A three-stage visual classification evaluation method for CO2 flooding and geological storage

Abstract

The present invention discloses a three-stage visual classification evaluation method for CO2 oil displacement and geological storage. First, the classification evaluation of each stage is performed in the physical stage of CO2 oil displacement-storage, the physical and chemical stage of CO2 oil displacement-storage, and the chemical stage of CO2 storage. Then, the logging identification and three-dimensional visual classification of various types of storage in each stage are performed. Finally, in combination with the three-stage classification model, a visual classification model of CO2 oil displacement is established to calculate various types of oil displacement; a visual staged classification model of CO2 storage is established to calculate various types of storage in each stage. The present invention realizes the visualization of the three-stage classification evaluation of CO2 oil displacement-storage, greatly improves the crude oil recovery rate to obtain economic benefits, and ensures the safe and effective storage of CO2, providing a refined and visual evaluation method for oilfield CCUS work.

Description

Technical Field

[0001] The present invention relates to CO 2 The field of geological storage suitability evaluation technology, especially a CO 2 A three-stage visual classification and evaluation method for oil displacement and geological storage. Background Art

[0002] CO 2 Climate change, centered on emissions, and energy security, centered on the shortage of oil resources, are two major challenges that restrict the sustainable development of my country's social economy. Carbon capture, utilization and storage (CCUS) is the most widely used cutting-edge technology in the oil and gas industry. It can economically and effectively realize CO2 reduction while tapping the potential of oil reservoirs. 2 Geological storage can solve the urgent environmental and resource problems. Generally, there is sufficient CO near the oil field. 2 Gas source, for CO 2 The oil displacement-storage work is more advantageous and can ensure a stable supply of gas for a relatively long period of time.

[0003] Injection pressure, oil recovery method, pore size of the injected formation, supercritical CO 2 The magnitude of interfacial tension is an important factor affecting the oil recovery effect. Since most of the crude oil in China's continental basins has the characteristics of high heavy hydrocarbon content, the increase in gas injection pressure will accelerate the supercritical CO 2 When the pressure reaches the miscible pressure, CO 2 Further enrichment will bring its density close to that of crude oil. At that time, the oil-gas interface will completely disappear, and the degree of crude oil recovery will be greatly improved. Hydraulic flooding is a more traditional development method. Compared with water flooding followed by CO 2 Miscible flooding and direct CO 2 The two methods of miscible flooding found that water flooding would disrupt the original oil-water distribution pattern of the formation and hinder the CO 2 Contact with crude oil to reduce CO 2 Mixing efficiency, increasing CO 2 Miscibility pressure; direct CO 2 The flooding will greatly increase the oil recovery and the miscible pressure is relatively low. Supercritical CO injected into the formation 2 Mixing occurs first in larger pores, and then complete mixing occurs as pressure increases to the minimum miscibility pressure. Therefore, the lower the porosity of the gas injection layer, the greater the minimum miscibility pressure required. 2 It is easier to peel off the crude oil with poor mobility in small pores and the oil film on the rock skeleton, so that it can be dispersed in CO 2 middle.

[0004] The oil reservoir is CO 2The most ideal place to store CO 2 The gas source is injected into the reservoir, dissolves in the reservoir fluid under the temperature and pressure conditions of the reservoir, and also reacts with the highly mineralized formation water to achieve CO 2 Permanent storage. The long-term practice of oilfield development has accumulated a lot of injection and production experience, and has a deeper understanding of the geological properties of reservoirs and adjacent formations, realizing CO 2 The safety of CO2 can be guaranteed while burying it. 2 Geological storage can also improve oil recovery and bring economic benefits. 2 Oil and gas separation can be achieved by reducing the pressure under surface conditions after miscible flooding.

[0005] Master's thesis "Inefficient CO injection in horizontal wells of JS oilfield 2 A study on the suitability of throughput and the evaluation of oil removal effect" (published in May 2019; author: Tang Haorui; supervisor: Li Chuanliang, Sun Lei) proposed a method for low-efficiency horizontal well CO injection. 2 The evaluation index system of throughput suitability (Table 1) systematically evaluates the performance of single well injection of CO 2 The suitability of the JS oilfield was finally identified as suitable for CO injection. 2 Horizontal wells, CO 2 It provides technical reference for the oil displacement-storage single well price assessment work.

[0006] Table 1 Low-efficiency CO injection in horizontal wells 2 Throughput suitability evaluation index system

[0007]

[0008] The article "CO injection based on fuzzy analytic hierarchy process 2 A comprehensive evaluation method for miscible flooding reservoirs (published in November 2002; author: Xiong Yu, Sun Liangtian, Sun Lei, etc.) proposed a set of CO2 injection methods for reservoirs. 2 Miscible flooding potential evaluation method is used to screen suitable CO injection sites. 2 Miscible flooding reservoir; Master's thesis "CO 2 "Evaluation of the sealing capacity of caprocks and the storage capacity of traps during burial process - taking the Gaotaizi structure and Xingshugang structure in Changheng, Daqing as examples" (published on June 7, 2014; author: Xu Meng; supervisor: Fu Xiaofei) quantitatively analyzed and calculated the storage capacity of CO in the Gaotaizi structure oil layer. 2 None of the above studies conducted CO 2 The phased visual classification evaluation of oil recovery and geological storage has not yet achieved CO 2 The staged and classified calculation of oil displacement and storage volume has its technical limitations in the context of the refinement of modern oilfield operations. Summary of the invention

[0009] Based on the existing standards for CO2 geological storage suitability evaluation, the present invention proposes a three-stage visual classification evaluation method for CO2 oil recovery and geological storage.

[0010] The objective of the present invention is achieved through the following technical solutions:

[0011] A CO 2 The three-stage visual classification evaluation method for oil displacement and geological storage includes the following specific steps:

[0012] S1: Conduct CO 2 3D visualization classification and evaluation of oil displacement and storage in three stages;

[0013] S2: Combine the three-stage 3D visualization classification model to establish CO 2 Oil displacement-physical storage stage and CO 2 During the oil recovery-physical and chemical storage phase, CO 2 Visual classification model of oil displacement, calculating various types of oil displacement;

[0014] S3: Combine the three-stage 3D visualization classification model to establish CO 2 The storage visualization and classification model of CO 2 Oil displacement-physical storage stage storage classification model, establishment of CO2 storage coefficient method 2 The classification model of storage capacity in the oil displacement-physical and chemical storage stage and the establishment of CO storage coefficient method 2 The chemical storage stage storage classification model is developed, and finally the storage quantities of each type in each stage are calculated.

[0015] Furthermore, the step S1 specifically includes:

[0016] S101: CO based on the 5-factor approach 2 Suitability classification for oil displacement-physical burial stage;

[0017] S102: CO based on the 6-factor approach 2 Suitability classification for oil displacement-physical and chemical storage stages;

[0018] S103: CO based on the 6-factor approach 2 Classification of suitability of chemical burial stages;

[0019] S104: CO 2 Oil displacement-storage logging identification and 3D visualization classification evaluation.

[0020] Furthermore, the step S101 specifically includes: according to the suitability, CO 2The five influencing factors in the oil displacement-physical burial stage are divided into three categories: I, II, and III. The five influencing factors include the porosity, permeability, oil saturation, crude oil density, and burial layer thickness of the oil layer.

[0021] Furthermore, the step S102 specifically includes: according to the suitability, CO 2 The six influencing factors in the oil displacement-physical and chemical burial stage are divided into three categories: I, II, and III. The six influencing factors include the porosity, permeability, oil saturation, crude oil density, burial layer thickness, and formation water mineralization of the oil and water layer.

[0022] Furthermore, the step S103 specifically includes: according to the suitability, CO 2 The six influencing factors in the chemical burial stage are divided into three categories: I, II, and III. The six influencing factors include the porosity, permeability, oil saturation, formation water mineralization, cap rock thickness, and burial layer thickness of the oil layer.

[0023] Further, the step S104 specifically includes: using the single well logging curve data characteristics to preliminarily identify and establish CO 2 The three-stage model of oil displacement and storage is combined with the classification of influencing factors in step S101 to step S103 to establish a visual CO 2 3D model of oil displacement and burial three-stage classification.

[0024] Furthermore, the establishment of a CO2 storage coefficient method 2 The steps of the storage classification model and calculation of various storage volumes in the oil displacement-physical storage stage are as follows: 2 The 3D models of Class I, Class II, and Class III in the oil displacement-physical storage stage are designed. Considering the characteristics of this stage where only physical storage occurs, the physical storage coefficient is calculated first, and then the CO 2 CO2 in the oil recovery and physical storage stage 2 The storage capacity classification model is constructed and the storage capacity of each category is calculated.

[0025] Furthermore, the establishment of a CO2 storage coefficient method 2 The steps of the storage classification model and calculation of various storage volumes in the oil displacement-physical and chemical storage stage are as follows: 2 The 3D models of Class I, Class II, and Class III of the oil displacement-physical and chemical storage stage are combined with the characteristics of physical and chemical storage in this stage. The physical storage coefficient and chemical storage coefficient are calculated first, and then the CO 2 CO2 in the oil recovery and physical storage stage 2 The storage capacity classification model is constructed and the storage capacity of each category is calculated.

[0026] Furthermore, the establishment of a CO2 storage coefficient method2 The steps of the chemical storage stage storage classification model and the steps of calculating the storage of each type are as follows: 2 The 3D models of Class I, Class II, and Class III in the chemical storage stage are designed to calculate the chemical storage coefficient first, and then perform CO 2 CO2 in the oil recovery and physical storage stage 2 The storage volume classification model is established and the storage volume of each category is calculated.

[0027] Furthermore, the storage volume calculation formula is:

[0028] Mco 2 =Mw·x,

[0029]

[0030] Among them: Mco 2 —CO 2 Buried stock, kg;

[0031] Mw—water content, kg;

[0032] x—chemical burial coefficient;

[0033] Φ—average porosity, %;

[0034] —CO 2 Solubility at reservoir conditions, kg / kg;

[0035] S w —Average oil saturation, %;

[0036] V w —Model water grid volume, m 3 ;

[0037] —CO 2 Density at reservoir temperature and pressure, kg / m 3 .

[0038] Beneficial effects of the present invention:

[0039] The present invention is used as carbon capture and oil field CO 2 The bridge between oil recovery and storage operations realizes the 2 The visualization of the three-stage classification evaluation of oil displacement and storage greatly improves the oil recovery rate to obtain economic benefits while ensuring CO 2 The safe and effective storage of carbon dioxide provides a refined and visual evaluation method for CCUS work in oil fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0041] Figure 1 It is a flow chart of the technical solution of the present invention;

[0042] Figure 2 is a comprehensive histogram of the W1 well in the example area of ​​the present invention;

[0043] Figure 3 It is a comprehensive histogram of the example area W3 well of the present invention;

[0044] Figure 4 The example area of ​​the present invention is CO 2 3D model diagram of three stages of oil displacement and burial storage;

[0045] Figure 5 The example area of ​​the present invention is CO 2 3D model diagram of three-stage classification of oil displacement and burial storage;

[0046] Figure 6 is a cross-sectional view of the 3D reservoir model of the W1 well of the present invention;

[0047] Figure 7 CO of the present invention 2 3D model cross-section diagram of the three-stage classification of oil displacement and burial storage;

[0048] Figure 8 It is a graph showing the variation of oil change rate of two groups in the example area of ​​the present invention;

[0049] Fig. 9 CO of the present invention 2 Oil displacement-physical burial stage Type I oil displacement volume distribution model diagram;

[0050] Fig.10 CO of the present invention 2 Oil displacement-physical burial stage II oil displacement volume distribution model diagram;

[0051] Fig.11 CO of the present invention 2 Oil displacement-physical burial stage III type oil displacement volume distribution model diagram;

[0052] Fig.12 CO of the present invention 2 Oil displacement-physical and chemical storage stage Type I oil displacement volume distribution model diagram;

[0053] Fig.13CO of the present invention 2 Oil displacement-physical and chemical storage stage II oil displacement volume distribution model diagram;

[0054] Fig.14 CO of the present invention 2 Oil displacement-physical and chemical storage stage III type oil displacement volume distribution model diagram;

[0055] Fig.15 CO of the present invention 2 Model diagram of Class I storage volume distribution in the oil displacement-physical storage stage;

[0056] Fig.16 CO of the present invention 2 Model diagram of Class II storage volume distribution in the oil displacement-physical storage stage;

[0057] Fig.17 CO of the present invention 2 Model diagram of Class III storage volume distribution in the oil displacement-physical storage stage;

[0058] Fig.18 CO of the present invention 2 Model diagram of Class I storage volume distribution in the oil displacement-physical and chemical storage stage;

[0059] Fig.19 CO of the present invention 2 Model diagram of Class II storage volume distribution in the oil displacement-physical and chemical storage stage;

[0060] Fig. 20 CO of the present invention 2 Model diagram of Class III storage volume distribution in the oil displacement-physical and chemical storage stage;

[0061] Fig.21 CO of the present invention 2 Distribution model diagram of Class I storage during the chemical storage stage;

[0062] Fig. 22 CO of the present invention 2 Distribution model diagram of Class II storage in the chemical storage stage;

[0063] Fig.23 CO of the present invention 2 Distribution model diagram of Class III storage volume in the chemical storage stage. DETAILED DESCRIPTION

[0064] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0065] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. 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 the present invention.

[0066] In CO 2 Based on the existing standards for evaluating the suitability of geological storage, the present invention proposes a CO 2 The three-stage visual classification evaluation technology for oil recovery and geological storage includes three key technical links and eight key steps. First, CO 2 3D visualization classification evaluation of oil recovery and storage in three stages, including CO based on the five-factor method 2 Suitability analysis of oil displacement-physical storage stage, CO based on six-factor method 2 Suitability analysis of oil displacement-physical and chemical storage stage, CO based on six-factor method 2 Chemical storage stage suitability analysis, CO 2 Oil recovery-storage logging identification and 3D visualization classification evaluation. Secondly, CO 2 The oil displacement classification model is built and the oil displacement of each type is calculated. Finally, combined with the visual classification results, the CO 2 The storage capacity of various types of storage is classified and modeled, including CO based on the storage coefficient method. 2 Oil displacement-physical storage stage storage volume classification calculation, CO based on storage coefficient method 2 Classification calculation of storage volume in the oil displacement-physical and chemical storage stage, CO storage coefficient method 2 Classification and calculation of storage volume in the chemical storage stage.

[0067] This technology is used as carbon capture and oil field CO 2 The bridge between oil recovery and storage operations realizes the 2 The visualization of the three-stage classification evaluation of oil displacement and storage greatly improves the oil recovery rate to obtain economic benefits while ensuring CO 2 The safe and effective storage of carbon dioxide provides a refined and visual evaluation method for CCUS work in oil fields.

[0068] Technical solution flow chart Figure 1 shown.

[0069] Furthermore, CO 2 The three-dimensional visualization classification evaluation of the three stages of oil displacement and burial storage is as follows:

[0070] Under the temperature and pressure conditions of the reservoir, the distribution law of oil and water is related to their density. Generally, from top to bottom, there is oil layer, oil-water layer, and water layer. Therefore, supercritical CO 2 The oil recovery and storage evaluation work also needs to be divided into three stages. 2 Oil recovery-physical storage stage: supercritical CO 2 After entering the reservoir, it will mix with the oil in the oil layer under high temperature and high pressure conditions, reduce the viscosity of the oil, increase the mobility of the oil, and greatly improve the oil washing efficiency. 2 Fill the pores of the oil layer rock to ensure the formation energy while achieving CO 2 Physical storage; ②CO 2 Oil displacement-physical and chemical storage stage: CO 2 The crude oil in the oil-water layer continues to be displaced in a mixed phase state and physically buried. At the same time, due to the high water saturation of the oil-water layer, part of the CO 2 Begins to react with formation water to form precipitation for chemical storage; ③CO 2 Chemical storage stage: supercritical CO 2 Entering the water layer, the water saturation further increases. At this time, almost no recoverable crude oil can be found, and a large amount of CO 2 It dissolves with high-mineralization formation water and undergoes chemical reactions to produce a large amount of precipitation to achieve chemical burial.

[0071] (1) CO based on the five-factor method 2 Suitability classification of oil displacement-physical storage stage

[0072] In CO 2 Oil recovery - physical storage stage, the oil in the reservoir is supercritical CO 2 The main displacement target is the continuous injection of supercritical CO 2 It fills the gap in crude oil volume and pressure, ensures the stability of the rock skeleton, and produces crude oil and realizes CO 2 Physical storage. Consider the following five factors based on the characteristics of this stage. ① Higher crude oil density and viscosity also place higher requirements on miscibility. As the pressure increases to the miscibility pressure, supercritical CO 2 Mix with crude oil, reduce crude oil viscosity, peel off rock skeleton oil film, and improve oil washing efficiency. Generally, crude oil density is positively correlated with viscosity, so it is necessary to classify according to crude oil density. ② This stage requires the target buried layer to have a certain thickness and storage and permeability to ensure the smooth flow of injected and produced fluids, so it is necessary to classify according to storage and permeability. ③ The upper part of the target oil layer needs to have a complete, dense, and certain thickness of cap rock to ensure CO 2During the oil displacement-storage operation, the pressure system is stable, there is no cross-flow with other layers, and there is no leakage for a long time after the operation is completed. ④ When the oil saturation of the target oil layer is low, the injected supercritical CO 2 The efficiency of displacing crude oil will be reduced, so it is necessary to classify the oil saturation. ⑤ When the oil layer is deep, it is usually accompanied by high temperature and high pressure oil layer conditions. Such conditions are not conducive to supercritical CO 2 injection, and CO 2 The miscible condition is not easy to achieve, so it is necessary to classify the reservoir depth and temperature and pressure conditions.

[0073] According to the basic conditions of the example area, the porosity, permeability, oil saturation, crude oil density, cap rock thickness, and buried layer thickness of the oil layer can be divided into three categories: good (I), medium (II), and poor (III). The oil reservoir is deep and has a high temperature, both of which are CO 2 The adverse factors of oil displacement and burial storage are not further classified. Considering the above “five factors”, the data of the example area are specifically classified as shown in Table 2.

[0074] Table 2 CO 2 Suitability classification standard for oil displacement-physical storage stage

[0075]

[0076] (2) CO based on the six-factor method 2 Suitability classification of oil displacement-physical and chemical storage stage

[0077] In CO 2 During the oil displacement-physical and chemical storage stage, the crude oil in the oil-water layer is heated by supercritical CO 2 While displacing and filling rock voids, some CO 2 Dissolved in high-mineralization formation water and reacted chemically with it to form precipitation. According to the characteristics of this stage, the following six factors are considered: ① The higher the density and viscosity of crude oil, the higher the requirements for miscibility. As the pressure increases to the miscibility pressure, supercritical CO 2 Mix with crude oil, reduce crude oil viscosity, peel off rock skeleton oil film, and improve oil washing efficiency, so it is necessary to classify according to crude oil density. ② This stage requires the target buried layer to have a certain thickness and good storage and permeability to reduce the adverse effects of chemical precipitation blocking some seepage channels, so it is necessary to classify according to storage and permeability. ③ Similarly, the upper part of the target oil-water layer needs to have a complete, dense, and certain thickness of cap rock to ensure CO 2 During the oil displacement-storage operation, the pressure system is stable, and there is no cross-flow with other layers. There is no leakage for a long time after the operation is completed. 2The impact on the efficiency of displacing crude oil will be more significant, so it is necessary to classify the oil saturation of the oil-water layer. ⑤ When the depth of the oil-water layer is large, it is usually accompanied by high temperature and high pressure oil-water layer conditions. Under such conditions, the oil-water transition zone is thicker. 2 Chemical burial first will not only affect the oil recovery rate, but also reduce the physical burial volume at this stage. Therefore, it is necessary to classify the depth of the oil-water layer and the temperature and pressure conditions. ⑥ The mineralization of the formation water in the oil-water layer should be kept within a reasonable range to ensure that there are sufficient seepage channels to produce crude oil and chemical burial can be achieved. Therefore, it is necessary to classify the mineralization of the formation water in the oil-water layer.

[0078] According to the basic conditions of the example area, the porosity, permeability, oil saturation, crude oil density, cap rock thickness, buried layer thickness, and formation water salinity of the oil and water layers can be divided into three categories: good (I), medium (II), and poor (III). Due to the large depth of the reservoir and the high temperature of the reservoir, all of them are CO 2 The adverse factors of oil displacement and burial storage are not further classified. Considering the above “6 factors”, the data of the example area are specifically classified as shown in Table 3.

[0079] Table 3 CO 2 Suitability classification standard for oil displacement-physical and chemical storage stage

[0080]

[0081] (3) CO based on the six-factor method 2 Classification of suitability of chemical storage stages

[0082] In CO 2 During the chemical storage stage, the injection target is the pure water layer at the bottom of the reservoir. During this stage, almost no crude oil is produced. 2 The main process is chemical reaction with formation water. According to the characteristics of this stage, the following five factors are considered. ① The storage object at this stage is a high-mineralization water layer. There is no need to consider factors such as blocking the seepage channel after the operation. Therefore, it can be classified according to the content of each ion in the formation water. ② Different water types have different effects on CO 2 ③This stage also requires the target storage water layer to have a certain thickness and seepage capacity to ensure supercritical CO 2 ④ The upper part of the target water layer needs to have a complete, dense, and certain thickness of cap layer to ensure the smooth injection of CO 2 The pressure system is stable during the storage operation, and there is no cross-flow with other layers. No leakage will occur for a long time after the operation is completed. ⑤ When the oil saturation of the target water layer is low, the injected supercritical CO 2 The storage efficiency will be significantly improved, so it is necessary to classify the oil saturation. ⑥ The deeper the water layer, the greater the temperature and pressure, which will significantly affect the CO2 Solubility in water, therefore it is necessary to classify it according to the depth of the water layer and temperature and pressure conditions.

[0083] According to the basic conditions of the listed area, the porosity, permeability, oil saturation, formation water mineralization, cap rock thickness, and buried layer thickness of the oil layer can be divided into three categories: good (I), medium (II), and poor (III). The oil reservoir is deep and has a high temperature, both of which are CO 2 The disadvantages of chemical storage are that the water type is uniform, which is Ca 2 CL water type, so these factors are not further classified. Considering the above "6 factors", the data of the example area are specifically classified as shown in Table 4.

[0084] Table 4 Classification criteria for suitability of CO2 chemical storage stages

[0085]

[0086] (4)CO 2 Oil displacement-buried storage logging identification and 3D visualization classification

[0087] First, use the single well logging curve data characteristics to make a preliminary identification. Suitable for storing CO 2 The site needs a dense caprock with a certain thickness to ensure the injection of CO 2 The target reservoir should not escape and should also have a certain thickness to be suitable for burial. Figure 2 As shown in the figure, at 3302.2m-3345m of Well W1 in the example area, the porosity and permeability curves have continuous "stable sections" at both low and high values, which means that a single well can be used to preliminarily locate this area suitable for storing CO 2 The reservoir classification phase model shows that there are 5 meters and 10 meters of high-quality interlayers in this section respectively. The fluid classification phase model shows that the reservoir fluid here is an oil layer. The buried layer-cap layer model shows that there is a good cap layer here. 2 The storage classification model shows that the area is mainly composed of Class II storage layers, with Class I storage layers locally. The three-stage model shows that the area is an oil layer CO 2 Displacement-physical storage stage, the three-stage classification model shows that the oil layer CO 2 Displacement-physical burial stage is mainly based on type II burial layer. Figure 3 As shown in Figure 2, at 3078.4m-3105m of Well W3, the porosity and permeability curves are not in a relatively stable state, and the interlayers in this section of the reservoir have not reached the effective thickness. Therefore, it can be directly judged that this section does not meet the CO 2 There is no data for the corresponding storage models in this location.

[0088] A three-stage model of CO2 flooding and storage was established based on the CO2 flooding and storage standard of the example area. Figure 4), and further establish a three-stage classification model of CO2 flooding and storage in the case area ( Figure 5 ), comparing the W1 reservoir 3D model with the CO2 flooding-storage three-stage classification 3D model cross-section ( Figure 6-Figure 7 ) to test the reliability of its model.

[0089] Furthermore, CO 2 The visualization classification evaluation of oil displacement is as follows:

[0090] Combined with the three-stage classification model, CO 2 Oil displacement-physical storage stage and CO 2 During the oil recovery-physical and chemical storage phase, CO 2 A visualization classification model of oil displacement is used to calculate various oil displacements. First, multiple core displacement experiments are conducted to calculate the oil exchange rate. Under reservoir conditions, CO is injected into two cores with different crude oil saturations. 2 , determination of CO 2 Oil displacement-physical storage stage and CO 2 The maximum oil change rate in the oil displacement-physical and chemical storage stage, the oil change rate curve of the example area is as follows Figure 8 As shown, the oil displacement coefficient is calculated to be 0.915.

[0091] Combined with the three-stage classification model of the instance area, CO 2 Oil displacement-physical storage stage, CO 2 Visual classification modeling of oil displacement during oil displacement-physical and chemical storage stage ( Figure 9-14 ), and calculated the displacement of various types of oil (Table 5). 2 Oil displacement-physical storage stage, CO 2 During the oil displacement-physical and chemical storage stage, a total of about 8.31 million tons of crude oil was displaced and produced.

[0092] Table 5 CO 2 Visual classification calculation results of oil displacement

[0093]

[0094] Furthermore, CO 2 The visualization and classification evaluation of the buried stock in stages is as follows:

[0095] Combined with the three-stage classification model, CO 2 The storage visualization and classification model of CO 2 Oil displacement-physical storage stage storage classification model, establishment of CO2 storage coefficient method 2 The storage capacity classification model of oil displacement-physical and chemical storage stage and the establishment of CO storage coefficient method 2The storage capacity classification model of the chemical storage stage is finally calculated. The storage capacity of each stage and each type of storage capacity is calculated. The storage coefficient includes the physical storage coefficient and the chemical storage coefficient. In miscible flooding, the physical storage coefficient is 2.475, that is, for every 1kg of crude oil added to the ground, 2.475kg of CO 2 ;CO 2 After dissolving in formation water, it will react with high-mineralization formation water after a period of time to achieve mineralization storage. The amount of mineralization storage is related to the content of formation water in the target layer. 2 The storage calculation formula is shown in formula (1). Its chemical storage coefficient changes with reservoir conditions and is a non-fixed value.

[0096] Mco 2 =Mw·x

[0097]

[0098] Where:

[0099] M CO2 —CO 2 Buried stock, kg;

[0100] Mw—water content, kg;

[0101] x—chemical burial coefficient;

[0102] M CO2 —CO 2 Buried stock, kg;

[0103] Φ—average porosity, %;

[0104] —CO 2 Solubility at reservoir conditions, kg / kg;

[0105] S w —Average oil saturation, %;

[0106] V w —Model water grid volume, m 3 ;

[0107] —CO 2 Density at reservoir temperature and pressure, kg / m 3 ;

[0108] (1) CO based on the storage coefficient method 2 Modeling and calculation of storage volume classification in the oil displacement-physical storage stage

[0109] According to CO 2The 3D models of Class I, Class II, and Class III in the oil displacement-physical storage stage are designed. Considering the characteristics of this stage where only physical storage occurs, the physical storage coefficient is calculated first, and then the CO 2 CO2 in the oil recovery and physical storage stage 2 The storage capacity classification model is used to calculate the storage capacity of each category. 2 3D model of Class I, Class II, and Class III storage distribution in the oil displacement-physical storage stage Figure 15-17 The classification calculation results of its storage volume are shown in Table 6.

[0110] Table 6 CO 2 Calculation results of storage volume during oil displacement-physical and chemical storage phase

[0111]

[0112] (2) CO based on the storage coefficient method 2 Classification modeling and calculation of storage volume in the oil displacement-physical and chemical storage stage

[0113] According to CO 2 The 3D models of Class I, Class II, and Class III of the oil displacement-physical and chemical storage stage are combined with the characteristics of physical and chemical storage in this stage. The physical storage coefficient and chemical storage coefficient are calculated first, and then the CO 2 CO2 in the oil recovery and physical storage stage 2 Sediment storage classification modeling and calculation of various types of sequestration storage. 2 The 3D model of the storage volume distribution of Class I, Class II, and Class III in the oil displacement-physical and chemical storage stage is as follows Figure 18-Figure 20 The classification calculation results of its storage volume are shown in Table 7.

[0114] Table 7 CO 2 Calculation results of storage volume during oil displacement-physical and chemical storage phase

[0115]

[0116] (3) CO based on the storage coefficient method 2 Classification modeling and calculation of chemical storage volume

[0117] According to CO 2 The 3D models of Class I, Class II, and Class III in the chemical storage stage are designed to calculate the chemical storage coefficient first, and then perform CO 2 CO2 in the oil recovery and physical storage stage 2 The storage capacity is classified and modeled, and the storage capacity of each type is calculated. 2 The 3D model of the distribution of Class I, Class II, and Class III storage in the chemical storage stage is as follows: Figure 21-23 The classification calculation results of its storage volume are shown in Table 8.

[0118] Table 8 CO 2 Calculation results of chemical storage stage

[0119]

[0120] Statistical example area S4 section through supercritical CO 2 Various CO 2 The total geological storage is about 22 million tons.

[0121] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A three-stage visual classification evaluation method for CO2 flooding and geological storage, characterized in that: The following specific steps are included: S1: Conduct three-dimensional visual classification evaluation of the three stages of CO2 flooding and storage, including: S101: Suitability classification of CO2 flooding-physical storage stage based on five-factor method; S102: Suitability classification of CO2 flooding-physical and chemical storage stage based on the six-factor method; S103: Classification of suitability of CO2 chemical storage stages based on the six-factor method; S104: CO2 flooding - burial logging identification and 3D visualization classification evaluation; S2: Combined with the three-stage three-dimensional visualization classification model, a visualization classification model for CO2 oil displacement in the CO2 oil displacement-physical storage stage and the CO2 oil displacement-physical and chemical storage stage is established to calculate various oil displacements, including: firstly, multiple groups of core displacement experiments are conducted to calculate the oil exchange rate, CO2 is injected into two groups of cores with different crude oil saturations under reservoir conditions, the maximum oil exchange rate in the CO2 oil displacement-physical storage stage and the CO2 oil displacement-physical and chemical storage stage is measured, and the oil displacement coefficient is calculated; S3: Combined with the three-stage three-dimensional visualization classification model, a visualization classification model for CO2 storage capacity is established in stages, including the establishment of a classification model for CO2 oil recovery-physical storage stage based on the storage coefficient method, the establishment of a classification model for CO2 oil recovery-physical and chemical storage stage based on the storage coefficient method, and the establishment of a classification model for CO2 chemical storage stage based on the storage coefficient method. Finally, the storage capacity of each stage and type is calculated. The steps of establishing a storage capacity classification model for the CO2 flooding-physical storage stage based on the storage coefficient method and calculating the storage capacity of each type are specifically as follows: based on the Class I, Class II, and Class III 3D models of the CO2 flooding-physical storage stage, combined with the characteristics that only physical storage occurs in this stage, the physical storage coefficient is first calculated, and then the CO2 storage capacity classification modeling for the CO2 flooding-physical storage stage is performed and each type of storage capacity is calculated; The steps of establishing a storage capacity classification model for the CO2 flooding-physical and chemical storage stage based on the storage coefficient method and calculating the various storage capacities are specifically as follows: based on the Class I, Class II, and Class III 3D models of the CO2 flooding-physical and chemical storage stage, combined with the characteristics of physical and chemical storage occurring in this stage, first calculate the physical storage coefficient and the chemical storage coefficient, then perform a classification modeling of the CO2 storage capacity in the CO2 flooding-physical storage stage and calculate various storage capacities; The steps of establishing a classification model for the CO2 storage capacity in the chemical storage stage based on the storage coefficient method and calculating each type of storage capacity are specifically as follows: based on the Class I, Class II, and Class III 3D models of the CO2 chemical storage stage, combined with the characteristics that only chemical storage occurs in this stage, the chemical storage coefficient is first calculated, and then the CO2 storage capacity classification modeling for the CO2 oil recovery-physical storage stage is carried out, and each type of storage capacity is calculated.

2. A three-stage visual classification evaluation method for CO2 oil recovery and geological storage according to claim 1, characterized in that: The step S101 specifically includes: according to suitability, the five influencing factors of the CO2 oil recovery-physical storage stage are divided into three categories: I, II, and III, wherein the five influencing factors include the porosity, permeability, oil saturation, crude oil density, and storage layer thickness of the oil layer.

3. A three-stage visual classification evaluation method for CO2 oil recovery and geological storage according to claim 1, characterized in that: The step S102 specifically includes: according to suitability, the six influencing factors of the CO2 oil recovery-physical and chemical storage stage are divided into three categories: I, II, and III, wherein the six influencing factors include the porosity, permeability, oil saturation, crude oil density, storage layer thickness, and formation water mineralization of the oil-water layer.

4. A three-stage visual classification evaluation method for CO2 oil recovery and geological storage according to claim 1, characterized in that: The step S103 specifically includes: according to suitability, the six influencing factors of the CO2 chemical storage stage are divided into three categories: I, II, and III, where the six influencing factors include the porosity, permeability, oil saturation, formation water mineralization, cap rock thickness, and storage layer thickness of the oil layer.

5. A three-stage visual classification evaluation method for CO2 oil recovery and geological storage according to claim 1, characterized in that: The step S104 specifically includes: using the single well logging curve data characteristics for preliminary identification, establishing a three-stage model of CO2 flooding-storage, and combining the classification of influencing factors in the steps S101 to S103 to establish a visualized CO2 flooding-storage three-stage classification 3D model.

6. A three-stage visual classification evaluation method for CO2 oil recovery and geological storage according to claim 1, characterized in that: The formula for calculating the buried storage volume is: ， ， in: —CO2 storage capacity, kg; Mw—water content, kg; x—chemical burial coefficient; Φ—average porosity, %; —Solubility of CO2 under reservoir conditions, kg / kg; S w —Average oil saturation, %; V w —Model water grid volume, m 3 ; —Density of CO2 at reservoir temperature and pressure, kg / m 3 .

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