A method for optimizing energy storage fracturing technology based on analysis of main control factors of production capacity

Abstract

The present invention discloses a method for optimizing an energy-storage fracturing process based on an analysis of the primary controlling factors of productivity. This method belongs to the field of oil and gas field development technology and includes the following steps: S1, constructing a gas-water two-phase triple medium productivity model; S2, calibrating the model; S3, formulating a productivity simulation plan and production forecast; and S4, determining the primary and secondary relationships of influencing factors and optimizing the energy-storage fracturing process. The present invention utilizes the aforementioned method for optimizing an energy-storage fracturing process based on an analysis of the primary controlling factors of productivity, effectively addressing issues such as insufficient formation energy, water lock effects, and low fracture complexity, enhancing reservoir permeability and production. Furthermore, by comprehensively evaluating relevant parameters, it ensures comprehensive consideration of factors influencing productivity, thereby significantly improving the production efficiency of individual wells and the overall development benefits of tight reservoirs.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field development, and in particular relates to an energy storage fracturing process optimization method based on analysis of main control factors of productivity. Background Art

[0002] Tight reservoirs generally have poor physical properties, characterized by low porosity and permeability, low reserve abundance, and strong heterogeneity. Conventional hydraulic fracturing technology often has limited production enhancement effects in such reservoirs and often faces problems such as water lock and insufficient formation energy, making oil and gas development much more difficult than in conventional gas reservoirs. Therefore, conventional fracturing processes often face multiple challenges in their application, such as insufficient formation energy and water lock. To address these issues, a storage fracturing process method is needed for tight reservoirs to achieve efficient fracturing transformation and production enhancement. However, selecting the right storage fracturing medium is key to improving fracturing effectiveness and productivity. Compared with carbon dioxide, liquid nitrogen is more effective in reservoir energy enhancement, and its ability to relieve water lock is stronger than that of carbon dioxide. Carbon dioxide is also more effective in creating complex fracture networks. Under the same conditions, if the tight reservoir needs to form a complex fracture network, pre-CO2 energy storage fracturing is preferred; if the tight reservoir needs to increase the formation pressure, pre-liquid nitrogen energy storage fracturing is preferred; if both energy enhancement and the formation of a complex fracture network are required, pre-CO2 energy storage fracturing is preferred.

[0003] Currently, Chinese patent publication CN115099062A proposes a method for designing energy-storage fracturing parameters for tight oil reservoirs. This method combines laboratory experiments and numerical simulations to quantitatively optimize energy-storage fracturing operation parameters. However, this method, which uses water as the fracturing medium, is only suitable for oil reservoirs and cannot provide a suitable energy-storage fracturing process for tight gas reservoirs.

[0004] In summary, existing energy storage fracturing technologies are mostly used in low-permeability tight oil reservoirs, typically using water as the energy storage fracturing medium. However, water is not suitable as a fracturing medium in tight gas reservoirs. Tight gas reservoirs are susceptible to water lock, and water injection can exacerbate this damage, leading to reduced reservoir permeability and production. Therefore, there is an urgent need to optimize more suitable energy storage fracturing media and energy storage fracturing processes for tight gas reservoirs. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for optimizing energy storage fracturing technology based on the analysis of the main controlling factors of production capacity. This method effectively solves problems such as insufficient formation energy and water lock, enhances reservoir permeability and production, and ensures comprehensive consideration of factors affecting production capacity through comprehensive evaluation of relevant parameters, thereby significantly improving the production efficiency of single wells and the overall development benefits of tight reservoirs.

[0006] To achieve the above objectives, the present invention provides a method for optimizing an energy storage fracturing process based on analysis of the main controlling factors of productivity, comprising the following steps:

[0007] S1. Combining the embedded discrete fracture model, dual medium model and single medium model, a gas-water two-phase triple medium productivity model for fractured horizontal wells in tight reservoirs is established;

[0008] S2. Use field data to calibrate the gas-water two-phase triple medium productivity model for tight reservoir fractured horizontal wells established in S1;

[0009] S3. Develop a productivity simulation program based on target reservoir parameters; execute the productivity simulation program using the calibrated tight reservoir fractured horizontal well gas-water two-phase triple medium productivity model to obtain simulated expected production data;

[0010] S4. Use grey correlation analysis to process the simulated production data from step S3, determine the degree of influence of each factor on the simulated production data and rank them, and select an energy storage fracturing scheme suitable for the target block based on the ranking results.

[0011] Preferably, in S1, the seepage region of the gas-water two-phase triple medium productivity model for a fractured horizontal well in a tight reservoir includes the matrix, the fracture stimulation region, and the hydraulic fractures. The matrix seepage region is simplified to a single medium, the fracture stimulation region is represented by a dual medium model, and the hydraulic fractures are represented by an embedded discrete fracture model.

[0012] Preferably, in S2, the finite difference method is used to solve the gas-water two-phase triple medium productivity model of the tight reservoir fractured horizontal well established in S1.

[0013] Preferably, in S3, the target reservoir parameters include geological and engineering parameters of the target reservoir block, which are used to determine the matrix water saturation, formation pressure, area of the fracturing zone, permeability of the fracturing zone, and range of hydraulic fracture conductivity.

[0014] Preferably, in S3, an arithmetic difference method is used to select level values within the target reservoir parameter range to formulate a production capacity simulation example plan.

[0015] Preferably, in S4, the target block energy storage fracturing treatment method includes: method 1 pre-injection of liquid nitrogen for energy enhancement, method 2 pre-injection of CO2 for energy enhancement, method 3 increasing the liquid intensity and method 4 increasing the sand addition intensity. The target block energy storage fracturing scheme obtained according to the above methods is specifically as follows: (1) if the first two main controlling factors are matrix water saturation and formation pressure, the energy storage fracturing process based on method 1 is adopted;

[0016] (2) If the top two controlling factors are matrix water saturation and SRV zone permeability, and matrix water saturation ranks first, the energy storage fracturing process based on method 1 is adopted; if SRV zone permeability ranks first, the energy storage fracturing process based on method 2 is adopted;

[0017] (3) If the top two controlling factors are matrix water saturation and SRV area, the energy storage fracturing process combining method 1 and method 3 is adopted;

[0018] (4) If the top two controlling factors are matrix water saturation and main fracture conductivity, the energy storage fracturing process combining method 1 and method 4 is adopted;

[0019] (5) If the top two controlling factors are formation pressure and SRV zone permeability, and formation pressure ranks first, the energy storage fracturing process based on method 1 is adopted; if SRV zone permeability ranks first, the energy storage fracturing process based on method 2 is adopted;

[0020] (6) If the top two controlling factors are formation pressure and SRV area, the energy storage fracturing process combining method 1 and method 3 is adopted;

[0021] (7) If the top two controlling factors are formation pressure and main fracture conductivity, the energy storage fracturing process combining method 1 and method 4 is adopted;

[0022] (8) If the top two controlling factors are SRV zone permeability and SRV zone area, the energy storage fracturing process combining method 2 and method 3 is adopted;

[0023] (9) If the top two controlling factors are SRV zone permeability and main fracture conductivity, the energy storage fracturing process combining method 2 and method 4 is adopted;

[0024] (10) If the top two controlling factors are SRV area and main fracture conductivity, the energy storage fracturing process combining methods 1, 3, and 4 is adopted.

[0025] Therefore, the present invention adopts the aforementioned energy-storage fracturing process optimization method based on analysis of the key factors controlling production capacity. Compared with existing technologies, the present invention has the following significant advantages: it provides an energy-storage fracturing method suitable for tight gas reservoirs that does not use water as an energizing medium. This method can effectively replenish formation energy, improve water lock effects, and increase fracture complexity. Furthermore, by determining the key factors controlling production capacity (geological parameters and engineering parameters) for different reservoirs, targeted energy-storage fracturing process plans suitable for each reservoir type can be developed, providing a scientific basis and technical support for reservoir development.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic flow chart of an optimization method for an energy storage fracturing process based on analysis of the main controlling factors of productivity according to the present invention;

[0028] Figure 2 A schematic diagram of a reservoir physical model of an energy storage fracturing process optimization method based on analysis of the main controlling factors of productivity according to the present invention;

[0029] Figure 3 This is a data diagram showing the validation of a gas-water two-phase triple medium productivity model for a tight reservoir fractured horizontal well according to an energy storage fracturing process optimization method based on productivity main controlling factor analysis of the present invention;

[0030] Figure 4 This is a contour map of micro-fracture pressure at different times of an energy storage fracturing process optimization method based on analysis of the main controlling factors of productivity of the present invention. Figure 4 a in the figure represents the SRV pressure contour map after 1 day; Figure 4 b in the figure shows the SRV pressure contour map after 10 days; Figure 4 The c in the figure represents the SRV pressure contour map after 100 days. Figure 4 Figure d shows the SRV pressure contour map after 450 days;

[0031] Figure 5 This is a contour map of matrix pressure at different times of an energy storage fracturing process optimization method based on analysis of the main controlling factors of productivity of the present invention. Figure 5 a in the figure represents the matrix pressure contour map after 1 day. Figure 5 b in the figure represents the matrix pressure contour map after 10 days. Figure 5 c in the figure shows the matrix pressure contour map after 100 days; Figure 5 The d in the figure shows the matrix pressure contour map after 450 days;

[0032] Figure 6 This is a ranking diagram of the influence degree of various factors in an energy storage fracturing process optimization method based on the analysis of the main controlling factors of production capacity according to the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0034] Example 1

[0035] like Figure 1As shown, the present invention provides an energy storage fracturing process optimization method based on the analysis of the main controlling factors of production capacity, comprising the following steps:

[0036] S1, such as Figure 2 As shown in the figure, the target block is Block Y of a tight sandstone gas reservoir in a certain area, which includes the YL well. Based on the embedded discrete fracture model and dual medium model, the complex fractures formed by energy storage fracturing in tight reservoirs are characterized. Taking into account the triple medium flow characteristics of matrix, SRV zone, and hydraulic fractures after energy storage fracturing in tight reservoirs, a gas-water two-phase triple medium productivity model for horizontal wells in tight reservoir fractures is established. The seepage areas of this model include the matrix, SRV zone, and hydraulic fractures.

[0037] S2, such as Figure 3-Figure 5 As shown in Figure 1, the finite difference method was used to solve the gas-water two-phase triple medium productivity model for fractured horizontal wells in tight reservoirs established in S1. The model was then fitted and verified using actual field data from a horizontal well (well YL) in a specific block (Block Y). Specifically, the daily gas production cycle was set to 450 days, the daily gas production was set according to actual field production data, and the bottomhole pressure data was fitted. This process verified the effectiveness and accuracy of the model.

[0038] After approximately 100 days of production, the pressure drop within the Stimulated Reservoir Volume (SRV) zone (the stimulated reservoir volume) rapidly diffused into the matrix, demonstrating excellent energy transfer. This phenomenon further demonstrates the significant impact of formation pressure on productivity improvement and demonstrates that the gas-water two-phase triple-medium productivity model for fractured horizontal wells in tight reservoirs accurately reflects the dynamic changes in actual production, ensuring the reliability of the foundation for subsequent process optimization.

[0039] S3. First, calculate the geological and engineering parameters of the target reservoir block Y to determine the range of matrix water saturation, formation pressure, SRV area, SRV permeability, and main fracture conductivity. The specific parameter ranges are shown in Table 1 below:

[0040] Table 1 Range of geological engineering parameters in Block Y

[0041] Parameter Type Block parameter range Water saturation 0.3～0.6 Formation pressure, unit: MPa 15～27 SRV area, unit: m*m 90*270～120*360 SRV permeability, unit: mD 1～10 Main fracture conductivity, unit: D·cm 2～20

[0042] Based on the above parameter ranges, this paper uses the arithmetic method to select different level values and develops a detailed capacity simulation example scheme. This ensures that each parameter is fully considered within a reasonable range, thereby providing diverse basic data for subsequent production forecasts. The specific example scheme design is shown in the table below:

[0043] Table 2 Simulation example scheme

[0044]

[0045]

[0046] The simulated production data is obtained through the capacity simulation example solution, as shown in the following table:

[0047] Table 3 Simulated production data

[0048]

[0049]

[0050] S4, such as Figure 6 As shown in Table 4, the grey correlation analysis method is used to process the simulated yield data from step S3 to obtain the influence degree ranking of the influencing factors on the simulated yield data, as shown in Table 4:

[0051] Table 4 Ranking of the influence of each factor

[0052] Evaluation items Correlation Ranking factor formation pressure 0.7063 1 Geology Main fracture conductivity 0.6568 2 project SRV zone area 0.6461 3 project SRV penetration 0.6414 4 project Matrix water saturation 0.6103 4 Geology

[0053] The treatment methods for energy storage fracturing in the target block include: Method 1: pre-injection of liquid nitrogen for energy enhancement. The high-pressure gas generated by the vaporization of liquid nitrogen and its diffusion can increase the local pressure of the gas reservoir; Method 2: pre-injection of CO2 for energy enhancement, which can locally increase the formation pressure, connect the formation pores, drive out the pore fluid, and induce the outflow of fluid in the non-active area. Method 3: increase the intensity of liquid use. High-intensity liquid use can provide higher fracture driving pressure, make the fractures longer and wider, and help more areas of the reservoir to be used; Method 4: increase the intensity of sand addition. More proppants fill the fractures to form high-conductivity channels, thereby slowing down the closure of the fractures and improving the long-term conductivity of the fractures. The energy storage fracturing scheme for the target block obtained according to the above methods is as follows: (1) If the top two main controlling factors are matrix water saturation and formation pressure, the energy storage fracturing process based on Method 1 is adopted;

[0054] (2) If the top two controlling factors are matrix water saturation and SRV zone permeability, and matrix water saturation ranks first, the energy storage fracturing process based on method 1 is adopted; if SRV zone permeability ranks first, the energy storage fracturing process based on method 2 is adopted;

[0055] (3) If the top two controlling factors are matrix water saturation and SRV area, the energy storage fracturing process combining method 1 and method 3 is adopted;

[0056] (4) If the top two controlling factors are matrix water saturation and main fracture conductivity, the energy storage fracturing process combining method 1 and method 4 is adopted;

[0057] (5) If the top two controlling factors are formation pressure and SRV zone permeability, and formation pressure ranks first, the energy storage fracturing process based on method 1 is adopted; if SRV zone permeability ranks first, the energy storage fracturing process based on method 2 is adopted;

[0058] (6) If the top two controlling factors are formation pressure and SRV area, the energy storage fracturing process combining method 1 and method 3 is adopted;

[0059] (7) If the top two controlling factors are formation pressure and main fracture conductivity, the energy storage fracturing process combining method 1 and method 4 is adopted;

[0060] (8) If the top two controlling factors are SRV zone permeability and SRV zone area, the energy storage fracturing process combining method 2 and method 3 is adopted;

[0061] (9) If the top two controlling factors are SRV zone permeability and main fracture conductivity, the energy storage fracturing process combining method 2 and method 4 is adopted;

[0062] (10) If the top two controlling factors are SRV area and main fracture conductivity, the energy storage fracturing process combining methods 1, 3 and 4 is adopted. Based on the results of the primary and secondary relationship analysis of the influencing factors determined by the grey correlation method, formation pressure and main fracture conductivity are confirmed to be the main factors affecting production capacity. Therefore, the energy storage fracturing process combining pre-injection of liquid nitrogen to increase energy and increase sand intensity is adopted. The specific design includes 250sm 3 / min liquid nitrogen displacement, 270sm 3 The liquid nitrogen intensity and sand addition intensity of the Y block are 1.5 times that of conventional sand addition intensity in the Y block. By implementing the above technology, the fracture network stimulation effect of the YL well was significant. Specifically, the formation pressure coefficient in the Y block increased from 1.2 to 1.4; the daily gas production of a single well exceeded 8.9×10 4 m 3 ; Compared with the energy storage fracturing process that does not use this technology, the production volume increased by 75%.

[0063] This optimized energy storage fracturing process not only improves the energy state of the reservoir, but also significantly increases the production efficiency of oil and gas wells, proving its effectiveness and superiority in practical applications.

[0064] Therefore, the present invention adopts the above-mentioned method for optimizing the energy storage fracturing process based on the analysis of the main controlling factors of production capacity. This method effectively solves the water lock problem, enhances the reservoir permeability and production, and ensures a comprehensive consideration of the factors affecting production capacity by comprehensively evaluating relevant parameters, thereby significantly improving the production efficiency of single wells and the overall development benefits of tight reservoirs.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for optimizing energy storage fracturing process based on analysis of main controlling factors of productivity, characterized in that: The following steps are involved: S1. A gas-water two-phase triple productivity model for fractured horizontal wells in tight reservoirs was established by combining an embedded discrete fracture model, a dual-medium model, and a single-medium model. The seepage region of this gas-water two-phase triple-medium productivity model for fractured horizontal wells in tight reservoirs includes the matrix, the fracture stimulation region, and the hydraulic fractures. The matrix seepage region is simplified to a single-medium model, the fracture stimulation region is represented by a dual-medium model, and the hydraulic fractures are represented by an embedded discrete fracture network. S2. Using the finite difference method to solve the gas-water two-phase triple medium productivity model of the tight reservoir fractured horizontal well established in S1; using field data to calibrate the gas-water two-phase triple medium productivity model of the tight reservoir fractured horizontal well established in S1; S3. Develop a production capacity simulation example plan based on target reservoir parameters. The target reservoir parameters include geological and engineering parameters of the target reservoir block, which are used to determine matrix water saturation, formation pressure, fracture stimulation area, fracture stimulation area permeability, and hydraulic fracture conductivity range. Use the calibrated tight reservoir fractured horizontal well gas-water two-phase triple medium production capacity model and the arithmetic difference method to select horizontal values within the target reservoir parameter range to develop a production capacity simulation example plan and obtain simulated expected production data. S4. Use the grey correlation analysis method to process the simulated expected production data from S3, determine the degree of influence of factors on the simulated production data and rank them, and recommend energy storage fracturing schemes suitable for the target block based on the ranking results; among them, the treatment methods for energy storage fracturing in the target block include: method 1: pre-injection of liquid nitrogen for energy enhancement, method 2: pre-injection of CO2 for energy enhancement, method 3: increasing the liquid intensity, and method 4: increasing the sand addition intensity.

2. The method for optimizing the energy storage fracturing process based on the analysis of the main controlling factors of productivity according to claim 1, characterized in that: In S4, the target block energy storage fracturing treatment methods include: method 1 pre-injection of liquid nitrogen for energy enhancement, method 2 pre-injection of CO2 for energy enhancement, method 3 increasing the intensity of liquid use, and method 4 increasing the intensity of sand addition. According to the above methods, the target block energy storage fracturing scheme is obtained, which is specifically as follows: (1) If the top two controlling factors are matrix water saturation and formation pressure, the energy storage fracturing process based on method 1 is adopted; (2) If the top two controlling factors are matrix water saturation and SRV zone permeability, and matrix water saturation ranks first, the energy storage fracturing process based on method 1 is adopted; if SRV zone permeability ranks first, the energy storage fracturing process based on method 2 is adopted; (3) If the top two controlling factors are matrix water saturation and SRV area, the energy storage fracturing process combining method 1 and method 3 is adopted; (4) If the top two controlling factors are matrix water saturation and main fracture conductivity, the energy storage fracturing process combining method 1 and method 4 is adopted; (5) If the top two controlling factors are formation pressure and SRV zone permeability, and formation pressure ranks first, the energy storage fracturing process based on method 1 is adopted; if SRV zone permeability ranks first, the energy storage fracturing process based on method 2 is adopted; (6) If the top two controlling factors are formation pressure and SRV area, the energy storage fracturing process combining method 1 and method 3 is adopted; (7) If the top two controlling factors are formation pressure and main fracture conductivity, the energy storage fracturing process combining method 1 and method 4 is adopted; (8) If the top two controlling factors are SRV zone permeability and SRV zone area, the energy storage fracturing process combining method 2 and method 3 is adopted; (9) If the top two controlling factors are SRV zone permeability and main fracture conductivity, the energy storage fracturing process combining method 2 and method 4 is adopted; (10) If the top two controlling factors are SRV area and main fracture conductivity, the energy storage fracturing process combining methods 1, 3 and 4 is adopted.

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