Method and device for predicting carbon sequestration capacity, equipment and medium

Abstract

The invention relates to the technical field of carbon sequestration, and discloses a carbon sequestration capacity prediction method and device, equipment and a medium, and the method comprises the steps: obtaining a preset rock pore volume of a water-bearing stratum; on the basis of the preset rock pore volume, the average pressure and the average saturation of the aquifer are obtained; pseudo-pressure and pseudo-time are obtained based on the average pressure and the average saturation; based on the pseudo-pressure and the pseudo-time, the initial rock pore volume and the initial permeability of the aquifer are obtained; based on the preset rock pore volume and the initial rock pore volume, determining the final rock pore volume of the aquifer and the final permeability of the aquifer; on the basis of the final permeability and the CO2 injection condition, critical yield normalized pseudo-pressure corresponding to the CO2 injection condition is obtained; determining a first superposition pseudo-time based on the critical yield normalized pseudo-pressure; and obtaining the carbon sequestration capacity based on the first superposition pseudo time, the CO2 injection condition and the final rock pore volume. According to the invention, the carbon sequestration capacity is accurately predicted.

Description

Technical Field

[0001] This application relates to the technical field of carbon sequestration, and specifically relates to a method, device, equipment and medium for predicting carbon sequestration capacity. Background Art

[0002] Carbon sequestration is used to store CO2 in geological formations or minerals for a long time to prevent it from returning to the atmosphere. Carbon sequestration mainly relies on geological sequestration. Among them, aquifer sequestration has become the most promising sequestration method due to its wide distribution and large trap structures suitable for sequestration.

[0003] However, an aquifer is usually a closed system formed by boundary faults, reservoir compression or heterogeneity. During the CO2 injection process, the in-situ saline water displaced in the aquifer cannot migrate outside the boundary, resulting in continuous accumulation of reservoir pressure. The safety sequestration pressure limit severely restricts the CO2 sequestration potential. Although injection pressure and injection rate can economically and effectively reflect reservoir characteristics and sequestration dynamics, most of the existing injection dynamics analysis methods are applicable to single-phase flow conditions and cannot accurately characterize the two-phase seepage characteristics of CO2 and saline water, thus unable to accurately predict carbon sequestration capacity. Summary of the Invention

[0004] The purpose of the embodiments of this application is to provide a method, device, equipment and medium for predicting carbon sequestration capacity, so as to solve the problem that most of the existing injection dynamics analysis methods are applicable to single-phase flow conditions and cannot accurately characterize the two-phase seepage characteristics of CO2 and saline water, thus unable to accurately predict carbon sequestration capacity.

[0005] To achieve the above purpose, the first aspect of this application provides a method for predicting carbon sequestration capacity, including:

[0006] Obtain the preset rock pore volume of the aquifer;

[0007] Based on the preset rock pore volume, obtain the average pressure and average saturation of the aquifer;

[0008] Based on the average pressure and average saturation, obtain the pseudo-pressure and pseudo-time;

[0009] Based on the pseudo-pressure and pseudo-time, obtain the initial rock pore volume and initial permeability of the aquifer;

[0010] Based on the preset rock pore volume and the initial rock pore volume, determine the final rock pore volume and final permeability of the aquifer;

[0011] Based on the final permeability and CO2 injection conditions, obtain the critical production normalized pseudo-pressure corresponding to the CO2 injection conditions, where the CO2 injection conditions include injecting CO2 at a fixed rate and injecting CO2 at a fixed pressure;

[0012] Determine the first superposition pseudo-time based on the critical production normalized pseudo-pressure;

[0013] Obtain the carbon sequestration capacity based on the first superposition pseudo-time, CO2 injection conditions, and the final rock pore volume.

[0014] In the embodiment of the present application, obtaining the initial rock pore volume and the initial permeability of the aquifer based on the pseudo-pressure and the pseudo-time includes:

[0015] Obtain the superposition pseudo-time based on the pseudo-time;

[0016] Obtain the production normalized pseudo-pressure based on the pseudo-pressure and the superposition pseudo-time;

[0017] Obtain the initial rock pore volume based on the slope of the production normalized pseudo-pressure;

[0018] Obtain the initial permeability based on the intercept of the production normalized pseudo-pressure.

[0019] In the embodiment of the present application, determining the final rock pore volume and the final permeability of the aquifer based on the preset rock pore volume and the initial rock pore volume includes:

[0020] Determine whether the error value between the preset rock pore volume and the initial rock pore volume is less than the preset error threshold;

[0021] In the case where the error value between the preset rock pore volume and the initial rock pore volume is greater than or equal to the preset error threshold, iteratively update the initial rock pore volume and the initial permeability until the error value between the preset rock pore volume and the updated rock pore volume is less than the preset error threshold, and end the iterative update;

[0022] Take the rock pore volume at the end of the iterative update as the final rock pore volume, and take the permeability at the end of the iterative update as the final permeability.

[0023] In the embodiment of the present application, determining the first superposition pseudo-time based on the critical production normalized pseudo-pressure includes:

[0024] Determine the critical pseudo-time corresponding to the critical production normalized pseudo-pressure based on the critical production normalized pseudo-pressure;

[0025] Obtain the first superposition pseudo-time based on the critical pseudo-time.

[0026] In the embodiment of the present application, obtaining the carbon sequestration capacity based on the first superposition pseudo-time, CO2 injection conditions, and the final rock pore volume includes:

[0027] Determine the CO2 injection rate based on the CO2 injection conditions;

[0028] Obtain the safety limit superposed pseudo-time corresponding to the CO2 injection conditions;

[0029] Based on the first superposed pseudo-time, the safety limit superposed pseudo-time, and the final rock pore volume, determine the total CO2 injection time;

[0030] Based on the CO2 injection rate and the total CO2 injection time, obtain the carbon sequestration capacity.

[0031] In the embodiments of the present application, determining the CO2 injection rate based on the CO2 injection conditions includes:

[0032] When the CO2 injection condition is that CO2 is injected at a fixed rate, determine that the CO2 injection rate is a preset rate;

[0033] When the CO2 injection condition is that CO2 is injected at a fixed pressure, determine the injection rate based on the final permeability and the pseudo-time.

[0034] In the embodiments of the present application, determining the total CO2 injection time based on the first superposed pseudo-time, the safety limit superposed pseudo-time, and the final rock pore volume includes:

[0035] Determine whether the first superposed pseudo-time is equal to the safety limit superposed pseudo-time;

[0036] When the first superposed pseudo-time is not equal to the safety limit superposed pseudo-time, based on the final rock pore volume, iteratively update the average pressure and the average saturation;

[0037] Based on the updated average pressure and average saturation, obtain the updated superposed pseudo-time until the updated superposed pseudo-time is equal to the safety limit superposed pseudo-time, and stop the iterative update;

[0038] Based on the safety limit superposed pseudo-time, determine the total CO2 injection time.

[0039] The second aspect of the present application provides a prediction device for carbon sequestration capacity, including:

[0040] An acquisition module for acquiring the preset rock pore volume of the aquifer;

[0041] A first obtaining module for obtaining the average pressure of the aquifer and the average saturation of the aquifer based on the preset rock pore volume;

[0042] A second obtaining module for obtaining the pseudo-pressure and the pseudo-time based on the average pressure and the average saturation;

[0043] A third obtaining module for obtaining the initial rock pore volume of the aquifer and the initial permeability of the aquifer based on the pseudo-pressure and the pseudo-time;

[0044] The first determination module is configured to determine the final rock pore volume of the aquifer and the final permeability of the aquifer based on a preset rock pore volume and an initial rock pore volume;

[0045] The fourth obtaining module is configured to obtain a critical production normalized pseudopressure corresponding to the CO2 injection condition based on the final permeability and the CO2 injection condition, where the CO2 injection condition includes injecting CO2 at a fixed rate and injecting CO2 at a fixed pressure;

[0046] The second determination module is configured to determine a first superimposed pseudotime based on the critical production normalized pseudopressure;

[0047] The fifth obtaining module is configured to obtain a carbon sequestration capacity based on the first superimposed pseudotime, the CO2 injection condition, and the final rock pore volume.

[0048] A third aspect of the present application provides a computing device, including:

[0049] A memory configured to store instructions;

[0050] A processor configured to call instructions from the memory and, when executing the instructions, be capable of implementing the carbon sequestration capacity prediction method of the first aspect above.

[0051] A fourth aspect of the present application provides a computing device, including: instructions stored on a machine-readable storage medium, the instructions being used to cause the machine to execute the carbon sequestration capacity prediction method of the first aspect above.

[0052] Through the above technical solutions, the two-phase seepage characteristics of CO2 and brine are accurately characterized, thereby accurately predicting the carbon sequestration capacity.

[0053] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementation, they are used to explain the embodiments of the present application, but do not constitute a limitation to the embodiments of the present application. In the drawings:

[0055] Figure 1 Schematically shows a flowchart of a method for predicting a carbon sequestration capacity according to an embodiment of the present application;

[0056] Figure 2 (a) Schematically shows a diagram of the average pressure when injecting CO2 at a fixed rate according to an embodiment of the present application;

[0057] Figure 2(b) Schematically shows the schematic diagram of the average water saturation with CO₂ injected at a fixed rate according to an embodiment of the present application;

[0058] Figure 2 (c) Schematically shows the schematic diagram of the diagnostic curve with CO₂ injected at a fixed rate according to an embodiment of the present application;

[0059] Figure 2 (d) Schematically shows the schematic diagram of the characteristic curve with CO₂ injected at a fixed rate according to an embodiment of the present application;

[0060] Figure 2 (e) Schematically shows the schematic diagram of the CO₂ injection time inversion with CO₂ injected at a fixed rate according to an embodiment of the present application;

[0061] Figure 3 (a) Schematically shows the schematic diagram of the average pressure with CO₂ injected at a fixed pressure according to an embodiment of the present application;

[0062] Figure 3 (b) Schematically shows the schematic diagram of the average water saturation with CO₂ injected at a fixed pressure according to an embodiment of the present application;

[0063] Figure 3 (c) Schematically shows the schematic diagram of the diagnostic curve with CO₂ injected at a fixed pressure according to an embodiment of the present application;

[0064] Figure 3 (d) Schematically shows the schematic diagram of the characteristic curve with CO₂ injected at a fixed pressure according to an embodiment of the present application;

[0065] Figure 3 (e) Schematically shows the schematic diagram of the curve of the CO₂ injection rate and the carbon sequestration capacity with CO₂ injected at a fixed pressure according to an embodiment of the present application. Detailed implementation manners

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be understood that the specific implementation manners described herein are only for explaining and illustrating the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0067] It should be noted that the acquisition, transmission, storage, use, processing, etc. of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations. In the embodiments of this application, certain industry-existing solutions such as software, components, models, etc. may be mentioned. They should be regarded as exemplary, and their purpose is only to illustrate the feasibility in the implementation of the technical solution of this application, but it does not mean that the applicant has already or necessarily used this solution.

[0068] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of this application, then this directional indication is only used to explain the relative positional relationship, movement conditions, etc. between components in a certain specific posture (as shown in the drawings). If this specific posture changes, then this directional indication will also change accordingly.

[0069] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of this application, then the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0070] Figure 1 Schematically shows a flowchart of a method for predicting carbon sequestration capacity according to an embodiment of the present application. As Figure 1 shown, the embodiments of the present application provide a method for predicting carbon sequestration capacity, and this method may include the following steps.

[0071] Step S110: Obtain the preset rock pore volume of the aquifer.

[0072] In step S110, the preset rock pore volume of the aquifer serves as a standard value for iterative update.

[0073] Step S120: Based on the preset rock pore volume, obtain the average pressure of the aquifer and the average saturation of the aquifer.

[0074] In step S120, based on the preset rock pore volume and the first formula, obtain the average pressure of the aquifer. The first formula includes:

[0075]

[0076] In the first formula, represents the average pressure of the aquifer, p iDenote pore pressure, V i Denote the preset rock pore volume, G i Denote the initial CO2 volume in pores under ground conditions, G p Denote the CO2 injection volume, B CO2 Denote the CO2 volume coefficient, W i Denote the initial water storage volume under ground state, B w Denote the brine volume coefficient, c m Denote the rock compressibility coefficient. Among them, the brine volume coefficient is obtained through the brine volume coefficient formula, and the brine volume coefficient formula includes:

[0077]

[0078] In the above formula, B w Denote the brine volume coefficient, B wi Denote the initial brine volume coefficient, c w Denote the brine compressibility coefficient.

[0079] Based on the preset rock pore volume, average pressure and the second formula, obtain the average saturation of the aquifer. The second formula includes:

[0080]

[0081] In the second formula, Denote the average saturation of the aquifer, p i Denote the initial pressure of the aquifer.

[0082] Step S130: Based on the average pressure and average saturation, obtain the pseudo-pressure and pseudo-time.

[0083] In step S130, based on the average pressure, average saturation and the third formula, obtain the pseudo-pressure. The third formula includes:

[0084]

[0085] In the third formula, p pj Denote the pseudo-pressure, μ j Denote the fluid viscosity, B j Denote the fluid volume coefficient, k denotes the pressure-dependent permeability, and the subscript i denotes the initial state, p b Denote the reservoir saturation pressure, p denotes the aquifer pressure, k rj Denote the relative permeability of the fluid in the aquifer, s j Denote the fluid saturation in the pores. For the convenience of calculation, the specific value of the fluid saturation s in the pores j is equal to the average saturation of the aquifer The specific value of the aquifer pressure p is equal to the average pressure of the aquifer Among them, the pressure-related permeability formula includes:

[0086] k = k i exp[-γ(p i -p)]

[0087] In the above formula, k i represents the initial permeability of the aquifer, and γ represents the permeability modulus. It can be seen that in the process of calculating the pseudo-pressure through the third formula and the pressure-related permeability formula, the unknown parameter pressure-related permeability k is exactly cancelled out.

[0088] Based on each time step, average pressure, average saturation, and the fourth formula during the CO2 injection process, the pseudo-time is obtained. Among them, the time step refers to the smallest unit for discretizing continuous time, and the time step represents the time interval for processing data. The fourth formula includes:

[0089]

[0090] In the fourth formula, t pj represents the pseudo-time, C ej represents the effective compressibility, φ represents the pressure-related porosity, and t represents the injection time. Among them, the calculation formula for the effective compressibility includes:

[0091]

[0092] In the above formula, c j represents the compressibility of the fluid in the pores.

[0093] The calculation formula for the pressure-related porosity includes:

[0094] φ = φ i exp[-c m (p i -p)]

[0095] In the above formula, φ i represents the initial pressure-related porosity.

[0096] Step S140: Based on the pseudo-pressure and pseudo-time, obtain the initial rock pore volume and the initial permeability of the aquifer.

[0097] In step S140, according to the pseudo-pressure and pseudo-time obtained in step S130, the initial rock pore volume and the initial permeability of the aquifer can be obtained.

[0098] Furthermore, step S140 may include the following steps:

[0099] Step S141: Based on the pseudo-time, obtain the superimposed pseudo-time;

[0100] Step S142: Based on the pseudo-pressure and the superposed pseudo-time, obtain the production-normalized pseudo-pressure of the boundary control flow during the CO2 injection process;

[0101] Step S143: Based on the slope of the production-normalized pseudo-pressure, obtain the initial rock pore volume;

[0102] Step S144: Based on the intercept of the production-normalized pseudo-pressure, obtain the initial permeability.

[0103] In step S141, according to the pseudo-time and the fifth formula, obtain the superposed pseudo-time. The fifth formula includes:

[0104]

[0105] In the above formula, t spj represents the superposed pseudo-time, q j,n represents the flow rate of the fluid at the surface conditions in the nth micro-element section, q j,n-1 represents the flow rate of the fluid at the surface conditions in the (n - 1)th micro-element section, t pj,N represents the pseudo-time of the Nth micro-element section, t pj,n-1 represents the pseudo-time of the (n - 1)th micro-element section, q j,N represents the flow rate of the fluid at the surface conditions in the Nth micro-element section.

[0106] In step S142, the flow stages during the CO2 injection process include transient radial flow and boundary control flow. The transient radial flow appears first, followed by the boundary control flow.

[0107] For the transient radial flow, taking the CO2 constant-rate injection as an example, the seepage control equation for the transient radial flow of CO2 and saline water includes:

[0108]

[0109] In the above formula, r represents the radial coordinate along the seepage direction.

[0110] The boundary conditions of the seepage control equation for the transient radial flow include:

[0111] p pj (r, 0) = p pj,i

[0112]

[0113] p pj (r → ∞, t) = p pj,i

[0114] In the above formula, μ ji represents the initial fluid viscosity, B ji represents the initial fluid volume coefficient, p pj,iDenote the initial pseudo - pressure.

[0115] It can be obtained that the productivity - normalized pseudo - pressure of the transient radial flow includes:

[0116]

[0117] In the above formula, C eji Denotes the initial effective compressibility.

[0118] It should be noted that most aquifers are located in sedimentary basins, generally having high porosity and permeability, fast pressure propagation speed, short transient radial flow time, and mainly boundary - controlled flow. Therefore, the embodiments of this application mainly focus on the boundary - controlled flow occurring during the CO2 injection process for research.

[0119] For the boundary - controlled flow, taking the constant - rate injection of CO2 as an example, establish the seepage control equations and boundary conditions of CO2 and brine. The seepage control equations of the boundary - controlled flow of CO2 and brine include:

[0120]

[0121] The boundary conditions of the seepage control equations of the boundary - controlled flow include:

[0122] p(r, 0) = p i

[0123]

[0124] In the above formula, h represents the aquifer thickness, r w Denotes the injection - well radius, q j Denotes the CO2 injection flow rate, r e Denotes the aquifer - boundary radius.

[0125] Linearize the seepage control equations and boundary conditions of the boundary - controlled flow through pseudo - pressure and pseudo - time. The linearized control equations include:

[0126]

[0127] The linearized boundary conditions include:

[0128] p pj (r, 0) = p pj,i

[0129]

[0130] It can be obtained that the approximate solution of the analytical solution of the linearized seepage control equations under the linearized boundary conditions includes:

[0131]

[0132] In the formula, p pj,wf represents the pseudo-pressure at the bottom of the well.

[0133] Define the production-normalized pseudo-pressure of the boundary control flow as:

[0134] RNP j =(p pj,i -p pj,wf ) / q j

[0135] In the formula, q j represents the flow rate under surface conditions.

[0136] Convert the formula for the production-normalized pseudo-pressure of the defined boundary control flow into an analytical solution in linear form:

[0137] RNP j =a BDF t pj +b BDF

[0138]

[0139] In the above formula, a BDF represents the slope of the production-normalized pseudo-pressure of the boundary control flow, and b BDF represents the intercept of the production-normalized pseudo-pressure of the boundary control flow.

[0140] In the actual CO2 injection process, affected by the instability of the gas source supply, the CO2 variable-rate injection method is usually adopted. To accurately describe the flow behavior under the condition of CO2 variable-rate injection, the embodiments of this application obtain the superimposed pseudo-time through the pseudo-time, and based on the Duhamel principle, extend the analytical solution of the pseudo-pressure under the condition of CO2 constant-rate injection to the condition of CO2 variable-rate injection, so as to obtain the linear relationship between the production-normalized pseudo-pressure of the boundary control flow and the superimposed pseudo-time. The Duhamel principle constructs the solution of the non-homogeneous equation by expressing the solution of the non-homogeneous equation as an integral form of the solution of the homogeneous equation, so as to solve the initial boundary value problem of the non-homogeneous partial differential equation. The linear relationship between the production-normalized pseudo-pressure and the superimposed pseudo-time includes:

[0141]

[0142] The accuracy and intuitiveness of flow stage identification are significantly improved through the embodiments of this application.

[0143] In step S143, based on the slope of the production-normalized pseudo-pressure of the boundary control flow and the sixth formula, the initial rock pore volume is obtained. The sixth formula includes:

[0144]

[0145] In the sixth formula, V i represents the initial rock pore volume.

[0146] In step S144, based on the intercept of the production-normalized pseudopressure, the initial permeability is obtained. The seventh formula includes:

[0147]

[0148] Step S150: Determine the final rock pore volume of the aquifer and the final permeability of the aquifer based on the preset rock pore volume and the initial rock pore volume.

[0149] In step S150, according to the preset rock pore volume obtained in step S110 and the initial rock pore volume obtained in step S150, the final rock pore volume of the aquifer and the final permeability of the aquifer can be determined.

[0150] Furthermore, step S150 may include the following steps:

[0151] Step S151: Determine whether the error value between the preset rock pore volume and the initial rock pore volume is less than the preset error threshold;

[0152] Step S152: In the case where the error value between the preset rock pore volume and the initial rock pore volume is greater than or equal to the preset error threshold, iteratively update the initial rock pore volume and the initial permeability until the error value between the preset rock pore volume and the updated rock pore volume is less than the preset error threshold, and end the iterative update;

[0153] Step S153: Take the rock pore volume at the end of the iterative update as the final rock pore volume, and take the permeability at the end of the iterative update as the final permeability.

[0154] In step S151, determine whether the error value between the preset rock pore volume obtained in step S110 and the initial rock pore volume obtained in step S150 is less than the preset error threshold. Schematically, the preset error threshold in this embodiment is set to 0.2% to meet a relatively high accuracy.

[0155] In step S152, when the error value between the preset rock pore volume and the initial rock pore volume is not less than the preset error threshold, it is necessary to iteratively update the initial rock pore volume and the initial permeability. This iterative process continues until the error value between the preset rock pore volume and the updated rock pore volume is less than the preset error threshold, and then the iteration is terminated.

[0156] In step S153, the final rock pore volume and the final permeability are respectively the pore volume and the permeability when the iterative calculation converges.

[0157] Step S160: Based on the final permeability and CO2 injection conditions, obtain the critical production normalized pseudopressure corresponding to the CO2 injection conditions, where the CO2 injection conditions include injecting CO2 at a fixed rate and injecting CO2 at a fixed pressure.

[0158] In step S160, the calculation formula for the critical production normalized pseudopressure when injecting CO2 at a fixed rate includes:

[0159] RNP j,con =(p pj,i -p pj,con ) / q j

[0160] In the above formula, RNP j,con represents the critical production normalized pseudopressure, and p pj,con represents the injection pressure of the safety constraint.

[0161] The calculation formula for the critical production normalized pseudopressure when injecting CO2 at a fixed pressure includes:

[0162] PNP j,con =(p pj,i -p pj,wf ) / q con

[0163] In the above formula, q con represents the injection rate of the economic constraint.

[0164] Step S170: Based on the critical production normalized pseudopressure, determine the first superposition pseudo-time.

[0165] In step S170, according to the critical production normalized pseudopressure obtained in step S160, the first superposition pseudo-time can be determined.

[0166] Furthermore, step S170 may include the following steps:

[0167] Step S171: Based on the critical production normalized pseudopressure, determine the critical pseudo-time corresponding to the critical production normalized pseudopressure;

[0168] Step S172: Based on the critical pseudo-time, obtain the first superposition pseudo-time.

[0169] In step S171, according to the critical production normalized pseudopressure, determine the critical pseudo-time corresponding to the critical production normalized pseudopressure.

[0170] In step S172, substitute the critical pseudo-time into the fifth formula to obtain the first superposition pseudo-time.

[0171] Step S180: Obtain the carbon sequestration capacity based on the first superimposed pseudo-time, CO2 injection conditions, and the final rock pore volume.

[0172] In step S180, the carbon sequestration capacity is obtained through the first superimposed pseudo-time, CO2 injection conditions, and the final rock pore volume.

[0173] Furthermore, step S180 may include the following steps:

[0174] Step S181: Determine the CO2 injection rate based on the CO2 injection conditions.

[0175] In step S181, different CO2 injection conditions correspond to different CO2 injection rates, so it is necessary to distinguish the CO2 injection rates corresponding to the CO2 injection conditions.

[0176] Furthermore, step S181 may include the following steps:

[0177] Step S1811: When the CO2 injection condition is that CO2 is injected at a fixed rate, determine that the CO2 injection rate is a preset rate;

[0178] Step S1812: When the CO2 injection condition is that CO2 is injected at a fixed pressure, determine the injection rate based on the final permeability and the pseudo-time.

[0179] In step S1811, when CO2 is injected at a fixed rate, the CO2 injection rate is a fixed preset rate.

[0180] In step S1812, when CO2 is injected at a fixed pressure, the injection rate is obtained through the final permeability, the pseudo-time, and the injection rate formula, where the injection rate formula includes:

[0181]

[0182] In the above formula, γ represents the Euler coefficient, C A represents the shape factor, and A represents the injection area of the saline aquifer.

[0183] Step S182: Obtain the safety limit superimposed pseudo-time corresponding to the CO2 injection conditions.

[0184] In step S182, when the CO2 injection condition is that CO2 is injected at a fixed rate, the safety limit superimposed pseudo-time is the time when the CO2 injection pressure reaches the safety constraint injection pressure. When the CO2 injection condition is that CO2 is injected at a fixed pressure, the safety limit superimposed pseudo-time is the time when the injection rate reaches the economic constraint injection rate.

[0185] Step S183: Determine the total CO2 injection time based on the first superposition pseudo-time, the safety limit superposition pseudo-time, and the final rock pore volume.

[0186] In step S183, the first superposition pseudo-time obtained through step S172 and the safety limit superposition pseudo-time obtained in step S182 are used to determine the total CO2 injection time.

[0187] Furthermore, step S183 may include the following steps:

[0188] Step S1831: Determine whether the first superposition pseudo-time is equal to the safety limit superposition pseudo-time;

[0189] Step S1832: In the case where the first superposition pseudo-time is not equal to the safety limit superposition pseudo-time, based on the final rock pore volume, iteratively update the average pressure and the average saturation;

[0190] Step S1833: Based on the updated average pressure and average saturation, obtain the updated superposition pseudo-time until the updated superposition pseudo-time is equal to the safety limit superposition pseudo-time, and stop the iterative update;

[0191] Step S1834: Determine the total CO2 injection time based on the safety limit superposition pseudo-time.

[0192] In step S1831, determine whether the first superposition pseudo-time is equal to the safety limit superposition pseudo-time.

[0193] In step S1832, substitute the preset rock pore volume with the final rock pore volume into the first formula to obtain the average pressure.

[0194] In the case where the first superposition pseudo-time is not equal to the safety limit superposition pseudo-time, based on each time step, iteratively update the average pressure. Correspondingly, substitute the preset rock pore volume with the final rock pore volume into the second formula, and based on the average pressure in step S1832, obtain the average saturation.

[0195] In the case where the first superposition pseudo-time is not equal to the safety limit superposition pseudo-time, based on each time step, iteratively update the average saturation.

[0196] In step S1833, recalculate the superposition pseudo-time based on the average pressure and average saturation after each update. When the superposition pseudo-time reaches the safety limit superposition pseudo-time, terminate the iterative process.

[0197] In step S1834, based on the initial superposition pseudo-time and the safety limit superposition pseudo-time, determine the total CO2 injection time. Among them, by substituting the initial pseudo-time into the fifth formula to obtain the initial superposition pseudo-time, the total CO2 injection time = safety limit superposition pseudo-time - initial superposition pseudo-time.

[0198] Step S184: Obtain the carbon sequestration capacity based on the CO2 injection rate and the total CO2 injection time.

[0199] In step S184, the calculation formula for the carbon sequestration capacity when CO2 is injected at a fixed rate includes:

[0200] V t =q in ×t in

[0201] In the above formula, V t represents the carbon sequestration capacity, q in represents the CO2 injection rate, and t in represents the total CO2 injection time. The CO2 injection rate q in is a preset rate.

[0202] The calculation formula for the carbon sequestration capacity when CO2 is injected at a fixed pressure includes:

[0203]

[0204] In the above formula, the CO2 injection rate q in is determined by the injection rate formula.

[0205] The embodiments of the present application adopt parameters applicable to both saline water and CO2 in the aquifer to construct a set of injection dynamic analysis methods. Through this injection dynamic analysis method, the final rock pore volume and the final permeability of the aquifer can be quickly and accurately obtained, and the carbon sequestration capacity can be accurately predicted through the final rock pore volume and the final permeability.

[0206] To verify the reliability of the carbon sequestration capacity prediction in the embodiments of the present application, the embodiments of the present application use oil and gas reservoir numerical simulation software to establish a CO2 sequestration numerical model for a closed-boundary aquifer, and design two working conditions: CO2 is injected at a fixed rate (2.5×10 4 ft 3 / d) and CO2 is injected at a fixed pressure (1750 psi, equivalent variable rate injection working condition). A logarithmic encryption grid system is used to accurately characterize the pressure distribution characteristics near the wellbore. When CO2 is injected at a fixed rate, the injection termination condition is set to the bottom-hole flowing pressure reaching 90% of the formation fracture pressure (1560 psi). When CO2 is injected at a fixed pressure, the economic constraint injection rate (2.0×10 4 ft 3 / d) Set as the injection termination condition. The parameter settings of the numerical model for CO2 storage in a closed - boundary aquifer are shown in Table 1.

[0207] Table 1

[0208]

[0209] Through the established numerical model for CO2 storage in a closed - boundary saline aquifer. Figure 2 (a) Schematically shows the schematic diagram of the average pressure when CO2 is injected at a fixed rate according to an embodiment of the present application. Figure 2 (b) Schematically shows the schematic diagram of the average water saturation when CO2 is injected at a fixed rate according to an embodiment of the present application. Figure 3 (a) Schematically shows the schematic diagram of the average pressure when CO2 is injected at a fixed pressure according to an embodiment of the present application. Figure 3 (b) Schematically shows the schematic diagram of the average water saturation when CO2 is injected at a fixed pressure according to an embodiment of the present application. As Figure 2 (a) and Figure 3 (a) shows, the simulated values of the average pressure when CO2 is injected at a fixed rate and the average pressure when CO2 is injected at a fixed rate basically coincide. As Figure 2 (b) and Figure 3 (b) shows, the simulated values of the average water saturation when CO2 is injected at a fixed rate and the average water saturation when CO2 is injected at a fixed rate also basically coincide. It can be seen that the embodiments of the present application can accurately obtain the average pressure and the average saturation.

[0210] Figure 2 (c) Schematically shows the diagnostic curve schematic diagram when CO2 is injected at a fixed rate according to an embodiment of the present application. As Figure 2 (c) shows, the abscissa represents the pseudo - time, and the ordinate represents the derivative of the production - normalized pseudo - pressure with respect to the pseudo - time. As Figure 2 (c) includes a transient radial flow (FR1) with a slope of 0 and a boundary - controlled flow (FR2) with a slope of 1. When CO2 is injected at a fixed rate, the starting time of the boundary - controlled flow is about 107.9 days.

[0211] Figure 3 (c) Schematically shows the diagnostic curve schematic diagram when CO2 is injected at a fixed pressure according to an embodiment of the present application. As Figure 3 (c) shows, the abscissa represents the pseudo - time, and the ordinate represents the derivative of the production - normalized pseudo - pressure with respect to the pseudo - time. As Figure 3 (c) includes a transient radial flow (FR1) with a slope of 0 and a boundary - controlled flow (FR2) with a slope of 1. When CO2 is injected at a fixed pressure, the starting time of the boundary - controlled flow is about 96.14 days.

[0212] Figure 2 (d) Schematically shows the characteristic curve diagram of CO2 injection at a fixed rate according to an embodiment of the present application. Based on Figure 2 (c), extract the boundary control flow partial curve with a slope of 1 to obtain Figure 2 (d). As shown in Figure 2 (d), for the case of CO2 injection at a fixed rate, set the safety constraint injection pressure to 1560 psi as the constraint condition. The critical production normalized pseudo-pressure RNP corresponding to the y-axis end point of the characteristic curve of CO2 injection at a fixed rate con , and determine the first superimposed pseudo-time corresponding to the x-axis end point to reach the safety constraint injection pressure. The simulation results of the closed boundary aquifer CO2 sequestration numerical model show that: under the condition of CO2 injection at a fixed rate, the time to reach the safety constraint injection pressure is about 103.59 days.

[0213] Figure 3 (d) Schematically shows the characteristic curve diagram of CO2 injection at a fixed pressure according to an embodiment of the present application. Based on Figure 3 (c), extract the boundary control flow partial curve with a slope of 1 to obtain Figure 3 (d). As shown in Figure 3 (d), for the case of CO2 injection at a fixed pressure, set the economic constraint injection rate to 2.0×104 ft3 / D as the constraint condition. The critical production normalized pseudo-pressure RNP corresponding to the y-axis end point of the characteristic curve of CO2 injection at a fixed pressure con , and determine the first superimposed pseudo-time corresponding to the x-axis end point to reach the economic constraint injection rate. The simulation results of the closed boundary aquifer CO2 sequestration numerical model show that: under the condition of CO2 injection at a fixed pressure, the time to reach the economic constraint injection rate is 4,495.21 days.

[0214] Figure 2 (e) Schematically shows the CO2 injection time inversion diagram of CO2 injection at a fixed rate according to an embodiment of the present application. As shown in Figure 2 (e), for the case of CO2 injection at a fixed rate, the simulated value of the total CO2 injection time is 947.1 days, and the calculated value of the total CO2 injection time is 930.1 days, and the relative error between the two is only 1.8%.

[0215] Figure 3 (e) Schematically shows the curve diagram of CO2 injection rate and carbon sequestration capacity of CO2 injection at a fixed pressure according to an embodiment of the present application. As shown in Figure 3 (e), the curve of the calculated value of the CO2 injection rate and the curve of the simulated value of the CO2 injection rate basically coincide, and the curve of the calculated value of the carbon sequestration capacity and the curve of the simulated value of the carbon sequestration capacity are highly consistent.

[0216] Table 2

[0217]

[0218]

[0219] The calculated values of the final permeability and the calculated values of the final rock pore volume are shown in Table 2. The relative error between the calculated value of the final permeability in Table 2 and the simulated value of the final permeability in Table 1 is less than 10%, and the relative error between the calculated value of the final rock pore volume in Table 2 and the simulated value of the final rock pore volume in Table 1 is less than 10%.

[0220] The calculated value of the carbon sequestration capacity and the simulated value of the carbon sequestration capacity are shown in Table 2, and the errors between the calculated value of the carbon sequestration capacity and the simulated value of the carbon sequestration capacity are all within 10%.

[0221] In the embodiment of the present application, through the established numerical model of CO2 sequestration in a closed - boundary aquifer, the accuracy of the prediction method for the carbon sequestration capacity provided by the embodiment of the present application is simulated and verified. The embodiment of the present application provides a more accurate theoretical tool for the optimization and safety monitoring of carbon sequestration projects.

[0222] Optionally, the embodiment of the present application further provides a prediction device for carbon sequestration capacity, including:

[0223] An acquisition module, configured to acquire the preset rock pore volume of the aquifer;

[0224] A first obtaining module, configured to obtain the average pressure of the aquifer and the average saturation of the aquifer based on the preset rock pore volume;

[0225] A second obtaining module, configured to obtain the pseudo - pressure and the pseudo - time based on the average pressure and the average saturation;

[0226] A third obtaining module, configured to obtain the initial rock pore volume of the aquifer and the initial permeability of the aquifer based on the pseudo - pressure and the pseudo - time;

[0227] A first determination module, configured to determine the final rock pore volume of the aquifer and the final permeability of the aquifer based on the preset rock pore volume and the initial rock pore volume;

[0228] A fourth obtaining module, configured to obtain the critical production normalized pseudo - pressure corresponding to the CO2 injection condition based on the final permeability and the CO2 injection condition, where the CO2 injection condition includes injecting CO2 at a fixed rate and injecting CO2 at a fixed pressure;

[0229] A second determination module, configured to determine the first superimposed pseudo - time based on the critical production normalized pseudo - pressure;

[0230] A fifth obtaining module, configured to obtain a carbon sequestration capacity based on a first superimposed pseudo-time, CO2 injection conditions, and a final rock pore volume.

[0231] It can be understood that the carbon sequestration capacity prediction device provided in the embodiments of the present application can implement each process of the carbon sequestration capacity prediction method in the above embodiments and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0232] Optionally, the embodiments of the present application further provide a computing device, including:

[0233] A memory, configured to store instructions;

[0234] A processor, configured to call instructions from the memory and, when executing the instructions, be able to implement the carbon sequestration capacity prediction method as described above. And it can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0235] Optionally, the embodiments of the present application further provide a machine-readable storage medium, on which instructions are stored, and the instructions are used to cause a machine to execute the carbon sequestration capacity prediction method as described above. And it can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0236] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0237] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0238] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one or more processes and / or blocks Figure 1 of the one or more processes and / or blocks Figure 1 specified in the one or more blocks or blocks.

[0239] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes and / or blocks Figure 1 of the one or more processes and / or blocks Figure 1 specified in the one or more blocks or blocks.

[0240] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and memory.

[0241] The memory may include non-permanent memory in the computer-readable medium, in the form of random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of a computer-readable medium.

[0242] Computer-readable media include permanent and non-permanent, removable and non-removable media that can store information by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media, such as modulated data signals and carrier waves.

[0243] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, commodity or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, commodity or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, commodity or device comprising the element.

[0244] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for predicting carbon sequestration capacity, characterized in that, Including: Obtaining a preset rock pore volume of an aquifer; Based on the preset rock pore volume, obtaining an average pressure of the aquifer and an average saturation of the aquifer; Based on the average pressure and the average saturation, obtaining a pseudo - pressure and a pseudo - time; Based on the pseudo - pressure and the pseudo - time, obtaining an initial rock pore volume of the aquifer and an initial permeability of the aquifer; Based on the preset rock pore volume and the initial rock pore volume, determining a final rock pore volume of the aquifer and a final permeability of the aquifer; Based on the final permeability and CO2 injection conditions, obtaining a critical production - normalized pseudo - pressure corresponding to the CO2 injection conditions, where the CO2 injection conditions include injecting CO2 at a fixed rate and injecting CO2 at a fixed pressure; Based on the critical production - normalized pseudo - pressure, determining a first superposition pseudo - time; Based on the first superposition pseudo - time, the CO2 injection conditions and the final rock pore volume, obtaining the carbon sequestration capacity.

2. The method according to claim 1, wherein The step of obtaining the initial rock pore volume of the aquifer and the initial permeability of the aquifer based on the pseudo - pressure and the pseudo - time includes: Based on the pseudo - pressure and the pseudo - time, determining a start pseudo - time and an end pseudo - time of boundary - controlled flow during the CO2 injection process; Based on the pseudo - pressure, obtaining a superposition pseudo - time; Based on the pseudo - pressure and the superposition pseudo - time, obtaining a production - normalized pseudo - pressure of boundary - controlled flow during the CO2 injection process; Based on the slope of the production - normalized pseudo - pressure, obtaining the initial rock pore volume; Based on the intercept of the production - normalized pseudo - pressure, obtaining the initial permeability.

3. The method according to claim 2, characterized in that The step of determining the final rock pore volume of the aquifer and the final permeability of the aquifer based on the preset rock pore volume and the initial rock pore volume includes: Determining whether an error value between the preset rock pore volume and the initial rock pore volume is less than a preset error threshold; In the case where the error value between the preset rock pore volume and the initial rock pore volume is greater than or equal to the preset error threshold, iteratively updating the initial rock pore volume and the initial permeability until the error value between the preset rock pore volume and the updated rock pore volume is less than the preset error threshold, and ending the iterative update; Taking the rock pore volume at the end of the iterative update as the final rock pore volume, and taking the permeability at the end of the iterative update as the final permeability.

4. The method according to claim 1, characterized in that, The step of determining the first superposition pseudo - time based on the critical production - normalized pseudo - pressure includes: Based on the critical production - normalized pseudo - pressure, determining a critical pseudo - time corresponding to the critical production - normalized pseudo - pressure; Based on the critical pseudo - time, obtaining the first superposition pseudo - time.

5. The method according to claim 1, characterized in that, The step of obtaining the carbon sequestration capacity based on the first superposition pseudo - time, the CO2 injection conditions and the final rock pore volume includes: Based on the CO2 injection conditions, determining a CO2 injection rate; Obtaining a safety - limit superposition pseudo - time corresponding to the CO2 injection conditions; Determine the total CO2 injection time based on the first superimposed pseudo-time, the safety limit superimposed pseudo-time, and the final rock pore volume; Obtain the carbon sequestration capacity based on the CO2 injection rate and the total CO2 injection time.

6. The method according to claim 5, wherein The determining the CO2 injection rate based on the CO2 injection conditions includes: When the CO2 injection condition is that CO2 is injected at a fixed rate, determine that the CO2 injection rate is a preset rate; When the CO2 injection condition is that CO2 is injected at a fixed pressure, determine the injection rate based on the final permeability and the pseudo-time.

7. The method according to claim 5, characterized in that The determining the total CO2 injection time based on the first superimposed pseudo-time, the safety limit superimposed pseudo-time, and the final rock pore volume includes: Determine whether the first superimposed pseudo-time is equal to the safety limit superimposed pseudo-time; When the first superimposed pseudo-time is not equal to the safety limit superimposed pseudo-time, iteratively update the average pressure and the average saturation based on the final rock pore volume; Based on the updated average pressure and average saturation, obtain the updated superimposed pseudo-time until the updated superimposed pseudo-time is equal to the safety limit superimposed pseudo-time, and stop the iterative update; Determine the total CO2 injection time based on the safety limit superimposed pseudo-time.

8. A prediction device for carbon sequestration capacity, characterized in that, It includes: An acquisition module, which acquires the preset rock pore volume of the aquifer; A first obtaining module, which obtains the average pressure of the aquifer and the average saturation of the aquifer based on the preset rock pore volume; A second obtaining module, which obtains the pseudo-pressure and the pseudo-time based on the average pressure and the average saturation; A third obtaining module, which obtains the initial rock pore volume of the aquifer and the initial permeability of the aquifer based on the pseudo-pressure and the pseudo-time; A first determining module, which determines the final rock pore volume of the aquifer and the final permeability of the aquifer based on the preset rock pore volume and the initial rock pore volume; A fourth obtaining module, which obtains the critical production normalized pseudo-pressure corresponding to the CO2 injection condition based on the final permeability and the CO2 injection condition, where the CO2 injection condition includes CO2 being injected at a fixed rate and CO2 being injected at a fixed pressure; A second determining module, which determines the first superimposed pseudo-time based on the critical production normalized pseudo-pressure; A fifth obtaining module, which obtains the carbon sequestration capacity based on the first superimposed pseudo-time, the CO2 injection condition, and the final rock pore volume.

9. A computing device, characterized in that, It includes: A memory, which is configured to store instructions; A processor, which is configured to call the instructions from the memory and be able to implement the prediction method of the carbon sequestration capacity according to any one of claims 1 to 7 when executing the instructions.

10. A machine-readable storage medium, characterized in that, Instructions are stored on the machine-readable storage medium, and the instructions are used to cause the machine to execute the prediction method of the carbon sequestration capacity according to any one of claims 1 to 7.

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