Compact sandstone gas reservoir dynamic reserve calculation method and device
By using numerical simulation of three-dimensional texture models and gas reservoir data, combined with production history fitting and dynamic prediction, the problems of low permeability and the single analytical model in the dynamic reserve calculation of single wells in tight sandstone gas reservoirs have been solved, achieving accurate reserve calculation and results with clear physical meaning.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2024-10-21
- Publication Date
- 2026-04-24
AI Technical Summary
The calculation of dynamic reserves of single wells in tight sandstone gas reservoirs faces problems such as slow pressure diffusion due to low reservoir permeability, underestimation of pressure recovery test results, single analytical model, large multiple solutions in the fitting process, and the need to determine the steady state of production, which lead to inaccurate calculation results.
Numerical simulation is performed using a three-dimensional texture model and gas reservoir data. Combined with production history fitting and dynamic prediction, the dynamic reserves of a single well are calculated through the gas reservoir numerical simulation model, avoiding the need to judge the flow stage and boundary flow. The reserves are calculated based on the actual shape of the working area using numerical simulation technology.
It enables accurate calculation of dynamic reserves of a single well under conditions of short production time or no clear boundaries, overcomes the limitations of analytical models, provides clear physical meaning, and reduces the influence of human factors.
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Figure CN121920254A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of petroleum exploration technology, and in particular to a method and apparatus for calculating the dynamic reserves of tight sandstone gas reservoirs. Background Technology
[0002] The dynamic reserves of a single well are actually a function of time, reflecting the geological reserves within the range of well production pressure diffusion.
[0003] The calculation of dynamic reserves in a single well of a tight sandstone gas reservoir is the foundation for calculating important indicators such as the EUR (Earnings Per Hour) of a single well. However, common methods for calculating the dynamic reserves in a single well of a tight sandstone gas reservoir have the following difficulties:
[0004] 1. The reservoir matrix has very low permeability, which leads to slow pressure diffusion and makes it difficult for the pressure drop to reach various boundaries (some wells have no clear boundaries), meaning it is greatly affected by the flow regime.
[0005] 2. The calculation results of pressure recovery well testing and the current mainstream unstable production analysis technology may be significantly underestimated, and they are all based on various single analytical models;
[0006] 3. The work area was simplified into an ideal geometric shape during the calculation process, which resulted in a certain deviation from the actual work area;
[0007] 4. The fitting process has a certain degree of ambiguity and is greatly affected by human factors; moreover, some calculation methods require the well's production to enter a quasi-steady state or boundary flow.
[0008] Therefore, there is an urgent need for a method to calculate the dynamic geological reserves of single wells with short production time or no clear boundaries. This method should be able to calculate reserves based on the actual shape of the work area, overcome the limitations of overly simplistic analytical models, eliminate the need to diagnose flow stages, and eliminate the need to determine whether production has entered a quasi-steady state or boundary flow. Summary of the Invention
[0009] The purpose of this application is to provide a method and apparatus for calculating the dynamic reserves of tight sandstone gas reservoirs, which can solve the problems that the calculation of the dynamic reserves of a single well in tight sandstone gas reservoirs is greatly affected by production time and flow state.
[0010] To achieve the above objectives, this application provides the following technical solution:
[0011] In a first aspect, embodiments of this application provide a method for calculating the dynamic reserves of tight sandstone gas reservoirs, including:
[0012] The numerical simulation model of the gas reservoir is initialized based on the three-dimensional texture model and gas reservoir data, and the numerical simulation model of the gas reservoir is established.
[0013] To perform production history fitting on the gas reservoir numerical simulation model and to validate the gas reservoir numerical simulation model;
[0014] By using a gas reservoir numerical simulation model to predict production dynamics and calculate the dynamic reserves of a single well over time, the dynamic reserves of a single well at a certain moment can be obtained.
[0015] Data processing and final value determination are performed on the dynamic reserves of a single well at different times to obtain the dynamic reserves of a single well at any time.
[0016] Secondly, embodiments of this application provide a device for calculating the dynamic reserves of tight sandstone gas reservoirs, including:
[0017] The initialization unit is used to initialize the gas reservoir numerical simulation model based on the three-dimensional texture model and gas reservoir data, and to complete the establishment of the gas reservoir numerical simulation model.
[0018] The fitting unit is used to fit the production history of the gas reservoir numerical simulation model, thereby verifying the gas reservoir numerical simulation model.
[0019] The calculation unit is used to perform dynamic production prediction and time-sharing calculation of dynamic reserves of a single well using a gas reservoir numerical simulation model, so as to obtain the dynamic reserves of a single well at a certain moment.
[0020] The data processing unit is used to process and determine the dynamic reserves of a single well at different times, so as to obtain the dynamic reserves of a single well at any time.
[0021] Thirdly, embodiments of this application also provide an electronic device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program or instructions to implement the steps of the aforementioned method for calculating the dynamic reserves of a tight sandstone gas reservoir.
[0022] Fourthly, embodiments of this application also provide a computer storage medium storing a computer program or instructions, which, when executed by a processor, implement the steps of the aforementioned method for calculating the dynamic reserves of a tight sandstone gas reservoir.
[0023] Fifthly, embodiments of this application also provide a computer program product, including a computer program or instructions, which, when executed by a processor, implement the steps of the aforementioned method for calculating the dynamic reserves of a tight sandstone gas reservoir.
[0024] The technical effects and advantages of this application are as follows: This application calculates the dynamic geological reserves of single wells with short production time or no clear boundaries. In this calculation process, numerical simulation technology is combined, making full use of a large amount of geological, production and fluid data, and the reserves are calculated based on the actual shape of the work area, which to some extent overcomes the characteristics of the analytical model being too simplistic. This application no longer diagnoses the flow stage and does not need to determine whether production has entered a quasi-steady state or boundary flow. The physical meaning of the determined dynamic reserves is clear and explicit.
[0025] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description
[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a flowchart illustrating a method for calculating the dynamic reserves of a tight sandstone gas reservoir according to an embodiment of this application;
[0028] Figure 2 This is a detailed flowchart of a method for calculating the dynamic reserves of a tight sandstone gas reservoir according to an embodiment of this application;
[0029] Figure 3 This is a schematic diagram of the structure of a dynamic reserve calculation device for tight sandstone gas reservoirs according to an embodiment of this application;
[0030] Figure 4 This is a schematic diagram of the structure of an electronic device according to an embodiment of this application;
[0031] Figure 5-1 This is a schematic diagram of the physical field of the model in the embodiments of this application. Figure 1 ;
[0032] Figure 5-2 This is a schematic diagram of the physical field of the model in the embodiments of this application. Figure 2 ;
[0033] Figure 6-1 This is a schematic diagram of the saturation field of the model in the embodiments of this application;
[0034] Figure 6-2 This is a schematic diagram of the pressure field of the model in the embodiments of this application;
[0035] Figure 7 This is a schematic diagram of the gas production of the model in the embodiments of this application;
[0036] Figure 8 This is a schematic diagram of wellhead pressure fitting for the model in the embodiments of this application;
[0037] Figure 9-1 This is a schematic diagram of the single-well depressurization range at different times in the embodiments of this application. Figure 1 ;
[0038] Figure 9-2 This is a schematic diagram of the single-well depressurization range at different times in the embodiments of this application. Figure 2 ;
[0039] Figure 9-3 This is a schematic diagram of the single-well depressurization range at different times in the embodiments of this application. Figure 3 ;
[0040] Figure 9-4 This is a schematic diagram of the single-well depressurization range at different times in the embodiments of this application. Figure 4 ;
[0041] Figure 10 This is a schematic diagram of the dynamic reserves of a single well at different times in the embodiments of this application. Detailed Implementation
[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0043] To address the shortcomings of existing technologies, this application discloses a method for calculating the dynamic reserves of tight sandstone gas reservoirs, such as... Figure 1 and Figure 2 As shown, it includes the following steps:
[0044] Step S1: Initialize the gas reservoir numerical simulation model based on the three-dimensional texture model and gas reservoir data to complete the establishment of the gas reservoir numerical simulation model;
[0045] Step S2: Perform production history fitting of the gas reservoir numerical simulation model to verify the gas reservoir numerical simulation model;
[0046] Step S3: Use the gas reservoir numerical simulation model to predict production dynamics and calculate the dynamic reserves of a single well over time to obtain the dynamic reserves of a single well at a certain moment.
[0047] Step S4: Process the data and determine the final value of the dynamic reserves of a single well at different times to obtain the dynamic reserves of a single well at any time.
[0048] In some specific embodiments, step S1: Initializing the gas reservoir numerical simulation model based on the three-dimensional texture model and gas reservoir data, and completing the establishment of the gas reservoir numerical simulation model, includes:
[0049] Step S11: The three-dimensional texture model is meshed into multiple mesh blocks. The gas reservoir data values are assigned to each mesh block using an algorithm to initialize the gas reservoir numerical simulation model.
[0050] The gas reservoir data includes: fluid and high-pressure physical property parameters, special core analysis data, and static pressure test data; the special core analysis data includes relative permeability curves and capillary pressure curves, and the static pressure test data includes test point elevation and test point static pressure.
[0051] Step S12: After the initialization of the gas reservoir numerical simulation model is completed, check whether the initial gas and water distribution of the gas reservoir numerical simulation model is reasonable, and use the volumetric method to fit the reserves of the gas reservoir numerical simulation model.
[0052] This includes checking whether the initial gas-water distribution of the gas reservoir numerical simulation model is reasonable, including:
[0053] Based on the numerical simulation model of the gas reservoir, the gas saturation, pressure and other parameters of each grid block are calculated by the algorithm. The distribution of fluids can be summarized by the gas saturation of the grid blocks. Then, it is judged whether the distribution of fluids conforms to conventional geological theory, that is, whether the initial gas-water distribution is reasonable.
[0054] The volumetric method is used to fit the reserves of the gas reservoir numerical simulation model, including:
[0055] During the initialization of the gas reservoir numerical simulation model, the geological reserves G of the entire gas reservoir numerical simulation model can also be calculated. x ; because in practical work, the geological reserve value G calculated using the volumetric method y For accuracy, therefore, geological reserves G x Geological reserves required G y Approaching, i.e., geological reserves G x It should be close to the geological reserves G y If there is a discrepancy between the two, the relevant parameters affecting the calculation of geological reserves (such as porosity and net-to-gross ratio) are adjusted to achieve the fitting of the gas reservoir numerical simulation model reserves.
[0056] Step S13: Load logging data, debug and run the gas reservoir numerical simulation model, and complete the establishment of the gas reservoir numerical simulation model; among which, logging data includes well trajectory data, well completion data and production dynamic data.
[0057] In some specific embodiments, step S2: performing production history fitting on the gas reservoir numerical simulation model to verify the gas reservoir numerical simulation model; including:
[0058] The production history fitting includes: single-well gas production fitting, single-well bottom or wellhead flowing pressure fitting, and single-well water production fitting.
[0059] (1) Fitting gas production of a single well: Set the generation mode of the well logging (e.g., gas production control mode) and the operation model, and adjust the production-related parameters of the gas reservoir numerical simulation model (e.g., permeability) to fit the gas production of a single well in the gas reservoir numerical simulation model so that the gas reservoir numerical simulation model can accept the actual gas production value.
[0060] (2) Bottom-outlet or wellhead flowing pressure fitting of a single well: Based on the actual pressure data from well logging, determine the single-well flowing pressure fitting target for the gas reservoir numerical simulation model, and calibrate the gas reservoir numerical simulation model, including:
[0061] Determine the quantity of bottom hole flowing pressure monitoring data for a single well;
[0062] If there is a large amount of bottom hole pressure monitoring data for a single well, then fitting the bottom hole pressure of the gas reservoir numerical simulation model can achieve a high-quality calibration of the gas reservoir numerical simulation model.
[0063] If the amount of bottom hole flowing pressure monitoring data for a single well is small, then wellhead flowing pressure fitting of the gas reservoir numerical simulation model is performed to calibrate the gas reservoir numerical simulation model.
[0064] The single-well flowing pressure fitting targets include the well bottom and the wellhead.
[0065] In some specific embodiments, the flow-pressure fitting process of the gas reservoir numerical simulation model includes:
[0066] The control range of a single well is estimated by integrating the interpretation of instability test results or the results of reservoir engineering calculations.
[0067] The permeability within the control range of a single well is adjusted multiple times, and the permeability adjusted each time is substituted into the gas reservoir numerical simulation model for trial calculation to obtain the calculated reserve value;
[0068] When the error between the calculated reserve value and the actual monitored reserve value is less than the set value, the bottom hole pressure fitting is completed.
[0069] If the error between the calculated reserve value and the actual monitored reserve value is small, the permeability is kept constant, and the gas reservoir numerical simulation model is recalculated by adjusting the well index until the error between the calculated reserve value and the actual monitored reserve value is less than the set value.
[0070] If the error between the calculated reserve value and the actual monitored reserve value is consistently greater than or equal to the set value, then the control range of a single well is expanded, and the permeability within the control range of the single well is adjusted multiple times. The permeability adjusted each time is substituted into the gas reservoir numerical simulation model for trial calculation to obtain the calculated reserve value. The error between the calculated reserve value and the actual monitored reserve value is less than the set value.
[0071] Among them, the basic theoretical formulas of gas reservoir numerical simulation were used to conduct trial calculations of the gas reservoir numerical simulation model. The basic theoretical formulas of gas reservoir numerical simulation are as follows:
[0072]
[0073]
[0074] In the formula, Let K represent the gradient operator, and K represent the absolute permeability. rg B represents the relative permeability of the gas phase. g μ represents the natural gas volume factor. g Indicates the viscosity of natural gas. This indicates a gradient calculation with respect to gas phase pressure, ρ g Let g represent the gas phase density and g represent the acceleration due to gravity. Represents the potential gradient. This represents the partial differential operator, and t represents time. S represents porosity. g K represents the gas saturation level. rw B represents the relative permeability of the aqueous phase. w The water volume factor, μ w Indicates water viscosity. This indicates a gradient calculation of the water phase pressure, ρ w S represents the density of water. w Indicates water saturation.
[0075] (3) For well logging of producing formation water, the single-well water production or single-well water-gas ratio is fitted to the gas reservoir numerical simulation model.
[0076] The process of fitting the single-well water production or single-well water-gas ratio in the numerical simulation model of the gas reservoir includes:
[0077] Determine the direction of incoming water, and gradually adjust the conductivity or permeability of the area between the well logging and the direction of incoming water based on the direction of incoming water. Substitute the conductivity or permeability of each adjustment into the gas reservoir numerical simulation model to perform trial calculations and obtain the reservoir calculation value.
[0078] If the error between the calculated reserve value and the actual monitored reserve value is less than the set value, then the single-well water production fitting or single-well water-gas ratio fitting is completed.
[0079] If the error between the calculated reserve value and the actual monitored reserve value is greater than or equal to the set value, it is necessary to adjust the area between the well logging and the direction of water inflow, and to gradually adjust and recalculate the conductivity or permeability of the area until the error between the calculated reserve value and the actual monitored reserve value is less than the set value; wherein, the recalculation formula is the same as step (2).
[0080] In some specific embodiments, step S3: using a gas reservoir numerical simulation model to predict production dynamics and calculate the dynamic reserves of a single well over time, to obtain the dynamic reserves of a single well at a certain moment; includes the following steps:
[0081] Step S31: Based on the completion of the production history fitting of the gas reservoir numerical simulation model, use the gas reservoir numerical simulation model to predict the dynamic production and calculate the production index data for each future time.
[0082] Among them, the use of gas reservoir numerical simulation models for production dynamic prediction includes: restarting the calculation of the gas reservoir numerical simulation model according to the logging operation system corresponding to the last date of the production history (e.g., predicting 20 years).
[0083] Restarting the calculation refers to starting the gas reservoir numerical simulation model from a specified point in time, which is different from starting the gas reservoir numerical simulation model from the initial point in time. For example, the gas reservoir numerical simulation model is divided into two time periods: the actual time period from 2000 to 2024 and the predicted time period from 2024 to 2044. The actual time period contains actual production data, while the predicted time period is used to predict production data. Therefore, when restarting the calculation, the data in 2024 is used as the starting point for the calculation, and the calculation continues until 2044, rather than using the initial time of 2000 as the starting point for the calculation.
[0084] During the restart calculation process, single-well condition constraints are added, including technical or economic constraints. These constraints include a production lower limit and a wellhead pressure lower limit. The production lower limit is obtained through economic evaluation calculations, and the wellhead pressure lower limit is determined by considering oil and gas gathering and transportation conditions.
[0085] For example, the minimum production value Q = 1200 cubic meters / day and the minimum wellhead pressure value 2 MPa; during model calculation, both production and pressure must not be lower than the set minimum values. If the lower limit conditions cannot be met, the well will be shut in.
[0086] Step S32: Utilize the gas reservoir numerical simulation model to perform time-sharing calculations of the dynamic reserves of a single well, obtaining the dynamic reserves of the single well at a specific moment, including:
[0087] At each predetermined time interval, a time point is selected, and the pressure relief range of a single well at the corresponding time is obtained according to the screening criteria.
[0088] Among them, the screening criterion is that the grid pressure constraint of the gas reservoir numerical simulation model at a certain moment is less than a predetermined threshold (e.g., 95%). The grid pressure constraint is the ratio of the grid block pressure at a certain moment to the original grid block pressure.
[0089] Based on the pressure relief range of a single well at a certain moment, calculate the original geological reserves within the pressure relief range of the single well, that is, obtain the dynamic reserve value of the single well at a certain moment; including:
[0090] Based on the pressure relief range of a single well at a certain moment, calculate the original geological reserves of a single grid block within the pressure relief range of the single well;
[0091] The original geological reserves of all grid blocks within the depressurization range of the single well are added together to obtain the dynamic reserves of the single well at a certain moment.
[0092] The original geological reserves of a single grid block within the depressurization range of a single well are calculated using the following formula:
[0093] G = V * pro * Sg / Bgi
[0094] In the formula, G represents the original geological reserves of a single grid block within the depressurization range of a single well, V represents the grid block volume, pro represents the grid block porosity, Sg represents the gas saturation of the grid block, and Bgi represents the original gas volume coefficient.
[0095] In this embodiment, the calculation of dynamic reserves of a single well in step S32 is quite labor-intensive. In actual practice, only the values for a portion of the time period need to be calculated, rather than all of them.
[0096] In some specific embodiments, step S4: processing and determining the final value of the dynamic reserves of a single well at different times to obtain the dynamic reserves of a single well at any time, including:
[0097] Because the dynamic reserves of a single well, without considering the influence of various boundaries (such as structural boundaries, lithological boundaries, and flow boundaries formed between wells), should gradually increase over time, with the pressure relief range gradually expanding, and eventually tending towards an asymptotic value; however, according to actual calculations, the relationship curve between the calculated dynamic reserves at different times and time shows an upward convex characteristic.
[0098] Therefore, based on the dynamic reserves of a single well at different times, a curve showing the relationship between the dynamic reserves of a single well and time is plotted, and the relationship between the dynamic reserves of a single well and time is described by the following mathematical formula:
[0099] y = ab / t,
[0100] In the formula, y represents the dynamic reserve value of a single well at a certain moment, and a and b are both fitting coefficients; t represents the time interval between the moment and the production start time, that is, the time difference between the moment and the production start time; assuming the production start time is the starting point of the timekeeping, the time difference between a certain moment of interest and the production start time is t; if the production start time is 0:00 on January 1, 2024, and you want to obtain the dynamic reserves at 0:00 on January 1, 2025, you can subtract January 1, 2024 from January 1, 2025, and the resulting time difference is t.
[0101] Linear fitting of the relationship between dynamic reserves of a single well and time: the time t is processed by taking the inverse, that is, directly regressing the linear relationship between y and 1 / t;
[0102] After the regression is completed, based on the relationship between the dynamic reserves of a single well and time, the dynamic reserves of a single well at any given time t can be calculated. At this time, a is the final dynamic reserve value. Therefore, step S32 does not need to calculate the entire time period, which can save a lot of time.
[0103] Based on the same inventive concept, this application also provides a device for calculating the dynamic reserves of tight sandstone gas reservoirs, such as... Figure 3 As shown, it includes:
[0104] The initialization unit is used to initialize the gas reservoir numerical simulation model based on the three-dimensional texture model and gas reservoir data, and to complete the establishment of the gas reservoir numerical simulation model.
[0105] The fitting unit is used to fit the production history of the gas reservoir numerical simulation model, thereby verifying the gas reservoir numerical simulation model.
[0106] The calculation unit is used to perform dynamic production prediction and time-sharing calculation of dynamic reserves of a single well using a gas reservoir numerical simulation model, so as to obtain the dynamic reserves of a single well at a certain moment.
[0107] The data processing unit is used to process and determine the dynamic reserves of a single well at different times, so as to obtain the dynamic reserves of a single well at any time.
[0108] Regarding the system in the above embodiments, the specific manner in which each unit module performs operations has been described in detail in the embodiments related to the method, and will not be elaborated here.
[0109] Based on the same inventive concept, embodiments of this application also provide an electronic device, the structure of which is as follows: Figure 4 As shown, it includes a memory, a processor, and a computer program stored in the memory. The processor executes the computer program or instructions to implement the aforementioned method for calculating the dynamic reserves of a tight sandstone gas reservoir.
[0110] Based on the same inventive concept, this application also provides a computer storage medium storing a computer program or instructions, which, when executed by a processor, implements the steps of the aforementioned method for calculating the dynamic reserves of a tight sandstone gas reservoir.
[0111] Based on the same inventive concept, this application also provides a computer program product, including a computer program or instructions, which, when executed by a processor, implement the steps of the aforementioned method for calculating the dynamic reserves of a tight sandstone gas reservoir.
[0112] Example 1: This application uses the mainstream commercial oil and gas reservoir numerical simulation software tnavigator and selects a typical model in the Sichuan Basin to verify the effect of this application. The work area is a single-well gas reservoir numerical simulation model.
[0113] like Figure 5-1 and Figure 5-2 As shown, the single-well model is located in a section of a river in the central part of the JQ gas field in Sichuan. Because the reservoir is tight sandstone, the well generally has no natural production capacity, so reservoir stimulation is required before production. According to the adaptability analysis, the main well type in this work area is horizontal well, so well A in the model is a multi-stage fracturing horizontal well.
[0114] After completing the model initialization, the main physical property fields, saturation fields, and pressure fields of the model can be obtained (e.g., ...). Figure 6-1 and 6-2 (As shown); after comparing the predicted reserves calculated by the model with the actual reserves calculated by the volumetric method, the parameters affecting the predicted reserves are adjusted to complete the fitting of the model reserves.
[0115] Load well logging data, debug and run the gas reservoir numerical simulation model, and complete the establishment of the gas reservoir numerical simulation model; then perform production history fitting of the gas reservoir numerical simulation model; among which, such as Figure 7 As shown, this represents the gas production of the gas reservoir numerical simulation model in this embodiment; Figure 8 The diagram shown is a schematic of wellhead flow pressure fitting in this embodiment.
[0116] Production dynamics prediction using gas reservoir numerical simulation model: Based on the last date of production history (December 2022 in this example) and the well logging operation system, production dynamics prediction is carried out over a period of 20 years. Technical and economic constraints, such as lower limit of production and lower limit of wellhead pressure, are applied during the calculation process.
[0117] Because the pressure relief range in the early stages of production is too small, the calculation results are not very meaningful. Therefore, this embodiment extracts a time point every year starting from the last date of the production history. The pressure relief range of a single well at that time is determined by using the ratio of the grid block pressure to the original grid block pressure in the gas reservoir numerical simulation model at that moment as a screening criterion. Figures 9-1 to 9-4 The figure shows the pressure relief range of a single well during a certain period of time;
[0118] Then, using the built-in statistical function of the tnavigator software, the original geological reserves of all grid blocks within the pressure relief range are calculated, thus obtaining the dynamic reserves of a single well at different times.
[0119] The dynamic reserves of a single well at different times are shown in Table 1:
[0120] Table 1. Time-based Dynamic Storage Table
[0121]
[0122]
[0123] Fitting the data in Table 1: First, reciprocalize the time. In this example, a good linear relationship exists between y and 1 / t. The relationship and correlation coefficient can be derived using common office software like Excel. Figure 10 As shown.
[0124] After the regression is completed, according to the relationship y = -5554.3 / t + 3.8195, the dynamic reserve value at any subsequent time can be predicted by specifying time t; 3.8195 is the final dynamic reserve value.
[0125] The technical method provided in this application uses a gas reservoir numerical model containing rich geological, fluid, and production data. After completing a fine history fitting, a series of time steps are specified. For a specific time step, the pressure relief range is determined according to the pressure reduction of the model grid block (pressure of the grid block at a certain moment / original pressure of the grid block) being less than a certain value (e.g., 95%). The original geological reserves within this range are calculated, thus obtaining the dynamic geological reserves for that time step. The time of all specified time steps is processed in a certain way, and an intersection plot is made with the dynamic geological reserves to fit the corresponding parameters.
[0126] Finally, it should be noted that the above description is only a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for calculating the dynamic reserves of tight sandstone gas reservoirs, characterized in that, include: The numerical simulation model of the gas reservoir is initialized based on the three-dimensional texture model and gas reservoir data, and the numerical simulation model of the gas reservoir is established. To perform production history fitting on the gas reservoir numerical simulation model and to validate the gas reservoir numerical simulation model; By using a gas reservoir numerical simulation model to predict production dynamics and calculate the dynamic reserves of a single well over time, the dynamic reserves of a single well at a certain moment can be obtained. Data processing and final value determination are performed on the dynamic reserves of a single well at different times to obtain the dynamic reserves of a single well at any time.
2. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 1, characterized in that, The initialization of the gas reservoir numerical simulation model is based on the three-dimensional texture model and gas reservoir data, thus completing the establishment of the gas reservoir numerical simulation model, including: The gas reservoir data includes: fluid and high-pressure physical property parameters, special core analysis data, and static pressure test data; Based on the three-dimensional texture model, combined with fluid and high-pressure physical parameters, special core analysis data, and static pressure test data, the numerical simulation model of the gas reservoir is initialized. After the initialization of the gas reservoir numerical simulation model is completed, check whether the initial gas and water distribution of the gas reservoir numerical simulation model is reasonable, and use the volumetric method to fit the reserves of the gas reservoir numerical simulation model. By incorporating well trajectory data, well completion data, and production dynamic data, the gas reservoir numerical simulation model is debugged and established. Among them, the special core analysis data includes relative permeability curves and capillary pressure curves, and the static pressure test data includes the test point elevation and the test point static pressure.
3. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 1, characterized in that, To validate the gas reservoir numerical simulation model, production history fitting is performed, including: The production history fitting includes: single-well gas production fitting, single-well bottom or wellhead flowing pressure fitting, and single-well water production fitting. Set the generation mode and operation model of well logging, and adjust the production-related parameters of the gas reservoir numerical simulation model in order to fit the single-well gas production of the gas reservoir numerical simulation model. Based on the actual pressure data from well logging, the single-well flowing pressure fitting target of the gas reservoir numerical simulation model is determined to achieve the calibration of the gas reservoir numerical simulation model; among which, the single-well flowing pressure fitting target includes the bottom of the well and the wellhead.
4. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 3, characterized in that, Based on the actual pressure data from well logging, the single-well flowing pressure fitting target of the gas reservoir numerical simulation model is determined, and the gas reservoir numerical simulation model is calibrated, including: Determine the quantity of bottom hole flowing pressure monitoring data for a single well; If there is a large amount of bottom hole pressure monitoring data for a single well, then fitting the bottom hole pressure of the gas reservoir numerical simulation model can achieve a high-quality calibration of the gas reservoir numerical simulation model. If the amount of bottomhole flowing pressure monitoring data for a single well is small, wellhead flowing pressure fitting of the gas reservoir numerical simulation model is performed to calibrate the gas reservoir numerical simulation model.
5. A method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 3 or 4, characterized in that, The process of fitting the single-well flowing pressure of the gas reservoir numerical simulation model includes: The control range of a single well is estimated by integrating the interpretation of instability test results or the results of reservoir engineering calculations. The permeability within the control range of a single well is adjusted multiple times, and the permeability adjusted each time is substituted into the gas reservoir numerical simulation model for trial calculation to obtain the calculated reserve value; When the error between the calculated reserve value and the actual monitored reserve value is less than the set value, the bottom hole pressure fitting is completed. If the error between the calculated reserve value and the actual monitored reserve value is small, the permeability is kept constant, and the gas reservoir numerical simulation model is recalculated by adjusting the well index until the error between the calculated reserve value and the actual monitored reserve value is less than the set value. If the error between the calculated reserve value and the actual monitored reserve value is consistently greater than or equal to the set value, then the control range of a single well is expanded, and the permeability within the control range of the single well is adjusted multiple times. The permeability adjusted each time is substituted into the gas reservoir numerical simulation model for trial calculation to obtain the calculated reserve value. The error between the calculated reserve value and the actual monitored reserve value is less than the set value.
6. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 3, characterized in that, For well logging of producing formation water, the single-well water production or single-well water-gas ratio is fitted to the gas reservoir numerical simulation model. The process of fitting the single-well water production or single-well water-gas ratio in the numerical simulation model of the gas reservoir includes: Determine the direction of incoming water, and gradually adjust the conductivity or permeability of the area between the well logging and the direction of incoming water based on the direction of incoming water. Substitute the conductivity or permeability of each adjustment into the gas reservoir numerical simulation model to perform trial calculations and obtain the reservoir calculation value. If the error between the calculated reserve value and the actual monitored reserve value is less than the set value, then the fitting of single-well water production or single-well water-gas ratio is completed. If the error between the calculated reserve value and the actual monitored reserve value is greater than or equal to the set value, it is necessary to adjust the area between the well logging and the direction of water inflow, and then gradually adjust and recalculate the conductivity or permeability of the area until the error between the calculated reserve value and the actual monitored reserve value is less than the set value.
7. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 1, characterized in that, Using gas reservoir numerical simulation models for dynamic production prediction and time-sharing calculation of dynamic reserves in single wells, including: Production dynamics are predicted using a gas reservoir numerical simulation model, and various production indicators are calculated for different future time periods. Based on various production indicators data at different future times, the dynamic reserves of a single well are calculated using a gas reservoir numerical simulation model. Among them, the use of gas reservoir numerical simulation models for production dynamic prediction includes: restarting the calculation of the gas reservoir numerical simulation model according to the logging operation system corresponding to the last date of the production history; During the restart calculation process, single-well condition constraints are added; the single-well condition constraints include: production lower limit and wellhead pressure lower limit.
8. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 1, characterized in that, The dynamic reserves of a single well are calculated over time using a gas reservoir numerical simulation model to obtain the dynamic reserves of the single well at a certain moment, including: At each predetermined time interval, a time point is selected, and the pressure relief range of a single well at the corresponding time is obtained according to the screening criteria. Based on the pressure relief range of a single well at a certain moment, the original geological reserves within the pressure relief range of the single well are calculated, that is, the dynamic reserve value of the single well at a certain moment is obtained. Among them, the screening criterion is that the grid pressure constraint of the gas reservoir numerical simulation model at a certain moment is less than a predetermined threshold. The grid pressure constraint is the ratio of the grid block pressure at a certain moment to the original grid block pressure.
9. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 8, characterized in that, Based on the pressure relief range of a single well at a certain moment, calculate the original geological reserves within the pressure relief range of the single well, including: Based on the pressure relief range of a single well at a certain moment, calculate the original geological reserves of a single grid block within the pressure relief range of the single well; The original geological reserves of all grid blocks within the depressurization range of the single well are added together to obtain the dynamic reserves of the single well at a certain moment. The original geological reserves of a single grid block within the depressurization range of a single well are calculated using the following formula: G = V * pro * Sg / Bgi In the formula, G represents the original geological reserves of a single grid block within the depressurization range of a single well, V represents the grid block volume, pro represents the grid block porosity, Sg represents the gas saturation of the grid block, and Bgi represents the original gas volume coefficient.
10. The method for calculating the dynamic reserves of tight sandstone gas reservoirs according to claim 1, characterized in that, Data processing and final value determination are performed on the dynamic reserves of a single well at different times to obtain the dynamic reserves of a single well at any given time, including: Based on the dynamic reserves of a single well at different times, a curve showing the relationship between the dynamic reserves of a single well and time was plotted, and the formula for the relationship between the dynamic reserves of a single well and time was obtained: y＝a- b / t ， In the formula, y represents the dynamic reserve value of a single well at a certain moment, t represents the time interval between that moment and the production start time, that is, the time difference between that moment and the production start time; a and b both represent fitting coefficients. Linear fitting of the relationship between dynamic reserves of a single well and time: the time t is processed by taking the inverse, that is, directly regressing the linear relationship between y and 1 / t; After the regression is completed, based on the relationship between the dynamic reserves of a single well and time, the dynamic reserves of a single well at any given time t can be calculated, and at this time 'a' is the final dynamic reserve value.
11. A device for calculating the dynamic reserves of tight sandstone gas reservoirs, characterized in that, include: The initialization unit is used to initialize the gas reservoir numerical simulation model based on the three-dimensional texture model and gas reservoir data, and to complete the establishment of the gas reservoir numerical simulation model. The fitting unit is used to fit the production history of the gas reservoir numerical simulation model, thereby verifying the gas reservoir numerical simulation model. The calculation unit is used to perform dynamic production prediction and time-sharing calculation of dynamic reserves of a single well using a gas reservoir numerical simulation model, so as to obtain the dynamic reserves of a single well at a certain moment. The data processing unit is used to process and determine the dynamic reserves of a single well at different times, so as to obtain the dynamic reserves of a single well at any time.
12. An electronic device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program or instructions to implement the steps of the method for calculating the dynamic reserves of a tight sandstone gas reservoir as described in any one of claims 1-10.
13. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instructions, which, when executed by a processor, implement the steps of the method for calculating the dynamic reserves of a tight sandstone gas reservoir as described in any one of claims 1-10.
14. A computer program product comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by the processor, they implement the steps of the method for calculating the dynamic reserves of a tight sandstone gas reservoir as described in any one of claims 1-10.