Method and system for evaluating fracturing transformation volume

Abstract

The invention discloses a method and system for evaluating the fracturing transformation volume, and the method comprises the steps: constructing a fracturing pump stopping water hammer pressure curve of each fracturing well section according to a hydraulic fracturing construction curve of a target fracturing well in a target block, and extracting a pump stopping water hammer pressure attenuation factor in the corresponding curve; according to the pump stop water hammer pressure attenuation factor of each fracturing well section and the corresponding fracturing transformation volume data, a first relation model representing the quantitative relation between the pump stop water hammer pressure attenuation factor and the transformation volume is established; and according to the pump stop water hammer pressure attenuation factor of the to-be-evaluated fractured well section in the target block, utilizing the first relation model to evaluate the reconstruction volume of the current to-be-evaluated fractured well. The method can guide fracturing transformation of unconventional oil and gas reservoirs such as shale reservoirs and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas field development engineering, and particularly to a method and system for evaluating the fracturing treatment volume. Background Art

[0002] Unconventional oil and gas reservoirs such as shale reservoirs are extremely dense, generally characterized by low porosity and ultra-low permeability. The large-scale hydraulic fracturing technology is an important means for effectively exploiting unconventional oil and gas reservoirs such as shale gas at present. Only by expanding the seepage area, increasing the production rate and the final cumulative production through the multi-stage fracturing technology of horizontal wells can the effective development of unconventional oil and gas such as shale gas be realized.

[0003] Quickly grasping the hydraulic fracturing treatment volume is of great significance for further optimizing the hydraulic fracturing construction parameters and reasonably deploying the development, and is a research hotspot for the current hydraulic fracturing fracture diagnosis. After the hydraulic fracturing pump is stopped, the pump-off water hammer pressure wave formed by the compression shock of the fluid remaining in the wellbore propagates reciprocally in the whole wellbore, resulting in high-amplitude, periodic and high-frequency oscillations of the fluid pressure in the wellbore, which further promotes the fluid in the wellbore to flow into the formation through the complex fracture network formed by hydraulic fracturing. This kind of fluid flow will inevitably lead to the attenuation of the pump-off water hammer pressure wave, thus affecting the hydraulic fracturing treatment volume.

[0004] However, the existing technology does not provide a hydraulic fracturing treatment volume evaluation scheme considering the factors of wellbore fluid drainage caused by the pump-off water hammer pressure wave. Summary of the Invention

[0005] The purpose of the present invention is to provide a hydraulic fracturing treatment volume evaluation scheme considering the factors of wellbore fluid drainage caused by the pump-off water hammer pressure wave.

[0006] To solve the above technical problems, an embodiment of the present invention provides a method for evaluating the fracturing treatment volume, including: constructing a pump-off water hammer pressure curve for each fracturing well section according to the hydraulic fracturing construction curve of the target fracturing well in the target block, and extracting the pump-off water hammer pressure attenuation factor in the corresponding curve; establishing a first relationship model characterizing the quantitative relationship between the pump-off water hammer pressure attenuation factor and the treatment volume according to the pump-off water hammer pressure attenuation factor of each fracturing well section and the corresponding fracturing treatment volume data; and evaluating the treatment volume of the current to-be-evaluated fracturing well in the target block by using the first relationship model according to the pump-off water hammer pressure attenuation factor of the to-be-evaluated fracturing well section.

[0007] Preferably, in the process of extracting the pump - stopping water - hammer pressure attenuation factor, it includes: determining an objective function for describing the periodic attenuation characteristics; using the objective function to respectively fit the pump - stopping water - hammer pressure curves of each fracturing well section, and establishing a pump - stopping attenuation function for each fracturing well section; extracting the pump - stopping water - hammer pressure attenuation factor of each fracturing well section according to the fitting coefficients in the pump - stopping attenuation function of each fracturing well section.

[0008] Preferably, the objective function is a decaying sine function, and the non - linear least - squares method is used to fit each pump - stopping water - hammer pressure curve respectively.

[0009] Preferably, the objective function is expressed by the following expression:

[0010] p - p t = Ae -αt sin(ωt + φ)

[0011] where P represents the pump - stopping water - hammer pressure, t represents time, p t represents the fitting reference value of the decaying sine function, A represents the fitting amplitude of the decaying sine function, α represents the fitting attenuation factor of the decaying sine function, ω represents the fitting angular frequency of the decaying sine function, and φ represents the fitting initial phase of the decaying sine function.

[0012] Preferably, in the step of constructing the pump - stopping water - hammer pressure curve of each fracturing well section according to the hydraulic fracturing construction curve of the target fracturing well in the target block, it includes: based on the hydraulic fracturing construction curves of each fracturing well section in the target fracturing well, extracting the curve segments with significant periodic high - frequency oscillation attenuation characteristics therefrom as the pump - stopping water - hammer pressure curves of the corresponding fracturing well sections.

[0013] Preferably, in the process of constructing the first relationship model, it includes: obtaining the first relationship model by performing correlation data fitting on the data sequence representing the pump - stopping water - hammer pressure attenuation factor of each fracturing well section and the data sequence representing the fracturing treatment volume of the corresponding well section.

[0014] On the other hand, an embodiment of the present invention also provides a computer - readable storage medium, which contains a series of instructions for executing the method steps as described above.

[0015] In addition, an embodiment of the present invention also provides a system for evaluating the fracture treatment volume, including: a water hammer pressure attenuation factor extraction module configured to construct a fracture shut-off water hammer pressure curve for each fracture interval according to the hydraulic fracturing construction curve of a target fracture well in a target block and extract the shut-off water hammer pressure attenuation factor in the corresponding curve; a quantitative relationship model generation module configured to establish a first relationship model characterizing the quantitative relationship between the shut-off water hammer pressure attenuation factor and the treatment volume according to the shut-off water hammer pressure attenuation factor of each fracture interval and the corresponding fracture treatment volume data; and a treatment volume evaluation module configured to evaluate the treatment volume of the currently to-be-evaluated fracture well in the target block by using the first relationship model based on the shut-off water hammer pressure attenuation factor of the to-be-evaluated fracture interval in the target block.

[0016] Preferably, the water hammer pressure attenuation factor extraction module includes: an attenuation factor calculation sub-module, wherein the attenuation factor calculation sub-module includes: a target function determination unit configured to determine a target function for describing the periodic attenuation characteristics; a fracture shut-off attenuation function calculation unit configured to respectively fit the fracture shut-off water hammer pressure curve of each fracture interval by using the target function to establish a fracture shut-off attenuation function for each fracture interval; and an attenuation factor extraction unit configured to extract the shut-off water hammer pressure attenuation factor of each fracture interval according to the fitting coefficients in the fracture shut-off attenuation function of each fracture interval.

[0017] Preferably, the quantitative relationship model generation module is further configured to obtain the first relationship model by performing correlation data fitting on the data sequence representing the shut-off water hammer pressure attenuation factor of each fracture interval and the data sequence representing the fracture treatment volume of the corresponding interval.

[0018] Compared with the prior art, one or more of the above embodiments may have the following advantages or beneficial effects:

[0019] The present invention provides a method and system for evaluating the fracture treatment volume. The method and system obtain the shut-in water hammer pressure curves of each fracturing stage of the target fracturing well in the target fracturing block of unconventional oil and gas such as shale gas, construct an attenuated sine function as the objective function to fit the shut-in water hammer pressure curves, establish the shut-in water hammer pressure attenuation functions of each fracturing stage of the target fracturing well, and extract the shut-in water hammer pressure attenuation factors therefrom; in combination with the stimulated reservoir volume (SRV) data obtained from the microseismic monitoring of each fracturing stage of the target fracturing well, establish a quantitative relationship model between the shut-in water hammer pressure attenuation factor and the stimulated reservoir volume (SRV) of each fracturing stage; on the basis of this model, as long as the shut-in water hammer pressure curve of the fracturing stage is fitted to obtain the corresponding attenuation function and the corresponding shut-in water hammer pressure attenuation factor of the shut-in water hammer pressure curve, the stimulated reservoir volume (SRV) of the corresponding fracturing stage can be preliminarily estimated, and the fracture treatment volume of the corresponding fracturing stage can be evaluated. The implementation principle of the present invention is simple, the conclusion is reliable, and the operation is convenient, which has important guiding significance and practical significance for guiding the fracturing transformation of unconventional oil and gas reservoirs such as shale reservoirs, and timely optimizing, implementing and adjusting the hydraulic fracturing plan.

[0020] Other features and advantages of the present invention will be described in the following specification, and in part will be obvious from the specification, or can be understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in the specification, claims and drawings. Brief Description of the Drawings

[0021] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0022] Figure 1 It is a schematic diagram of the steps of the method for evaluating the fracture treatment volume according to the embodiment of the present application.

[0023] Figure 2 It is a schematic diagram of the principle of establishing the shut-in water hammer pressure curve for a certain fracturing stage in the method for evaluating the fracture treatment volume according to the embodiment of the present application.

[0024] Figure 3 It is an example diagram of the curve after fitting the fracturing shut-in water hammer pressure curve for a certain fracturing stage in the method for evaluating the fracture treatment volume according to the embodiment of the present application.

[0025] Figure 4 It is an example diagram of the fitting of the first relationship model in the method for evaluating the fracture treatment volume according to the embodiment of the present application.

[0026] Figure 5It is a block diagram of the module of the system for evaluating the fracture treatment volume according to the embodiments of the present application. Detailed implementation manners

[0027] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, so as to fully understand how the present invention uses technical means to solve technical problems and the implementation process of achieving technical effects and implement accordingly. It should be noted that as long as there is no conflict, the various embodiments in the present invention and the various features in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0028] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0029] The terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "a" and "an" used herein are also intended to include the plural. It should also be understood that the terms "comprises" and / or "comprising" used herein specify the presence of the stated features, integers, steps, operations, units and / or components, and do not exclude the presence or addition of one or more other features, integers, steps, operations, units, components and / or their combinations.

[0030] Unconventional oil and gas reservoirs such as shale reservoirs are extremely dense and generally have the characteristics of low porosity and ultra-low permeability. The large-scale hydraulic fracturing technology is an important means for effectively exploiting unconventional oil and gas reservoirs such as shale gas at present. Only by expanding the seepage area, increasing the production rate and the final cumulative production through the horizontal well multi-stage fracturing technology can the effective development of unconventional oil and gas such as shale gas be realized.

[0031] Quickly mastering the fracture treatment volume is of great significance for further optimizing the hydraulic fracturing construction parameters and reasonably deploying the development, and it is a research hotspot for the current hydraulic fracturing fracture diagnosis. After the hydraulic fracturing pump stops, the pump shut-in water hammer pressure wave formed by the compression shock of the fluid remaining in the wellbore propagates back and forth in the entire wellbore, resulting in high-amplitude, periodic, and high-frequency oscillations of the fluid pressure in the wellbore, which further promotes the fluid in the wellbore to flow into the formation through the complex fracture network formed by hydraulic fracturing. This kind of fluid flow will inevitably cause the attenuation of the pump shut-in water hammer pressure wave, thus affecting the fracture treatment volume.

[0032] In the actual application process, the larger the modified volume and the stronger the flow capacity of the complex fracture network formed by hydraulic fracturing, the greater the flow rate of the fluid in the wellbore flowing through the complex fracture network into the formation. This is manifested as a faster decay rate of the shut-in water hammer pressure, that is, the larger the decay factor value of the shut-in pressure decay function.

[0033] Therefore, to solve the above technical problems, the embodiments of the present application propose a method and system for evaluating the fracturing modified volume. By combining the modified volume (SRV) data obtained from the microseismic monitoring of each fracturing stage of the target fracturing well and the shut-in water hammer pressure decay factor of each fracturing stage, a quantitative correlation relationship between the two is established. Then, the shut-in water hammer pressure decay factor can be used to evaluate the fracturing modified volume, clarify the modified volume (SRV) of each segment of horizontal wells for unconventional oil and gas such as shale gas, and provide timely and reliable engineering and technical guidance for the optimization, implementation, and adjustment of large-scale hydraulic fracturing.

[0034] Example 1

[0035] Figure 1 It is a schematic diagram of the steps of the method for evaluating the fracturing modified volume according to the embodiments of the present application. The following refers to Figure 1 to illustrate the specific step flow of the method for evaluating the fracturing modified volume (also referred to as the "modified volume evaluation method") described in the embodiments of the present invention.

[0036] As Figure 1 shown, in step S110, according to the hydraulic fracturing construction curve of the target fracturing well in the target block, the fracturing shut-in water hammer pressure curve of each fracturing stage is constructed and the shut-in water hammer pressure decay factor in the corresponding curve is extracted.

[0037] It should be noted that in the embodiments of the present invention, the target block is intended to be applied in unconventional oil and gas scenarios such as shale gas.

[0038] In step S110, first, according to the hydraulic fracturing construction curves of each fracturing stage in the target fracturing well in the target block, the fracturing shut-in water hammer pressure curve of each fracturing stage is constructed.

[0039] In one embodiment, based on the hydraulic fracturing construction curves of each fracturing stage in the target fracturing well, a (characteristic) curve segment with significant periodic high-frequency oscillation decay characteristics is respectively extracted from the fracturing construction curves of each well section. Then, the specified characteristic position segment (the position with significant periodic high-frequency oscillation decay characteristics) in the current characteristic curve segment is intercepted to be used as the fracturing shut-in water hammer pressure curve of the corresponding fracturing stage. Refer to Figure 2 .

[0040] Figure 2 (a) shows the hydraulic fracturing construction curve diagram of a certain fracturing stage.Figure 2 (b) shows Figure 2 an example graph of the (feature) curve segment with the characteristic of significant periodic high-frequency oscillation attenuation in (a), Figure 2 (c) shows the position segment with the characteristic of significant periodic high-frequency oscillation attenuation extracted (intercepted) from the feature curve segment, that is, the pressure curve of the hydraulic shock during pump shutdown of the current fracturing well section.

[0041] After obtaining the pressure curves of the hydraulic shock during pump shutdown for each fracturing well section in the target fracturing well, step S110 also extracts the attenuation factor of the hydraulic shock during pump shutdown for the corresponding well section from the pressure curves of the hydraulic shock during pump shutdown for each fracturing well section.

[0042] In one embodiment, in the process of extracting the attenuation factor of the hydraulic shock during pump shutdown for the current well section from the pressure curve of the hydraulic shock during pump shutdown for a certain fracturing well section, in the first step, the objective function for describing the periodic attenuation characteristic is first determined.

[0043] In one embodiment, the objective function is the decaying sine function. Specifically, the objective function is expressed by the following expression:

[0044] p - p t = Ae^(-α t sin(ωt + φ)

[0045] where P represents the pressure of the hydraulic shock during pump shutdown, with the unit of MPa; t represents time, with the unit of s; p t represents the fitting reference value of the decaying sine function, with the unit of MPa; A represents the fitting amplitude of the decaying sine function, with the unit of MPa; α represents the fitting attenuation factor of the decaying sine function, dimensionless; ω represents the fitting angular frequency of the decaying sine function, with the unit of rad; φ represents the fitting initial phase of the decaying sine function, with the unit of rad.

[0046] In the second step, using the objective function established in the first step, the pressure curves of the hydraulic shock during pump shutdown for each fracturing well section are respectively fitted to establish the decay function of the hydraulic shock during pump shutdown for each fracturing well section.

[0047] In one embodiment, the nonlinear least squares method is used to fit each pressure curve of the hydraulic shock during pump shutdown respectively.

[0048] Specifically, in the second step, the decaying sine function of the pump shutdown pressure needs to be used as the objective function, and the nonlinear least squares method is used to fit the pressure curve of the hydraulic shock during pump shutdown for the current fracturing well section to obtain the decaying sine function of the pump shutdown pressure and its corresponding coefficients for the current fracturing well section, so as to use the fitted objective function with a series of coefficient values as the decay function of the hydraulic shock during pump shutdown for the current fracturing well section.

[0049] Step 3: According to the fitting coefficients in the pump shut - down decay function of each fracturing well section, extract the pump - shut - down water hammer pressure decay factor of each fracturing well section. That is to say, in Step 3, the fitting decay factor in the pump shut - down decay function of each fracturing well section is used as the pump - shut - down water hammer pressure decay factor of the corresponding fracturing well section.

[0050] After obtaining the pump - shut - down water hammer pressure decay factor of each fracturing well section, enter Step S120.

[0051] Step S120: According to the pump - shut - down water hammer pressure decay factor of each fracturing well section and the fracturing treatment volume data of the corresponding well section, establish a first relationship model that characterizes the quantitative relationship between the pump - shut - down water hammer pressure decay factor and the treatment volume.

[0052] In the embodiment of the present invention, the fracturing treatment volume data of each fracturing well section is obtained based on the micro - seismic monitoring results of each fracturing well section in the target fracturing well.

[0053] In one embodiment, by performing correlation data fitting on the data sequence representing the pump - shut - down water hammer pressure decay factor of each fracturing well section and the data sequence representing the fracturing treatment volume of each fracturing well section, a first relationship model is obtained and the correlation coefficient (R 2 ) between these two data sequences is calculated. Among them, the first relationship model is a quantitative relationship model that characterizes the pump - shut - down water hammer pressure decay factor and the treatment volume of each well section.

[0054] In one embodiment, the first relationship model is a linear relationship model.

[0055] After completing the construction of the first relationship model, enter Step S130.

[0056] Step S130: According to the pump - shut - down water hammer pressure decay factor of the fracturing well section to be evaluated in the target block, use the first relationship model to evaluate the treatment volume of the current fracturing well to be evaluated.

[0057] It should be noted that in the embodiment of the present invention, the fracturing well to be evaluated is a fracturing well in the same block as the target block.

[0058] In step S130, when evaluating the stimulation volume of co-located fracturing wells in unconventional oil and gas target blocks such as shale gas, after the hydraulic fracturing construction of the to-be-evaluated fracturing well section in the co-located to-be-evaluated fracturing well is completed, in the manner described in step S110 above, the shut-in water hammer pressure curve of the to-be-evaluated fracturing well section is fitted to obtain the fitted target function corresponding to the shut-in water hammer pressure curve of the to-be-evaluated fracturing well section and the shut-in water hammer pressure decay factor of the corresponding well section. Then, by inputting the shut-in water hammer pressure decay factor of the current to-be-evaluated fracturing well section into the first relationship model obtained in step S120, the stimulation volume (SRV) of the to-be-evaluated fracturing well section of the co-located fracturing well can be quickly estimated to evaluate the fracturing stimulation volume of the target fracturing well section of the co-located fracturing well.

[0059] Example 2

[0060] Based on the stimulation volume evaluation method described in Embodiment 1, an embodiment of the present invention provides a data example. The specific step process is as follows:

[0061] 1. In unconventional oil and gas target blocks such as shale gas, select a target fracturing well and obtain the hydraulic fracturing construction curves of each fracturing well section of the well, and extract the fracturing shut-in water hammer pressure curves of each fracturing well section with significant periodic high-frequency oscillation attenuation characteristics, as Figure 2 shown.

[0062] 2. Construct a shut-in pressure decay sine function as the target function, and use the non-linear least squares method to fit the fracturing shut-in water hammer pressure curves of each fracturing well section, as Figure 3 shown, obtain the coefficients corresponding to the shut-in pressure decay sine function of each fracturing well section, as shown in Table 1, and establish the shut-in pressure decay sine function of each fracturing well section. At the same time, separate the shut-in water hammer pressure decay factors of each fracturing well section from the shut-in pressure decay sine functions of each fracturing well section, as shown in Table 2.

[0063] Table 1 Coefficient fitting data table of the shut-in pressure decay sine function

[0064] Serial number <![CDATA[p t > A a ω Φ <![CDATA[R 2 > 1 64.7780 2.2550 0.0713 1.0579 0.8028 0.9905 2 68.2580 2.7962 0.0503 1.0623 0.8003 0.9978 3 67.9453 1.7359 0.0554 1.0626 1.7279 0.9897 4 69.5853 1.3691 0.0671 1.0627 0.6881 0.9876 5 71.6762 1.4373 0.0520 1.0664 0.8087 0.9905 6 73.2917 2.4317 0.0484 1.0676 0.7339 0.9928 7 69.7692 1.8116 0.0575 1.0694 0.7155 0.9854 8 72.9201 2.4172 0.0479 1.0694 0.7542 0.9950 9 70.9195 2.0327 0.0544 1.0699 0.7321 0.9928 10 72.7623 0.6515 0.0642 1.0739 0.8256 0.9571 11 72.7156 2.4235 0.0611 1.0721 0.7288 0.9954 12 73.9739 1.9648 0.0390 1.0714 0.6998 0.9864 13 78.0971 2.3878 0.0424 1.0729 0.7188 0.9834 14 75.3739 1.8335 0.0507 1.0730 0.7158 0.9877 15 78.8851 2.3122 0.0448 1.0738 0.7201 0.9831 16 76.5696 2.4771 0.0320 1.0746 0.7168 0.9888

[0065] Table 2 Shut-in water hammer pressure decay factors and corresponding well section stimulation volumes (SRV)

[0066]

[0067]

[0068] 3. Combine the pump shut - in water hammer pressure attenuation factors of each fracturing interval with the stimulation volume (SRV) data obtained from micro - seismic monitoring of each fracturing interval in the target fracturing well to establish a quantitative relationship model between the pump shut - in water hammer pressure attenuation factor and the stimulation volume (SRV) of each fracturing interval, as Figure 4 shown.

[0069] 4. When evaluating the stimulation volume of co - area fracturing wells in unconventional oil and gas target blocks such as shale gas, after the hydraulic fracturing construction of the target fracturing interval in the co - area fracturing well is completed, by fitting the pump shut - in water hammer pressure curve of the target fracturing interval in the co - area fracturing well, obtain the decaying sine function corresponding to the pump shut - in water hammer pressure curve of the target fracturing interval in the co - area fracturing well and the corresponding pump shut - in water hammer pressure attenuation factor. Based on the quantitative relationship model between the pump shut - in water hammer pressure attenuation factor and the stimulation volume (SRV), the stimulation volume (SRV) of the target fracturing interval in the co - area fracturing well can be quickly estimated, and the fracturing stimulation volume of the target fracturing interval in the co - area fracturing well can be evaluated.

[0070] Example 3

[0071] Based on the stimulation volume evaluation method described in the above - mentioned Example 1 and / or Example 2, an embodiment of the present invention also provides a computer - readable storage medium. A computer program is stored on the storage medium, and the computer program is executed to run a method for evaluating the fracturing stimulation volume. The computer program can run computer instructions, and the computer instructions include computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc.

[0072] The computer - readable storage medium may include: any entity or device capable of carrying computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read - only memory (ROM, Read - Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium, etc.

[0073] It should be noted that the content included in the computer - readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, it is appropriately increased or decreased according to the requirements of legislation and patent practice. For example, in some jurisdictions, according to patent practice, the computer - readable storage medium does not include electrical carrier signals and telecommunication signals.

[0074] Example 4

[0075] Based on the fracturing volume evaluation method described in the above-mentioned Embodiment 1 and / or Embodiment 2, the present invention further provides a system for evaluating the fracturing volume (also referred to as the "fracturing volume evaluation system").

[0076] Figure 5 It is a module block diagram of the system for evaluating the fracturing volume according to the embodiments of the present application. As Figure 5 shown, the fracturing volume evaluation system described in the embodiments of the present invention includes: a water hammer pressure attenuation factor extraction module 51, a quantitative relationship model generation module 52, and a fracturing volume evaluation module 53.

[0077] Specifically, the water hammer pressure attenuation factor extraction module 51 is implemented according to the method described in the above step S110, and is configured to construct a fracturing pump-stop water hammer pressure curve for each fracturing well section based on the hydraulic fracturing construction curve of the target fracturing well in the target block, and extract the pump-stop water hammer pressure attenuation factor in the corresponding curve; the quantitative relationship model generation module 52 is implemented according to the method described in the above step S120, and is configured to establish a first relationship model characterizing the quantitative relationship between the pump-stop water hammer pressure attenuation factor and the fracturing volume based on the pump-stop water hammer pressure attenuation factor of each fracturing well section and the corresponding fracturing volume data; the fracturing volume evaluation module 53 is implemented according to the method described in the above step S130, and is configured to evaluate the fracturing volume of the current to-be-evaluated fracturing well by using the first relationship model based on the pump-stop water hammer pressure attenuation factor of the to-be-evaluated fracturing well section in the target block.

[0078] In one embodiment, the water hammer pressure attenuation factor extraction module 51 includes: a water hammer pressure curve extraction sub-module 511 and an attenuation factor calculation sub-module 512.

[0079] In one embodiment, the water hammer pressure curve extraction sub-module 511 is configured to extract, from the hydraulic fracturing construction curves of each fracturing well section in the target fracturing well, a curve segment with significant periodic high-frequency oscillation attenuation characteristics as the fracturing pump-stop water hammer pressure curve of the corresponding fracturing well section.

[0080] In one embodiment, the attenuation factor calculation sub-module 512 includes: a target function determination unit 5121, a fracturing pump-stop attenuation function calculation unit 5122, and an attenuation factor extraction unit 5123. Specifically, the target function determination unit 5121 is configured to determine a target function for describing the periodic attenuation characteristics; the fracturing pump-stop attenuation function calculation unit 5122 is configured to use the target function to respectively fit the fracturing pump-stop water hammer pressure curve of each fracturing well section to establish a fracturing pump-stop attenuation function for each fracturing well section; the attenuation factor extraction unit 5123 is configured to extract the pump-stop water hammer pressure attenuation factor of each fracturing well section according to the fitting coefficients in the fracturing pump-stop attenuation function of each fracturing well section.

[0081] Further, the quantitative relationship model generation module 52 is further configured to obtain a first relationship model by performing correlation data fitting on the data sequence representing the shut-in water hammer pressure decay factor of each fracturing well section and the data sequence representing the fracturing treatment volume of the corresponding well section.

[0082] The present invention discloses a method and system for evaluating fracturing treatment volume. The method and system obtain the shut-in water hammer pressure curves of each fracturing well section of a target fracturing block of unconventional oil and gas such as shale gas, and construct a decaying sine function as the objective function to fit the shut-in water hammer pressure curves, thereby constructing the shut-in water hammer pressure decay function of each fracturing well section of the target fracturing well, and extracting the shut-in water hammer pressure decay factor therefrom; combining the data of the stimulated reservoir volume (SRV) obtained by microseismic monitoring of each fracturing well section of the target fracturing well, a quantitative relationship model between the shut-in water hammer pressure decay factor and the stimulated reservoir volume (SRV) of each fracturing well section is established; based on this model, as long as the shut-in water hammer pressure curve of the fracturing well section is fitted to obtain the decay function corresponding to the shut-in water hammer pressure curve and the corresponding shut-in water hammer pressure decay factor, the stimulated reservoir volume (SRV) of the corresponding fracturing well section can be preliminarily estimated, and the fracturing treatment volume of the corresponding fracturing well section can be evaluated. The implementation principle of the present invention is simple, the conclusion is reliable, and the operation is convenient, which has important guiding significance and practical significance for guiding the fracturing transformation of unconventional oil and gas reservoirs such as shale reservoirs, and timely optimizing, implementing and adjusting the hydraulic fracturing plan.

[0083] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

[0084] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0085] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0086] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and do not imply limitation.

[0087] The phrase "an embodiment" or "embodiments" mentioned in the specification means that the specific features, structures or characteristics described in connection with the embodiments are included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment" or "embodiments" that appear throughout the specification do not necessarily all refer to the same embodiment.

[0088] Although the embodiments disclosed in the present invention are as described above, the content described is only an embodiment adopted for the convenience of understanding the present invention and is not intended to limit the present invention. Any person skilled in the art within the technical field to which the present invention pertains may make any modifications and changes in the form of implementation and details without departing from the spirit and scope disclosed by the present invention. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A method for evaluating the fracturing treatment volume, characterized in that, comprising: Constructing a fracturing shut - in water - hammer pressure curve for each fracturing well section according to the hydraulic fracturing construction curve of the target fracturing well in the target block, and extracting the shut - in water - hammer pressure decay factor in the corresponding curve; Establishing a first relationship model characterizing the quantitative relationship between the shut - in water - hammer pressure decay factor and the treatment volume according to the shut - in water - hammer pressure decay factor of each fracturing well section and the corresponding fracturing treatment volume data; Evaluating the treatment volume of the current fracturing well to be evaluated by using the first relationship model according to the shut - in water - hammer pressure decay factor of the fracturing well section to be evaluated in the target block.

2. The method according to claim 1, characterized in that, in the process of extracting the shut - in water - hammer pressure decay factor, it includes: Determining an objective function for describing the periodic decay characteristics; Using the objective function to respectively fit the fracturing shut - in water - hammer pressure curve of each fracturing well section, and establishing a fracturing shut - in decay function for each fracturing well section; Extracting the shut - in water - hammer pressure decay factor of each fracturing well section from the fitting coefficients of each fracturing shut - in decay function of each fracturing well section.

3. The method according to claim 2, characterized in that, the objective function is a decaying sine function, and the nonlinear least - squares method is used to respectively fit each fracturing shut - in water - hammer pressure curve.

4. The method according to claim 2 or 3, characterized in that, the objective function is represented by the following expression: p-p t = Ae -αt sin(ωt + φ) Among them, P represents the water hammer pressure during pump shutdown, t represents time, and p t represents the fitting reference value of the decaying sine function, A represents the fitting amplitude of the decaying sine function, α represents the fitting decay factor of the decaying sine function, ω represents the fitting angular frequency of the decaying sine function, and φ represents the fitting initial phase of the decaying sine function.

5. The method according to any one of claims 1 - 4, characterized in that, in the step of constructing a fracturing shut - in water - hammer pressure curve for each fracturing well section according to the hydraulic fracturing construction curve of the target fracturing well in the target block, it includes: Based on the hydraulic fracturing construction curves of each fracturing well section in the target fracturing well, extracting the curve segments with significant periodic high - frequency oscillation decay characteristics therefrom as the fracturing shut - in water - hammer pressure curves of the corresponding fracturing well sections.

6. The method according to any one of claims 1 - 5, characterized in that, in the process of constructing the first relationship model, it includes: Obtaining the first relationship model by performing correlation data fitting on the data sequence representing the shut - in water - hammer pressure decay factor of each fracturing well section and the data sequence representing the fracturing treatment volume of the corresponding well section.

7. A computer - readable storage medium, characterized in that, it contains a series of instructions for executing the method steps according to any one of claims 1 - 6.

8. A system for evaluating the fracturing treatment volume, characterized in that, comprising: A water - hammer pressure decay factor extraction module configured to construct a fracturing shut - in water - hammer pressure curve for each fracturing well section according to the hydraulic fracturing construction curve of the target fracturing well in the target block, and extract the shut - in water - hammer pressure decay factor in the corresponding curve; A quantitative relationship model generation module configured to establish a first relationship model characterizing the quantitative relationship between the shut - in water - hammer pressure decay factor and the treatment volume according to the shut - in water - hammer pressure decay factor of each fracturing well section and the corresponding fracturing treatment volume data; A modified volume evaluation module, configured to evaluate the modified volume of the current fracturing well to be evaluated according to the shut-in water hammer pressure decay factor of the fracturing well section to be evaluated in the target block by using the first relationship model.

9. The system according to claim 8, wherein, the water hammer pressure decay factor extraction module includes: a decay factor calculation sub-module, wherein the decay factor calculation sub-module has: a target function determination unit, configured to determine a target function for describing the periodic decay characteristics; a fracturing shut-in decay function calculation unit, configured to respectively fit the fracturing shut-in water hammer pressure curves of each fracturing well section by using the target function to establish a fracturing shut-in decay function for each fracturing well section; a decay factor extraction unit, configured to extract the shut-in water hammer pressure decay factors of each fracturing well section according to the fitting coefficients of each fracturing well section in the fracturing shut-in decay function.

10. The system according to claim 8 or 9, wherein, the quantitative relationship model generation module is further configured to obtain the first relationship model by performing correlation data fitting on the data sequence representing the shut-in water hammer pressure decay factor of each fracturing well section and the data sequence representing the fracturing modification volume of the corresponding well section.

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