Well group injection allocation method based on streamline simulation

Abstract

The invention provides a well group injection-allocation method based on streamline simulation, relates to the technical field of oil and gas exploitation, and aims to accurately match a water injection scheme with an actual water injection rate. The core process comprises the following steps: integrating geological and oil reservoir data, and constructing a numerical model; in combination with geological features and production dynamics, model parameters are optimized, and simulation precision is ensured; performing streamline simulation by using the optimization model, generating a contribution ratio map, and quantitatively dividing the contribution of the water injection well to the liquid production capacity of each oil production well according to the contribution ratio map; a three-phase injection-production ratio formula is used for calculating the daily water injection distribution rate of the water injection well to each oil producing well; and accumulating the injection allocation quantity of each producing well to obtain the total injection allocation quantity of the water injection wells. The method has the following advantages that the flow line simulation contribution proportion is introduced, and the underground oil-water flow relation is accurately reflected; the consistency of the injection allocation scheme and the actual water injection rate is improved; the water injection strategy is adjusted, invalid water injection is reduced, economy and rationality of water injection operation are improved, and oilfield development benefits are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, and specifically to a method for well group injection based on streamline simulation. Background Technology

[0002] During the development of water-injected oilfields, the continuous changes in well network layout and production conditions result in dynamic characteristics in the injection-production relationship between wells. In order to maintain formation pressure, achieve effective displacement, and optimize oilfield production efficiency, on-site management personnel need to accurately formulate and implement water injection well group allocation plans based on actual conditions to ensure that the injected water volume can meet geological requirements and conform to the actual underground fluid movement patterns.

[0003] Current mainstream water injection well allocation methods are primarily based on mathematical and statistical principles, aiming at balanced displacement and combining material balance analysis and geological studies to allocate the injected water volume of injection wells. However, these methods require a large amount of field measurement and experimental data, such as pressure data and permeability gradients, which are often difficult to collect comprehensively. Therefore, in practical applications, traditional methods are usually simplified to consider only reservoir connectivity, for example, by statistically analyzing the number of water injection wells connected to production wells or the percentage of effective perforated thickness as the production volume splitting factor.

[0004] However, in reality, the flow of oil and water underground is influenced by a more complex array of factors, including but not limited to the complexity of inter-well connectivity, reservoir pressure distribution, differences in reservoir properties, and well network layout and spacing. Existing well-group injection methods fail to adequately consider the significant impact of these variables on the displacement effect of injected water, resulting in a large discrepancy between the geological injection volume designed using traditional methods and the actual injection volume, thus limiting the optimization potential and economic benefits of the injection method.

[0005] In summary, the technical problem that this invention aims to solve is: how to overcome the problem that existing water injection well allocation technology ignores key factors such as pressure distribution and reservoir heterogeneity, and to provide a new method that can more accurately reflect the underground seepage law and improve the consistency between the allocation scheme and the actual water injection volume. Summary of the Invention

[0006] The purpose of this invention is to provide a method for well group injection based on streamline simulation, and to provide a new method that can more accurately reflect the underground seepage law and improve the consistency between the injection scheme and the actual injection volume.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for well group injection based on streamline simulation includes the following steps:

[0009] S1: Establish a reservoir numerical model: Construct a basic reservoir model based on geological data, reservoir parameters, and production data;

[0010] S2: Model parameter fitting and optimization: Combining geological understanding and dynamic characteristic analysis, the basic reservoir model in S1 is improved to obtain a well-fitted reservoir numerical model.

[0011] S3: Perform streamline simulation: Use the reservoir numerical model fitted in S2 to perform streamline simulation, generate detailed streamline distribution map, and quantitatively describe the flow path, flow distribution and specific contribution of each injection well to the production of each production well in the reservoir.

[0012] S4: Production volume splitting: The proportion of the contribution of water injection wells to the production of each oil production well is used as the splitting coefficient to divide the production volume of the oil production wells; the proportion of the contribution of water injection wells to the production of each oil production well obtained from the streamline simulation is used as the new production volume splitting coefficient to replace the number of connected wells or the proportion of connected reservoir thickness in the traditional method, so as to more scientifically divide the oil production and water production of each oil production well in the well group;

[0013] S5: Calculate the daily water injection volume: Calculate the daily water injection volume of the injection well in each direction affecting the oil production well using the three-phase injection-production ratio formula;

[0014] S6: Summarize the total injection volume of injection wells: Add up the injection volumes of all oil wells affected by the injection wells to obtain the overall reasonable injection volume of the injection wells.

[0015] Furthermore, the specific steps to improve the basic reservoir model of S1 in S2 are: to adjust the relevant parameters of the reservoir numerical model so that the model can accurately simulate the changes in oil production, water production, gas production, water injection and pressure at the whole reservoir and single well levels.

[0016] Furthermore: In step S5, the three-phase injection-production ratio formula used is:

[0017] Z = Q winj / ((Q o ×B oi ) / ρ o +(Q w ×B w ) / ρ w +Q o ×(GOR-R si )×B gi )

[0018] In the formula: Q winj The daily water injection volume allocated to the injection wells corresponds to the direction in which they affect the production wells.

[0019] Q o This represents the daily oil production after the well is split, in tons per day (t / d).

[0020] B oi This is the crude oil volume coefficient.

[0021] ρ o Crude oil density, g / cm³ 3 ,

[0022] Q w This represents the daily water production after the oil well is split, in tons per day (t / d).

[0023] B w The volume factor is the water volume coefficient.

[0024] ρ w The density of water is in g / cm³. 3 ,

[0025] GOR represents the gas-oil production ratio, m 3 / t,

[0026] R si m represents the original dissolved gas-oil ratio. 3 / t,

[0027] B gi The gas volume coefficient,

[0028] Z represents the reservoir geological injection-production ratio.

[0029] Furthermore, the geological knowledge described in step S2 includes knowledge of structural features, sedimentary features, reservoir features, reserve distribution, fluid properties, and temperature and pressure systems.

[0030] Furthermore, the dynamic characteristic analysis described in step S2 includes the analysis of changes in oil, gas, and water production, pressure changes, the effectiveness of measures, utilization status, injection-production balance, well group connectivity, and water breakthrough status for single wells, well groups, and blocks. This refines the basic reservoir model in S1, resulting in a well-fitted reservoir numerical model.

[0031] Furthermore, the relevant parameters include permeability, conductivity, relative permeability curve, well index, and water volume ratio.

[0032] Compared with the original technology, the present invention has the following beneficial effects:

[0033] I. Improve injection accuracy: By using the contribution ratio of water injection wells to the production of oil wells in the streamline simulation results as the splitting coefficient, instead of the number of connected wells or the reservoir thickness ratio in the traditional method, the actual influence relationship and effect of underground oil and water flow are reflected more accurately.

[0034] Second, it comprehensively considers multiple factors: It overcomes the shortcomings of traditional methods that simply rely on the number of interconnected wells while ignoring important factors such as pressure, reservoir property differences, and well spacing. It can comprehensively consider the impact of these variables on the injection water displacement efficiency, thereby improving the consistency between the injection scheme and the actual water injection volume in the mine.

[0035] III. Optimized Water Injection Management: Compared to the original injection plan, the number of injection well groups was adjusted, reducing the daily injection volume and making the injection volume closer to the actual on-site needs. This significantly improved the precision and rationality of water injection operations, enhancing the efficiency of water injection development.

[0036] IV. Guiding Field Practice: Based on the data obtained from streamline simulation, more accurate injection suggestions can be provided to field managers to ensure that while maintaining formation pressure and achieving effective displacement, unnecessary waste of injection volume is avoided, which is conducive to optimizing the injection method and the long-term sustainable development of the oilfield. Attached Figure Description

[0037] Figure 1 This is a flowchart of the method of the present invention;

[0038] Figure 2 This is a geological model diagram of the oil reservoir.

[0039] Figure 3 Fitting curves for daily oil production, daily water production, and water content of the model;

[0040] Figure 4 Fitting curves for cumulative oil and water production in the model;

[0041] Figure 5 A schematic diagram showing the flow direction of injected water and the specific contribution percentage of injected water to the production of each oil well. Detailed Implementation

[0042] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] A method for well group injection based on streamline simulation includes the following steps:

[0045] S1: Establish a reservoir numerical model: Construct a basic reservoir model based on geological data, reservoir parameters, and production data;

[0046] S2: Model Parameter Fitting and Optimization: Combining geological understanding and dynamic characteristic analysis, the basic reservoir model in S1 was improved to obtain a well-fitted reservoir numerical model. The geological understanding includes knowledge of structural features, sedimentary features, reservoir features, reserve distribution, fluid properties, and temperature and pressure systems. The dynamic characteristic analysis includes analysis of changes in oil, gas, and water production, pressure changes, effectiveness of measures, utilization status, injection-production balance, well group connectivity, and water breakthrough effectiveness at the individual well, well group, and block levels. This improved the basic reservoir model in S1, resulting in a well-fitted reservoir numerical model.

[0047] S3: Perform streamline simulation: Use the reservoir numerical model fitted in S2 to perform streamline simulation, generate detailed streamline distribution map, and quantitatively describe the flow path, flow distribution and specific contribution of each injection well to the production of each production well in the reservoir.

[0048] S4: Production volume splitting: The proportion of the contribution of water injection wells to the production of each oil production well is used as the splitting coefficient to divide the production volume of the oil production wells; the proportion of the contribution of water injection wells to the production of each oil production well obtained from the streamline simulation is used as the new production volume splitting coefficient to replace the number of connected wells or the proportion of connected reservoir thickness in the traditional method, so as to more scientifically divide the oil production and water production of each oil production well in the well group;

[0049] S5: Calculate the daily water injection volume: Calculate the daily water injection volume of the injection well in each direction affecting the oil production well using the three-phase injection-production ratio formula;

[0050] S6: Summarize the total injection volume of injection wells: Add up the injection volumes of all oil wells affected by the injection wells to obtain the overall reasonable injection volume of the injection wells.

[0051] In some embodiments, the specific steps for improving the basic reservoir model of S1 in S2 are: adjusting the permeability, conductivity, relative permeability curve, well index, and water volume ratio of the reservoir numerical model so that the model can accurately simulate the changes in oil production, water production, gas production, water injection, and pressure at the whole reservoir and single well levels.

[0052] In other embodiments: In step S5, the three-phase injection-sampling ratio formula used is:

[0053] Z = Q winj / ((Q o ×B oi ) / ρ o +(Q w ×B w ) / ρ w +Q o ×(GOR-R si )×B gi )

[0054] In the formula: Q winj The daily water injection volume allocated to the injection wells corresponds to the direction in which they affect the production wells.

[0055] Q o This represents the daily oil production after the well is split, in tons per day (t / d).

[0056] B oi This is the crude oil volume coefficient.

[0057] ρ o Crude oil density, g / cm³ 3 ,

[0058] Q w This represents the daily water production after the oil well is split, in tons per day (t / d).

[0059] B w The volume factor is the water volume coefficient.

[0060] ρ w The density of water is in g / cm³. 3 ,

[0061] GOR represents the gas-oil production ratio, m 3 / t,

[0062] R si m represents the original dissolved gas-oil ratio. 3 / t,

[0063] B gi The gas volume coefficient,

[0064] Z represents the reservoir geological injection-production ratio.

[0065] The present invention also provides an example of its application in a reservoir to illustrate the superiority of the method of the present invention.

[0066] 1. Numerical Model Establishment: Based on geological data, a numerical model of the reservoir reflecting its internal structure and parametric characteristics was constructed. Figure 2 As shown in the figure, this ensures that the model can accurately describe the physical characteristics of the underground reservoir.

[0067] 2. Model Parameter Fitting and Validation: Based on geological understanding, key parameters such as permeability are adjusted. A numerical model is fitted to match the changing trends of actual oil production, water production, water injection, and pressure data (e.g., ...). Figure 3 and Figure 4 The curves showing the daily output, cumulative output, and moisture content changes are shown. After multiple iterations and optimizations, a well-fitted numerical model that closely matches the field observation data was obtained.

[0068] 3. Streamline Simulation Analysis: Streamline simulation calculations were performed using the fitted numerical model described above. This revealed in detail the flow direction and flow rate distribution of injected water in the reservoir, as well as the specific contribution ratio of each injection well to the production volume of different oil wells (e.g., ...). Figure 5 (As shown). For example, the results show that the contribution of injection well 670 to the production of well 667 is 13.62%, indicating that a considerable portion of the production of well 667 is driven by the injection water from well 670.

[0069] 4. Production volume allocation and injection calculation: The proportion of the contribution of the injection well to the production of the oil well shown by the streamline simulation results is used as the new production volume allocation coefficient. Based on this, according to the three-phase injection-production ratio formula and the geological injection-production ratio, the corresponding injection volume of the injection well is calculated for each affected oil well direction (as shown in Table 1).

[0070] Table 1

[0071]

[0072] 5. Determination of Overall Injection Volume: The total daily injection volume of all oil wells affected by the injection wells is calculated by summing the injection volumes in all directions. For example, for well group 670, the injection scheme calculated using streamline simulation is a daily injection volume of 49 m³ / s. 3 This is compared to the daily injection volume of 256m calculated by traditional methods. 3 It is clearly more accurate and economical.

[0073] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for well group injection based on streamline simulation, characterized in that: Includes the following steps: S1: Establish a reservoir numerical model: Construct a basic reservoir model based on geological data, reservoir parameters, and production data; S2: Model parameter fitting and optimization: Combining geological understanding and dynamic characteristic analysis, the basic reservoir model in S1 is improved to obtain a well-fitted reservoir numerical model. S3: Perform streamline simulation: Use the reservoir numerical model fitted in S2 to perform streamline simulation, generate detailed streamline distribution map, and quantitatively describe the flow path, flow distribution and specific contribution of each injection well to the production of each production well in the reservoir. S4: Production volume splitting: The proportion of the contribution of water injection wells to the production volume of each oil production well is used as the splitting coefficient to divide the production volume of the oil production wells. S5: Calculate the daily water injection volume: Calculate the daily water injection volume of the injection well in each direction affecting the oil production well using the three-phase injection-production ratio formula; S6: Summarize the total injection volume of injection wells: Add up the injection volumes of all oil wells affected by the injection wells to obtain the overall reasonable injection volume of the injection wells.

2. The method for well group injection based on streamline simulation according to claim 1, characterized in that: The specific steps to improve the basic reservoir model of S1 in S2 are: adjust the relevant parameters of the reservoir numerical model so that the model can accurately simulate the changes in oil production, water production, gas production, water injection and pressure at the whole reservoir and single well levels.

3. The method for well group injection based on streamline simulation according to claim 1, characterized in that: In step S5, the three-phase injection-production ratio formula used is: Z=Q winj / ((Q o ×B oi ) / ρ o +(Q w ×B w ) / ρ w +Q o ×(GOR-R si )×B gi ) In the formula: Q winj The daily water injection volume allocated to the injection wells corresponds to the direction in which they affect the production wells. Q o This represents the daily oil production after the well is split, in tons per day (t / d). B oi This is the crude oil volume coefficient. ρ o Crude oil density, g / cm³ 3 , Q w This represents the daily water production after the oil well is split, in tons per day (t / d). B w The volume factor is the water volume coefficient. ρ w The density of water is in g / cm³. 3 , COR is the production gas-oil ratio, m 3 / t, R si m represents the original dissolved gas-oil ratio. 3 / t, B gi The gas volume coefficient, Z represents the reservoir geological injection-production ratio.

4. The method for well group injection based on streamline simulation according to claim 1, characterized in that: The geological knowledge mentioned in step S2 includes knowledge of structural features, sedimentary features, reservoir features, reserve distribution, fluid properties, and temperature and pressure systems.

5. The method for well group injection based on streamline simulation according to claim 1, characterized in that: The dynamic characteristic analysis described in step S2 includes the analysis of changes in oil, gas and water production, pressure changes, effectiveness of measures, utilization status, injection-production balance, well group connectivity, and water breakthrough status of single wells, well groups, and blocks.

6. The method for well group injection based on streamline simulation according to claim 2, characterized in that: The relevant parameters include permeability, conductivity, relative permeability curve, well index, and water volume ratio.

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