to shale gas content, establish a mapping relationship between the geological characteristic parameters and shale gas content through the BP neural network model, obtain the optimal weights of various geological characteristic parameters, and obtain a sweet spot distribution prediction model for shale reservoirs by quantitatively superimposing various parameter plane maps. This prediction method systematically analyzes the influence of various geological parameters in reservoir sweet spots, preservation sweet spots and pressure coefficient sweet spots on shale gas content, combines BP neural networks, clarifies the weights of geological parameters in sweet spots in different tectonic areas, and quantitatively predicts the distribution of shale gas sweet spots in shale reservoirs.

[0007] Yu Qian proposed to list sedimentary conditions, reservoir conditions and preservation conditions as criterion layers, and to list the parameters of sedimentary conditions, reservoir conditions and preservation conditions as indicator layers respectively. The indicators of the same layer were compared in pairs to form multiple discriminant matrices, and the weights of each parameter in each indicator layer relative to the corresponding criterion layer were calculated. The shale gas sweet spots were confirmed according to the measured values ​​of each parameter and its corresponding weight. Through systematic analysis of the influence of various geological parameters in sedimentary conditions, reservoir conditions and preservation conditions on shale gas content, combined with multi-level fuzzy recognition methods, the weights of geological parameters of sweet spots in different tectonic areas were clarified, and combined with the quantitative plane distribution map of each parameter, the distribution of shale gas sweet spots was predicted by weighted summation.

[0008] Chen Zhiwei et al. proposed to first obtain the tank top gas samples obtained from logging, measure the methane carbon isotope values ​​in the tank top gas samples in different time periods, and then perform curve fitting on the data series of methane carbon isotope values ​​obtained in different time periods. The obtained curves are integrated and differentiated in turn to form a model algorithm that characterizes the storage characteristics of shale reservoirs and analyzes the gas volume. The shale gas reservoir quality is then classified according to the above-mentioned model algorithm to divide the sweet spot layer.

[0009] The above-mentioned existing technical methods are mainly based on geological, geochemical, geophysical means to study and evaluate shale gas sweet spots. However, there are no reports on methods for using field analytical data and microscopic bedding fracture data to construct models for shale gas sweet spots.

[0010] Therefore, it is necessary to develop a shale gas sweet spot layer evaluation method, electronic equipment and medium.

[0011] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0012] The present invention proposes a shale gas sweet spot layer evaluation method, electronic equipment and medium, which can establish a dual-factor evaluation parameter through total gas content and escape velocity index, can quickly and conveniently identify shale gas sweet spot layers, and overcome the risks that may occur when evaluating sweet spot layers using total gas content alone.

[0013] In a first aspect, the present disclosure provides a method for evaluating a shale gas sweet spot layer, comprising:

[0014] Obtain the inlet temperature and outlet temperature of the drilling fluid mud of the core well and calculate the average temperature;

[0015] Removing the core, weighing the core and performing on-site analysis;

[0016] Obtain the lost gas volume and analyzed gas volume, and then calculate the total gas content of the sample;

[0017] The analyzed samples are vertically cut, cleaned and dried to obtain the microscopic bedding fracture data of the samples;

[0018] Constructing the escape velocity index;

[0019] A dual-factor evaluation model of the total gas content and the escape velocity index is established to evaluate shale gas sweet spots.

[0020] Preferably, performing on-site analysis includes:

[0021] After the core is weighed, it is placed in a sealed analysis tank, the analysis tank is placed in a water bath at the average temperature, and connected to an instrument for on-site analysis;

[0022] After the first period of analysis, the analysis tank is placed in an electric heating box at a temperature of 120° C. to continue analysis until the analysis is completed.

[0023] Preferably, the first duration is 3 hours.

[0024] Preferably, obtaining the lost gas volume and the analyzed gas volume includes:

[0025] The lost gas volume is obtained according to the data of the first time period, and the analyzed gas volume is obtained according to the instrument data.

[0026] Preferably, the total gas content is:

[0027] G 总含气量 =G 解析气 +G 损失气

[0028] Among them, G 总含气量 is the total gas content, G 损失气 is the gas loss, G 解析气 To analyze the gas volume.

[0029] Preferably, the microscopic bedding fracture data is a bedding fracture density parameter.

[0030] Preferably, the escape velocity index is:

[0031] EVI=1.06EXP(0.0175X)

[0032] Among them, X is the bedding fracture density parameter, and EVI is the escape velocity index.

[0033] Preferably, if the total gas content and the escape velocity index are both higher than the corresponding set thresholds, it is a shale gas sweet spot layer.

[0034] In a second aspect, an embodiment of the present disclosure further provides an electronic device, the electronic device comprising:

[0035] A memory storing executable instructions;

[0036] A processor runs the executable instructions in the memory to implement the shale gas sweet spot layer evaluation method.

[0037] In a third aspect, the embodiments of the present disclosure further provide a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the shale gas sweet spot layer evaluation method is implemented.

[0038] Its beneficial effects are:

[0039] 1. The present invention establishes dual-factor evaluation parameters based on total gas content and escape velocity index, which can quickly and conveniently identify shale gas sweet spots, overcoming the risks that may occur when evaluating sweet spots using only total gas content;

[0040] 2. The escape velocity index of the present invention can effectively replace the initial diffusion coefficient, overcoming the shortcoming that the initial diffusion coefficient of shale gas wells is difficult to obtain under normal conditions.

[0041] The methods and apparatus of the present invention have other features and advantages that will be apparent from, or will be described in detail in, the accompanying drawings and subsequent detailed descriptions incorporated herein, which together serve to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0043] Figure 1A schematic diagram of a shale gas sweet spot layer evaluation template based on total gas content and EVI index according to an embodiment of the present invention is shown.

[0044] Figure 2 A flow chart showing the steps of a shale gas sweet spot layer evaluation method according to an embodiment of the present invention.

[0045] Figure 3a and Figure 3b Schematic diagrams comparing the correlation between the total gas content and the escape velocity index and the escape velocity index and the initial production capacity of Well A and Well B according to an embodiment of the present invention are respectively shown. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0047] The present invention provides a shale gas sweet spot layer evaluation method, comprising:

[0048] Obtain the inlet temperature and outlet temperature of the drilling fluid mud of the core well and calculate the average temperature;

[0049] Remove the core, weigh it and analyze it on site;

[0050] Obtain the lost gas volume and analyzed gas volume, and then calculate the total gas content of the sample;

[0051] The analyzed samples are vertically cut, cleaned and dried to obtain the microscopic bedding fracture data of the samples;

[0052] Constructing the escape velocity index;

[0053] A dual-factor evaluation model of total gas content and escape velocity index was established to evaluate shale gas sweet spots.

[0054] In one example, performing on-site resolution includes:

[0055] After the core is weighed, it is placed in a sealed analytical tank, which is then placed in a water bath at an average temperature and connected to an instrument for on-site analysis;

[0056] After the first period of analysis, the analysis tank was placed in an electric heating box at a temperature of 120°C and continued to analyze until the analysis was completed.

[0057] In one example, the first duration is 3 hours.

[0058] In one example, obtaining the lost gas volume and the analyzed gas volume includes:

[0059] The lost gas volume is obtained based on the data of the first period, and the analyzed gas volume is obtained based on the instrument data.

[0060] In one example, the total air content is:

[0061] G 总含气量 =G 解析气 +G 损失气

[0062] Among them, G 总含气量 is the total gas content, G 损失气 is the gas loss, G 解析气 To analyze the gas volume.

[0063] In one example, the microscopic bedding fracture data is a bedding fracture density parameter.

[0064] In one example, the escape velocity exponent is:

[0065] EVI=1.06EXP(0.0175X)

[0066] Among them, X is the bedding fracture density parameter, and EVI is the escape velocity index.

[0067] In one example, if the total gas content and the escape velocity index are both higher than the corresponding set thresholds, it is a shale gas sweet spot layer.

[0068] Specifically, high gas content does not necessarily mean high production capacity. To achieve high production capacity, a high initial diffusion coefficient (IDC) is usually required. However, the initial diffusion coefficient (IDC) is sometimes difficult to obtain. Micro-bedding fractures are high-speed channels for shale gas escape and production. This method proposes the idea of ​​constructing an escape velocity index based on the density of micro-bedding fractures. The constructed escape velocity index (EVI) is combined with the total gas content (G 总含气量 ) can well identify shale gas sweet spots and have a good indication of high-yield and stable-yield layers.

[0069] This method mainly includes the following steps:

[0070] Get the inlet temperature of the core well drilling fluid (T in ) and outlet temperature (T out ), calculate the average temperature (T mean );

[0071] When the core reaches the wellhead, quickly take out the core of appropriate length, weigh the weight m of the core, and then quickly place it in a desorption tank and seal it. Place the desorption tank at an average temperature (T mean ) in a water bath and connected to an instrument for on-site analysis for 3 h;

[0072] After 3 hours, place the desorption tank in an electric heating box at a temperature of 120°C to continue desorption until the desorption is completed, and continue desorption until the desorption gas volume per hour is less than 0.5 ml;

[0073] According to the data of the previous 3 hours, the gas loss volume (G 损失气 ), and obtain the analytical gas volume (G 解析气 ), and at the same time obtain the total gas content G of the sample 总含气量 =G 解析气 +G 损失气 ;

[0074] The analyzed samples are vertically cut, cleaned and dried to obtain the microscopic bedding fracture data of the samples, mainly the bedding fracture density parameter X;

[0075] Construct the escape velocity index (EVI), EVI = 1.06EXP (0.0175X);

[0076] Figure 1 A schematic diagram of a shale gas sweet spot layer evaluation template based on total gas content and EVI index according to an embodiment of the present invention is shown.

[0077] Establish the total gas content (G 总含气量 ) and the escape velocity index (EVI) dual factor evaluation model, such as Figure 1 As shown, the double high (high total gas content (G 总含气量 ) and the high escape velocity index (EVI) have a good indication of gas content and can make a good prediction for high-yield and stable-yield wells, which can effectively avoid the use of total gas content (G 总含气量 )Predict deficiencies and risks in the dessert layer.

[0078] The present invention also provides an electronic device, which includes: a memory storing executable instructions; and a processor, which runs the executable instructions in the memory to implement the above-mentioned shale gas sweet spot layer evaluation method.

[0079] The present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned shale gas sweet spot layer evaluation method is implemented.

[0080] To facilitate understanding of the solutions and effects of the embodiments of the present invention, three specific application examples are given below. Those skilled in the art should understand that the examples are only for facilitating understanding of the present invention, and any specific details thereof are not intended to limit the present invention in any way.

[0081] Example 1

[0082] Figure 2A flow chart showing the steps of a shale gas sweet spot layer evaluation method according to an embodiment of the present invention.

[0083] like Figure 2 As shown, the shale gas sweet spot layer evaluation method includes: step 101, obtaining the inlet temperature and outlet temperature of the drilling fluid mud of the coring well, and calculating the average temperature; step 102, taking out the core, weighing the core and performing on-site analysis; step 103, obtaining the lost gas volume and the analyzed gas volume, and then calculating the total gas content of the sample; step 104, vertically cutting the analyzed sample, cleaning and drying it, and obtaining the microscopic bedding fracture data of the sample; step 105, constructing the escape velocity index; step 106, establishing a double-factor evaluation model of the total gas content and the escape velocity index to evaluate the shale gas sweet spot layer.

[0084] Taking shale gas wells A and B in the Sichuan Basin as examples, according to test data, the average gas content of the organic-rich shale layer in the core section of well A is 2.51m 3 / t, gas content is between 0.44 and 5.19m 3 / t, the observed bedding density of Well A is between 50-300 / cm, and the average bedding density is about 197 / m. The average gas content of Well B is 2.68m 3 / t, gas content is between 0.31 and 5.32 m 3 / t, the fracture density is between 60-200 / m, and the average bedding fracture density is about 158 / m. According to this method, the escape velocity index EVI of Well A is 31.4, and the escape velocity index EVI of Well B is 15.9.

[0085] Figure 3a and Figure 3b Schematic diagrams comparing the correlation between the total gas content and the escape velocity index and the escape velocity index and the initial production capacity of Well A and Well B according to an embodiment of the present invention are respectively shown.

[0086] like Figure 3a-Figure 3b As shown in the figure, according to the above ideas, the average total gas content of the core section of Well A is 2.51m 3 / t, the average total gas content of Well B is 2.68m 3 / t, both meet the standards of Class I gas-bearing layers. In terms of average total gas content, the above two wells are not much different; according to the EVI index constructed by this method, the EVI index of Well A is 32.4, and the EVI index of Well B is 15.9. The EVI of Well A is significantly better than that of Well B. The actual initial production capacity also reveals that the initial capacity of Well A is about 500,000 cubic meters per day, and the initial capacity of Well B is about 330,000 cubic meters per day.

[0087] Example 2

[0088] The present disclosure provides an electronic device, which includes: a memory storing executable instructions; and a processor, which runs the executable instructions in the memory to implement the above-mentioned shale gas sweet spot layer evaluation method.

[0089] An electronic device according to an embodiment of the present disclosure includes a memory and a processor.

[0090] The memory is used to store non-temporary computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0091] The processor may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of the present disclosure, the processor is used to run the computer-readable instructions stored in the memory.

[0092] Those skilled in the art should be able to understand that in order to solve the technical problem of how to obtain a good user experience, the present embodiment may also include well-known structures such as a communication bus and an interface, and these well-known structures should also be included in the protection scope of the present disclosure.

[0093] For detailed description of this embodiment, reference may be made to the corresponding descriptions in the aforementioned embodiments, which will not be repeated here.

[0094] Example 3

[0095] An embodiment of the present disclosure provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the shale gas sweet spot layer evaluation method is implemented.

[0096] According to the computer-readable storage medium of the embodiment of the present disclosure, non-transitory computer-readable instructions are stored thereon. When the non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the above-mentioned methods of each embodiment of the present disclosure are executed.

[0097] The above-mentioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or mobile hard disk), media with built-in rewritable non-volatile memory (e.g., memory card) and media with built-in ROM (e.g., ROM box).

[0098] Those skilled in the art should understand that the purpose of the above description of the embodiments of the present invention is only to exemplarily illustrate the beneficial effects of the embodiments of the present invention, and is not intended to limit the embodiments of the present invention to any given examples.

[0099] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for evaluating shale gas sweet spot layers, characterized in that: include: Obtain the inlet temperature and outlet temperature of the drilling fluid mud of the core well and calculate the average temperature; Removing the core, weighing the core and performing on-site analysis; Obtain the lost gas volume and analyzed gas volume, and then calculate the total gas content of the sample; The analyzed samples are vertically cut, cleaned and dried to obtain the microscopic bedding fracture data of the samples; Constructing the escape velocity index; A dual-factor evaluation model of the total gas content and the escape velocity index is established to evaluate shale gas sweet spots.

2. The shale gas sweet spot evaluation method according to claim 1, wherein: On-site analysis includes: After the core is weighed, it is placed in a sealed analysis tank, the analysis tank is placed in a water bath at the average temperature, and connected to an instrument for on-site analysis; After the first period of analysis, the analysis tank is placed in an electric heating box at a temperature of 120° C. to continue analysis until the analysis is completed.

3. The shale gas sweet spot evaluation method according to claim 2, wherein: The first duration is 3 hours.

4. The shale gas sweet spot evaluation method according to claim 2, wherein: Obtaining the lost gas volume and analyzed gas volume includes: The lost gas volume is obtained according to the data of the first time period, and the analyzed gas volume is obtained according to the instrument data.

5. The shale gas sweet spot evaluation method according to claim 1, wherein: The total gas content is: G 总含气量 =G 解析气 +G 损失气 Among them, G 总含气量 is the total gas content, G 损失气 is the gas loss, G 解析气 To analyze the gas volume.

6. The shale gas sweet spot evaluation method according to claim 1, wherein: The microscopic bedding fracture data is a bedding fracture density parameter.

7. The shale gas sweet spot evaluation method according to claim 6, wherein: The escape velocity index is: EVI=1.06EXP(0.0175X) Among them, X is the bedding fracture density parameter, and EVI is the escape velocity index.

8. The shale gas sweet spot evaluation method according to claim 1, wherein: If the total gas content and the escape velocity index are both higher than the corresponding set thresholds, it is a shale gas sweet spot layer.

9. An electronic device, characterized in that: The electronic device comprises: A memory storing executable instructions; A processor, wherein the processor runs the executable instructions in the memory to implement the shale gas sweet spot layer evaluation method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the shale gas sweet spot layer evaluation method according to any one of claims 1 to 8 is implemented.

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