Carbon dioxide inter-section displacement pre-fracturing process and design method and related equipment thereof

Abstract

The invention discloses a carbon dioxide inter-section displacement pre-fracturing process and a design method and related equipment thereof, and belongs to the technical field of oil and gas production, the design method comprises the following steps: establishing an integrated fractured horizontal well numerical simulation model according to seismic data of a target well, logging interpretation data and an engineering parameter range given by an oil production scheme; the integrated fractured horizontal well numerical simulation model is used for simulating single well yields under different section intervals and different single-section carbon dioxide injection amounts by adopting a section-separated gas injection method; drawing a parameter optimization chart based on the single well yield and the carbon dioxide injection section number obtained under different section distances and different single-section carbon dioxide injection amounts; and according to the parameter optimization plate, determining the final segment spacing and the single-segment carbon dioxide injection amount. While the recovery efficiency is improved, the construction efficiency is improved, and the fracturing cost is saved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas production technology, specifically relating to a carbon dioxide interstage displacement pre-fracturing process, its design method, and related equipment. Background Technology

[0002] The Jinlong 2 well area is a large, blocky oil reservoir with abundant geological reserves, making it an important block for future production capacity development. However, its reservoir is characterized by tight lithology, poor physical properties, strong heterogeneity, and fine pore throats, classifying it as an unconventional tight oil reservoir. After preliminary exploration, research, and field trials, a development approach primarily based on horizontal well volumetric fracturing technology has been established. While volumetric fracturing of horizontal wells initially results in high production, problems such as rapid formation pressure decline, rapid production reduction, and difficulty in stabilizing production are common. Relying solely on formation energy elastic development leads to low recovery rates, with primary recovery rates of only 10%-15%.

[0003] Regarding enhanced oil recovery (EOR) through gas injection, many scholars both domestically and internationally have conducted laboratory studies and field tests on nitrogen, deoxygenated air flooding, hydrocarbon gases, and carbon dioxide. The mechanism involves a series of physicochemical reactions between the injected gas and underground crude oil, primarily improving oil displacement efficiency by maintaining formation pressure and reducing crude oil viscosity, thus establishing effective displacement and increasing recovery. However, field tests have shown that continuous gas injection can easily lead to gas channeling in wells within the same row, and low effectiveness in lateral wells due to excessive spacing. Carbon dioxide, on the other hand, is soluble in crude oil, improving its fluidity, increasing dissolved gas drive energy, reducing surface adhesion, and improving displacement efficiency and recovery. Many researchers have conducted theoretical and experimental studies on carbon dioxide flooding, achieving good experimental results. In field applications, some oilfields have adopted carbon dioxide pre-fracturing technology, achieving good production increases. However, the CO2 pre-fracturing process requires drying, cooling, and pressure testing, resulting in a long injection cycle and a 44% reduction in construction efficiency compared to conventional fracturing. Currently, the source of CO2 is singular, and the construction cost is 28.6% higher than conventional fracturing. Furthermore, the optimal matching relationship between the effective displacement distance of CO2, i.e., the injection volume and the spacing of the horizontal fracturing sections, is not entirely clear.

[0004] The relevant existing technologies are as follows: Thesis: ① Zou Wanli took the K block of the S oilfield as the research object, established a geological model and a reservoir numerical simulation model, and optimized the construction design parameters of carbon dioxide pre-storage fracturing for single wells and well groups in the vertical well reverse nine-point well network. He optimized the reasonable fracture length, conductivity, and fracturing sequence of the nine-point well network. For single-well carbon dioxide injection huff and puff, he optimized the reasonable construction displacement and injection volume. (Zou Wanli. Research on Optimization Design of Carbon Dioxide Pre-storage Volumetric Fracturing [D]. Northeast Petroleum University, 2018.) Journal articles: ① To address the problems of excessive equipment usage, low construction efficiency, and high construction costs caused by alternating operations of two fracturing units at the construction site, Chen Saifeng et al. prepared a pipeline antifreeze isolation fluid for CO2 pre-fracturing and designed an isolation fluid injection process. After injecting pre-liquid CO2, nitrogen pressure control and replacement are performed, and the antifreeze isolation fluid is circulated. This allows a single fracturing unit to complete CO2 pre-fracturing, solving the problems existing in conventional CO2 pre-fracturing and achieving the goal of cost reduction, efficiency improvement, and high-quality and efficient construction. (Chen Saifeng, Li Jun, Wang Pengtao. Application of CO2 pre-fracturing technology in ultra-low permeability reservoirs [J]. Shihezi Science and Technology, 2024, (02): 40-42.) ② Zang Yuxi et al., using shale oil reservoirs in the Ordos Basin as an example, studied the effects of CO2 injection rate, well shut-in time, reservoir horizontal / vertical permeability ratio, and dual-horizontal well perforation fracturing method on fluid distribution based on reservoir numerical simulation software. The results showed that the difference in permeability between the horizontal and vertical directions resulted in a larger CO2 sweep range in the horizontal direction, and the injection rate was more sensitive to the sweep length. Extending the well shut-in time could increase the CO2 sweep range, but the injection rate had a greater impact; it is recommended to control the sweep range by adjusting the injection rate. The horizontal / vertical permeability ratio had a significant impact on the CO2 sweep range; the larger the ratio, the wider the horizontal sweep and the narrower the vertical sweep, exhibiting a flattened distribution. Comparing dual-horizontal well zipper fracturing and synchronous perforation fracturing, zipper fracturing helped to increase the CO2 sweep range, which is beneficial for oil and gas development. (Zang Yuxi, Wang Haizhu, Wang Bin, et al. Distribution characteristics of CO2 fracturing fluid in shale oil reservoirs in the Ordos Basin [J]. Journal of Xi'an Petroleum University (Natural Science Edition), 2024, 39 (02):55-61.) The relevant patents are as follows: ① Song Bo et al. invented a method for fracturing tight oil wells using carbon dioxide pre-storage combined with proppant injection. This method utilizes a large-scale, high-flow-rate injection of slickwater and liquid carbon dioxide for pre-storage, pure liquid carbon dioxide flowback for energy storage, and continuous proppant injection with cross-linked fracturing fluid. This effectively enhances formation energy, increases the driving pressure and fluidity of underground crude oil flow, and improves fracturing fluid flowback efficiency and fracture conductivity. (Song Bo, Yang Xiyong, Li Lubing, et al. Method for Fracturing Tight Oil Wells Using Carbon Dioxide Pre-storage Combined with Propane Injection, Application No.: CN201711319242.7, Publication Date: 2018-05-18.) ② Zuo Luo et al. invented a method for optimizing the amount of carbon dioxide injected before fracturing shale oil reservoirs. First, the minimum miscibility pressure of the target reservoir is measured to obtain the relationship between the carbon dioxide injection rate and reservoir pressure under the target reservoir conditions, thus obtaining the carbon dioxide injection rate Q1 corresponding to the minimum miscibility pressure. Then, the relationship between the carbon dioxide injection rate and oil exchange rate under the target reservoir conditions after the fracturing fractures are fully formed is obtained, thus obtaining the carbon dioxide injection rate Q2 corresponding to the maximum oil exchange rate. The larger of Q1 and Q2 is selected as the pre-fracturing carbon dioxide dosage. (Zuo Luo, Wang Haitao, Jiang Tingxue, et al. A method for optimizing the amount of carbon dioxide injected before fracturing shale oil reservoirs, Application No.: CN202210750258.8, Publication Date: 2024-01-09.) Existing technological shortcomings: The dissertation ① focuses on vertical wells and well groups, optimizing fracturing operation parameters, displacement and fracturing fluid injection volume, but does not provide an optimization method for carbon dioxide injection volume.

[0005] The journal article ① focuses on optimizing carbon dioxide injection equipment, which is different from the optimization objective of this invention.

[0006] Journal article ② focuses on optimizing a single factor, without optimizing the matching relationship between carbon dioxide injection amount and segment spacing.

[0007] Patent ① only provides a carbon dioxide pre-storage fracturing method, but does not provide an optimization method for the carbon dioxide injection volume and segment spacing for horizontal well fracturing.

[0008] Patent ② considers the relationship between carbon dioxide injection volume, reservoir pressure, and half-fracture length. However, this patent does not provide an optimization method for carbon dioxide injection volume and segment spacing for horizontal well fracturing.

[0009] In summary, the existing technology has the following main defects: ① It only optimizes the fracturing construction parameters, but does not optimize the matching relationship between the carbon dioxide injection volume and the segment spacing; ② It does not optimize the carbon dioxide pre-fracturing process in terms of construction efficiency and economic benefits. Summary of the Invention

[0010] The purpose of this invention is to provide a pre-fracturing process for carbon dioxide interstage displacement, its design method, and related equipment, which can improve the recovery rate, increase construction efficiency, and save fracturing costs.

[0011] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for designing a pre-fracturing process for carbon dioxide interstage displacement, comprising: Based on the seismic data of the target well, the logging interpretation data, and the range of engineering parameters given in the oil production plan, an integrated numerical simulation model of a fracturing horizontal well is established. The numerical simulation model of the integrated horizontal well fracturing was used to simulate the single well production under different intervals and different single-stage carbon dioxide injection rates when using the inter-stage gas injection method. Based on the single-well production and number of injected carbon dioxide segments obtained under different segment spacing and different single-segment carbon dioxide injection rates, a parameter optimization chart was drawn. Based on the parameter optimization chart, the final average segment spacing and single-segment carbon dioxide injection volume are determined.

[0012] A further improvement of the present invention is as follows: The parameter optimization chart is drawn based on the single-well production and number of injected carbon dioxide segments obtained under different segment spacings and different single-segment carbon dioxide injection volumes, including: The single-stage oil production is calculated based on the single-well production and the number of stages of carbon dioxide injection under different stage spacing and different single-stage carbon dioxide injection rates; the dimensionless oil production is calculated based on the single-stage oil production and the corresponding single-stage carbon dioxide injection rate. A parameter optimization chart was plotted, showing the interval between segments, the amount of carbon dioxide injected per segment, and the corresponding dimensionless oil production.

[0013] A further improvement of the present invention is that the step size of the different segment spacing is 5m-20m, and the step size of the single segment carbon dioxide injection amount is 50 m³-200 m³.

[0014] A further improvement of the present invention is that the method for calculating the single-stage oil production based on the single-well production and the number of carbon dioxide injection stages obtained under different segment spacing and different single-stage carbon dioxide injection volumes is as follows: the single-well production obtained from the numerical simulation model of each integrated fracturing horizontal well is divided by the number of carbon dioxide injection stages to obtain the single-stage oil production.

[0015] A further improvement of the present invention is that: the dimensionless oil production based on the single-stage oil production and the corresponding single-stage carbon dioxide injection is calculated by dividing the single-stage oil production by the corresponding single-stage carbon dioxide injection to obtain the dimensionless oil production.

[0016] Secondly, the present invention provides a pre-fracturing process for carbon dioxide interstage displacement, comprising: Step 1: Using the carbon dioxide inter-segment displacement pre-fracturing process design method described in claim 1, the average segment spacing and single-segment carbon dioxide injection volume are obtained; Step 2: Divide the horizontal well into segments based on the segment spacing, and inject carbon dioxide into different segments of the horizontal well at intervals. The amount of carbon dioxide injected into each segment is the amount of carbon dioxide injected in a single segment. Carbon dioxide displacement is formed between the fractures of adjacent fracturing segments.

[0017] Thirdly, the present invention provides a carbon dioxide interstage displacement pre-fracturing process design system, comprising: The numerical simulation model construction module is used to establish an integrated numerical simulation model of a fracturing horizontal well based on the seismic data of the target well, the logging interpretation data, and the range of engineering parameters given by the oil production scheme. The simulation module is used to simulate the single-well production under different intervals and different single-stage carbon dioxide injection rates using an integrated fracturing horizontal well numerical simulation model. The chart drawing module is used to draw parameter optimization charts based on the single-well production and number of injected carbon dioxide segments obtained under different segment spacing and different single-segment carbon dioxide injection volumes. The output module is used to optimize the diagram based on parameters and determine the final average segment spacing and the amount of carbon dioxide injected per segment.

[0018] A further improvement of the present invention is as follows: The drawing module includes: The calculation module calculates the single-segment oil production based on the single-well production and the number of segments injected with carbon dioxide under different segment spacing and different single-segment carbon dioxide injection amounts; and calculates the dimensionless oil production based on the single-segment oil production and the corresponding single-segment carbon dioxide injection amount. The plotting module generates a parameter-optimized chart of the segment spacing, single-segment carbon dioxide injection volume, and corresponding dimensionless oil production.

[0019] Fourthly, the present invention provides an electronic device, comprising: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the carbon dioxide interstage displacement pre-fracturing process design method as described in any one of the first aspects of the present invention.

[0020] Fifthly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the carbon dioxide interstage displacement pre-fracturing process design method as described in any one of the first aspects of the present invention.

[0021] Compared with the prior art, the present invention has at least the following beneficial technical effects: This invention provides a pre-fracturing process design method for carbon dioxide inter-segment displacement, which uses model simulation to optimize key parameters of carbon dioxide inter-segment displacement: average segment spacing and single-segment injection volume. This method is highly versatile and can optimize the combination relationship with high recovery rate according to the actual situation of different wells. This method can optimize the segment spacing and single-segment injection volume without actually carrying out fracturing operations, which greatly reduces the risks and costs in actual operation.

[0022] Furthermore, the optimization of the plot based on the segment spacing and single-segment carbon dioxide injection volume and the corresponding dimensionless oil production parameters of the model can eliminate the differences between different reservoirs and production conditions. This allows data from different reservoirs or different production stages of the same reservoir to be compared and analyzed on the same plot. This processing method simplifies complex geological and engineering problems and makes the analysis more intuitive.

[0023] The fracturing process described in this invention involves injecting a certain amount of carbon dioxide in intervals before fracturing. Carbon dioxide easily enters the micropore throats, dissolves in crude oil, reduces crude oil flow resistance, and improves displacement efficiency. Through interval CO2 injection, the injected section can simultaneously displace crude oil into two adjacent uninjected sections, and the uninjected sections can simultaneously receive crude oil displaced by the two adjacent injected sections, thereby improving the overall crude oil flowability and displacement efficiency. The fracturing process provided by this invention improves recovery rate while increasing construction efficiency and saving fracturing costs. It also provides a scientific and reasonable basis for optimizing the matching relationship between carbon dioxide injection volume and interval spacing to maximize benefits.

[0024] Compared with pre-fracturing of carbon dioxide in the entire well section, pre-fracturing of carbon dioxide in the section before injection, with comparable predicted cumulative production per well, improved construction efficiency by 40% and reduced single-section fracturing cost by 11%. The resulting parameter optimization charts provide a scientific, reasonable, simple, and intuitive reference for optimizing carbon dioxide injection volume and horizontal well spacing. Attached Figure Description

[0025] Appendix Figure 1 Flowchart of the design method for fracturing process parameters before inter-segment displacement by carbon dioxide segment injection; Appendix Figure 2 Schematic diagram of inter-segment displacement by injecting carbon dioxide into a horizontal well section; Appendix Figure 3 Optimize the chart for carbon dioxide injection volume and segment spacing; Figure 4 A comparison of the efficiency and cost of carbon dioxide pre-fracturing; Figure 5 A chart showing the predicted cumulative production / CO2 injection volume of a single well under different injection methods; Figure 6 This is a structural block diagram of the pre-fracturing process design system for inter-stage carbon dioxide displacement provided in an embodiment of the present invention; Figure 7 This is a block diagram of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings: Example 1 Reference Figure 1 This embodiment provides a design method for pre-fracturing process of inter-stage CO2 displacement. It adopts an integrated numerical simulation method to establish fluid-structure interaction control equations. The CO2 injection section and non-injection section are divided into multi-level cross fracture grids. The relationship between different section spacing and CO2 injection volume is studied. A relationship chart between section spacing, CO2 injection volume and single well production is established, providing a basis for optimizing the process parameters of pre-fracturing process of CO2 inter-stage injection.

[0029] A method for designing a pre-fracturing process using carbon dioxide interstage displacement includes the following steps: S1. Based on the collected seismic data, geological data, and the range of engineering parameters given in the oil production plan, a numerical simulation model of an integrated fracturing horizontal well is established using commercial software. S2. The integrated fracturing horizontal well numerical simulation model was used to simulate the single well production under different intervals and different single-segment carbon dioxide injection rates when using the inter-segment gas injection method. The segment spacing in step S2 is set to 30m, 40m, 50m, 60m, 70m, 80m, 90m, 100m, and 110m respectively; The single-stage carbon dioxide injection amounts in step S2 are 100m³, 200m³, 300m³, 400m³, 500m³, 600m³, 700m³, 800m³, and 900m³, respectively. S3. Divide the single-well production obtained from the numerical simulation model of each integrated fracturing horizontal well by the number of carbon dioxide injection stages to obtain the single-stage oil production, so as to eliminate the influence of the horizontal stage length. S4. Divide the single-stage oil production obtained in step S3 by the corresponding single-stage carbon dioxide injection amount to obtain the dimensionless oil production. This method helps to eliminate the differences in oil production under different conditions, allowing for direct comparison of oil production in different oilfields or at different times. In addition, changes in dimensionless oil production can reflect changes in the reservoir, such as changes in dimensionless oil production when water cut increases or production decreases.

[0030] S5. Plot the segment spacing and single-segment carbon dioxide injection volume described in step S2, along with the corresponding dimensionless oil production of their models, into an appendix. Figure 3 The parameter optimization diagram shown is as follows. Figure 3 The left vertical axis represents the carbon dioxide injection volume of a single section, while the right axis represents the oil production of a single well and the total carbon dioxide injection volume of all sections of a single well.

[0031] S6. Optimize the chart based on the parameters obtained in step S5, and determine the final average segment spacing and the final single-segment carbon dioxide injection amount.

[0032] There are two methods for determining the final average segment spacing and the final single-segment carbon dioxide injection volume: One approach is to optimize the chart, calculate the economic benefits of each well under different single-segment carbon dioxide injection rates, and select the segment spacing and single-segment carbon dioxide injection rate with the best economic benefits as the final segment spacing and final single-segment carbon dioxide injection rate.

[0033] Another method is to calculate the economic benefits of a single well under different single-section carbon dioxide injection volumes based on the intervals determined in the charts and oil production plans, and determine the final single-section carbon dioxide injection volume based on the expected benefits.

[0034] In some embodiments, the seismic data in step S1 includes: tectonic interpretation, stratigraphic interpretation, lithological interpretation, and other data. Geological data includes: well logging interpretation, well logging interpretation, and other data; The engineering parameters given in the oil production plan include: segmented process, displacement, sand addition, etc. In some embodiments, step S2 includes the following steps: The simulation used the intermittent gas injection method with an interval of 30m and the single-segment carbon dioxide injection volume of 100m³, 200m³, 300m³, 400m³, 500m³, 600m³, 700m³, 800m³, and 900m³ for single-segment production. The simulation used the intermittent gas injection method with an interval of 40m and the single-section carbon dioxide injection volume of 100m³, 200m³, 300m³, 400m³, 500m³, 600m³, 700m³, 800m³ and 900m³ for single well production. The simulation used the intermittent gas injection method with an interval of 50m and the single-section carbon dioxide injection volume of 100m³, 200m³, 300m³, 400m³, 500m³, 600m³, 700m³, 800m³ and 900m³ respectively to calculate the single well production. The simulation used the intermittent gas injection method with an interval of 60m and the single-section carbon dioxide injection volume of 100m³, 200m³, 300m³, 400m³, 500m³, 600m³, 700m³, 800m³ and 900m³ for single well production. The simulation used the intermittent gas injection method with an interval of 70m and the single-section carbon dioxide injection volume of 100m³, 200m³, 300m³, 400m³, 500m³, 600m³, 700m³, 800m³ and 900m³ respectively to calculate the single well production. And so on.

[0035] It should be noted that: the interval between segments is not limited to 10m, but can also be 5m, 15m, 20m, etc.; the minimum interval between segments is not limited to 30m, but can also be 20m, 25m, 35m, etc.; the interval of carbon dioxide injection volume per segment is not limited to 100 m³, but can also be 50 m³, 150 m³, 200 m³, etc.; the minimum carbon dioxide injection volume per segment is not limited to 100 m³, but can also be 50 m³, 80 m³, 90 m³, 150 m³, etc.

[0036] Taking a horizontal well in the Jinlong 2 well area as an example, the parameter optimization chart obtained from step S5 is as follows, following steps S1 to S6 above. Figure 3 As shown, an average interval of 60m ± 10m and a single-segment carbon dioxide injection volume of 300 cubic meters were selected as the final average interval and final single-segment carbon dioxide injection volume. Comparison with continuous injection wells yielded the following results: Figure 5 As shown, the cumulative oil production of the two wells is comparable. By using the inter-stage displacement fracturing technology provided by this invention, the construction efficiency is increased by 40% and the cost of single-stage fracturing is reduced by 11%.

[0037] Example 2 Reference Figure 2 This embodiment provides a pre-fracturing process using carbon dioxide inter-stage displacement. In the pre-fracturing stage before formal fracturing of a horizontal well, a certain amount of carbon dioxide is injected into the formation at a specific rate. Then, volumetric fracturing is performed on the horizontal well according to a pumping procedure, creating a certain number of artificial hydraulic fractures. Carbon dioxide injection during the pre-fracturing stage is carried out in intermittent stages within the horizontal well section, resulting in effective carbon dioxide displacement between fractures in adjacent fracturing sections.

[0038] A pre-fracturing process using carbon dioxide interstage displacement includes the following steps: Step 1: Obtain the average segment spacing and single-segment carbon dioxide injection amount using the method described in Example 1; Step 2: Based on the average segment spacing obtained in Step 1, the horizontal well is segmented, and carbon dioxide is injected into the horizontal well in a segmented manner. The carbon dioxide injection volume is the single segment carbon dioxide injection amount obtained in Step 1.

[0039] When segmenting, the segments are divided according to the average segment spacing and geological conditions. All segment spacings can be taken as the average segment spacing, or the segments can be divided within ±10m of the average segment spacing, as long as the average segment spacing is equal to the average segment spacing obtained in step 1.

[0040] The segments are numbered sequentially according to their positions as: segment 1, segment 2, segment 3, segment 4, segment 5, ...

[0041] In some embodiments, carbon dioxide can be injected into all segments numbered odd, such as segment 1, segment 3, segment 5, segment 7, etc., and carbon dioxide can be injected into all segments numbered even, such as segment 2, segment 4, segment 6, segment 8, etc.

[0042] Example 3 Please see Figure 6 In this embodiment, a pre-fracturing process design system for carbon dioxide interstage displacement is provided, including: The numerical simulation model construction module is used to establish an integrated numerical simulation model of a fracturing horizontal well based on the collected seismic data, logging interpretation data, and the range of engineering parameters given by the oil production plan. The simulation module is used to simulate the single-well production under different intervals and different single-stage carbon dioxide injection rates using an integrated fracturing horizontal well numerical simulation model. The chart drawing module is used to draw parameter optimization charts based on the single-well production and number of injected carbon dioxide segments obtained under different segment spacing and different single-segment carbon dioxide injection volumes. The segment spacing is set to 30m, 40m, 50m, 60m, 70m, 80m, 90m, 100m, and 110m respectively; The single-stage carbon dioxide injection volumes are 100m³, 200m³, 300m³, 400m³, 500m³, 600m³, 700m³, 800m³, and 900m³, respectively. The output module is used to optimize the diagram based on parameters and determine the final average segment spacing and the final single-segment carbon dioxide injection amount.

[0043] Preferably, the drawing module includes a calculation module and a drawing module.

[0044] The calculation module is used to calculate the single-segment oil production based on the single-well production and the number of segments injected with carbon dioxide under different segment spacing and different single-segment carbon dioxide injection amounts; and to calculate the dimensionless oil production based on the single-segment oil production and the corresponding single-segment carbon dioxide injection amount.

[0045] The drawing module is used to create a parameter-optimized chart of the segment spacing, single-segment carbon dioxide injection volume, and their corresponding dimensionless oil production.

[0046] All relevant content of each step involved in the aforementioned embodiments of the carbon dioxide interstage displacement pre-fracturing process design method can be referenced to the functional description of the corresponding functional module of the carbon dioxide interstage displacement pre-fracturing process design system in the embodiments of the present invention, and will not be repeated here.

[0047] Example 4 Reference Figure 7This embodiment provides an electronic device including a processor and a memory, with the processor and memory connected via a bus. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to achieve corresponding method flows or corresponding functions. The processor described in this embodiment can be used for the operation of a carbon dioxide interstage displacement pre-fracturing process design method. The bus may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. Buses can be categorized into address buses, data buses, control buses, etc. For ease of representation, Figure 7 The symbol is represented by only one line, but this does not mean that there is only one bus or one type of bus.

[0048] Example 5 This embodiment provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in an electronic device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the electronic device and extended storage media supported by the electronic device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the carbon dioxide interstage displacement pre-fracturing process design method in the above embodiment.

[0049] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0050] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0051] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.

[0052] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for designing a carbon dioxide interzone displacement pre-frac process, characterized in that, include: Based on the seismic data of the target well, the logging interpretation data, and the range of engineering parameters given in the oil production plan, an integrated numerical simulation model of a fracturing horizontal well is established. The numerical simulation model of the integrated horizontal well fracturing was used to simulate the single well production under different intervals and different single-stage carbon dioxide injection rates when using the inter-stage gas injection method. Based on the single-well production and number of injected carbon dioxide segments obtained under different segment spacing and different single-segment carbon dioxide injection rates, a parameter optimization chart was drawn. Based on the parameter optimization chart, the final average segment spacing and single-segment carbon dioxide injection volume are determined.

2. The carbon dioxide interstage displacement pre-fracturing process design method according to claim 1, characterized in that, The parameter optimization chart is drawn based on the single-well production and number of injected carbon dioxide segments obtained under different segment spacings and different single-segment carbon dioxide injection volumes, including: The single-stage oil production is calculated based on the single-well production and the number of stages of carbon dioxide injection under different stage spacing and different single-stage carbon dioxide injection rates; the dimensionless oil production is calculated based on the single-stage oil production and the corresponding single-stage carbon dioxide injection rate. A parameter optimization chart was plotted, showing the interval between segments, the amount of carbon dioxide injected per segment, and the corresponding dimensionless oil production.

3. The design method of a carbon dioxide interzone displacement pre-frac process according to claim 2, characterized in that, The step size of the different segment spacing is 5m-20m, and the step size of the single segment carbon dioxide injection amount is 50 m³-200 m³.

4. The design method of a carbon dioxide interzone displacement pre-frac process according to claim 2, characterized in that, The method for calculating the single-stage oil production based on the single-well production and the number of carbon dioxide injection stages obtained under different segment spacing and different single-stage carbon dioxide injection volumes is as follows: divide the single-well production obtained from the numerical simulation model of each integrated fracturing horizontal well by the number of carbon dioxide injection stages to obtain the single-stage oil production.

5. The design method of a carbon dioxide interzone displacement pre-frac process of claim 2, wherein, The dimensionless oil production is calculated by dividing the single-stage oil production by the corresponding single-stage carbon dioxide injection.

6. A carbon dioxide interzone displacement preflush fracturing process characterized by, include: Step 1: Using the carbon dioxide inter-segment displacement pre-fracturing process design method described in claim 1, the average segment spacing and single-segment carbon dioxide injection volume are obtained; Step 2: Divide the horizontal well into segments based on the segment spacing, and inject carbon dioxide into different segments of the horizontal well in an intermittent manner. The amount of carbon dioxide injected into each segment is the amount of carbon dioxide injected in a single segment. Carbon dioxide displacement is formed between the fractures of adjacent fracturing segments.

7. A system for designing a carbon dioxide interzone displacement pre-frac process, the system comprising: include: The numerical simulation model construction module is used to establish an integrated numerical simulation model of a fracturing horizontal well based on the seismic data of the target well, the logging interpretation data, and the range of engineering parameters given by the oil production scheme. The simulation module is used to simulate the single-well production rate under different intervals and different single-stage carbon dioxide injection rates using an integrated fracturing horizontal well numerical simulation model. The chart drawing module is used to draw parameter optimization charts based on the single-well production and number of injected carbon dioxide segments obtained under different segment spacing and different single-segment carbon dioxide injection volumes. The output module is used to optimize the diagram based on parameters and determine the final average segment spacing and the amount of carbon dioxide injected per segment.

8. The design system for carbon dioxide inter-zone displacement preflush fracturing process of claim 7, wherein, The drawing module includes: The calculation module calculates the single-segment oil production based on the single-well production and the number of segments injected with carbon dioxide under different segment spacing and different single-segment carbon dioxide injection amounts; and calculates the dimensionless oil production based on the single-segment oil production and the corresponding single-segment carbon dioxide injection amount. The plotting module generates a parameter-optimized chart of the segment spacing, single-segment carbon dioxide injection volume, and corresponding dimensionless oil production.

9. An electronic device, comprising: include: At least one processor; as well as, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, which, when executed by the at least one processor, enables the at least one processor to perform the carbon dioxide interstage displacement pre-fracturing process design method as described in any one of claims 1 to 5.

10. A computer readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the carbon dioxide interstage displacement pre-fracturing process design method as described in any one of claims 1 to 5.

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