A method and related device for quantitatively evaluating watered-out grades of low-permeability oil reservoirs
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2024-11-28
- Publication Date
- 2026-05-29
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of oilfield development technology, specifically a method and related equipment for quantitative evaluation of water flooding level in low-permeability oil reservoirs. Background Technology
[0002] In oilfield development, water injection is a common method. By injecting water into the oil-bearing formation, crude oil is displaced from the reservoir, thereby achieving a higher recovery rate. Water injection development is currently the most common development method in oilfields both domestically and internationally. As development progresses, the amount of water injected increases, leading to a continuous increase in the water content of the reservoir and the formation of water-flooded layers of varying degrees. The water-flood level directly reflects the water cut of the oil well and serves as a primary basis for infill drilling and tapping remaining oil. Quantitative evaluation of the water-flood level is one of the important research tasks in the mid-to-late stages of oilfield development.
[0003] Currently, quantitative evaluation of waterflood levels mainly includes methods based on production dynamic data, methods based on well logging characteristics, and comprehensive methods combining production dynamics and well logging characteristics. Due to the strong heterogeneity of low-permeability reservoirs, their fine pore throats, and high reservoir capillary forces, there are significant differences in oil and water content, resulting in large variations in oil-bearing capacity both horizontally and vertically. Some reservoirs are even highly water-saturated, leading to large differences in water cut during well testing and production, with some wells exhibiting high water cut. Quantitative evaluation methods based on water production rate using dynamic data ignore the water cut differences caused by geological factors and have poor applicability in low-permeability reservoirs. The strong heterogeneity of low-permeability reservoirs, coupled with the effects of different water injection types (clear water, produced water, and mixed injection of clear water and produced water) and formation channeling during development, exacerbates the complexity of reservoir physical properties after water flooding. This leads to an unclear understanding of the water flooding mechanism and complex logging response characteristics of the water flooded layer, making it difficult to evaluate the water flooding level through logging. Even when evaluation is conducted by combining dynamic data with logging characteristics, the quantitative evaluation accuracy of water flooding levels in low-permeability reservoirs remains low (below 70%), which cannot meet the needs of oilfield development. Summary of the Invention
[0004] This invention provides a method and related equipment for quantitative evaluation of water flooding level in low-permeability reservoirs, which solves the problem of low accuracy in quantitative evaluation of water flooding level in low-permeability reservoirs.
[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for quantitatively evaluating the water flooding level of low-permeability reservoirs includes: The normalized relative permeability curve of a low-permeability reservoir is divided into intervals for the two-phase flow region to obtain the initial saturation. A set of three-dimensional tracer flow conceptual models was constructed based on initial saturation and low-permeability reservoir parameters. Based on the three-dimensional tracer flow conceptual model, a quantitative classification chart of flooding levels and a quantitative evaluation formula for flooding levels were established. Based on the established reservoir prediction model, the quantitative classification map of water flooding level, and the quantitative evaluation formula of water flooding level, a three-dimensional quantitative evaluation of water flooding level is carried out.
[0006] Preferably, the step of dividing the two-phase flow region of the normalized relative permeability curve of a low-permeability reservoir into intervals to obtain the initial saturation is as follows: Divide the two-phase seepage zone of the normalized relative permeability curve into N equal parts, read the water saturation values corresponding to the N-1 division points, and take the water saturation values corresponding to the N-1 division points as the initial saturation.
[0007] Preferably, the steps for constructing a three-dimensional tracer flow conceptual model set based on initial saturation and low-permeability reservoir parameters are as follows: Collect information on the target reservoir, fluids, and development well network, and establish a reservoir conceptual model based on the target reservoir, fluids, and development well network; The injected water in the reservoir conceptual model was marked using a tracer, and the dimensionless concentration of the tracer was set to 1.0. A set of three-dimensional tracer flow conceptual models was constructed by using a reservoir conceptual model with labeled water injection and initial saturation.
[0008] Preferably, the steps for establishing a quantitative classification map of flooding levels based on the three-dimensional tracer flow conceptual model group are as follows: Run the three-dimensional tracer flow conceptual model set until the model water content reaches 100%. End when the set threshold is reached; Output flow conceptual model group corresponding to water cut at each time step and tracer concentration Numerical value; Establish model group moisture content With tracer concentration The relationship curve is divided from left to right into an initial, gentle upward phase, a middle, rapid upward phase, and a later, gentle upward phase. The inflection points between adjacent segments of each curve are determined. The inflection point between the initial, gentle upward phase and the middle, rapid upward phase is designated as "Inflection Point Series I," and the inflection point between the rapid upward phase and the later, gentle upward phase is designated as "Inflection Point Series II." The tracer concentrations corresponding to Inflection Point Series I and Inflection Point Series II are then recorded. value; Plot the tracer concentration corresponding to the inflection point Value and initial water saturation A scatter plot of the relationship was used to regress the tracer concentrations of inflection point series I and inflection point series II, respectively. Value and initial water saturation The relationship curves are labeled A, B, and C from bottom to top, respectively. tracer concentration A value of 0 indicates no flooding, zone A indicates weak flooding, zone B indicates moderate flooding, and zone C indicates severe flooding, thus forming a quantitative classification chart for flooding levels.
[0009] Preferably, the model moisture content Greater than or equal to 95%.
[0010] Preferably, the step of determining the inflection points of two adjacent segments on each curve is as follows: Calculation of water content in model group With tracer concentration The curvature of the relationship curve is calculated using the following formula:
[0011] In the formula: For curvature Moisture content derivative Moisture content The second derivative Drawing curvature and The relationship curve is used to obtain the first and second peak values, where the first peak value is the inflection point series I and the second peak value is the inflection point series II.
[0012] Preferably, the formula for quantitatively evaluating flooding levels is obtained by: based on the tracer concentration. Value and initial water saturation The linear regression equations for inflection point series I and inflection point series II are obtained from the scatter plot of the relationship. Based on the linear regression equations for inflection point series I and inflection point series II, the quantitative evaluation formula for flooding level is determined.
[0013] A quantitative evaluation system for water flooding levels in low-permeability oil reservoirs includes: The partitioning module is used to partition the two-phase flow region of the normalized relative permeability curve of low-permeability reservoirs and obtain the initial saturation. Building Module: Used to construct a set of three-dimensional tracer flow conceptual models based on initial saturation and low-permeability reservoir parameters; The chart creation module is used to create quantitative flooding level classification charts and quantitative flooding level evaluation formulas based on the three-dimensional tracer flow conceptual model group. Evaluation module: Used to perform three-dimensional quantitative evaluation of water flooding level based on the established reservoir prediction model, quantitative water flooding level classification map, and quantitative water flooding level evaluation formula.
[0014] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of a method for quantitatively evaluating the water flooding level of a low-permeability oil reservoir.
[0015] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a method for quantitatively evaluating the water flooding level of a low-permeability oil reservoir.
[0016] Compared with existing technologies, this invention has the following advantages: This invention provides a method for quantitatively evaluating the water flooding level of low-permeability reservoirs. By dividing the two-phase flow zone of the normalized relative permeability curve into intervals, the characteristics of different flow intervals can be more accurately defined, providing accurate initial conditions for subsequent tracer flow simulation. By establishing a three-dimensional tracer flow conceptual model set, the actual flow of tracers in low-permeability reservoirs can be simulated, including flow path, velocity, and distribution, thereby more accurately reflecting the water flooding status of the reservoir. Based on the three-dimensional tracer flow conceptual model set, a quantitative water flooding level classification chart can be established. This chart simplifies the complex water flooding situation into an intuitive level classification, making it easier for engineers and decision-makers to quickly understand the water flooding degree of the reservoir. By combining the three-dimensional prediction model and the quantitative water flooding level classification chart, a comprehensive and accurate three-dimensional quantitative evaluation of the water flooding level of low-permeability reservoirs can be carried out, thereby improving the accuracy rate of quantitative evaluation of water flooding level in low-permeability reservoirs.
[0017] Furthermore, by dividing the two-phase seepage zone of the normalized relative permeability curve into N equal parts, the seepage interval can be accurately divided into multiple small segments, providing more detailed initial conditions for subsequent simulation and analysis. Reading the water saturation values corresponding to the N-1 division points as the initial saturation can ensure that each initial saturation accurately reflects the characteristics of the corresponding seepage interval, thereby improving the accuracy of the evaluation. Furthermore, by collecting basic data on the target reservoir and establishing a reservoir conceptual model, the influence of various factors such as geology, fluid, and development history on the water-drive oil displacement law can be comprehensively considered. By using tracers to mark the injected water and setting dimensionless concentrations of the tracers, the actual flow of injected water in low-permeability reservoirs can be quantitatively tracked, thereby improving the reliability of the evaluation. Furthermore, by running the model group and outputting water cut and tracer concentration data, a relationship curve between water cut and tracer concentration can be established, thereby classifying flooding levels and forming an intuitive evaluation chart. By regressing the relationship curve between tracer concentration and initial water saturation, a quantitative evaluation of the degree of flooding can be achieved, providing a scientific basis for formulating oilfield development adjustment plans. Furthermore, by reasonably setting the threshold range of water cut in the model, the endpoint of the simulation can be controlled, ensuring that the simulation results can reflect the water flooding status of the reservoir without increasing unnecessary computation due to excessive simulation time. Furthermore, by calculating the curvature and plotting the relationship curve between curvature and tracer concentration, the inflection point on the relationship curve between water content and tracer concentration can be accurately found, thereby accurately dividing the different stages of flooding. The accurate determination of the inflection point helps to more accurately classify the flooding level and improve the accuracy and reliability of the evaluation. Attached Figure Description
[0018] Figure 1 This is a flowchart of a method for quantitatively evaluating the water flooding level of a low-permeability oil reservoir according to the present invention; Figure 2 This is a permeability profile diagram of the conceptual model group in an embodiment of the present invention; Figure 3 The curves showing the relationship between tracer concentration and water production rate under different initial water saturation levels in embodiments of the present invention are shown. Figure 4 This is a curve showing the relationship between the initial water saturation and the tracer concentration in an embodiment of the present invention. Figure 5 This is a block diagram of a quantitative evaluation system for water flooding levels in low-permeability oil reservoirs according to the present invention. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0022] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.
[0023] like Figure 1As shown, this invention provides a method for quantitatively evaluating the waterflooding level of low-permeability oil reservoirs, comprising: The normalized relative permeability curve of a low-permeability reservoir is divided into intervals for the two-phase flow region to obtain the initial saturation. A set of three-dimensional tracer flow conceptual models was constructed based on initial saturation and low-permeability reservoir parameters. Based on the three-dimensional tracer flow conceptual model, a quantitative classification chart of flooding levels and a quantitative evaluation formula for flooding levels were established. A three-dimensional quantitative evaluation of water flooding level is conducted based on the three-dimensional reservoir prediction model, the quantitative classification map of water flooding level, and the quantitative evaluation formula of water flooding level. The specific steps for dividing the two-phase flow region of the normalized relative permeability curve of a low-permeability reservoir into intervals and obtaining the initial saturation are as follows: Divide the two-phase seepage zone of the normalized relative permeability curve into N equal parts, read the water saturation values corresponding to the N-1 division points, and take the water saturation values corresponding to the N-1 division points as the initial saturation.
[0024] The specific steps for constructing a three-dimensional tracer flow conceptual model set based on initial saturation and low-permeability reservoir parameters are as follows: Collect basic data on the target reservoir and establish a reservoir conceptual model based on the basic data. The injected water in the reservoir conceptual model was marked using a tracer, and the dimensionless concentration of the tracer was set. A conceptual model of the reservoir with water injection and initial saturation was established, and a set of three-dimensional tracer flow conceptual models was constructed.
[0025] The dimensionless concentration setting range for the tracer is 1.0.
[0026] The specific steps for establishing a quantitative classification chart and quantitative evaluation formula for flooding levels based on the three-dimensional tracer flow conceptual model are as follows: Run the three-dimensional tracer flow conceptual model set until the model water content reaches 100%. End when the set threshold is reached; Output flow conceptual model group corresponding to water cut at each time step and tracer concentration Numerical value; Establish model group moisture content With tracer concentration The relationship curve is divided from left to right into an initial, gentle upward phase, a middle, rapid upward phase, and a later, gentle upward phase. The inflection points between adjacent segments of each curve are determined. The inflection point between the initial, gentle upward phase and the middle, rapid upward phase is designated as "Inflection Point Series I," and the inflection point between the rapid upward phase and the later, gentle upward phase is designated as "Inflection Point Series II." The tracer concentrations corresponding to Inflection Point Series I and Inflection Point Series II are then recorded. value; Plot the tracer concentration corresponding to the inflection point Value and initial water saturation A scatter plot of the relationship was used to regress the tracer concentrations of inflection point series I and inflection point series II, respectively. Value and initial water saturation The relationship curves are labeled A, B, and C from bottom to top, respectively. Define tracer concentration A value of 0 indicates no flooding; area A is weakly flooded; area B is moderately flooded; and area C is severely flooded. A quantitative classification chart and evaluation formula for flooding levels are established, and tracer concentrations are set for areas A, B, and C respectively. The interval range function forms a quantitative evaluation formula for flooding level.
[0027] Model moisture content Greater than or equal to 95%.
[0028] The specific steps for determining the inflection points of two adjacent segments on each curve are as follows: Calculation of water content in model group With tracer concentration The curvature of the relationship curve is calculated using the following formula:
[0029] In the formula: For curvature, For function The derivative, For function f w The second derivative Drawing curvature and The relationship curve is used to obtain the first and second peak values, where the first peak value is the inflection point series I and the second peak value is the inflection point series II.
[0030] The formula for quantitatively evaluating flood levels is obtained specifically based on the tracer concentration. Value and initial water saturation The linear regression equations for inflection point series I and inflection point series II are obtained from the scatter plot of the relationship. Based on the linear regression equations for inflection point series I and inflection point series II, the quantitative evaluation formula for flooding level is determined.
[0031] Another embodiment of the present invention provides a method for quantitatively evaluating the waterflooding level of low-permeability reservoirs, comprising: ① Divide the two-phase flow region of the normalized phase permeability curve into intervals.
[0032] ② Construct a set of three-dimensional tracer flow conceptual models.
[0033] ③ Establish a quantitative classification chart for flood levels.
[0034] ④ Quantitative evaluation of three-dimensional water flooding level using reservoir prediction models.
[0035] Step ① involves dividing the two-phase seepage zone of the normalized relative permeability curve into intervals, determined as follows: the two-phase seepage zone of the normalized relative permeability curve is divided into 8 equal parts, and the water saturation values corresponding to the 7 division points are read.
[0036] Step ② involves constructing a set of three-dimensional tracer flow conceptual models, determined using the following method: A. Collect data on the physical properties, rhythm, grade difference, PVT, relative permeability, etc. of the target reservoir, and establish a reservoir conceptual model based on the reservoir, fluid and development well network of the target reservoir; B. Use a tracer to mark the injected water, and set the dimensionless concentration of the tracer to 1.0; C. Use the water saturation value determined in step ① as the initial saturation. A three-dimensional tracer flow conceptual model set was constructed.
[0037] Step ③, establishing a quantitative classification chart for flood levels, is determined according to the following method: A. Run the three-dimensional tracer flow conceptual model group established in step ② until the model water content reaches... End when 95% is reached; B. Water content at each time step of the output flow conceptual model group tracer concentration Numerical value; C. Establish the moisture content of the model group With tracer concentration The relationship curve is divided from left to right into an initial, gradual upward trend; a middle, rapid upward trend; and a later, gradual upward trend. The inflection points between adjacent segments of each curve are then determined. The inflection point between the initial, gradual upward trend and the middle, rapid upward trend is designated as "Inflection Point Series I," and the inflection point between the rapid upward trend and the later, gradual upward trend is designated as "Inflection Point Series II." The tracer concentrations corresponding to Inflection Point Series I and Inflection Point Series II are then recorded. value; D. Plotting tracer concentrations Value and initial water saturation A scatter plot of the relationship was used to regress the tracer concentrations of inflection point series I and inflection point series II, respectively. Value and initial water saturation The relationship curves are labeled A, B, and C from left to right, respectively. E. Define tracer concentration A value of 0 indicates no flooding, zone A indicates weak flooding, zone B indicates moderate flooding, and zone C indicates severe flooding, thus forming a quantitative classification chart and quantitative evaluation formula for flooding levels.
[0038] Step ③ involves using a reservoir prediction model to quantitatively evaluate the three-dimensional waterflood level, determined according to the following method: A. The water injected into the reservoir prediction model is labeled with a tracer. The dimensionless concentration of the tracer is set to 1.0. After calculation, a three-dimensional distribution field of tracer concentration is formed. B. Based on the flood level quantitative classification chart and quantitative evaluation formula established in step ③, conduct a three-dimensional quantitative evaluation of the flood level.
[0039] Another embodiment of the present invention provides a method for quantitatively evaluating the water flooding level of low-permeability reservoirs: This invention can accurately determine the waterflood level of production layers in low-permeability reservoirs, providing a reliable basis for tapping remaining oil potential. Taking the C4+5 reservoir double-row well network area in Block G of a certain region as an example, by comparing with the results of remaining oil testing and the logging interpretation conclusions of newly drilled and infill wells, it is proven that this method can accurately determine the waterflood level.
[0040] The specific steps are as follows: Step 1 involves dividing the two-phase flow zone of the normalized relative permeability curve into intervals. The purpose of this step is to provide initial water saturation data for the three-dimensional tracer flow conceptual model to be established in Step 2. To ensure the accuracy of the statistically derived patterns, a large sample size is needed; however, too many samples will increase the computational load of the flow conceptual model and consume more time. Therefore, a reasonable sample size needs to be controlled. Based on geological statistical experience, seven sample data points are sufficient to regress geological patterns with good correlation. Therefore, the two-phase flow zone of the normalized relative permeability curve needs to be divided into eight equal parts, and the water saturation values corresponding to the seven division points are read. In Block G, the bound water saturation of the normalized relative permeability curve for reservoir C4+5 is 32.0%, the residual oil saturation is 38.0%, and the water saturation range of the oil-water two-phase flow zone is 32.0%-62.0%. The water saturation values corresponding to the seven division points are shown in Table 1.
[0041] Table 1 Initial water saturation data for the three-dimensional tracer flow conceptual model group
[0042] Step two, construct a three-dimensional tracer flow conceptual model set, including the following steps: Step 201: Collect data on the target reservoir's physical properties, rhythm, permeability gradient, PVT, and relative permeability. Based on the target reservoir's reservoir structure, fluid characteristics, and development well pattern, establish a reservoir conceptual model. The vertical rhythm of the C4+5 reservoir in Block G is a composite rhythm, with an average permeability of 1.5 md and a permeability range of 15. The well pattern is a 300m × 300m square inverted nine-point well pattern. The permeability profile of the conceptual model group is shown below. Figure 2 As shown.
[0043] Step 202: The injected water is labeled with a tracer, and the dimensionless concentration of the tracer is set to 1.0. In the model definition, the injected water is labeled as the tracer, and the dimensionless concentration of the tracer is set to 1.0. Its properties are kept consistent with those of the injected water. In the output results, the model tracer production, model tracer concentration, single-well tracer production, and single-well tracer concentration are output respectively.
[0044] Step 203: Use the water saturation value determined in Step 1 as the initial saturation. A three-dimensional tracer flow conceptual model set was constructed. During initialization, the water saturation value determined in step one was used as the initial saturation. By assigning values to the saturation, a conceptual model set of three-dimensional tracer flow under different initial water saturation is constructed.
[0045] Step 3: Establish a quantitative classification map of flood levels, including the following steps: Step 301: Perform calculations on the three-dimensional tracer flow conceptual model group established in step ②, until the model's water content reaches a certain level. The process ends when 95% is reached.
[0046] Step 302: Output the water content corresponding to each time step of the flow conceptual model group. tracer concentration Numerical value; Step 303, establish the moisture content of the model group With tracer concentration Relationship curve, moisture content With tracer concentration The relationship curve approximates an "S" shape, which can be divided from left to right into an initial, gently rising segment, a middle-term, rapidly rising segment, and a later, gently rising segment. Based on the curve's trend, the inflection points between adjacent segments on each curve are determined. The inflection point between the initial, gently rising segment and the rapidly rising segment is denoted as "Inflection Point Series I," and the inflection point between the rapidly rising segment and the later, gently rising segment is denoted as "Inflection Point Series II," such as... Figure 3 .
[0047] Step 304: Read the tracer concentrations corresponding to inflection point series I and inflection point series II. Values, plotting tracer concentrations Value and initial water saturation A scatter plot of the relationship was used to regress the tracer concentration C in inflection point series I and inflection point series II, respectively. t Value and initial water saturation The relationship curves are labeled A, B, and C from left to right; for example... Figure 4 .
[0048] Step 305, Define tracer concentration A value of 0 indicates no flooding, zone A indicates weak flooding, zone B indicates moderate flooding, and zone C indicates severe flooding. This forms a quantitative classification chart and quantitative evaluation formula for flooding levels, as shown in Table 2.
[0049] Table 2 Quantitative Evaluation Formula for Flood Level
[0050] Step four involves using a reservoir prediction model to quantitatively evaluate the three-dimensional waterflooding level, including the following steps: Step 401: Based on the established prediction model for the C4+5 reservoir in Block G, the injected water is labeled using a tracer. The dimensionless concentration of the tracer is set to 1.0, and its properties are kept consistent with those of the injected water. The output includes the predicted model tracer production, model tracer concentration, single-well tracer production, and single-well tracer concentration. The calculations generate a three-dimensional distribution field of the tracer concentration.
[0051] Step 402: Based on the quantitative classification map and quantitative evaluation formula of water flooding level established in Step 3, a three-dimensional quantitative evaluation of water flooding level is carried out based on the initial saturation field of reservoir C4+5 in block G and the tracer concentration field of the prediction model.
[0052] Comparing the flooding levels obtained by different methods with the results of mine tests, it can be seen that the conventional water production rate flooding level determination method has a low consistency rate with the conclusions obtained from mine tests, while the tracer concentration method has a high consistency rate (Table 3).
[0053] Table 3G Block C4+5 Reservoir Double-row Well Network Area Waterflood Level Determination Using Different Theoretical Methods
[0054] like Figure 5 As shown, one embodiment of the present invention provides a quantitative evaluation system for water flooding levels in low-permeability oil reservoirs, comprising: The partitioning module is used to partition the two-phase flow region of the normalized relative permeability curve of low-permeability reservoirs and obtain the initial saturation. Building Module: Used to construct a set of three-dimensional tracer flow conceptual models based on initial saturation and low-permeability reservoir parameters; The chart creation module is used to create quantitative flooding level classification charts and quantitative flooding level evaluation formulas based on the three-dimensional tracer flow conceptual model group. Evaluation module: Used to perform three-dimensional quantitative evaluation of water flooding level based on the established reservoir prediction model, quantitative water flooding level classification map, and quantitative water flooding level evaluation formula.
[0055] An embodiment of the present invention provides a terminal device. This terminal device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.
[0056] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.
[0057] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.
[0058] 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.
[0059] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.
[0060] If the modules / units integrated into the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.
[0061] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.
Claims
1. A method for quantitatively evaluating the water flooding level of low-permeability oil reservoirs, characterized in that, include: The normalized relative permeability curve of a low-permeability reservoir is divided into intervals for the two-phase flow region to obtain the initial saturation. A set of three-dimensional tracer flow conceptual models was constructed based on initial saturation and low-permeability reservoir parameters. Based on the three-dimensional tracer flow conceptual model, a quantitative classification chart of flooding levels and a quantitative evaluation formula for flooding levels were established. Based on the established reservoir prediction model, the quantitative classification map of water flooding level, and the quantitative evaluation formula of water flooding level, a three-dimensional quantitative evaluation of water flooding level is carried out.
2. The method for quantitatively evaluating the waterflooding level of a low-permeability reservoir according to claim 1, characterized in that, The specific steps for dividing the two-phase flow region of the normalized relative permeability curve of a low-permeability reservoir into intervals and obtaining the initial saturation are as follows: Divide the two-phase seepage zone of the normalized relative permeability curve into N equal parts, read the water saturation values corresponding to the N-1 division points, and take the water saturation values corresponding to the N-1 division points as the initial saturation.
3. The method for quantitatively evaluating the water flooding level of a low-permeability reservoir according to claim 2, characterized in that, The specific steps for constructing a three-dimensional tracer flow conceptual model set based on initial saturation and low-permeability reservoir parameters are as follows: Collect information on the target reservoir, fluids, and development well network, and establish a reservoir conceptual model based on the target reservoir, fluids, and development well network; The injected water in the reservoir conceptual model was marked using a tracer, and the dimensionless concentration of the tracer was set to 1.
0. A set of three-dimensional tracer flow conceptual models was constructed by using a reservoir conceptual model with labeled water injection and initial saturation.
4. The method for quantitatively evaluating the waterflooding level of a low-permeability reservoir according to claim 1, characterized in that, The specific steps for establishing a quantitative classification map of flooding levels based on the three-dimensional tracer flow conceptual model are as follows: Run the three-dimensional tracer flow conceptual model set until the model water content reaches 100%. End when the set threshold is reached; Output flow conceptual model group corresponding to water cut at each time step and tracer concentration Numerical value; Establish model group moisture content With tracer concentration The relationship curve is divided from left to right into an initial, gentle upward phase, a middle, rapid upward phase, and a later, gentle upward phase. The inflection points between adjacent segments of each curve are determined. The inflection point between the initial, gentle upward phase and the middle, rapid upward phase is designated as "Inflection Point Series I," and the inflection point between the rapid upward phase and the later, gentle upward phase is designated as "Inflection Point Series II." The tracer concentrations corresponding to Inflection Point Series I and Inflection Point Series II are then recorded. value; Plot the tracer concentration corresponding to the inflection point Value and initial water saturation A scatter plot of the relationship was used to regress the tracer concentrations of inflection point series I and inflection point series II, respectively. Value and initial water saturation The relationship curves are labeled A, B, and C from bottom to top, respectively. tracer concentration A value of 0 indicates no flooding, zone A indicates weak flooding, zone B indicates moderate flooding, and zone C indicates severe flooding, thus forming a quantitative classification chart for flooding levels.
5. The method for quantitatively evaluating the water flooding level of a low-permeability reservoir according to claim 4, characterized in that, Model moisture content Greater than or equal to 95%.
6. The method for quantitatively evaluating the water flooding level of a low-permeability reservoir according to claim 4, characterized in that, The specific steps for determining the inflection points of two adjacent segments on each curve are as follows: Calculation of water content in model group With tracer concentration The curvature of the relationship curve is calculated using the following formula: In the formula: For curvature Moisture content derivative Moisture content The second derivative Drawing curvature and The relationship curve is used to obtain the first and second peak values, where the first peak value is the inflection point series I and the second peak value is the inflection point series II.
7. The method for quantitatively evaluating the water flooding level of a low-permeability reservoir according to claim 4, characterized in that, The formula for quantitatively evaluating flood levels is obtained specifically based on the tracer concentration. Value and initial water saturation The linear regression equations for inflection point series I and inflection point series II are obtained from the scatter plot of the relationship. Based on the linear regression equations for inflection point series I and inflection point series II, the quantitative evaluation formula for flooding level is determined.
8. A quantitative evaluation system for water flooding levels in low-permeability oil reservoirs, characterized in that, include: The partitioning module is used to partition the two-phase flow region of the normalized relative permeability curve of low-permeability reservoirs and obtain the initial saturation. Building Module: Used to construct a set of three-dimensional tracer flow conceptual models based on initial saturation and low-permeability reservoir parameters; The chart creation module is used to create quantitative flooding level classification charts and quantitative flooding level evaluation formulas based on the three-dimensional tracer flow conceptual model group. Evaluation module: Used to perform three-dimensional quantitative evaluation of water flooding level based on the established reservoir prediction model, quantitative water flooding level classification map, and quantitative water flooding level evaluation formula.
9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for quantitative evaluation of water flooding level of low-permeability reservoirs as described in any one of claims 1 to 7.
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 steps of the method for quantitative evaluation of water flooding level of low-permeability reservoirs as described in any one of claims 1 to 7.