Method for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement and device system thereof
By using nuclear magnetic resonance core displacement technology, the amount and capacity of carbon dioxide buried in different types of pores were calculated, which solved the problem of lack of microscopic evaluation in the existing technology, realized the accurate assessment of carbon dioxide burial capacity, and improved the completeness of the burial mechanism.
Patent Information
- Application Number
- CN202110887675.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-08-03
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2041-08-03
AI Technical Summary
Existing methods for calculating carbon dioxide reserves mainly focus on macroscopic perspectives and do not involve microscopic calculations, thus failing to comprehensively evaluate the carbon dioxide storage capacity in depleted oil and gas reservoirs.
The method based on nuclear magnetic resonance core displacement is adopted. By obtaining T2 relaxation time and T2 amplitude values, T2 spectrum diagram is drawn, the core is divided into different types of pores, the pore volume and carbon dioxide saturation are calculated, and then the burial amount and burial capacity in each type of pore are calculated.
This study provides a method for evaluating carbon dioxide storage capacity from a microscopic perspective, which enriches existing evaluation methods, improves the accuracy of storage mechanisms and the fit with actual production, and is applicable to evaluating carbon dioxide storage capacity in depleted oil and gas reservoirs.
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Figure CN115704785B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of carbon dioxide storage technology, and relates to a method for evaluating carbon dioxide storage capacity, and more particularly to a method and apparatus system for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement. Background Technology
[0002] Currently, large-scale industrial carbon dioxide emission reduction is mainly achieved globally through "Chemical Carbon Dioxide Storage and Utilization (CCUS)." CCUS refers to the process of separating, capturing, and injecting carbon dioxide from concentrated emission sources in industry or related energy sources into suitable deep underground strata, where it is stored underground through physical and chemical processes and isolated from the atmosphere for a long period. Common storage sites include depleted oil and gas reservoirs, unexploitable coal seams, deep salt marshes, and deep aquifers. Among these, utilizing depleted oil and gas reservoirs for carbon dioxide storage can both achieve greenhouse gas storage and improve oil and gas recovery rates.
[0003] Calculating carbon dioxide (CO2) reserves and evaluating its storage capacity are crucial research tasks in CCUS (Carbon Dioxide Storage and Retention) processes. Currently, the main storage mechanisms of CO2 in depleted oil and gas reservoirs and saline aquifers include: structural trap storage, free gas storage, dissolution storage, and mineral storage. Furthermore, existing methods for calculating CO2 reserves include: volumetric methods, area methods, solubility methods, storage mechanism methods, capacity factor methods, and numerical simulation methods. However, current methods for calculating CO2 reserves and evaluating its storage capacity are all macroscopic in nature, neglecting microscopic calculation methods.
[0004] Therefore, how to provide a method for evaluating carbon dioxide storage capacity and calculate the amount of carbon dioxide stored from a microscopic perspective, thereby further supplementing and improving the storage mechanism of carbon dioxide in depleted oil and gas reservoirs, has become an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention
[0005] The purpose of this invention is to provide a method and apparatus system for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a method for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement, the method comprising the following steps:
[0008] (1) Based on the carbon dioxide burial experiment of nuclear magnetic resonance core displacement, the T2 relaxation time and T2 amplitude value were obtained;
[0009] (2) Based on the T2 relaxation time and T2 amplitude values obtained in step (1), draw the T2 spectrum diagram of the core, divide the core into different types of pores, and calculate the pore volume of each type of pore and the saturation of carbon dioxide in each type of pore.
[0010] (3) Calculate the amount of carbon dioxide buried in each type of pore based on the pore volume and saturation obtained in step (2);
[0011] (4) Evaluate the carbon dioxide storage capacity in various types of pores based on the storage amount obtained in step (3).
[0012] This invention provides a method for calculating the carbon dioxide storage capacity and burial capacity in different types of pores at the core scale by combining core displacement experiments and nuclear magnetic resonance testing. It is suitable for evaluating the carbon dioxide burial capacity of depleted oil and gas reservoirs from a microscopic perspective. In essence, it is an extension of the free gas burial mechanism. Its core is that it can characterize the carbon dioxide burial capacity in different pores within the reservoir, thereby further supplementing and improving the carbon dioxide burial mechanism in depleted oil and gas reservoirs.
[0013] Preferably, the carbon dioxide burial experiment based on nuclear magnetic resonance core displacement described in step (1) includes the following steps:
[0014] (A) Clean the core and measure its permeability and dry weight in sequence;
[0015] (B) After vacuuming the core, immerse it in simulated formation water until saturation, measure the wet weight of the core, and sample the core using the first nuclear magnetic resonance T2 spectrum;
[0016] (C) Apply confining pressure to the core, and after the confining pressure stabilizes, use manganese chloride solution to displace the simulated formation water in the core. After the displacement is complete, stop the displacement and perform second nuclear magnetic resonance T2 spectrum sampling on the core.
[0017] (D) The manganese chloride solution in the core was displaced by simulated oil. After the displacement was complete, the displacement was stopped, and the core was sampled by the third nuclear magnetic resonance T2 spectrum.
[0018] (E) The simulated oil in the core was displaced using manganese chloride solution. The displacement was stopped when the water content of the produced fluid at the core outlet was 97-99 wt%. The core was then sampled using the fourth nuclear magnetic resonance T2 spectrum.
[0019] (F) Inject carbon dioxide gas into the core, and stop the displacement after the oil content of the produced fluid at the core outlet reaches a constant state. Then, perform fifth nuclear magnetic resonance T2 spectrum sampling on the core.
[0020] In this invention, step (E) ends when the water content of the produced liquid at the core outlet reaches 97-99 wt%, for example, it can be 97 wt%, 97.2 wt%, 97.4 wt%, 97.6 wt%, 97.8 wt%, 98 wt%, 98.2 wt%, 98.4 wt%, 98.6 wt%, 98.8 wt%, or 99 wt%, but it is not limited to the listed values. Other unlisted values within this range are also applicable.
[0021] This invention terminates displacement when the water content of the produced fluid at the core outlet reaches 97-99 wt%. At this point, the oil-water composition in the core is closest to that in a depleted oil and gas reservoir. Subsequent carbon dioxide injection is then carried out, which better reflects the actual carbon dioxide burial process and improves the consistency between the carbon dioxide burial mechanism in depleted oil and gas reservoirs and actual production.
[0022] The rock core used in this invention can be an artificial sandstone resin cemented rock core, which helps to avoid the chemical reaction between carbon dioxide and the clay minerals of the real rock core, which would block the pores. It also prevents the extraction of carbon dioxide from crude oil, which would produce asphaltene precipitation that would block the pores and destroy the original pore space.
[0023] This invention utilizes manganese chloride solution to replace simulated formation water displacement in establishing oil-water relationships in depleted oil and gas reservoirs, aiming to eliminate water... 1 The effect of H signal on the results of nuclear magnetic resonance testing.
[0024] Preferably, the simulated formation water in steps (B) and (C) is independently a sodium chloride solution.
[0025] Preferably, the salinity of the sodium chloride solution is 14-16 g / L, for example, it can be 14 g / L, 14.2 g / L, 14.4 g / L, 14.6 g / L, 14.8 g / L, 15 g / L, 15.2 g / L, 15.4 g / L, 15.6 g / L, 15.8 g / L or 16 g / L, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0026] Preferably, step (C) involves applying confining pressure to the core using fluorinated oil.
[0027] Preferably, the mineralization of the manganese chloride solution in steps (C), (D) and (E) is independently 14-16 g / L, for example, it can be 14 g / L, 14.2 g / L, 14.4 g / L, 14.6 g / L, 14.8 g / L, 15 g / L, 15.2 g / L, 15.4 g / L, 15.6 g / L, 15.8 g / L or 16 g / L, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0028] Preferably, the simulated oil in steps (D) and (E) is anhydrous kerosene, each independently.
[0029] Preferably, the displacement liquid phase velocity in steps (C), (D) and (E) is independently 0.04-0.06 mL / min, for example, it can be 0.04 mL / min, 0.042 mL / min, 0.044 mL / min, 0.046 mL / min, 0.048 mL / min, 0.05 mL / min, 0.052 mL / min, 0.054 mL / min, 0.056 mL / min, 0.058 mL / min or 0.06 mL / min, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0030] Preferably, the injection rate of the gas phase in step (F) is 0.04-0.06 mL / min, for example, it can be 0.04 mL / min, 0.042 mL / min, 0.044 mL / min, 0.046 mL / min, 0.048 mL / min, 0.05 mL / min, 0.052 mL / min, 0.054 mL / min, 0.056 mL / min, 0.058 mL / min or 0.06 mL / min, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0031] Preferably, the absolute pressure injected in step (F) is 8-12 MPa, for example, it can be 8 MPa, 8.5 MPa, 9 MPa, 9.5 MPa, 10 MPa, 10.5 MPa, 11 MPa, 11.5 MPa or 12 MPa, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0032] Preferably, the classification standard for each type of pore in step (2) is the T2 relaxation time, and the types of pores are divided into micropores, small pores, medium pores and large pores.
[0033] Preferably, the T2 relaxation time period corresponding to the micropores is <1ms.
[0034] Preferably, the T2 relaxation time period corresponding to the small pore is 1-10ms.
[0035] Preferably, the T2 relaxation time period corresponding to the mesopore is 10-100ms.
[0036] Preferably, the T2 relaxation time period corresponding to the large pore size is >100ms.
[0037] Preferably, the formula for calculating the pore volume of each type of pore in step (2) is as follows:
[0038]
[0039] In the formula, The pore volume of the micropores is expressed in cm³. 3 ; The pore volume of the small pores is expressed in cm³. 3 ; The pore volume is the mesopore size, expressed in cm³. 3 ; The pore volume of the macropores is expressed in cm. 3 ; These correspond to the time points when the T2 relaxation time is at its minimum, maximum, 1ms, 10ms, and 100ms, respectively. The T2 amplitude value represents the core sample immersed in simulated formation water to saturation. The dry weight of the core is expressed in grams. The wet weight of the core, in grams; To simulate the density of formation water, g / cm³ 3 .
[0040] Preferably, the formula for calculating the saturation of carbon dioxide in various types of pores in step (2) is as follows:
[0041]
[0042] In the formula, The saturation level of carbon dioxide in micropores, % The saturation level of carbon dioxide in small pores, % The saturation level of carbon dioxide in the mesopores, % The saturation level of carbon dioxide in macropores, % The T2 amplitude value is the core sample immersed in simulated formation water to saturation within the micropore range; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution within the micropore range; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection within the micropore range; The T2 amplitude value is the simulated formation water saturation state of the core sample within the small pore area; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the small pore area; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection within the small pore area; The T2 amplitude value is the core sample immersed in simulated formation water to saturation within the mesopore range; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the mesopore range; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection in the mesopore range; The T2 amplitude value is the simulated formation water saturation state when the core sample is immersed in the macropore region. The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the macropore region; The T2 amplitude value represents the residual simulated oil in the core after carbon dioxide gas injection within the large pore area.
[0043] Preferably, the formula for calculating the amount of carbon dioxide buried in various types of pores in step (3) is as follows:
[0044]
[0045] In the formula, The amount of carbon dioxide buried in the micropores, in grams; The amount of carbon dioxide buried in the small pores, in grams; The amount of carbon dioxide buried in the mesopores, in grams; The amount of carbon dioxide buried in macropores, in grams; The total amount of carbon dioxide buried in the core, in g.
[0046] Preferably, the formula for evaluating the carbon dioxide storage capacity in various types of pores in step (4) is:
[0047]
[0048] In the formula, This refers to the ability of carbon dioxide to be stored in micropores. This refers to the ability of carbon dioxide to be stored in small pores. The ability of carbon dioxide to be stored in mesopores; This refers to the ability of carbon dioxide to be stored in macropores.
[0049] This invention improves the calculation method of carbon dioxide saturation by representing the carbon dioxide saturation of different types of pores in the reservoir as a piecewise function. It calculates the carbon dioxide storage capacity of different types of pores in the reservoir from a microscopic perspective, enriches and improves the existing evaluation method of carbon dioxide storage capacity, and provides a basis for judging the selection of carbon dioxide storage sites at the microscopic level.
[0050] In a second aspect, the present invention provides an apparatus system for evaluating carbon dioxide storage capacity using the method described in the first aspect, the apparatus system comprising a core displacement unit and a nuclear magnetic resonance testing unit.
[0051] The core displacement unit includes a pump device, an intermediate container, a core holder, and a gas-liquid collector connected in sequence.
[0052] The core holder is also connected to a confining pressure device and a back pressure device.
[0053] The nuclear magnetic resonance testing unit includes a real-time nuclear magnetic resonance instrument, a control system, and a data collection and imaging system.
[0054] The control system and the data acquisition and imaging system are each independently connected to the real-time nuclear magnetic resonance imaging (NMR) instrument.
[0055] The real-time nuclear magnetic resonance (NMR) tester is used to acquire the NMR T2 spectrum of the core in the core holder in real time.
[0056] Compared with the prior art, the present invention has the following beneficial effects:
[0057] (1) This invention provides a method for calculating the amount and capacity of carbon dioxide in different types of pores at the core scale by combining core displacement experiments and nuclear magnetic resonance testing. It is suitable for evaluating the carbon dioxide storage capacity of depleted oil and gas reservoirs from a microscopic perspective. In essence, it is an extension of the free gas storage mechanism. The core is that it can characterize the carbon dioxide storage capacity in different pores within the reservoir, thereby further supplementing and improving the carbon dioxide storage mechanism in depleted oil and gas reservoirs.
[0058] (2) This invention improves the calculation method of carbon dioxide saturation, expresses the carbon dioxide saturation of different types of pores in the reservoir as a piecewise function, calculates the carbon dioxide burial amount of different types of pores in the reservoir from a microscopic perspective, enriches and improves the existing evaluation method of carbon dioxide burial capacity, and provides a basis for judging the selection of carbon dioxide burial sites from a microscopic level. Attached Figure Description
[0059] Figure 1 This is a flowchart of a method for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement provided by the present invention;
[0060] Figure 2 This is the T2 spectrum of a core obtained by a method for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement provided by this invention;
[0061] Figure 3 This is a schematic diagram of a device system for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement, provided by the present invention.
[0062] Among them: 10-ISCO pump; 20-intermediate container; 21-carbon dioxide container; 22-simulated oil container; 23-manganese chloride solution container; 30-core holder; 40-gas-liquid collector; 50-containing pressure device; 51-containing pressure pump; 52-fluorinated oil container; 60-backpressure device; 61-backpressure pump; 62-backpressure regulator; 70-real-time nuclear magnetic resonance spectrometer; 80-control system; 90-data collection and imaging system. Detailed Implementation
[0063] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0064] This invention provides a method for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement, such as... Figure 1 As shown, the method includes the following steps:
[0065] S101. Carbon dioxide burial experiment based on nuclear magnetic resonance core displacement to obtain T2 relaxation time and T2 amplitude value;
[0066] S102. Based on the T2 relaxation time and T2 amplitude values obtained in S101, draw the T2 spectrum diagram of the core, classify the core into different types of pores, and calculate the pore volume of each type of pore and the saturation of carbon dioxide in each type of pore.
[0067] S103. Based on the pore volume and saturation obtained in S102, calculate the amount of carbon dioxide buried in each type of pore.
[0068] S104. Based on the burial amount obtained in S103, evaluate the burial capacity of carbon dioxide in various types of pores.
[0069] Example 1
[0070] This embodiment provides a method and apparatus system for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement. The method includes the following steps:
[0071] (1) Carbon dioxide burial experiment based on nuclear magnetic resonance core displacement, obtaining T2 relaxation time and T2 amplitude values; the carbon dioxide burial experiment based on nuclear magnetic resonance core displacement includes the following steps:
[0072] (A) Clean the core with acetone, dry and cool to room temperature, and measure the permeability and dry weight of the core in sequence;
[0073] (B) After vacuuming the core for 48 hours using a vacuum pump, the core was immersed in simulated formation water until saturation. The wet weight of the core was measured, and the core was sampled for the first nuclear magnetic resonance T2 spectrum.
[0074] (C) Fluorine oil was used to apply confining pressure to the core. After the confining pressure stabilized, manganese chloride solution was used to displace the simulated formation water in the core at a liquid phase rate of 0.05 mL / min. After the displacement was complete, the displacement was stopped, and the core was sampled for the second nuclear magnetic resonance T2 spectrum.
[0075] (D) The manganese chloride solution in the core was displaced by simulated oil at a liquid phase rate of 0.05 mL / min. After the displacement was complete, the displacement was stopped, and the core was sampled for the third nuclear magnetic resonance T2 spectrum.
[0076] (E) The simulated oil in the core was displaced by manganese chloride solution at a liquid phase rate of 0.05 mL / min. The displacement was stopped when the water content of the produced liquid at the core outlet was 98 wt%. The core was then sampled for the fourth nuclear magnetic resonance T2 spectrum.
[0077] (F) Carbon dioxide gas was injected into the core at an absolute pressure of 10 MPa and a gas phase velocity of 0.05 mL / min. Displacement was stopped after the oil content of the produced liquid at the core outlet reached a constant state, and the core was sampled for the fifth nuclear magnetic resonance T2 spectrum.
[0078] In this process, the simulated formation water in steps (B) and (C) is a sodium chloride solution with a salinity of 15 g / L; the manganese chloride solution in steps (C), (D) and (E) has a salinity of 15 g / L; and the simulated oil in steps (D) and (E) is anhydrous kerosene.
[0079] (2) Based on the T2 relaxation time and T2 amplitude value obtained in step (1), plot as follows Figure 2 The T2 spectrum of the core is shown. The core is divided into different types of pores according to the T2 relaxation time. Each type of pore is further divided into micropores (T2 < 1 ms), small pores (1 ms < T2 < 10 ms), medium pores (10 ms < T2 < 100 ms), and large pores (T2 > 100 ms). The pore volume of each type of pore and the saturation of carbon dioxide in each type of pore are calculated.
[0080] The methods for calculating the pore volume of each type of pore are as follows:
[0081] Taking micropores as an example, the total pore volume of the core is first calculated as follows:
[0082]
[0083] Secondly, based on the classified pore types, the volume percentage of micropores is calculated as follows:
[0084]
[0085] Finally, based on the total pore volume and the proportion of micropores in the core, the pore volume of the micropores is calculated as follows:
[0086]
[0087] Similarly, we can conclude that:
[0088] The pore volume of the small pores is:
[0089]
[0090] The pore volume of the mesopores is:
[0091]
[0092] The pore volume of large pores is:
[0093]
[0094] In the formula, The pore volume of the micropores is expressed in cm³. 3 ; The pore volume of the small pores is expressed in cm³. 3 ; The pore volume is the mesopore size, expressed in cm³. 3 ; The pore volume of the macropores is expressed in cm. 3 ; These correspond to the time points when the T2 relaxation time is at its minimum, maximum, 1ms, 10ms, and 100ms, respectively. The T2 amplitude value represents the core sample immersed in simulated formation water to saturation. The dry weight of the core is expressed in grams. The wet weight of the core, in grams; To simulate the density of formation water, g / cm³ 3 .
[0095] The methods for calculating the saturation of carbon dioxide in various types of pores are as follows:
[0096] Taking micropores as an example, the residual simulated oil saturation in the core after displacement by manganese chloride solution within the micropore range is first calculated as follows:
[0097]
[0098] Secondly, the remaining simulated oil saturation in the core after carbon dioxide gas injection within the micropore range is calculated as follows:
[0099]
[0100] Because the designed carbon dioxide burial experiment eliminated changes in the original pore space caused by the chemical reaction between carbon dioxide and rocks and the interaction between carbon dioxide and crude oil, and because manganese chloride solution was used to replace simulated formation water displacement, the effects of water displacement were eliminated. 1 The influence of H signal on the nuclear magnetic resonance test results shows that the decrease in oil saturation after carbon dioxide gas injection is the increase in carbon dioxide saturation.
[0101] Therefore, the saturation degree of carbon dioxide in the micropores is:
[0102]
[0103] Similarly, we can conclude that:
[0104] The saturation of carbon dioxide in small pores is:
[0105]
[0106] The saturation level of carbon dioxide in mesopores is:
[0107]
[0108] The saturation level of carbon dioxide in macropores is:
[0109]
[0110] In the formula, The saturation level of carbon dioxide in micropores, % The saturation level of carbon dioxide in small pores, % The saturation level of carbon dioxide in the mesopores, % The saturation level of carbon dioxide in macropores, % The T2 amplitude value is the core sample immersed in simulated formation water to saturation within the micropore range; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution within the micropore range; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection within the micropore range; The T2 amplitude value is the simulated formation water saturation state of the core sample within the small pore area; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the small pore area; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection within the small pore area; The T2 amplitude value is the core sample immersed in simulated formation water to saturation within the mesopore range; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the mesopore range; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection in the mesopore range; The T2 amplitude value is the simulated formation water saturation state when the core sample is immersed in the macropore region. The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the macropore region; The T2 amplitude value represents the residual simulated oil in the core after carbon dioxide gas injection within the large pore area.
[0111] (3) Based on the pore volume and saturation obtained in step (2), calculate the amount of carbon dioxide buried in each type of pore. The specific calculation method is as follows:
[0112] The amount of carbon dioxide buried in micropores is:
[0113]
[0114] The amount of carbon dioxide buried in small pores is:
[0115]
[0116] The amount of carbon dioxide buried in mesopores is:
[0117]
[0118] The amount of carbon dioxide buried in macropores is:
[0119]
[0120] The total amount of carbon dioxide buried in the core is:
[0121]
[0122] In the formula, The amount of carbon dioxide buried in the micropores, in grams; The amount of carbon dioxide buried in the small pores, in grams; The amount of carbon dioxide buried in the mesopores, in grams; The amount of carbon dioxide buried in macropores, in grams; The total amount of carbon dioxide buried in the core, in g.
[0123] (4) Based on the amount of carbon dioxide buried in step (3), evaluate the carbon dioxide burial capacity in various types of pores. The specific evaluation method is as follows:
[0124] The carbon dioxide storage capacity in micropores is:
[0125]
[0126] The ability of carbon dioxide to be stored in small pores is:
[0127]
[0128] The carbon dioxide storage capacity in mesopores is:
[0129]
[0130] The carbon dioxide storage capacity in macropores is:
[0131]
[0132] In the formula, This refers to the ability of carbon dioxide to be stored in micropores. This refers to the ability of carbon dioxide to be stored in small pores. The ability of carbon dioxide to be stored in mesopores; This refers to the ability of carbon dioxide to be stored in macropores.
[0133] Furthermore, this embodiment also provides an apparatus system for evaluating carbon dioxide storage capacity using the above method, such as... Figure 3 As shown, the device system includes a core displacement unit and a nuclear magnetic resonance testing unit.
[0134] In this embodiment, the core displacement unit includes an ISCO pump 10, an intermediate container 20, a core holder 30, and a gas-liquid collector 40 connected in sequence; the core holder 30 is also connected to a confining pressure device 50 and a backpressure device 60. The intermediate container 20 includes a carbon dioxide container 21, a simulated oil container 22, and a manganese chloride solution container 23 connected in parallel; the confining pressure device 50 includes a confining pressure pump 51 and a fluorinated oil container 52 connected in sequence; the backpressure device 60 includes a backpressure pump 61 and a backpressure regulator 62 connected in sequence.
[0135] In this embodiment, the nuclear magnetic resonance testing unit includes a real-time nuclear magnetic resonance instrument 70, a control system 80, and a data collection and imaging system 90; the control system 80 and the data collection and imaging system 90 are independently connected to the real-time nuclear magnetic resonance instrument 70; the real-time nuclear magnetic resonance instrument 70 is used to acquire the nuclear magnetic resonance T2 spectrum of the core in the core holder 30 in real time.
[0136] Therefore, this invention provides a method for calculating the carbon dioxide burial amount and capacity in different types of pores at the core scale by combining core displacement experiments and nuclear magnetic resonance testing. This method is suitable for evaluating the carbon dioxide burial capacity of depleted oil and gas reservoirs from a microscopic perspective. Essentially, it is an extension of the free gas burial mechanism, with the core being its ability to characterize the carbon dioxide burial capacity in different pores within the reservoir, thus further supplementing and improving the carbon dioxide burial mechanism in depleted oil and gas reservoirs. Furthermore, this invention improves the calculation method for carbon dioxide saturation by representing the carbon dioxide saturation of different types of pores in the reservoir as a piecewise function, calculating the carbon dioxide burial amount in different types of pores from a microscopic perspective. This enriches and improves existing methods for evaluating carbon dioxide burial capacity and provides a microscopic basis for selecting carbon dioxide burial sites.
[0137] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A method for evaluating carbon dioxide storage capacity based on nuclear magnetic resonance core displacement, characterized in that, The method includes the following steps: (1) Based on the carbon dioxide burial experiment of nuclear magnetic resonance core displacement, the T2 relaxation time and T2 amplitude value were obtained; (2) Based on the T2 relaxation time and T2 amplitude values obtained in step (1), draw the T2 spectrum diagram of the core, classify the core into different types of pores, and calculate the pore volume and carbon dioxide saturation in each type of pore. The classification standard for each type of pore is the T2 relaxation time, and the types of pores are divided into micropores, small pores, medium pores and large pores. The T2 relaxation time period corresponding to the micropores is <1ms, the T2 relaxation time period corresponding to the small pores is 1-10ms, the T2 relaxation time period corresponding to the medium pores is 10-100ms, and the T2 relaxation time period corresponding to the large pores is >100ms. (3) Calculate the amount of carbon dioxide buried in each type of pore based on the pore volume and saturation obtained in step (2); (4) Evaluate the carbon dioxide storage capacity in various types of pores based on the storage amount obtained in step (3); The carbon dioxide burial experiment based on nuclear magnetic resonance core displacement described in step (1) includes the following steps: (A) Clean the core and measure its permeability and dry weight in sequence; (B) After vacuuming the core, immerse it in simulated formation water until saturation, measure the wet weight of the core, and sample the core using the first nuclear magnetic resonance T2 spectrum; (C) Apply confining pressure to the core, and after the confining pressure stabilizes, use manganese chloride solution to displace the simulated formation water in the core. After the displacement is complete, stop the displacement and perform second nuclear magnetic resonance T2 spectrum sampling on the core. (D) The manganese chloride solution in the core was displaced by simulated oil. After the displacement was complete, the displacement was stopped, and the core was sampled by the third nuclear magnetic resonance T2 spectrum. (E) The simulated oil in the core was displaced using manganese chloride solution. The displacement was stopped when the water content of the produced fluid at the core outlet was 97-99 wt%. The core was then sampled using the fourth nuclear magnetic resonance T2 spectrum. (F) Inject carbon dioxide gas into the core, and stop the displacement after the oil content of the produced fluid at the core outlet reaches a constant state. Then, perform fifth nuclear magnetic resonance T2 spectrum sampling on the core. The formula for calculating the pore volume of each type of pore in step (2) is as follows: In the formula, The pore volume of the micropores is expressed in cm³. 3 ; The pore volume of the small pores is expressed in cm³. 3 ; The pore volume is the mesopore size, expressed in cm³. 3 ; The pore volume of the macropores is expressed in cm. 3 ; These correspond to the time points when the T2 relaxation time is at its minimum, maximum, 1ms, 10ms, and 100ms, respectively. The T2 amplitude value represents the core sample immersed in simulated formation water to saturation. The dry weight of the core is expressed in grams. The wet weight of the core, in grams; To simulate the density of formation water, g / cm³ 3 ; The formula for calculating the saturation of carbon dioxide in various types of pores in step (2) is as follows: In the formula, The saturation level of carbon dioxide in micropores, % The saturation level of carbon dioxide in small pores, % The saturation level of carbon dioxide in the mesopores, % The saturation level of carbon dioxide in macropores, % The T2 amplitude value is the core sample immersed in simulated formation water to saturation within the micropore range; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution within the micropore range; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection within the micropore range; The T2 amplitude value is the simulated formation water saturation state of the core sample within the small pore area; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the small pore area; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection within the small pore area; The T2 amplitude value is the core sample immersed in simulated formation water to saturation within the mesopore range; The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the mesopore range; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection in the mesopore range; The T2 amplitude value is the simulated formation water saturation state when the core sample is immersed in the macropore region. The T2 amplitude value is the residual simulated oil in the core after displacement by manganese chloride solution in the macropore region; The T2 amplitude value of the simulated oil remaining in the core after carbon dioxide gas injection in the macropore region; The formula for calculating the amount of carbon dioxide buried in various types of pores in step (3) is as follows: In the formula, The amount of carbon dioxide buried in the micropores, in grams; The amount of carbon dioxide buried in the small pores, in grams; The amount of carbon dioxide buried in the mesopores, in grams; The amount of carbon dioxide buried in macropores, in grams; The total amount of carbon dioxide buried in the core, in g.
2. The method according to claim 1, characterized in that, The simulated formation water in steps (B) and (C) is independently a sodium chloride solution.
3. The method according to claim 2, characterized in that, The salinity of the sodium chloride solution is 14-16 g / L.
4. The method according to claim 1, characterized in that, Step (C) involves applying confining pressure to the core using fluorinated oil.
5. The method according to claim 1, characterized in that, The mineralization of the manganese chloride solution described in steps (C), (D) and (E) is independently 14-16 g / L.
6. The method according to claim 1, characterized in that, The simulated oils described in steps (D) and (E) are each independently anhydrous kerosene.
7. The method according to claim 1, characterized in that, The displacement liquid phase velocities described in steps (C), (D), and (E) are each independently 0.04-0.06 mL / min.
8. The method according to claim 1, characterized in that, The gas phase injection rate in step (F) is 0.04-0.06 mL / min.
9. The method according to claim 1, characterized in that, The absolute pressure injected in step (F) is 8-12 MPa.
10. The method according to claim 1, characterized in that, The formula for evaluating the carbon dioxide storage capacity in various types of pores in step (4) is as follows: In the formula, This refers to the ability of carbon dioxide to be stored in micropores. This refers to the ability of carbon dioxide to be stored in small pores. The ability of carbon dioxide to be stored in mesopores; This refers to the ability of carbon dioxide to be stored in macropores.
11. An apparatus system for evaluating carbon dioxide storage capacity using the method described in any one of claims 1-10, characterized in that, The device system includes a core displacement unit and a nuclear magnetic resonance testing unit; The core displacement unit includes a pump device, an intermediate container, a core holder, and a gas-liquid collector connected in sequence. The core holder is also connected to a confining pressure device and a back pressure device; The nuclear magnetic resonance testing unit includes a real-time nuclear magnetic resonance instrument, a control system, and a data acquisition and imaging system; The control system and the data acquisition and imaging system are each independently connected to the real-time nuclear magnetic resonance imaging instrument. The real-time nuclear magnetic resonance (NMR) tester is used to acquire the NMR T2 spectrum of the core in the core holder in real time.