A reservoir difference occurrence state oil-water quantitative analysis method based on thermal gravimetric-infrared combined use

Abstract

The present application belongs to the technical field of oilfield reservoir analysis, and particularly relates to a reservoir difference occurrence state oil-water quantitative analysis method based on thermal gravimetric-infrared combined use. The present application performs thermal gravimetric and infrared online combined measurement analysis on the pretreated core sample, calculates the oil and water content of each occurrence state of the reservoir rock according to the thermal weight loss at each temperature stage in the thermal gravimetric quantitative analysis, and combines the infrared functional group proportion of each occurrence state of oil and water obtained by infrared quantitative analysis in the temperature programming process; each occurrence state of water includes free water, adsorbed water, crystal water and structural water; each occurrence state of oil includes free oil, adsorbed oil and thermal cracking oil. The present application uses the fluid loss amount in the thermal gravimetric quantitative heating process of the temperature programming, continuously quantifies the heating volatile matter through infrared combined measurement, distinguishes the oil and water proportion, and combines temperature interval and component detection to realize accurate evaluation of the oil and water amount of different occurrence states of the reservoir sample.

Description

Technical Field

[0001] This invention belongs to the field of oilfield reservoir analysis technology, specifically relating to a quantitative analysis method for oil and water in reservoir differential occurrence state based on thermogravimetric-infrared spectroscopy. Background Technology

[0002] Accurately assessing the oil content of rock samples is crucial for oil and gas exploration, sweet spot evaluation, and resource calculation. With the continued deepening of oil and gas resource exploration and development, and the simultaneous pursuit of both conventional and unconventional exploration, as well as the exploration of deep and ultra-deep oil and gas resources, the accurate assessment of the fluid content characteristics of rock samples is becoming increasingly important.

[0003] Regardless of the type of oil and gas reservoir, it contains both water and oil phases, which are also the basis for calculating oil saturation. Existing core fluid evaluation techniques aim to evaluate the total amount of oil and water, but cannot quantify fluids such as free oil, adsorbed oil, secondary cracked oil, free water, adsorbed water, crystal water, and structural water. Therefore, they cannot accurately quantify the characteristics of oil and water in the reservoir under different occurrence states.

[0004] Currently, there are many methods for evaluating the oil content of rocks, mainly including Soxhlet extraction, dry distillation, nuclear magnetic resonance, pyrolysis, and fluorescence methods. Among them, Soxhlet extraction utilizes the principle of "like dissolves like." The main components of oil in rocks are various organic hydrocarbon compounds. Polar organic solvents are used to extract oil from core samples to obtain and quantify the oil content characteristics of the core samples. However, the components of oil-based mud are also mainly hydrocarbon compounds. Therefore, this extraction method cannot be used to analyze the water content in the sample.

[0005] The principles of dry distillation and pyrolysis are similar; both involve heating and evaporating the sample to quantitatively analyze the fluids contained within. Dry distillation directly heats the sample at temperatures above 100°C for an extended period, recovering the evaporated fluid components using a condenser, and then uses a calibration method to evaluate the total oil and water content of the reservoir sample. Pyrolysis offers a more precise heating procedure, using programmed temperature control to gradually heat the sample from 300°C to 600°C at a rate of 25°C / min. Infrared and flame ionization detectors are used to quantitatively detect the hydrocarbon volatiles at different temperature stages to determine the oil content, but it cannot quantify the water content.

[0006] Existing fluorescence methods for determining oil content in core samples primarily rely on the typical fluorescence characteristics of hydrocarbon compounds, and the principle that fluorescence intensity is positively correlated with oil content. Similar to extraction methods, this involves first using a non-fluorescent organic solvent and ultrasonic vibration to extract crude oil from the rock sample, obtaining an extract of a certain concentration. Simultaneously, wellhead oil is collected, and by preparing standard solutions of different oil concentrations, a conversion formula between oil content and fluorescence intensity is determined, thereby quantifying the oil content in the rock sample. However, this method cannot quantify water content characteristics.

[0007] Nuclear magnetic resonance (NMR) is a highly efficient and non-destructive method for core fluid analysis. It can quantitatively analyze and evaluate hydrogen-containing fluids. Relying on two-dimensional NMR technology, it can quantitatively evaluate free and adsorbed oils. However, it cannot provide comprehensive information on water content characteristics, and only provides information on total water content characteristics.

[0008] To date, there is a lack of effective methods and means for quantitative analysis of oil and water content in reservoirs under different occurrence states. Therefore, a new method is needed to achieve accurate analysis of oil and water characteristics in reservoirs under different occurrence states. Summary of the Invention

[0009] In view of this, the purpose of this invention is to provide a quantitative analysis method for oil and water in reservoirs based on thermogravimetric-infrared spectroscopy (TGS-IR) combined analysis. The method provided by this invention mainly utilizes TGS-IR technology to determine the thermogravimetric weight loss of fluids in reservoir samples at different temperature stages, and uses infrared spectroscopy to determine the oil and water content, thereby accurately quantifying the oil and water content in different reservoir states. This method can provide direction for conventional, unconventional, and deep / ultra-deep oil and gas exploration, and provide data support for the refined evaluation of reservoir fluids.

[0010] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a quantitative analysis method for reservoir differential occurrence state oil and water based on thermogravimetric-infrared spectroscopy, comprising the following steps: The pretreated core samples were subjected to thermogravimetric and infrared online joint analysis. Based on the thermogravimetric quantitative analysis of the heat loss at each temperature stage, and combined with the proportion of infrared functional groups of oil and water in each occurrence state obtained by infrared quantitative analysis during the programmed heating process, the oil and water content of reservoir rocks in each occurrence state was calculated. Water in various states includes free water, adsorbed water, crystal water, and structural water; Oils in various states include free oil, adsorbed oil, and thermally cracked oil.

[0011] Preferably, the steps of the thermogravimetric and infrared online joint analysis are as follows: under reducing conditions, the core sample is subjected to programmed heating for quantitative thermogravimetric analysis, and the composition at each temperature stage is subjected to quantitative infrared analysis.

[0012] Preferably, the total fluid thermal weight loss A1 for the heating stage to 80°C is determined by the quantitative analysis of thermal weight loss, where A1 = thermal weight loss at this temperature stage / M × 100%; the total fluid thermal weight loss A2 for the heating stage from 80 to 110°C is determined, where A2 = thermal weight loss at this temperature stage / M × 100%; the total fluid thermal weight loss A3 for the heating stage from 110 to 350°C is determined, where A3 = thermal weight loss at this temperature stage / M × 100%; the total fluid thermal weight loss A4 for the heating stage from 350 to 400°C is determined, where A4 = thermal weight loss at this temperature stage / M × 100%; the total fluid thermal weight loss A5 for the heating stage from 400 to 500°C is determined, where A5 = thermal weight loss at this temperature stage / M × 100%; and the total fluid thermal weight loss A6 for the heating stage from >500°C is determined, where A6 = thermal weight loss at this temperature stage / M × 100%, and M is the weight of the pretreated core sample.

[0013] Preferably, during the infrared quantitative analysis, the detection wavenumber range is set to 4000~400cm. -1 4cm resolution -1 The number of scans is 32, ensuring that one infrared scan is completed within 2 minutes.

[0014] Preferably, the statistical process for determining the proportion of infrared functional groups in oil and water at each state during the programmed heating process includes: statistically analyzing the peak areas of water characteristic functional groups (B), aliphatic hydrocarbon functional groups (C), aromatic hydrocarbon functional groups (D), unsaturated hydrocarbon functional groups (E), and carbon dioxide functional groups (F) in each infrared test result; simultaneously, summing the peak areas of various functional groups heated to 80°C to obtain B1, C1, D1, E1, and F1; and summing the peak areas of various functional groups heated from 80°C to 110°C to obtain... The peaks of various functional groups heated to 110~350℃ yield B2, C2, D2, E2, and F2; the peaks of various functional groups heated to 350~400℃ yield B4, C4, D4, E4, and F4; the peaks of various functional groups heated to 400~500℃ yield B5, C5, D5, E5, and F5; and the peaks of various functional groups heated to >500℃ yield B6, C6, D6, E6, and F6.

[0015] Preferably, the process of calculating the oil and water content of reservoir rocks in various occurrence states includes: based on the overall characteristics of the thermal desorption sequence of water: free water is removed by thermal weight loss at 50~80℃, adsorbed water at 80~110℃, crystal water at 110~500℃, and structural water at >500℃; and based on the overall characteristics of the thermal desorption sequence of oil: free oil is removed by thermal weight loss at <350℃, adsorbed oil at 350~400℃, and thermally cracked oil at >400℃, the following is determined: The free water content (G) per gram of sample is: G = A1 × [B1 / (B1 + C1 + D1 + E1 + F1)], unit: g; The adsorbed water (H) content per gram of sample is: H = A² × [B² / (B² + C² + D² + E² + F²)], unit: g; The water of crystallization I content per gram of sample is: I=(A3+A4+A5)×[(B3+B4+B5) / (B3+C3+D3+E3+F3+B4+C4+D4+E4+F4+B5+C5+D5+E5+F5)], unit: g; The structural water J content per gram of sample is: J = A6 × [(B6) / (B6 + C6 + D6 + E6 + F6)], unit: g; The free oil K content per gram of sample is: K=(A1+A2+A3)×[(C1+D1+E1+C2+D2+E2+C3+D3+E3) / (B1+C1+D1+E1+F1+B2+C2+D2+E2+F2+B3+C3+D3+E3+F3)], unit: g; The adsorbed oil content per gram of sample is: L = A4 × [(C4 + D4 + E4) / (B4 + C4 + D4 + E4 + F4)], unit: g; The M content of thermally cracked oil per gram of sample is: M = (A5 + A6) × [(C5 + D5 + E5 + C6 + D6 + E6) / (B5 + C5 + D5 + E5 + F5 + B6 + C6 + D6 + E6 + F6)], unit: g.

[0016] Preferably, the reducing condition is that the equipment used for the quantitative thermogravimetric analysis is purged with protective gas for more than 60 minutes before the sample is subjected to thermogravimetric analysis.

[0017] Preferably, the heating rate of the programmed heating is 10~25℃ / min.

[0018] This invention provides a quantitative analysis method for reservoir differential occurrence state oil and water based on thermogravimetric-infrared spectroscopy, comprising the following steps: The pretreated core samples were subjected to thermogravimetric and infrared online joint analysis. Based on the thermogravimetric quantitative analysis of the heat loss at each temperature stage, and combined with the proportion of infrared functional groups of oil and water in each occurrence state obtained by infrared quantitative analysis during the programmed heating process, the oil and water content of reservoir rocks in each occurrence state was calculated. Water in various states includes free water, adsorbed water, crystal water, and structural water; Oils in various states include free oil, adsorbed oil, and thermally cracked oil.

[0019] Beneficial effects: Compared with traditional methods for evaluating oil content, the present invention provides a quantitative oil-water analysis method based on thermogravimetric analysis (TGA) and infrared spectroscopy (IR). This method utilizes programmed temperature rise TGA to quantify fluid loss during heating, and IR spectroscopy continuously quantifies the volatile matter released during heating, distinguishing the proportions of oil and water. By combining temperature range and component detection, it achieves accurate evaluation of oil and water content in reservoir samples under different occurrence states. This invention considers the quantitative analysis of oil and water content in reservoir samples under different occurrence states, compensating for the lack of water content coverage in conventional testing and analysis, and the insufficient consideration of fluid occurrence states. Through the evaluation of oil and water characteristics in reservoir samples, this invention can achieve detailed classification and evaluation of reservoir fluids, providing key parameters for fluid occurrence evaluation, resource analysis, and reservoir fluid evolution and classification in the field of petroleum geological exploration. Attached Figure Description

[0020] Figure 1 The thermogravimetric analysis results of the sample in Example 1 are shown in the figure. Figure 2 This is an infrared test result image of key temperature points in the rock thermogravimetric analysis in Example 1; Figure 3 This is a correlation diagram between the content of free hydrocarbons S1 from rock pyrolysis and the content of free oil from thermogravimetric analysis in Example 1; Figure 4 This is a correlation diagram between the content of rock pyrolysis cracked hydrocarbon S2 and thermogravimetric adsorption oil in Example 1; Figure 5 This is a correlation diagram between the content of rock pyrolysis cracked hydrocarbon S2 and thermal heavy pyrolysis oil in Example 1; Figure 6 This is a correlation diagram of the content of rock pyrolysis cracked hydrocarbon S2 and thermogravimetric adsorption oil + cracked oil in Example 1; Figure 7 The graph shows the correlation between total organic carbon (TOC) and the content of thermogravimetric free oil + adsorbed oil in Example 1. Detailed Implementation

[0021] This invention provides a quantitative analysis method for reservoir differential occurrence state oil and water based on thermogravimetric-infrared spectroscopy, comprising the following steps: The pretreated core samples were subjected to thermogravimetric and infrared online joint analysis. Based on the thermogravimetric quantitative analysis of the heat loss at each temperature stage, and combined with the proportion of infrared functional groups of oil and water in each occurrence state obtained by infrared quantitative analysis during the programmed heating process, the oil and water content of reservoir rocks in each occurrence state was calculated. Water in various states includes free water, adsorbed water, crystal water, and structural water; Oils in various states include free oil, adsorbed oil, and thermally cracked oil.

[0022] Unless otherwise specified, the present invention does not have special requirements on the source of raw materials used, and commercially available products well known to those skilled in the art can be used.

[0023] In one implementation method, the pretreatment involves grinding more than 10g of fresh core sample to a mesh size of 200 or finer; in a specific embodiment, this is 10.5g. This invention uses a sample size of more than 10g to avoid the influence of sample heterogeneity.

[0024] As one implementation method, the steps of the thermogravimetric and infrared online joint analysis are as follows: under reducing conditions, the core sample is subjected to programmed heating for quantitative thermogravimetric analysis, and the composition at each temperature stage is subjected to quantitative infrared analysis.

[0025] Infrared quantitative analysis of components at various temperature stages: Under reducing conditions, the main fluid products of heating in rocks are water, hydrocarbons, and carbon dioxide, with carbon dioxide being a pyrolysis product of carbonate minerals or organic matter. Therefore, by thermogravimetric analysis (TGA) based on the Lambert-Beer law—that is, the absorption intensity (peak area or peak height) of a specific chemical bond to infrared light is proportional to its content—the content of the substance can be quantitatively determined, and the areas (or peak heights) of characteristic functional groups of water, aliphatic hydrocarbons, aromatic hydrocarbons, unsaturated hydrocarbons, and carbon dioxide functional groups can be identified.

[0026] The calculation of oil and water content in different occurrence states was based on differential thermogravimetric curves from thermogravimetric analysis. The overall characteristics of the thermal desorption sequence of water were: free water (50~80℃), adsorbed water (80~110℃), water of crystallization (110~500℃), and structural water (>500℃). The overall characteristics of the thermal desorption sequence of oil were: free oil (<350℃), adsorbed oil (350~400℃), and thermally cracked oil (>400℃). Based on the weight loss at the corresponding temperature stage and the proportion of infrared functional groups of oil and water in each occurrence state during the programmed temperature rise process, the oil and water content of the reservoir rock in each occurrence state was determined.

[0027] As one implementation method, the reducing condition involves purging the equipment used for the quantitative thermogravimetric analysis with a protective gas for at least 60 minutes before the sample is subjected to thermogravimetric analysis. This achieves programmed heating of the reservoir sample under reducing conditions, preventing thermal oxidation of hydrocarbon compounds and thus avoiding interference with the infrared quantitative analysis of hydrocarbon content. The protective gas includes nitrogen or an inert gas, with nitrogen being used in a specific embodiment. The heating rate of the programmed heating is 10~25℃ / min, with 25℃ / min being used in a specific embodiment. The heating rate used in this invention ensures sufficient thermogravimetric analysis.

[0028] As one implementation method, the total fluid thermal weight loss A1 is determined by the aforementioned quantitative thermogravimetric analysis, where A1 = (weight loss at this temperature stage / M) × 100%; the total fluid thermal weight loss A2 is determined for the 80~110℃ stage, where A2 = (weight loss at this temperature stage / M) × 100%; the total fluid thermal weight loss A3 is determined for the 110~350℃ stage, where A3 = (weight loss at this temperature stage / M) × 100%; the total fluid thermal weight loss A4 is determined for the 350~400℃ stage, where A4 = (weight loss at this temperature stage / M) × 100%; the total fluid thermal weight loss A5 is determined for the 400~500℃ stage, where A5 = (weight loss at this temperature stage / M) × 100%; and the total fluid thermal weight loss A6 is determined for the >500℃ stage, where A6 = (weight loss at this temperature stage / M) × 100%, where M is the weight of the pretreated core sample.

[0029] In one implementation, the weight of the pretreated core sample is M = 10~20 mg, and in a specific embodiment it is 10.2 mg.

[0030] As one implementation method, in the infrared quantitative analysis process, the detection wavenumber range is set to 4000~400cm. -1 4cm resolution -1 The number of scans is 32, ensuring that one infrared scan is completed within 2 minutes.

[0031] As one implementation method, the statistical process for determining the proportion of infrared functional groups in oil and water at each state during the programmed heating process includes: statistically analyzing the peak areas of water characteristic functional groups (B), aliphatic hydrocarbon functional groups (C), aromatic hydrocarbon functional groups (D), unsaturated hydrocarbon functional groups (E), and carbon dioxide functional group surface areas (F) in each infrared test result; simultaneously, summing the surface areas of various functional group peaks heated to 80°C to obtain B1, C1, D1, E1, and F1; and summing the surface areas of various functional group peaks heated from 80°C to 110°C. Addition yields B2, C2, D2, E2, and F2; accumulating the peak surface of various functional groups heated to 110~350℃ yields B3, C3, D3, E3, and F3; accumulating the peak surface of various functional groups heated to 350~400℃ yields B4, C4, D4, E4, and F4; accumulating the peak surface of various functional groups heated to 400~500℃ yields B5, C5, D5, E5, and F5; accumulating the peak surface of various functional groups heated to >500℃ yields B6, C6, D6, E6, and F6.

[0032] As one implementation method, the process of calculating the oil and water content of reservoir rocks in various occurrence states includes: based on the overall characteristics of the thermal desorption sequence of water: free water is removed by thermal weight loss at 50~80℃, adsorbed water at 80~110℃, crystal water at 110~500℃, and structural water at >500℃; and based on the overall characteristics of the thermal desorption sequence of oil: free oil is removed by thermal weight loss at <350℃, adsorbed oil at 350~400℃, and thermally cracked oil at >400℃, the following is determined: The free water content (G) per gram of sample is: G = A1 × [B1 / (B1 + C1 + D1 + E1 + F1)], unit: g; The adsorbed water (H) content per gram of sample is: H = A² × [B² / (B² + C² + D² + E² + F²)], unit: g; The water of crystallization I content per gram of sample is: I=(A3+A4+A5)×[(B3+B4+B5) / (B3+C3+D3+E3+F3+B4+C4+D4+E4+F4+B5+C5+D5+E5+F5)], unit: g; The structural water J content per gram of sample is: J = A6 × [(B6) / (B6 + C6 + D6 + E6 + F6)], unit: g; The free oil K content per gram of sample is: K=(A1+A2+A3)×[(C1+D1+E1+C2+D2+E2+C3+D3+E3) / (B1+C1+D1+E1+F1+B2+C2+D2+E2+F2+B3+C3+D3+E3+F3)], unit: g; The adsorbed oil content per gram of sample is: L = A4 × [(C4 + D4 + E4) / (B4 + C4 + D4 + E4 + F4)], unit: g; The M content of thermally cracked oil per gram of sample is: M = (A5 + A6) × [(C5 + D5 + E5 + C6 + D6 + E6) / (B5 + C5 + D5 + E5 + F5 + B6 + C6 + D6 + E6 + F6)], unit: g.

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0034] Example 1 Three shale samples (A, B, and C) from the Qingshankou Formation in the Songliao Basin were collected. The free hydrocarbon, heavy cracked hydrocarbon, and total organic carbon (TOC) contents were determined through rapid pyrolysis and TOC testing. Free hydrocarbon content characterizes the hydrocarbon content in free oil, while cracked hydrocarbon content characterizes the hydrocarbon content in adsorbed oil and thermally cracked oil. TOC content is positively correlated with total oil content (results are shown in Table 1). Organic matter content is also positively correlated with total oil content, verifying the accuracy of the oil and water content parameters determined by this method.

[0035] The experimental procedure is as follows: Take 10.5g of core sample and grind it to a fineness of 200 mesh or finer. Perform quantitative thermogravimetric analysis on the sample. Take 10.2mg of the pretreated sample obtained after grinding and perform thermogravimetric and infrared online analysis. Before the experiment, the instrument system is purged with nitrogen for more than 60 minutes, and the heating rate is set to 25℃ / min. Thermogravimetric analysis (TGA) was used to determine the total thermal weight loss of the fluid heated to 80℃ (A1 = weight loss at this temperature range / M × 100%); 80~110℃ (A2 = weight loss at this temperature range / M × 100%); 110~350℃ (A3 = weight loss at this temperature range / M × 100%); 350~400℃ (A4 = weight loss at this temperature range / M × 100%); 400~500℃ (A5 = weight loss at this temperature range / M × 100%); and >500℃ (A6 = weight loss at this temperature range / M × 100%). The thermogravimetric results for the samples are shown below. Figure 1 During the thermogravimetric analysis, infrared testing and analysis were continuously performed, with the detection wavenumber range set to 4000~400cm. -1 4cm resolution -1 The number of scans is 32, ensuring that one infrared scan is completed within 2 minutes (see infrared spectrum for typical temperature range). Figure 2 The quantitative analysis of components is shown in Table 2.

[0036] Infrared quantitative analysis of components at each temperature stage was performed, and the peak areas of water functional groups (B), aliphatic hydrocarbon functional groups (C), aromatic hydrocarbon functional groups (D), unsaturated hydrocarbon functional groups (E), and carbon dioxide functional groups (F) were statistically analyzed from each infrared test result. Simultaneously, the peak surface accumulation of various functional groups heated to 80℃ yields B1, C1, D1, E1, and F1; the peak surface accumulation of various functional groups heated to 80~110℃ yields B2, C2, D2, E2, and F2; the peak surface accumulation of various functional groups heated to 110~350℃ yields B3, C3, D3, E3, and F3; the peak surface accumulation of various functional groups heated to 350~400℃ yields B4, C4, D4, E4, and F; the peak surface accumulation of various functional groups heated to 400~500℃ yields B5, C5, D5, E5, and F5; and the peak surface accumulation of various functional groups heated to >500℃ yields B6, C6, D6, E6, and F6.

[0037] The calculation of oil and water content in different occurrence states, based on the overall characteristics of the thermal desorption sequence of water (free water (50~80℃), adsorbed water (80~110℃), water of crystallization (110~500℃), and structural water (>500℃), and the overall characteristics of the thermal desorption sequence of oil (free oil S1 (<350℃), adsorbed oil S2 (350~400℃), and thermally cracked oil S3 (>400℃), can be determined as follows: The free water content (G) per gram of sample is: G = A1 × [B1 / (B1 + C1 + D1 + E1 + F1)], unit: g; The adsorbed water (H) content per gram of sample is: H = A² × [B² / (B² + C² + D² + E² + F²)], unit: g; The water of crystallization I content per gram of sample is: I=(A3+A4+A5)×[(B3+B4+B5) / (B3+C3+D3+E3+F3+B4+C4+D4+E4+F4+B5+C5+D5+E5+F5)], unit: g; The structural water J content per gram of sample is: J = A6 × [(B6) / (B6 + C6 + D6 + E6 + F6)], unit: g; The free oil K content per gram of sample is: K=(A1+A2+A3)×[(C1+D1+E1+C2+D2+E2+C3+D3+E3) / (B1+C1+D1+E1+F1+B2+C2+D2+E2+F2+B3+C3+D3+E3+F3)], unit: g; The adsorbed oil content per gram of sample is: L = A4 × [(C4 + D4 + E4) / (B4 + C4 + D4 + E4 + F4)], unit: g; The M content of thermally cracked oil per gram of sample is: M = (A5 + A6) × [(C5 + D5 + E5 + C6 + D6 + E6) / (B5 + C5 + D5 + E5 + F5 + B6 + C6 + D6 + E6 + F6)], unit: g.

[0038] The results are shown in Table 3.

[0039] Table 1. Results of Pyrolysis Tests on Sample Rocks

[0040] Table 2. Peak area percentage of representative functional groups for water, oil, and carbon dioxide at typical temperatures.

[0041] Table 3. Results of Thermogravimetric-Infrared Quantitative Analysis of Samples

[0042] Figure 1 The mass loss of the sample during the entire temperature program was determined by infrared chromatographic detection at each temperature point. The results showed that the temperature increase caused simultaneous loss of both oil and water from the sample, with significant differences in the amount of oil and water lost at each temperature stage. Figure 2 Based on the total oil and water loss at each temperature stage obtained from thermogravimetric analysis, and the results of infrared spectroscopy distinguishing the relative amounts of oil and water at each temperature stage, the free oil content obtained by thermogravimetric analysis shows a good positive correlation with the free hydrocarbon content obtained by pyrolysis. Figure 3 The content of adsorbed oil and thermally cracked oil by thermogravimetric analysis showed a good positive correlation with the content of hydrocarbons cracked by pyrolysis. Figure 4 , Figure 5 Furthermore, the content of thermogravimetric adsorbed oil + thermal cracking oil is comparable to that of cracked hydrocarbons. Figure 6 Meanwhile, there is a high positive correlation between the total oil content obtained by the TOC thermogravimetric method and the total oil content. Figure 7 This also indicates that the organic matter content controls the oil content, which is consistent with general objective laws. In addition, the amount of all free oil and adsorbed oil obtained by thermogravimetric analysis is significantly greater than that of free hydrocarbons and cracked hydrocarbons obtained by pyrolysis, confirming that non-hydrocarbon compounds are present in the oil obtained by thermogravimetric analysis, and the pyrolysis method cannot characterize and quantify this part of the content.

[0043] Furthermore, thermogravimetric analysis or infrared analysis alone cannot achieve quantitative classification of oil and hydrocarbon components, nor can they characterize the fluid's state of occurrence.

[0044] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A quantitative analysis method for reservoir differential occurrence state oil and water based on thermogravimetric-infrared spectroscopy, characterized in that, Includes the following steps: The pretreated core samples were subjected to thermogravimetric and infrared online joint analysis. Based on the thermogravimetric quantitative analysis of the heat loss at each temperature stage, and combined with the proportion of infrared functional groups of oil and water in each occurrence state obtained by infrared quantitative analysis during the programmed heating process, the oil and water content of reservoir rocks in each occurrence state was calculated. Water in various states includes free water, adsorbed water, crystal water, and structural water; Oils in various states include free oil, adsorbed oil, and thermally cracked oil; The total fluid thermal weight loss A1 was determined through the quantitative analysis of thermal weight loss, where A1 = (weight loss at this temperature / M) × 100%; the total fluid thermal weight loss A2 was determined, where A2 = (weight loss at this temperature / M) × 100%; the total fluid thermal weight loss A3 was determined, where A3 = (weight loss at this temperature / M) × 100%; and the total fluid thermal weight loss A4 was determined, where A4 = (weight loss at this temperature / M) × 100%. The total fluid thermal weight loss in the 400~500℃ range is A5, where A5 = thermal weight loss in this temperature range / M × 100%; the total fluid thermal weight loss in the >500℃ range is A6, where A6 = thermal weight loss in this temperature range / M × 100%, and M is the weight of the pretreated core sample. The statistical process for determining the proportion of infrared functional groups in oil and water at each state during the programmed heating process includes: calculating the peak areas of water characteristic functional groups (B), aliphatic hydrocarbon functional groups (C), aromatic hydrocarbon functional groups (D), unsaturated hydrocarbon functional groups (E), and carbon dioxide functional group (F) in each infrared test result; simultaneously, summing the peak areas of various functional groups heated to 80℃ to obtain B1, C1, D1, E1, and F1; and summing the peak areas of various functional groups heated from 80 to 110℃ to obtain B1.

2. C2, D2, E2, F2; B3, C3, D3, E3, F3 are obtained by accumulating the peak surfaces of various functional groups heated to 110~350℃; B4, C4, D4, E4, F4 are obtained by accumulating the peak surfaces of various functional groups heated to 350~400℃; B5, C5, D5, E5, F5 are obtained by accumulating the peak surfaces of various functional groups heated to 400~500℃; B6, C6, D6, E6, F6 are obtained by accumulating the peak surfaces of various functional groups heated to >500℃.

2. The method for quantitative analysis of oil and water in reservoir differential occurrence states according to claim 1, characterized in that, The steps of the thermogravimetric and infrared online joint analysis are as follows: under reducing conditions, the core sample is heated in a programmed manner to perform quantitative thermogravimetric analysis, and the composition at each temperature stage is quantitatively analyzed by infrared radiation.

3. The method for quantitative analysis of oil and water in reservoir differential occurrence states according to claim 1 or 2, characterized in that, During the infrared quantitative analysis, the detection wavenumber range is set to 4000~4000 cm⁻¹. -1 4cm resolution -1 The number of scans is 32, ensuring that one infrared scan is completed within 2 minutes.

4. The method for quantitative analysis of oil and water in reservoir differential occurrence states according to claim 1, characterized in that, The process of calculating the oil and water content of reservoir rocks in various occurrence states includes: based on the general characteristics of the thermal desorption sequence of water: free water is removed by thermal weight loss in the 50~80℃ stage, adsorbed water in the 80~110℃ stage, crystal water in the 110~500℃ stage, and structural water in the >500℃ stage; and based on the general characteristics of the thermal desorption sequence of oil: free oil is removed by thermal weight loss in the <350℃ stage, adsorbed oil in the 350~400℃ stage, and thermally cracked oil in the >400℃ stage, the following is determined: The free water content (G) per gram of sample is: G = A1 × [B1 / (B1 + C1 + D1 + E1 + F1)], unit: g; The adsorbed water (H) content per gram of sample is: H = A² × [B² / (B² + C² + D² + E² + F²)], unit: g; The water of crystallization I content per gram of sample is: I=(A3+A4+A5)×[(B3+B4+B5) / (B3+C3+D3+E3+F3+B4+C4+D4+E4+F4+B5+C5+D5+E5+F5)], unit: g; The structural water J content per gram of sample is: J = A6 × [(B6) / (B6 + C6 + D6 + E6 + F6)], unit: g; The free oil K content per gram of sample is: K=(A1+A2+A3)×[(C1+D1+E1+C2+D2+E2+C3+D3+E3) / (B1+C1+D1+E1+F1+B2+C2+D2+E2+F2+B3+C3+D3+E3+F3)], unit: g; The adsorbed oil content per gram of sample is: L = A4 × [(C4 + D4 + E4) / (B4 + C4 + D4 + E4 + F4)], unit: g; The M content of thermally cracked oil per gram of sample is: M = (A5 + A6) × [(C5 + D5 + E5 + C6 + D6 + E6) / (B5 + C5 + D5 + E5 + F5 + B6 + C6 + D6 + E6 + F6)], unit: g.

5. The method for quantitative analysis of oil and water in reservoir differential occurrence states according to claim 2, characterized in that, The reducing condition is that, before the quantitative thermogravimetric analysis of the sample, the equipment used for the quantitative thermogravimetric analysis is purged with protective gas for more than 60 minutes.

6. The method for quantitative analysis of oil and water in reservoir differential occurrence states according to claim 2, characterized in that, The heating rate of the program is 10~25℃ / min.

Images