Method and device for calculating heat energy efficiency of thickened oil developed by chemical reaction and steam

Abstract

The invention discloses a thermal energy efficiency calculation method and device for thick oil development through chemical reaction in cooperation with steam, and relates to the technical field of reservoir engineering / reservoir numerical simulation, and the method comprises the steps that a control equation is deduced based on the exploitation principle; wherein the control equation comprises a mass conservation equation and an energy conservation equation of the thermal reaction; constructing a mining simulation model based on the mining environment, and partitioning the mining simulation model based on the shaft position; setting boundary conditions and initial conditions of the mining simulation model, and performing numerical simulation; solving a control equation based on a simulation result of numerical simulation, and establishing a heat balance relational expression according to a solving result of the control equation; and calculating the heat energy efficiency through a heat balance relational expression. The problem that in the prior art, a heat energy efficiency calculation method for the CHEOR technology is poor in applicability is solved, the calculation speed is effectively increased, and the experiment period is shortened.

Description

Technical Field

[0001] The present application relates to the field of reservoir engineering / reservoir numerical simulation technology, and in particular to a method and device for calculating the thermal energy efficiency of heavy oil developed by chemical reaction and steam synergism. Background Art

[0002] Heavy oil, also known as heavy crude oil, refers to crude oil that is difficult to flow or does not flow at formation conditions, with a viscosity greater than 50 mPa·s (milliPascal·second) or an API gravity (the American Petroleum Institute, a standard for measuring the density and fluidity of oil) less than 20. This includes conventional heavy oil, extra-heavy oil, super-heavy oil, oil sands, and natural asphalt. Special components in heavy oil are an important source of chemical raw materials.

[0003] Following the development direction of "efficient, low-carbon, and green" heavy oil recovery, CNOOC has developed a chemical reaction heat enhanced oil recovery (CHEOR) technology, combining traditional chemical hydrocarbon generation exothermic reactions. This technology utilizes chemical reaction heat to heat the reservoir. By inducing a targeted chemical reaction, the heat released during the reaction is captured. This can be used to directly heat the reservoir or indirectly heat the injection medium, achieving thermal recovery. This technology provides clean, economical, high-temperature, highly diffusive ultra-dry steam and high-temperature, low-carbon hydrocarbons in situ for crude oil recovery. This improves the recovery of heavy and extra-heavy oil while simultaneously achieving quality improvement. It offers advantages such as low energy consumption, water consumption, and carbon emissions during the recovery process. CHEOR involves complex thermochemical reactions and heat / hydrocarbon diffusion processes in a multi-dimensional space: surface, wellbore, and surface. Current methods for calculating the thermal efficiency of CHEOR include simulation software and physical model testing.

[0004] Existing simulation software has limited applicability in applications involving thermal effects and chemical changes. Although Fluent software can provide high-precision calculation results in wellbore flow simulation analysis considering chemical reactions, its computational efficiency is low, and it usually takes hours or even days to complete the calculation of a case. In addition, when simulating the dynamics of heat transfer, it fails to fully consider the non-uniform heat dissipation between the wellbore and the surrounding medium, which will lead to increased errors in the calculation of the overall thermal energy efficiency of the system. PipeSim software is suitable for simulating complex flow models under steady-state conditions, but has limitations when dealing with dynamically changing unsteady flow models. OLGA software excels at simulating unsteady flow models, but does not incorporate heat transfer and chemical reactions into its simulation framework, so its simulation results cannot fully represent the behavioral characteristics of the real system. Compared with simulation experiments, the entire process of physical simulation experiments, from experimental design, device customization, material preparation to data processing, has a longer preparation cycle and higher cost, and the accuracy of the experimental results is greatly affected by the model and experimental environment. Summary of the Invention

[0005] The embodiments of the present application provide a method and device for calculating the thermal energy efficiency of heavy oil development using chemical reaction and steam, thereby solving the problem of poor applicability of thermal energy efficiency calculation methods for CHEOR technology in the prior art.

[0006] In a first aspect, an embodiment of the present application provides a method for calculating the thermal energy efficiency of heavy oil developed by chemical reaction and steam synergism, comprising: deriving a control equation based on the mining principle; wherein the control equation includes the mass conservation equation and the energy conservation equation of the thermal reaction; constructing a mining simulation model based on the mining environment, and partitioning the mining simulation model based on the wellbore position; setting boundary conditions and initial conditions based on the partitioned mining simulation model, and performing numerical simulation; solving the control equation based on the simulation results of the numerical simulation, and establishing a heat balance relationship according to the solution results of the control equation; and calculating the thermal energy efficiency through the heat balance relationship.

[0007] In combination with the first aspect, in a possible implementation method, the construction of a mining simulation model based on the mining environment includes: collecting experimental data based on the mining environment, and establishing a wellbore model based on the experimental data; dividing the wellbore model into multiple concentric radial grid units, and subdividing the radial grid units along their radial and axial directions to obtain a wellbore grid model; setting a wellbore area grid outside the wellbore grid model, and the wellbore area grid is composed of multiple annular grids of the same thickness; connecting the top grid of the wellbore grid model with the external grid as a source-sink node; the wellbore grid model, the wellbore area grid and the external grid constitute the mining simulation model.

[0008] In combination with the first aspect, in a possible implementation, the boundary conditions include a temperature boundary condition, an outlet boundary condition, and an inlet boundary condition.

[0009] In combination with the first aspect, in a possible implementation method, after the heat balance relationship is established, it includes: performing heat balance based on the heat balance relationship to solve the energy value; wherein the energy value includes steam heating energy consumption, injection energy, outflow energy, and heat loss; based on the heat balance relationship, using the energy value to determine the wellbore energy accumulation item.

[0010] In conjunction with the first aspect, in a possible implementation, calculating the thermal energy efficiency using the heat balance equation includes: calculating the thermal energy efficiency using the total proportion of reaction heat release as follows: ; Where, It represents the thermal energy efficiency calculated by the total proportion of reaction heat release, The heat released by the reaction, It indicates the steam heating energy consumption at medium temperature T, where T is the medium temperature.

[0011] In conjunction with the first aspect, in a possible implementation, calculating the thermal energy efficiency using the heat balance equation includes: calculating the thermal energy efficiency using the effective proportion of reaction heat release method using the following formula: ; Where, It represents the thermal energy efficiency calculated by the effective proportion method of reaction heat release, The heat released by the reaction, represents the injection energy of the wellbore, Indicates heat loss.

[0012] In conjunction with the first aspect, in one possible implementation, the reaction releases heat as follows: ; Where, The heat released by the reaction, Indicates reactants or products The stoichiometric number, Indicates reactants or products The standard enthalpy of formation at a given medium temperature T.

[0013] In the second aspect, an embodiment of the present application provides a device for calculating the thermal energy efficiency of heavy oil developed by chemical reaction and steam, including: a derivation module for deriving a control equation based on the mining principle; wherein the control equation includes the mass conservation equation and the energy conservation equation of the thermal reaction; a construction module for constructing a mining simulation model based on the mining environment, and partitioning the mining simulation model based on the wellbore position; a setting module for setting boundary conditions and initial conditions based on the partitioned mining simulation model, and performing numerical simulation; a solution establishment module for solving the control equation based on the simulation results of the numerical simulation, and establishing a heat balance relationship according to the solution results of the control equation; and a calculation module for calculating the thermal energy efficiency through the heat balance relationship.

[0014] In a third aspect, an embodiment of the present application provides a device comprising: a processor; a memory for storing processor-executable instructions; and when the processor executes the executable instructions, implementing the method described in the first aspect or any possible implementation method of the first aspect.

[0015] In a fourth aspect, an embodiment of the present application provides a non-volatile computer-readable storage medium, which includes a device for storing a computer program or instruction, and when the computer program or instruction is executed, the method described in the first aspect or any possible implementation method of the first aspect is implemented.

[0016] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages: By constructing a mining simulation model, the embodiments of this application can consider the impact of the high-temperature environment inside the wellbore on the heat transfer process, ensuring the accuracy and reliability of thermal energy efficiency calculations. By partitioning the mining simulation model, it can accurately reflect the heat conduction characteristics of each region during chemical reaction heat release and steam injection, thereby improving the accuracy of model predictions. This effectively solves the problem of poor applicability of existing thermal energy efficiency calculation methods for CHEOR technology, thereby effectively improving calculation speed, shortening the experimental cycle, and achieving thermal energy efficiency calculation for CHEOR technology with high computational efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1A flow chart of a method for calculating the thermal energy efficiency of heavy oil development using chemical reactions and steam provided in an embodiment of the present application; Figure 2 A schematic diagram of the structure of a device for calculating the thermal energy efficiency of heavy oil development using chemical reaction and steam in an embodiment of the present application; Figure 3 A two-dimensional schematic diagram of a radial grid provided in an embodiment of the present application; Figure 4 A three-dimensional schematic diagram of a radial grid provided in an embodiment of the present application; Figure 5 A schematic diagram of partitioning a mining simulation model provided in an embodiment of the present application; Figure 6 A schematic diagram of heat transfer in a mining simulation model provided in an embodiment of the present application; Figure 7 A schematic diagram of a wellbore grid model provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] The following description of some of the technologies involved in the embodiments of this application is provided to facilitate understanding and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of this application. Similarly, for the sake of clarity and conciseness, some descriptions of well-known functions and structures are omitted from the following description.

[0021] CHEOR technology involves complex thermochemical reactions and heat / hydrocarbon diffusion processes in the multi-dimensional space of ground-wellbore-ground. The heat released is a key indicator for the application of CHEOR technology in the field of heavy oil extraction. According to the principle of conservation of energy, the heat released by the reaction will be absorbed by the various media in the sand-filled pipe, causing the temperature of each medium to rise.

[0022] Figure 1 This is a flow chart of a method for calculating the thermal energy efficiency of heavy oil development using chemical reaction and steam according to an embodiment of the present application, comprising steps 101 to 105. Figure 1 This is only an execution order shown in the embodiment of the present application, and does not represent the only execution order of the method for calculating the thermal energy efficiency of heavy oil developed by chemical reaction and steam. Figure 1The steps shown may be performed in parallel or reversed.

[0023] Step 101: Derive the control equation based on the mining principle, wherein the control equation includes the mass conservation equation and the energy conservation equation of the thermal reaction.

[0024] In the embodiment of the present application, in the wellbore, for any component of the fluid The mass conservation equation in a thermal reaction component flow problem can be expressed as formula (1): (1) The energy conservation equation considering thermal reactions can be expressed as follows (2): (2) Where, Indicates time, represents the total porosity (i.e. 1-rock volume fraction), Indicates the flow phase saturation, Indicates the flow phase The molar density of Indicates the Components in the mobile phase The mole fraction in Indicates the flow phase The Darcy rate, represents the molar concentration of the reactant in the porous medium, Indicates the The molar rate of the reaction, Indicates the flow phase The production rate of the wells, Indicates the flow phase The internal energy, represents the internal energy of the rock, Indicates the flow phase The enthalpy value, represents the thermal conductivity of the reservoir, Indicates the medium temperature, represents the enthalpy of reaction k, represents the injection heat of the heating well, Represents divergence.

[0025] in, describes the effect of the wellbore on fluid transport in porous media. , which means injecting fluid into the mining simulation model. If , indicating that fluid is produced from the mining simulation model.

[0026] Among them, the Darcy rate is determined based on Darcy's law It can be expressed as the following formula (3): (3) Where, Indicates the flow phase Darcy rate, K represents the permeability tensor, Indicates the flow phase The relative permeability, Indicates the flow phase The viscosity, represents the divergence, Indicates the flow phase pressure, Indicates the flow phase The gravitational acceleration component of , D represents the depth.

[0027] In high-velocity wellbore flow environments, Darcy's law is no longer sufficient to accurately describe fluid transport behavior. Non-Darcy effects become particularly pronounced. These nonlinear flow effects can cause discrepancies between actual flow rates and those predicted based on Darcy's law.

[0028] In the embodiment of the present application, in order to more accurately characterize such flow phenomena, the Forchheimer equation (a nonlinear seepage model used to describe flow behavior in porous media) is used as an extended form of the traditional Darcy's law, which is specifically expressed as follows: (4) Where, Indicates the flow phase The momentum, represents the divergence, represents the permeability of the porous medium, Indicates the flow phase The non-Darcy coefficient is used to describe the nonlinear effect under high-speed flow. Indicates the flow phase Velocity vector The model, Indicates the flow phase The average velocity vector, Indicates the flow phase The Darcy rate, Indicates the flow phase The relative permeability, Indicates the flow phase The molar density of .

[0029] Among them, the molar concentration of the reactants in the porous medium is , its chemical reaction kinetics equation can be expressed as the following formula (5): (5) Where, represents the molar concentration of the reactant in the porous medium, and Indicates in In the step reaction, the products and reactants The stoichiometric coefficients of the components, Indicates the The molar rate of the reaction, Indicates time, represents the total porosity (i.e. 1-rock volume fraction), Indicates the flow phase saturation, Indicates the flow phase The molar density of Indicates the Components in the mobile phase The mole fraction in .

[0030] The chemical reaction targeted by this application is a catalytic reaction, so the first The molar rate of the reaction The following chemical reaction kinetics equation (6) can be used for calculation: (6) Where, represents the pre-exponential factor, represents the activation energy, represents the gas constant, Indicates the medium temperature.

[0031] The calculation formula (7) for the source and sink terms in the well grid under a specific pressure difference is: (7) Where, Indicates the flow phase The bottom hole flow rate (positive for injection and negative for production) describes the transmission of fluid inside the porous medium and is usually determined by factors such as pressure gradient and permeability. represents the well production index, Indicates the flow phase The fluidity, Indicates the flow phase The injection pressure, Indicates the flow phase The wellbore grid pressure where the source and sink are located.

[0032] Step 102: Construct a mining simulation model based on the mining environment, and partition the mining simulation model based on the wellbore position. In an embodiment of the present application, experimental data is collected based on the mining environment, and a wellbore model is established based on the experimental data. The wellbore model is divided into a plurality of concentric radial grid units, and the radial grid units are subdivided along their radial and axial directions to obtain a wellbore grid model. A peri-well area grid is set outside the wellbore grid model, and the peri-well area grid is composed of a plurality of annular grids of the same thickness. The top grid of the wellbore grid model is connected to the external grid as a source-sink node. The wellbore grid model, the peri-well area grid and the external grid constitute a mining simulation model.

[0033] Specifically, if Figure 7 As shown in , the wellbore model is divided into a series of concentric radial grid cells, and each radial grid cell is subdivided along the radial and axial directions to accurately capture the temperature distribution and flow characteristics inside the wellbore. Figure 3 and Figure 4 As shown in the figure, drn represents the nth radial grid cell in the wellbore model. In this application, the wellbore model is exemplarily divided into 10 radial grid cells, i.e., n is 10, and k represents the number of grid layers in the axial direction of the wellbore model. The top grid of the radial grid cell is the only part connected to the external grid, acting as a source-sink node to ensure the continuity of steam injection and heavy oil production.

[0034] In addition, if Figure 6 The figure shows a schematic diagram of heat transfer in the mining simulation model. Given the impact of the high-temperature environment inside the wellbore on the heat transfer process, this application sets a peri-wellbore grid outside the wellbore. The peri-wellbore grid, composed of several annular grids of equal thickness, aims to reduce phenomena such as uneven heat transfer caused by sudden temperature changes, thereby improving the computational convergence of the mining simulation model and enhancing the simulation accuracy of complex heat transfer processes, ultimately ensuring the accuracy and reliability of thermal energy efficiency calculations. The design of the peri-wellbore grid not only helps improve flow conditions near the wellbore but also effectively simulates complex heat conduction and convection phenomena under high-temperature conditions.

[0035] In the embodiment of this application, in order to more accurately simulate the thermal efficiency of the chemical reaction and steam development process of heavy oil, this application has made detailed zoning settings for the wellbore and the surrounding area before the numerical model. Figure 5 As shown, the wellbore and the area adjacent to the wellbore are defined as Area, the area farther from the wellbore is defined as Regions, such as Figure 5 shown.

[0036] and The main difference in regional parameter settings lies in the heat capacity and thermal conductivity of the rock. The region is set to have a higher heat capacity, so under the same external conditions, that is, when absorbing or releasing the same amount of heat, the temperature changes less, showing better thermal stability. Setting a lower thermal capacity in the area is beneficial to enhance Heat conduction and convection effects within the region.

[0037] also, The higher the thermal conductivity of the region, the more effectively it can conduct heat, helping to quickly transfer the heat from the underground high-temperature area to the wellhead, thereby improving the efficiency of geothermal energy extraction. The low thermal conductivity of the region results in slower heat conduction in the rock, which may cause heat to accumulate in the rock and form a significant temperature gradient.

[0038] Through the above-mentioned zoning and setting different heat capacities and thermal conductivities, the heat conduction characteristics of each area during the chemical reaction heat release and steam injection process can be accurately reflected, thereby improving the accuracy of the mining simulation model prediction, which is of great significance to the development and utilization of geothermal energy.

[0039] Step 103: Set boundary conditions and initial conditions based on the partitioned production simulation model and perform numerical simulation. In the present embodiment, the thermal efficiency of chemical reaction-assisted steam recovery of heavy oil is affected by a series of factors, the primary requirement being accurate simulation of the wellbore environment. Therefore, the present invention exemplarily uses the input file format of the CMG-STARS numerical simulation software. The wellbore model in this application is configured with two injection wells and one production well, where the injection wells consist of a water injection well and a synthesis gas injection well. Boundary conditions are then applied to each wellbore model.

[0040] In the embodiment of the present application, the boundary conditions include temperature boundary conditions, outlet boundary conditions and inlet boundary conditions, which are specifically as follows.

[0041] This application sets the temperature of the mining simulation model grid in different zones. For example, the highest temperature is set to 300°C and the lowest temperature is set to 30°C. This application sets 10 layers of radial grids, which decrease step by step to form a temperature gradient. In this case, the mining simulation model temperature rises by 30°C for every 100m of depth. Therefore, when When , the temperature boundary condition is as follows (9): (9) During the cyclic heating process, the formation far enough away from the wellbore center is not affected by the heating process, and its temperature is always equal to the initial formation temperature. The boundary condition is expressed as follows (10): (10) Where, represents the temperature boundary condition, represents the initial formation temperature, represents angle, z represents axial distance, t represents time, represents geothermal gradient, D represents depth, Indicates radial distance. hour, is a constant, indicating that the formation temperature away from the center of the wellbore remains constant. represents the critical radius, .

[0042] In this application, the outlet boundary condition adopts a constant pressure boundary condition, and the pressure is the reservoir pressure. The following equation (11) is the pressure boundary condition: (11) Where, represents the pressure boundary condition, represents the reservoir pressure, represents the radial distance, represents angle, z represents axial distance, and t represents time.

[0043] In this application, the inlet boundary condition is defined by specifying the flow rate of the injected fluid as follows (12): (12) Where, represents the inlet boundary condition, represents the flow rate of the injected fluid, represents the radial distance, represents angle, z represents axial distance, and t represents time.

[0044] In addition, in traditional reservoir numerical simulation, the well production index is used to characterize the strength of the connectivity between the wellbore and the reservoir. The value of the well production index comprehensively considers factors such as the connection position between the wellbore and the grid, the skin coefficient, etc. The well production index is expressed as the following formula (13): (13) Where W represents the well production index, Indicates the flow phase The bottom hole flow rate (positive for injection and negative for production) Indicates the flow phase The fluidity, Indicates the flow phase The injection pressure, Indicates the flow phase The grid pressure where the source and sink are located.

[0045] In the mining simulation model set up in this application, the main body of the mining simulation model is the wellbore grid model itself, and the injection pressure is close to the source and sink grid pressure. Therefore, the value of the well production index needs to be as large as possible. However, during the numerical simulation process, an excessively large value of the well production index can easily lead to a decrease in numerical convergence. Therefore, in this application, the well production index is set so that the pressure difference is 1% of the injection pressure, as shown in the following formula (14): (14) Therefore, in the embodiment of the present application, the well production index is specifically as follows (15): (15) Where W represents the well production index, Indicates the flow phase The bottom hole flow rate (positive for injection and negative for production) Indicates the flow phase The fluidity, Indicates the flow phase The injection pressure, Indicates the flow phase The grid pressure where the source and sink are located, Indicates pressure difference.

[0046] In the examples of this application, the initial conditions represent the state of the wellbore at the beginning of the study period, such as the initial temperature, pressure, or flow rate distribution, and are a prerequisite for transient simulation. However, over time, the impact of the initial conditions on the wellbore state decreases. Even for the same transient process, when other conditions are the same but different initial conditions are used, after a sufficiently long run, the system will reach a nearly identical final state.

[0047] In the embodiment of the present application, the mining simulation model is provided with 10 layers of radial grid units, and the grid temperature decreases layer by layer. Therefore, the initial temperature condition can be expressed as the following formula (16): (16) The initial pressure field of the mining simulation model obeys the hydrostatic pressure balance. The pore pressure increases with the depth of the formation. The initial pressure distribution can be expressed as follows (17): (17) The fluid in the mining simulation model includes gas and water phases, and their saturations are set as 、 , and satisfies the following formula (18), the initial condition of fluid flow is the following formula (19): (18) (19) Where, , represents the density of the mixture, represents the initial temperature, represents the initial formation temperature, represents the geothermal gradient, represents depth, V represents fluid velocity, represents the critical radius, represents the initial pressure, represents the original formation pressure, Indicates angle, Indicates the axial distance, Indicates gas saturation, Indicates the liquid saturation, represents the permeability, represents the relative permeability, represents the fluid viscosity, Indicates the pressure difference, represents the gas density, Indicates the density of the liquid.

[0048] In the presence of mixtures, the dryness of the mining simulation model satisfies the following relationship (20): (20) From the physical property data sheet (a table used to record and display the various physical and chemical properties of a substance), we can know the enthalpy values ​​of pure water and pure steam under specific constant pressure conditions. The initial enthalpy value of the mixture here can be expressed as the following formula (21): (twenty one) Where, Indicates the initial time The dryness of Indicates the medium temperature ,pressure The enthalpy of the mixture under the conditions Indicates the medium temperature ,pressure The enthalpy of steam under the conditions, Indicates the medium temperature ,pressure The enthalpy of water under these conditions.

[0049] After determining the above boundary conditions and initial conditions, the numerical simulation operation of the mining simulation model is started and run to the next time step. This application exemplarily uses the CMG-STARS numerical simulation software. After a time step operation is updated, the numerical simulation software will output the grid properties to a result file in a specific format. For example, the CMG reservoir numerical simulator outputs an SR3 binary file, which includes information such as the temperature, pressure, component changes during the chemical reaction, and heat release of the grid. This application calculates the thermal energy efficiency by analyzing the cumulative material balance table in the output simulation results as .OUT files.

[0050] Step 104: Solve the governing equations based on the numerical simulation results, and establish a heat balance equation based on the solution of the governing equations. In the embodiments of the present application, the present application focuses on data such as the temperature, pressure, saturation of each phase, and mole fraction of each component in each phase of each grid.

[0051] In the embodiment of the present application, the heat balance equation (22) is as follows: (twenty two) Where, represents the injection energy of the wellbore, that is, the total energy of all substances injected into the well during the entire time step, It represents the outflow energy of the wellbore, that is, the total energy of all substances flowing out of the bottom of the well (into the reservoir), is the wellbore energy accumulation term, that is, the change in material energy in the wellbore, It represents the heat loss, that is, the heat consumed by the heating of the well wall and surrounding rocks, as well as the heat loss caused by the source and sink terms.

[0052] In the embodiment of the present application, the task of the subsequent steps is to accurately calculate the values ​​of each item in the heat balance equation (22), as follows.

[0053] This application realizes a certain exothermic reaction simulation in a wellbore environment, and its core chemical conversion process follows the principle in the following formula (23): (twenty three) Where, and Represent reactant 1 and reactant 2, respectively. and Represent product 1 and product 2, respectively. Indicates the The enthalpy change of the step reaction reflects the exothermic or endothermic characteristics of the reaction at that time step. 、 、 and represent the reaction coefficients of reactant 1, reactant 2, product 1, and product 2, respectively.

[0054] When steam is injected into the wellbore, along with the injection of syngas, the temperature inside the wellbore will change, causing the steam to exhibit latent heat. To calculate the energy consumption for steam heating, this application analyzes the saturated steam enthalpy table in the simulation results (.OUT file) to determine the enthalpy of water corresponding to the surface temperature and the enthalpy of the water vapor mixture under specific conditions. The specific calculation method can be expressed as the following equations (24) and (25): (twenty four) (25) Therefore, the steam heating energy consumption in this application can be expressed as the following formula (26): (26) Where, Indicates saturated steam at medium temperature The enthalpy value under Indicates the reference temperature The enthalpy value under Indicates the medium temperature The latent heat of phase change between water and water vapor is only the medium temperature A single variable function of The steam enthalpy changes with temperature Secondary coefficient, Indicates water at medium temperature The enthalpy value under represents the critical temperature, Indicates the energy consumption of steam heating, Indicates the steam quality, Indicates the enthalpy of dry saturated steam.

[0055] In the embodiment of the present application, the calculation method of the injected energy and the outflow energy in the heat balance equation (22) is as follows: The injection energy per unit volume is given by the following formula (27): (27) The outflow energy per unit volume is as follows (28): (28) Therefore, the injection energy of the wellbore is as follows (29): (29) The outflow energy of the wellbore can be expressed as follows (30): (30) Where, represents the injection energy per unit volume, is expressed as the fluid flow rate injected into the well, is expressed as the specific heat capacity of the injected fluid, represents the density of the injected fluid, represents the temperature of the injected fluid, Expressed as reference temperature, represents the outflow energy per unit volume, is the flow rate of the production well, Expressed as the temperature of the produced fluid, is expressed as the specific heat capacity of the injected fluid, represents the density of the injected fluid, represents the injection energy of the wellbore, express The grid in the area, Indicates the current The area numbered The temperature of the grid, Indicates the current The area numbered The initial temperature of the grid, Indicates the outflow energy of the wellbore.

[0056] In the embodiments of this application, This includes the heat consumed by the heating of the wellbore wall and surrounding rocks, as well as the heat loss caused by the source and sink. Since the heat of the wellbore heating is relatively small, it is ignored in this application. Specifically, the heat absorbed by the surrounding rock heating can be divided into the wellbore ( ) The calculation and analysis of the two parts of regional rock temperature rise heat loss and environmental heat loss are as follows.

[0057] The heat loss of rock heating refers to the part of the injected heat energy consumed in the process of heating the rock. The heat absorption and release per unit volume of rock is calculated by the following expression (31): (31) Therefore, the heat loss due to rock temperature rise in the area around the well (32) is as follows: (32) Where, Indicates the heat content of the rocks in the area around the well. represents the volumetric heat capacity, represents the temperature coefficient, Indicates the medium temperature, represents the reference temperature, Indicates the well circumference ( ) Regional rock temperature rise heat loss, For the current The area numbered The temperature of the grid, For the current The initial temperature of the cell numbered i in the region.

[0058] Environmental heat loss refers to the heat energy lost during the thermal recovery process through heat conduction, convection, and radiation between the wellbore, formation, and surrounding non-target areas. It is primarily described by the heat conduction equation, which is expressed using Fourier's law as follows (33): (33) According to the superposition principle of discrete domains, the ambient heat loss (34) is expressed as: (34) Where, represents the heat flow, represents the thermal conductivity of the reservoir, Indicates The temperature gradient in the direction, represents the amount of heat loss to the environment, The grid at the current model boundary (the grid adjacent to the wellbore grid and the external environment) is numbered The temperature of the grid, For the current The area numbered The initial temperature of the grid, Representation and Grid The connected ambient temperature, express The grid in the area, Representation Grid The area of ​​the boundary surface (i.e. the surface where the wellbore is adjacent to the external environment), Representation Grid The vertical distance from the center point to the center of the boundary surface, It is The time step length (i.e., the time interval), Indicates the total number of time steps.

[0059] Therefore, the heat loss can be expressed as follows (35): (35) Where, represents the heat loss, Indicates the well circumference ( ) Regional rock temperature rise heat loss, Indicates the amount of heat loss to the environment.

[0060] In the embodiments of the present application, two methods for wellbore energy accumulation are provided, as follows.

[0061] Method 1: Energy changes of materials in the wellbore (accumulated wellbore energy) The value of can be calculated by formulas (24) to (35), and substituted into formula (22) for further analysis, namely the following formula (36): (36) Where, represents the wellbore energy accumulation term, that is, the change in the energy of the material in the wellbore, represents the injection energy of the wellbore, represents the outflow energy of the wellbore, Indicates heat loss.

[0062] Method 2: Set the reference point of enthalpy to the reference temperature .

[0063] (1) The enthalpy of a pure substance is calculated as follows (37): (37) Where, Indicates medium temperature The pure substance Grid in the area The enthalpy value, Indicates reference temperature The pure substance Grid in the area The enthalpy value, express Grid in the area The specific heat capacity, , represents the temperature at the nth temperature interval, , , indicating that the reference temperature To medium temperature Divided into temperature intervals, and N represents the number of temperature intervals.

[0064] (2) The enthalpy of the mixture is calculated as follows (38): (38) Where, Indicates medium temperature The mixture is Grid in the area The enthalpy value, Indicates Grid in the area The mole fraction of Indicates medium temperature The pure substance Grid in the area enthalpy value, m represents the component.

[0065] The change in the energy of the wellbore material is equal to the sum of the differences between the material enthalpy in the final state and the material enthalpy in the initial state, which is the following formula (39): (39) Where, represents the change in wellbore material energy (wellbore energy accumulation term), The final state of the substance Grid in the area The enthalpy value, The initial state of the substance Grid in the area enthalpy value.

[0066] In the embodiment of the present application, the reaction heat release is directly obtained by analyzing the cumulative material balance table in the output simulation results (.out file). The specific calculation method can be expressed as the following formula (40): (40) Where, The heat released by the reaction, Indicates reactants or products The stoichiometric number, Indicates reactants or products The standard enthalpy of formation at a given medium temperature T.

[0067] Calculate the total amount of reactants consumed during the reaction using the following expression: (41) Where, Indicates the reactants consumed during the reaction The total amount, Represents reactants The total amount of injection, represents the total amount of output S, Represents the reactants in each grid i in the wellbore The number of moles.

[0068] Step 105: Calculate the thermal energy efficiency using the heat balance equation. In the embodiment of the present application, the thermal energy efficiency is calculated mainly by two methods, namely, the following equations (42) and (43): The thermal energy efficiency is evaluated by calculating the ratio of chemical reaction heat release to steam energy consumption using the total reaction heat release ratio method. The specific calculation formula (42) is as follows: (42) The effective ratio of reaction heat release method evaluates thermal energy efficiency by calculating the ratio of chemical reaction heat release to the total injected heat after deducting formation heat loss. The specific calculation formula (43) is as follows: (43) Where, and Respectively represent the thermal energy efficiency calculated by different methods, The heat released by the reaction, Indicates the steam heating energy consumption at medium temperature T, where T represents the medium temperature. represents the injection energy of the wellbore, Indicates heat loss.

[0069] For example, the two thermal efficiency calculation methods above yielded results of 8.6% and 191%, respectively. The numerical simulation of the thermal efficiency using the proposed method using CMG-STARS software took 43 seconds, while the solution using Fluent software took 57 seconds, demonstrating the proposed method's high computational efficiency.

[0070] Although this application provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on routine or non-creative work. The order of steps listed in this embodiment is only one way of executing the steps among many, and does not represent the only execution order. When an actual device or client product executes, the method shown in this embodiment or the accompanying drawings may be executed sequentially or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0071] like Figure 2 As shown, the embodiment of the present application also provides a device 200 for calculating the thermal energy efficiency of heavy oil development by chemical reaction and steam. The device includes: a derivation module 201, a construction module 202, a setting module 203, a solution establishment module 204 and a calculation module 205, as follows.

[0072] The derivation module 201 is used to derive the control equations based on the mining principle, wherein the control equations include the mass conservation equation and the energy conservation equation of the thermal reaction.

[0073] The construction module 202 is used to construct a mining simulation model based on the mining environment and partition the mining simulation model based on the wellbore location.

[0074] The setting module 203 is used to set boundary conditions and initial conditions based on the partitioned mining simulation model and perform numerical simulation.

[0075] The solution establishment module 204 is used to solve the control equation based on the simulation results of the numerical simulation, and establish a heat balance relationship according to the solution results of the control equation.

[0076] The calculation module 205 is used to calculate the thermal energy efficiency through a heat balance equation.

[0077] Some modules in the apparatus described herein may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform specific tasks or implement specific abstract data types. The present application may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communications network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0078] The devices or modules described in the above application embodiments can be implemented by computer chips or physical devices, or by products with certain functions. For ease of description, the above devices are described separately by function in various modules. When implementing the embodiments of this application, the functions of each module can be implemented in the same or multiple software and / or hardware. Of course, a module that implements a certain function can also be implemented by combining multiple sub-modules or sub-units.

[0079] The methods, devices, or modules described herein can be implemented in the form of computer-readable program code. The controller can be implemented in any suitable manner. For example, the controller can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, an application-specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicone Labs C8051F320. The memory controller can also be implemented as part of the memory control logic. Those skilled in the art will also appreciate that, in addition to implementing the controller in pure computer-readable program code, the controller can also be implemented in the form of logic gates, switches, an application-specific integrated circuit, a programmable logic controller, an embedded microcontroller, etc. by logically programming the method steps. Therefore, such a controller can be considered a hardware component, and the devices included therein for implementing various functions can also be considered as structures within the hardware component. Or even, the means for implementing various functions may be considered to be both a software module for implementing the method and a structure within a hardware component.

[0080] An embodiment of the present application further provides a device comprising: a processor; a memory for storing processor-executable instructions; and when the processor executes the executable instructions, the method described in the embodiment of the present application is implemented.

[0081] The embodiments of the present application also provide a non-volatile computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed, the method described in the embodiments of the present application is implemented.

[0082] In addition, each functional module in each embodiment of the present invention may be integrated into one processing module, or each module may exist independently, or two or more modules may be integrated into one module.

[0083] The above-mentioned storage media include, but are not limited to, random access memory (RAM), read-only memory (ROM), cache, hard disk drive (HDD), or memory card. Such memory can be used to store computer program instructions.

[0084] Through the description of the above implementation methods, it can be seen that those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary hardware. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, or can be embodied through the implementation process of data migration. The computer software product can be stored in a storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a mobile terminal, a server, or a network device, etc.) to execute the methods described in each embodiment of the present application or certain parts of the embodiments.

[0085] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments. All or part of this application can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, mobile communication terminals, multi-processor systems, microprocessor-based systems, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, etc.

[0086] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for calculating the thermal energy efficiency of heavy oil development by chemical reaction and steam, characterized in that: include: The control equation is derived based on the mining principle; wherein the control equation includes the mass conservation equation and the energy conservation equation of the thermal reaction; Constructing a mining simulation model based on the mining environment, and partitioning the mining simulation model based on the wellbore location; Setting boundary conditions and initial conditions based on the mining simulation model of the partitions, and performing numerical simulation; Solving the control equation based on the simulation results of the numerical simulation, and establishing a heat balance relationship according to the solution results of the control equation; The thermal energy efficiency is calculated by the heat balance relationship.

2. The method according to claim 1, characterized in that The mining simulation model is constructed based on the mining environment, including: Collecting experimental data based on the mining environment, and establishing a wellbore model based on the experimental data; Dividing the wellbore model into a plurality of concentric radial grid units, and subdividing the radial grid units along radial and axial directions to obtain a wellbore grid model; A wellbore area grid is set outside the wellbore grid model, and the wellbore area grid is composed of a plurality of annular grids with the same thickness; Connecting the top grid of the wellbore grid model to the external grid as source and sink nodes; The wellbore grid model, the wellbore area grid and the external grid constitute the mining simulation model.

3. The method according to claim 1, characterized in that The boundary conditions include temperature boundary conditions, outlet boundary conditions and inlet boundary conditions.

4. The method according to claim 1, characterized in that: The heat balance equation is established, including: Perform heat balance based on the heat balance relationship to solve the energy value; wherein the energy value includes steam heating energy consumption, injection energy, outflow energy, and heat loss; Based on the heat balance relationship, the energy value is used to determine the wellbore energy accumulation term.

5. The method according to claim 4, characterized in that The calculating of thermal energy efficiency by the heat balance equation includes: The formula for calculating thermal energy efficiency by the total proportion of reaction heat release is as follows: ； In the formula, It represents the thermal efficiency calculated by the total proportion of reaction heat release. The heat released by the reaction, It indicates the steam heating energy consumption at medium temperature T, where T represents the medium temperature.

6. The method according to claim 4, characterized in that The calculating of thermal energy efficiency by the heat balance equation includes: The formula for calculating thermal energy efficiency by the effective proportion method of reaction heat release is as follows: ； In the formula, It represents the thermal efficiency calculated by the effective proportion method of reaction heat release, The heat released by the reaction, represents the injection energy of the wellbore, Represents heat loss.

7. The method according to claim 5 or 6, characterized in that: The reaction exothermicity is as follows: ； In the formula, The heat released by the reaction, Indicates reactants or products The stoichiometric number, Indicates reactants or products The standard enthalpy of formation at a given medium temperature T.

8. A device for calculating the thermal energy efficiency of heavy oil development by chemical reaction and steam, characterized in that: include: A derivation module, used to derive control equations based on mining principles; wherein the control equations include mass conservation equations and energy conservation equations of thermal reactions; A construction module, used to construct a mining simulation model based on the mining environment, and partition the mining simulation model based on the wellbore location; A setting module, used for setting boundary conditions and initial conditions based on the mining simulation model of the partitions, and performing numerical simulation; A solution establishment module, used for solving the control equation based on the simulation results of the numerical simulation, and establishing a heat balance relationship according to the solution results of the control equation; The calculation module is used to calculate the thermal energy efficiency through the heat balance relationship.

9. A device for executing a method for calculating the thermal energy efficiency of heavy oil development by chemical reaction and steam, characterized in that: include: processor; a memory for storing processor-executable instructions; When the processor executes the executable instructions, the method according to any one of claims 1 to 7 is implemented.

10. A non-volatile computer-readable storage medium, characterized in that: The device comprises a computer program or an instruction for storing the computer program or the instruction, which, when executed, enables the method according to any one of claims 1 to 7 to be implemented.

Images