Method and system for quantitatively characterizing generation and discharge of organic acid in thermal evolution process of hydrocarbon source rock

Abstract

The invention belongs to the technical field of oil-gas exploration and development, and relates to a method and a system for quantitatively characterizing organic acid generation and discharge in a hydrocarbon source rock thermal evolution process, and the method comprises the following steps: selecting a target area hydrocarbon source rock sample; preparing the hydrocarbon source rock sample into hydrocarbon source rock powder, and dividing the hydrocarbon source rock powder into a plurality of powder samples with the same weight; mixing each powder sample with distilled water according to a preparation ratio to obtain a plurality of mixtures, placing each mixture in a high-pressure kettle of a closed system high-pressure kettle thermal simulation experiment device, and performing a hydrocarbon source rock thermal evolution process simulation experiment; measuring the volume of a liquid product in each simulation experiment, and measuring the concentration of organic acid in the liquid product in each simulation experiment by adopting a high performance liquid chromatography; and calculating the acid production rate according to the mass of the powder sample, the volume of the liquid product and the concentration of the organic acid. The method can rapidly, accurately and quantitatively characterize organic acid generation and discharge in the thermal evolution process of the hydrocarbon source rock.

Description

Technical Field

[0001] This application belongs to the field of oil and gas exploration and development technology, and relates to acoustic remote detection imaging logging technology, specifically to a method and system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks. Background Technology

[0002] In the field of oil and gas exploration, source rocks refer to rocks that have already formed, may form, or have the potential to generate oil and gas. Their distribution characteristics and their contact relationship with transport channels play a crucial role in controlling the migration and accumulation of oil and gas. Currently, conventional source rock evaluation methods are mainly based on single-well stratigraphic development data, obtaining the relative content of dark mudstone thickness and stratigraphic thickness revealed by different wells, and combining this with sedimentary facies analysis to perform planar digitization, thereby forming data such as the planar distribution of dark mudstone to stratigraphic layers. Subsequently, the mudstone thickness is determined by seismic inversion profiles to infer the distribution of source rocks.

[0003] However, in low-exploration areas, due to limited drilling and coring data, traditional source rock evaluation methods based on geochemical and well logging data are insufficient to meet the demands for high-precision resource estimation. In these regions, source rock identification and prediction rely more heavily on seismic data, especially seismic inversion techniques. Seismic inversion techniques combine geophysical and geological data to calibrate seismic reflection characteristics and establish seismic identification models for source rocks, identifying their seismic characteristics and development patterns to predict their spatial distribution. However, this method is primarily used for qualitative characterization of source rock distribution and is insufficient to meet the requirements for high-precision resource estimation. Summary of the Invention

[0004] This application addresses the problems existing in the prior art by providing a method and system for quantitatively characterizing the generation and expulsion of organic acids during the thermal evolution of source rocks. By using thermal simulation experiments of source rocks to analyze the generation and expulsion of organic acids in source rocks, it is possible to quickly and accurately quantitatively characterize the generation and expulsion of organic acids during the thermal evolution of source rocks.

[0005] In a first aspect, this application provides a method for quantitatively characterizing the generation and expulsion of organic acids during the thermal evolution of source rocks, the steps of which are as follows: Sample selection steps: Select source rock samples from the target area; Sample processing steps: The source rock sample is made into source rock powder and divided into multiple powder samples of equal weight; Simulation experiment steps: Mix each powder sample with distilled water according to the configuration ratio to obtain multiple mixtures. Place each mixture in the autoclave of the closed system autoclave thermal simulation experimental device to conduct a simulation experiment on the thermal evolution process of hydrocarbon source rocks. Detection steps: Measure the volume of liquid product in each simulation experiment, and determine the concentration of organic acid in the liquid product in each simulation experiment using high performance liquid chromatography; Acid production rate calculation steps: Calculate the acid production rate based on the powder sample mass, the volume of the liquid product, and the concentration of the organic acid.

[0006] In some embodiments, the method for preparing the source rock sample into source rock powder in the sample processing step is as follows: The source rock sample was cleaned; The cleaned source rock samples were air-dried. The dried source rock sample was crushed to obtain powder; Powder with a mesh size less than or equal to the set value is selected to obtain source rock powder.

[0007] In some embodiments, during the simulation experiment, the thermal evolution conditions of source rocks under real formation conditions are simulated using a closed-system high-pressure autoclave thermal simulation experimental device in each simulation experiment.

[0008] In some embodiments of the simulation experiment step, after the mixture is placed in the autoclave, before conducting the simulation experiment of the thermal evolution process of the source rock, the air in the autoclave is displaced by nitrogen, and the autoclave is evacuated after nitrogen displacement.

[0009] In some embodiments, during the simulation experiment, when conducting the simulation experiment of the thermal evolution process of the source rock, multiple set temperature points with equal temperature intervals are set between 200℃ and 450℃. Each simulation experiment corresponds to one set temperature point. During each simulation experiment, the temperature is raised to the set temperature point corresponding to the simulation experiment at a set heating rate and kept at the temperature for a set time.

[0010] In some embodiments, the method for measuring the volume of liquid product in each simulation experiment in the measurement step is as follows: After each simulation experiment is stopped, when the autoclave is naturally cooled to room temperature, the solid products and liquid products generated in the simulation experiment are separated by a solid-liquid separator. The liquid product is aspirated using a pipette and transferred to a glass bottle with volume markings on its surface. The volume of the liquid product is read using a volume scale.

[0011] In some embodiments, the method for determining the concentration of organic acids in the liquid product of each simulation experiment using high-performance liquid chromatography in the measurement step is as follows: Prepare standard solutions of organic acids; The standard solution of organic acid was placed in a high performance liquid chromatograph, and a standard curve was plotted with the concentration of organic acid on the x-axis and the peak area of ​​organic acid in the high performance liquid chromatograph on the y-axis. The liquid products from each simulation experiment were subjected to high-performance liquid chromatography to obtain the peak area of ​​organic acids in the liquid products. The concentration of organic acids in the liquid product is obtained from the standard curve based on the peak area of ​​the organic acid in the liquid product.

[0012] In some embodiments, in the acid production rate calculation step, the formula for calculating the acid production rate is expressed as: Y = m / (M * TOC) Where m = C * V; In the formula, Y is the acid production rate, in mg / g; m is the mass of organic acid, in mg; M is the mass of powder sample, in g; TOC is the organic carbon content, expressed as %; C is the organic acid concentration, in mg / L; and V is the volume of liquid product, in L.

[0013] A second aspect of this application provides a system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks, used to implement the method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in the first aspect of this application, comprising: The sample processing device converts selected source rock samples from the target area into source rock powder. A weighing device is used to divide the source rock powder into multiple powder samples of equal weight. A mixing container is used to mix each powder sample with distilled water according to the specified ratio to obtain multiple mixtures. A closed-system high-pressure autoclave thermal simulation experimental device is used to hold mixtures and conduct simulation experiments on the thermal evolution process of hydrocarbon source rocks; The detection device measures the volume of the liquid product in each simulation experiment and determines the concentration of organic acids in the liquid product. The calculation module calculates the acid production rate based on the powder sample mass, the volume of the liquid product, and the concentration of the organic acid.

[0014] In some embodiments, the closed-system autoclave thermal simulation experimental apparatus includes: Autoclave, used for holding mixtures; Gas container, filled with nitrogen; A displacement pump is used to connect the autoclave and the gas container to fill the autoclave with nitrogen gas from the gas container, thereby displacing the gas in the autoclave. A vacuum pump is used to connect to the autoclave and evacuate the autoclave. A heating container is used to hold the autoclave and to heat the mixture inside the autoclave; A temperature control unit, connected to the heating container, is used to adjust the heating temperature of the heating container in order to regulate the reaction temperature of the mixture inside the autoclave.

[0015] Compared with the prior art, the advantages and positive effects of this application are as follows: This application provides a method and system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks. By combining sample selection, sample processing, closed-system thermal simulation experiments, high-performance liquid chromatography (HPLC) detection, and acid production rate calculation, it achieves precise quantitative characterization of organic acid generation and excretion during the thermal evolution of source rocks. Specifically, the source rocks are prepared into uniform powder and divided into equal portions to ensure the consistency and comparability of experimental samples at different thermal evolution stages. A closed-system high-pressure autoclave thermal simulation experimental device is used to realistically reproduce the acid-generating environment of source rocks under formation conditions, ensuring that the experimental results closely reflect geological reality. The concentration of organic acids in the liquid products is accurately determined by HPLC, and the acid production rate is calculated by combining the product volume and sample mass, achieving quantitative and precise characterization of the organic acid generation and excretion process. This application is controllable, provides reliable data, and has good repeatability. It can systematically obtain the organic acid generation patterns at different thermal evolution stages, providing scientific and accurate quantitative methodological support for studying the thermal evolution of source rocks, the genesis of organic acids, reservoir mineral dissolution, and secondary porosity development mechanisms. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks, as described in the embodiments of this application. Figure 2 This is a flowchart illustrating the method for preparing source rock powder from the source rock sample according to an embodiment of this application. Figure 3 This is a flowchart illustrating a method for measuring the volume of liquid products in each simulation experiment according to an embodiment of this application. Figure 4 This is a flowchart illustrating the method for determining the concentration of organic acids in the liquid products of each simulation experiment using high performance liquid chromatography, as described in this application. Figure 5 This is a structural block diagram of the system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks, as described in the embodiments of this application. Figure 6 This is a diagram showing the distribution characteristics of acid production types in a well at a depth of 3210.1m in the A1 depression of a basin under different simulated temperatures in an embodiment of this application. Figure 7 This is a diagram showing the distribution characteristics of acid production types in a well at depths 4074-4106m of coal-bearing source rocks in depression A2 of a basin under different simulated temperatures, according to an embodiment of this application. Figure 8 This is a diagram showing the distribution characteristics of acid production types in a well at depths 3140-3225m in a basin A depression A3 depression of this application under different simulated temperatures.

[0017] In the diagram, 1 is the sample processing device, 2 is the weighing device, 3 is the mixing container, 4 is the closed system autoclave thermal simulation experimental device, 5 is the detection device, and 6 is the calculation module. Detailed Implementation

[0018] The present application will now be described in detail with reference to the accompanying drawings through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0019] See Figure 1 The first aspect of this application provides a method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks, the steps of which are as follows: S1. Sample selection steps: Select source rock samples from the target area.

[0020] Specifically, fresh, low-mature / lithic source rock samples that reflect the characteristics of the target area are selected. Low-mature source rocks are those that have not yet generated a large amount of oil and have only entered the early stage of hydrocarbon generation. They have the following characteristics: (1) The degree of thermal evolution of organic matter is low, generally corresponding to: vitrinite reflectance Ro≈0.3%~0.7%, which has not reached or has just entered the early stage of oil generation. (2) Organic matter is mainly in an immature to low-mature state, generating only low-mature oil, biogas (low-temperature pyrolysis gas), and soluble organic matter (asphalt, lipids, etc.). Low-mature source rocks are suitable for thermal simulation experiments to restore the original hydrocarbon generation potential, study hydrocarbon kinetics, hydrocarbon generation process, and hydrocarbon expulsion mechanism. Lithic source rocks are hydrocarbon source rock fragments identified and picked out from drilling cuttings. They have the characteristics of small particle size, low cost, high sampling density, and complete overburden strata, and are suitable for rapid geochemical analysis, pyrolysis analysis, extraction, chromatography-mass spectrometry, etc.

[0021] S2. Sample processing steps: The source rock sample is made into source rock powder and divided into multiple powder samples of equal weight.

[0022] For example, the source rock powder is divided into 6 equal-weight powder samples. It should be noted that the number of powder samples is not limited to 6, and can be limited according to actual needs, for example, it can also be 4 or 5 samples.

[0023] In this embodiment, the method of preparing the source rock sample into powder and dividing it into multiple samples of equal weight can ensure that the initial mass, particle size distribution and organic matter content of multiple sets of parallel experimental samples are highly consistent, effectively eliminating systematic errors caused by sample differences. This provides a unified, homogeneous and highly comparable experimental basis for subsequent comparative and repeatable experiments, and significantly improves the parallelism, reliability and persuasiveness of experimental data.

[0024] In one embodiment of this application, see [link to embodiment]. Figure 2 The method for preparing the source rock sample into source rock powder is as follows: S21. The source rock sample is cleaned.

[0025] The cleaning process effectively removes non-mudstone impurities (including non-rock particles, sand and gravel particles, and mineral crystals), preserving pure source rock samples and preventing impurities from interfering with subsequent thermal simulation experiments, hydrocarbon generation evaluation, and component analysis, thereby improving the purity of source rock samples.

[0026] S22. Dry the cleaned source rock samples.

[0027] By drying the cleaned source rock samples, moisture is removed from the sample surface and pores, preventing moisture from vaporizing and causing additional pressure interference in subsequent high-temperature and high-pressure thermal simulation experiments. This ensures the accuracy and stability of temperature and pressure control in the experimental system, while also preventing moisture from affecting the organic matter test results and improving the reliability of experimental data.

[0028] S23. The dried source rock sample is crushed to obtain powder.

[0029] Specifically, the dried source rock samples were pulverized and ground into powder using an agate mortar. This process avoids introducing external impurities, metal contamination, or iron interference, ensuring the purity of the source rock sample components and the accuracy of its organic matter information. Furthermore, the uniform grinding force and thorough particle breakage result in source rock powder with uniform particle size and good dispersibility. This provides a homogeneous and representative sample for subsequent thermal simulation experiments, improving the accuracy and repeatability of the experimental results.

[0030] S24. Select powders with a mesh size less than or equal to the set size to obtain source rock powder.

[0031] Preparing source rocks into powder with uniform particle size less than or equal to a set mesh size (e.g., 100 mesh) can significantly increase the reaction surface area, making the organic matter of source rocks more uniformly heated and reacting more fully in the closed-system autoclave thermal simulation experiment, thereby improving the pyrolysis hydrocarbon generation efficiency and the accuracy, repeatability and reliability of experimental data.

[0032] S3. Simulation Experiment Procedure: Mix each powder sample with distilled water according to the specified ratio to obtain multiple mixtures. Place each mixture in the autoclave of the closed system autoclave thermal simulation experimental device to conduct a simulation experiment on the thermal evolution process of hydrocarbon source rocks.

[0033] In one embodiment of this application, the thermal evolution conditions of source rocks under real geological conditions are simulated using a closed-system high-pressure autoclave thermal simulation experimental device during each simulation experiment.

[0034] In this embodiment, a closed-system high-pressure autoclave thermal simulation experimental device is used to simulate the thermal evolution environment of hydrocarbon source rocks under real strata conditions. This device can highly reproduce the geological conditions of high temperature, high pressure, and closed reduction in deep strata, making the experimental conditions highly consistent with the actual geological background.

[0035] In one embodiment of this application, after the mixture is placed in the autoclave, before conducting a simulation experiment on the thermal evolution process of the source rock, the air in the autoclave is displaced by nitrogen, and the autoclave is evacuated after nitrogen displacement.

[0036] In this embodiment, nitrogen is used to displace the air inside the autoclave, and the autoclave is evacuated to completely eliminate oxygen, moisture, and residual air from the system, creating an oxygen-free, reducing, closed experimental environment. This avoids interference from oxidation, cracking, and metamorphism of the source rocks and generated hydrocarbons under high-temperature conditions, ensuring the authenticity and reliability of the thermal evolution products and geochemical characteristics. Furthermore, it eliminates the interference of air on the monitoring of system pressure and temperature, improving the stability of experimental conditions and the accuracy of data, thus accurately reproducing the thermal evolution process of source rocks under a reducing stratigraphic environment.

[0037] In one embodiment of this application, when conducting a simulation experiment of the thermal evolution process of hydrocarbon source rocks, multiple set temperature points with equal temperature intervals are set between 200℃ and 450℃. Each simulation experiment corresponds to one set temperature point. During each simulation experiment, the temperature is raised to the set temperature point corresponding to that simulation experiment at a set heating rate, and the temperature is kept constant for a set time.

[0038] In this embodiment, by setting multiple temperature points with equal temperature intervals within the range of 200℃-450℃, each experiment corresponds to only a single set temperature. With a uniform heating rate and a constant holding time, the hydrocarbon generation characteristics and evolution patterns of source rocks at different thermal evolution stages can be accurately and systematically simulated. This method ensures the consistency and comparability of experimental conditions at each temperature point, effectively eliminates interference from variables such as heating rate and holding time, and obtains continuous and complete thermal evolution sequence data. This facilitates quantitative analysis of the influence of temperature on hydrocarbon generation kinetics, product composition, and hydrocarbon generation patterns, improving the regularity, accuracy, and repeatability of experimental results, and providing reliable and systematic experimental evidence for the study of the thermal evolution mechanism of source rocks.

[0039] For example, there are 6 powder samples. Each powder sample is mixed with distilled water at a ratio of 1.5:1 to obtain 6 mixtures. In the simulation experiment of the thermal evolution process of hydrocarbon source rocks, 6 set temperature points with equal temperature intervals are set between 200℃ and 450℃: 200℃, 250℃, 300℃, 350℃, 400℃, and 450℃. 200℃ corresponds to the first simulation experiment (using the first mixture), 250℃ corresponds to the second simulation experiment (using the second mixture), 300℃ corresponds to the third simulation experiment (using the third mixture), 350℃ corresponds to the fourth simulation experiment (using the fourth mixture), 400℃ corresponds to the fifth simulation experiment (using the fifth mixture), and 450℃ corresponds to the sixth simulation experiment (using the sixth mixture).

[0040] S4. Detection steps: Measure the volume of the liquid product in each simulation experiment, and determine the concentration of organic acid in the liquid product in each simulation experiment using high performance liquid chromatography.

[0041] Specifically, see Figure 3 The method for measuring the volume of liquid products in each simulation experiment is as follows: S411. After each simulation experiment is stopped, when the autoclave is naturally cooled to room temperature, the solid products and liquid products generated in the simulation experiment are separated by a solid-liquid separator. S412. Using a pipette, the liquid product is aspirated and transferred to a glass bottle with volume markings on its surface; S413. Read the volume of the liquid product using the volume scale.

[0042] The measurement method described in this application involves naturally cooling the autoclave to room temperature after the simulation experiment, separating the solid and liquid products using a solid-liquid separator, and then transferring the liquid product to a graduated glass bottle using a pipette to read the volume. This achieves efficient separation and accurate quantification of the liquid product, reducing losses and errors during the transfer process and ensuring accurate and reliable liquid product volume measurement results. This measurement method is simple to operate and provides intuitive quantification, effectively improving the accuracy of hydrocarbon generation yield calculations and the repeatability of experimental data, providing stable and reliable quantitative data support for the evaluation of hydrocarbon generation from the thermal evolution of source rocks.

[0043] Specifically, see Figure 4 The method for determining the concentration of organic acids in the liquid products of each simulation experiment using high performance liquid chromatography is as follows: S421. Prepare standard solutions of organic acids; S422. Place the standard solution of organic acid in a high performance liquid chromatograph and plot a standard curve with the concentration of organic acid on the x-axis and the peak area of ​​organic acid in the high performance liquid chromatograph on the y-axis. S423. The liquid products from each simulation experiment are placed in high performance liquid chromatography to obtain the peak area of ​​organic acids in the liquid products. S424. Based on the peak area of ​​organic acids in the liquid product, the concentration of organic acids in the liquid product is obtained through the standard curve.

[0044] In this embodiment, high-performance liquid chromatography (HPLC) is employed. By preparing standard solutions, plotting standard curves, measuring the peak area of ​​liquid products, and quantitatively calculating the organic acid concentration based on the standard curve, accurate, efficient, and quantitative detection of organic acid concentration in liquid products can be achieved, ensuring high sensitivity, good repeatability, and high accuracy of the detection results. This method effectively eliminates matrix interference, and the quantitative results are stable and reliable. It provides high-precision quantitative data support for subsequent calculation of acid production rate and analysis of the organic acid generation patterns during the thermal evolution of source rocks, thereby enhancing the scientific validity and credibility of the experimental results.

[0045] S5. Acid production rate calculation steps: Calculate the acid production rate based on the powder sample mass, the volume of the liquid product, and the concentration of the organic acid.

[0046] Specifically, the formula for calculating the acid production rate is expressed as follows: Y = m / (M * TOC) Where m = C * V; In the formula, Y is the acid production rate, in mg / g; m is the mass of organic acid, in mg; M is the mass of powder sample, in g; TOC is the organic carbon content, expressed as % and is a known amount; C is the concentration of organic acid, in mg / L; and V is the volume of liquid product, in L.

[0047] In this embodiment, by combining the powder sample mass, liquid product volume, and organic acid concentration to calculate the acid production rate, a precise quantitative evaluation of the amount of organic acid generated during the thermal evolution of source rocks can be achieved. This organically correlates the basic physical properties of the sample, product volume, and component concentration, eliminating the influence of single-parameter measurement errors on the results and significantly improving the accuracy and scientific rigor of the acid production rate calculation. This calculation method can quantify the acid production capacity of source rocks under different thermal evolution temperatures and experimental conditions, clearly reflecting the correlation between the degree of thermal evolution and the organic acid generation pattern. It provides accurate and reliable quantitative data support for in-depth research on the hydrocarbon generation mechanism of source rock thermal evolution, the kinetic characteristics of organic acid generation, and related studies on hydrocarbon accumulation.

[0048] The method described above for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks in this application combines sample selection, sample processing, closed-system thermal simulation experiments, high-performance liquid chromatography detection, and acid production rate calculation to achieve precise quantitative characterization of the generation and excretion of organic acids during the thermal evolution of source rocks.

[0049] A second aspect of this application provides a system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks, used to implement the method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in the first aspect of this application.

[0050] See Figure 5 The system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks includes: Sample processing device 1 prepares the selected source rock sample from the target area into source rock powder; Weighing device 2 divides the source rock powder into multiple powder samples of equal weight; Mixing container 3 is used to mix each powder sample with distilled water according to the specified ratio to obtain multiple mixtures; The closed-system high-pressure autoclave thermal simulation experimental device 4 is used to hold the mixture and conduct simulation experiments on the thermal evolution process of hydrocarbon source rocks; Detection device 5 measures the volume of liquid product in each simulation experiment and determines the concentration of organic acid in the liquid product; Calculation module 6 calculates the acid production rate based on the powder sample mass, the volume of the liquid product, and the concentration of the organic acid.

[0051] In this embodiment, the system, through the coordinated operation of a sample processing device, a weighing device, a mixing container, a closed-system autoclave thermal simulation experimental device, a detection device, and a calculation module, achieves automated, standardized, and quantitative characterization of the entire process of source rock thermal evolution and organic acid generation and expulsion. By uniformly preparing source rock samples into powder and grouping them into equal masses, the initial conditions of multiple parallel experimental samples are consistent, improving experimental repeatability and comparability. Mixing the powder samples with distilled water in a specific ratio and conducting thermal simulation in a closed system can realistically reproduce the formation temperature and pressure conditions and water-rock interaction environment, avoiding oxidation and material loss, and making the organic acid generation and expulsion process closer to geological reality. The detection device can accurately obtain the volume of liquid products and the concentration of organic acids, and combined with the calculation module, it can accurately quantify the acid production rate, thereby systematically and quantitatively characterizing the acid generation and expulsion patterns of source rocks at different thermal evolution stages. This provides stable, reliable, and high-precision experimental support and data assurance for research on the thermal evolution mechanism of source rocks, the geochemical behavior of organic acids, and hydrocarbon accumulation.

[0052] In some embodiments of this application, the sample processing apparatus includes: A cleaning machine is used to clean the hydrocarbon source rock sample; Agate mortar and pestle are used to crush the dried source rock sample into powder. A mesh screen is used to sift out powder with a mesh size less than or equal to a set value to obtain hydrocarbon source rock powder.

[0053] Using a cleaning machine can effectively remove impurities and contaminants from the sample surface, avoiding interference from exogenous components; using an agate mortar and pestle for grinding avoids the introduction of metal impurities and secondary pollution, ensuring the authenticity and reliability of the sample's organic matter information; sieving through a mesh screen can obtain hydrocarbon source rock powder with uniform particle size and strong consistency, improving the stability and repeatability of subsequent thermal simulation experiments.

[0054] Specifically, in one embodiment of this application, the weighing device is an electronic scale. Using an electronic scale enables rapid and accurate sample separation by mass, ensuring high uniformity of initial conditions for multiple parallel experiments, reducing systematic errors, and improving the comparability, accuracy, and reliability of experimental data. This provides a stable, standardized, and high-precision sample basis for the quantitative characterization of organic acids generated and excreted during the thermal evolution of source rocks.

[0055] In some embodiments of this application, the closed-system autoclave thermal simulation experimental apparatus includes: Autoclave, used for holding mixtures; Gas container, filled with nitrogen; A displacement pump is used to connect the autoclave and the gas container to fill the autoclave with nitrogen gas from the gas container, thereby displacing the gas in the autoclave. A vacuum pump is used to connect to the autoclave and evacuate the autoclave. A heating container is used to hold the autoclave and to heat the mixture inside the autoclave; A temperature control unit, connected to the heating container, is used to adjust the heating temperature of the heating container in order to regulate the reaction temperature of the mixture inside the autoclave.

[0056] The aforementioned closed-system autoclave thermal simulation experimental device integrates an autoclave, nitrogen source, displacement pump, vacuum pump, heating container, and temperature control unit, achieving a unified design for sealed sample loading, oxygen-free environment construction, and precise heating and temperature control. The displacement pump and vacuum pump work together to quickly and thoroughly remove air and oxygen from the system, creating a stable reducing experimental atmosphere and preventing oxidation interference from samples and products. The heating container and temperature control unit work synergistically to precisely control the reaction temperature, achieving programmed heating and stable isothermal maintenance, realistically simulating the thermal evolution environment of source rocks under geological conditions. The entire device is compact, functionally complete, and precisely controlled, improving the convenience of experimental operation, the accuracy of condition control, and the reliability and repeatability of experimental results. It provides a stable, efficient, and highly compatible experimental platform for studying the thermal evolution of source rocks, hydrocarbon generation, and acid production.

[0057] In one embodiment of this application, the detection device includes: A solid-liquid separator is used to separate solid products from liquid products generated in a simulation experiment. A glass bottle with volume graduations on its surface for measuring the volume of the liquid product; A pipette is used to aspirate the separated liquid product and transfer the liquid product into the glass bottle; A configuration unit for preparing standard organic acid solutions; High performance liquid chromatography (HPLC) is used to measure the peak area of ​​organic acids in standard solutions and liquid products of organic acids. The plotting unit is used to plot standard curves based on the concentration of organic acids and the area of ​​organic peaks in organic acid standard solutions.

[0058] In this embodiment, a solid-liquid separator can quickly and efficiently separate solid and liquid products, ensuring no loss or contamination of product components. The use of a graduated glass bottle and a pipette allows for precise measurement of the liquid product volume, improving data accuracy. By preparing a standard solution using a configuration unit, measuring the peak area using a high-performance liquid chromatograph, and then establishing a standard curve using a plotting unit, precise quantitative detection of the organic acid concentration in the liquid product can be achieved, improving the accuracy, reliability, and repeatability of the detection results.

[0059] Specifically, in one embodiment of this application, the configuration unit includes: An electronic analytical balance is used to weigh organic acid standards. A volumetric flask for measuring the volume of distilled water in which the organic acid standard is dissolved; Erlenmeyer flask, used to dissolve the organic acid standard in distilled water to obtain an organic acid standard solution; Reagent bottles are used to store prepared organic acid standard solutions. In this embodiment, an electronic analytical balance, volumetric flask, and conical flask are used in combination to prepare organic acid standard solutions, which can ensure that the standard solution concentration is accurate and has good repeatability, providing a reliable benchmark for subsequent quantitative detection; the reagent bottle can stably store the standard solution and avoid its deterioration or concentration change.

[0060] To verify the effectiveness of the method and system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in the above embodiments of this application, the following specific embodiments are provided for illustration.

[0061] Example 1: Taking a 3210.1m core sample of the Huxiang source rock from a well in the A1 depression of a basin as an example, the TOC of the Huxiang source rock core sample is known to be 2.95%.

[0062] The source rock core samples were pretreated by washing, drying, crushing and screening with a 100-mesh sieve to obtain source rock powder. The source rock powder was weighed in equal weight and divided into 6 powder samples.

[0063] Six powders were mixed with distilled water at a ratio of 1.5:1 to obtain six mixtures. Six sets of simulation experiments on the thermal evolution process of source rocks were conducted using a closed-system high-pressure autoclave thermal simulation apparatus. The autoclave had a maximum pressure of 100 MPa, a maximum reaction temperature of 800℃, and a volume of 150 ml. For the six sets of simulations, six set temperature points with equal intervals between 200℃ and 450℃ were established. The experimental temperature for the first simulation was 200℃, the second was 250℃, the third was 300℃, the fourth was 350℃, the fifth was 400℃, and the sixth was 450℃. The heating rate for each simulation was 20℃ / min, and the temperature was held at the set point for 48 hours.

[0064] For each experiment, the mixture was placed in an autoclave, and nitrogen was first introduced to displace the air inside the autoclave before a vacuum was created. The autoclave containing the mixture was then placed in a heating container, and the heating container was controlled by a temperature control unit to heat at a set rate of 20°C / min until the set temperature was reached and held at that temperature for 48 hours.

[0065] After each experiment, the autoclave was allowed to cool naturally to room temperature. The liquid products generated in the simulation experiment were collected, the volume of the liquid products was measured, and the concentration of organic acids in the liquid products was measured using high performance liquid chromatography. The acid production rate was calculated based on the mass of each sample, the volume of the liquid products, and the concentration of organic acids.

[0066] Figure 6 The image shows the distribution characteristics of acid production types in the 3210.1m Huxiang source rock of a well in the A1 depression at different simulated temperatures. Figure 6 It is known that the lacustrine source rock samples produced a relatively large amount of propionic acid during thermal evolution, especially at 400℃, where the acid production rate reached as high as 1.225 mg / g. Secondly, oxalic acid, acetic acid, and formic acid were also mainly produced, along with small amounts of various organic acids such as butyric acid, valeric acid, malonic acid, glutaric acid, and pyruvic acid.

[0067] Example 2: Taking a coal-bearing source rock fragment sample from well 4074-4106m in the A2 depression of a basin as an example, the TOC of the coal-bearing source rock fragment sample is known to be 2.14%.

[0068] The source rock fragments were pretreated by washing, drying, crushing and screening with a 100-mesh sieve to obtain source rock powder. The source rock powder was weighed in equal weight and divided into 6 powder samples.

[0069] Six powders were mixed with distilled water at a ratio of 1.5:1 to obtain six mixtures. Six sets of simulation experiments on the thermal evolution process of source rocks were conducted using a closed-system high-pressure autoclave thermal simulation apparatus. The autoclave had a maximum pressure of 100 MPa, a maximum reaction temperature of 800℃, and a volume of 150 ml. For the six sets of simulations, six set temperature points with equal intervals between 200℃ and 450℃ were established. The experimental temperature for the first simulation was 200℃, the second was 250℃, the third was 300℃, the fourth was 350℃, the fifth was 400℃, and the sixth was 450℃. The heating rate for each simulation was 20℃ / min, and the temperature was held at the set point for 48 hours.

[0070] For each experiment, the mixture was placed in an autoclave, and nitrogen was first introduced to displace the air inside the autoclave before a vacuum was created. The autoclave containing the mixture was then placed in a heating container, and the heating container was controlled by a temperature control unit to heat at a set rate of 20°C / min until the set temperature was reached and held at that temperature for 48 hours.

[0071] After each experiment, the autoclave was allowed to cool naturally to room temperature. The liquid products generated in the simulation experiment were collected, the volume of the liquid products was measured, and the concentration of organic acids in the liquid products was measured using high performance liquid chromatography. The acid production rate was calculated based on the mass of each sample, the volume of the liquid products, and the concentration of organic acids.

[0072] Figure 7 The image shows the distribution characteristics of acid production types in the coal-bearing source rocks at depths of 4074-4106m in a well in the A2 depression under different simulated temperatures. Figure 7 It can be seen that the coal-bearing source rock samples have the highest acid production rate overall, with thermal evolution producing more pyruvic acid. Secondly, acetic acid, formic acid and oxalic acid are also mainly produced. Acetic acid has an acid production peak at 250℃. At the same time, small amounts of different kinds of organic acids such as butyric acid, valeric acid, malonic acid, glutaric acid and propionic acid are also produced.

[0073] Example 3: Taking a hydrogen-rich source rock core sample from well 3140-3225m in depression A3 of a basin as an example, the TOC of the hydrogen-rich source rock core sample is known to be 3.65%.

[0074] The source rock core samples were pretreated by washing, drying, crushing and screening with a 100-mesh sieve to obtain source rock powder. The source rock powder was weighed in equal weight and divided into 6 powder samples.

[0075] Six powders were mixed with distilled water at a ratio of 1.5:1 to obtain six mixtures. Six sets of simulation experiments on the thermal evolution process of source rocks were conducted using a closed-system high-pressure autoclave thermal simulation apparatus. The autoclave had a maximum pressure of 100 MPa, a maximum reaction temperature of 800℃, and a volume of 150 ml. For the six sets of simulations, six set temperature points with equal intervals between 200℃ and 450℃ were established. The experimental temperature for the first simulation was 200℃, the second was 250℃, the third was 300℃, the fourth was 350℃, the fifth was 400℃, and the sixth was 450℃. The heating rate for each simulation was 20℃ / min, and the temperature was held at the set point for 48 hours.

[0076] For each experiment, the mixture was placed in an autoclave, and nitrogen was first introduced to displace the air inside the autoclave before a vacuum was created. The autoclave containing the mixture was then placed in a heating container, and the heating container was controlled by a temperature control unit to heat at a set rate of 20°C / min until the set temperature was reached and held at that temperature for 48 hours.

[0077] After each experiment, the autoclave was allowed to cool naturally to room temperature. The liquid products generated in the simulation experiment were collected, the volume of the liquid products was measured, and the concentration of organic acids in the liquid products was measured using high performance liquid chromatography. The acid production rate was calculated based on the mass of each sample, the volume of the liquid products, and the concentration of organic acids.

[0078] Figure 8 The image shows the distribution characteristics of acid production types in the hydrogen-rich source rock at depths of 3140-3225m in a well in the A3 depression under different simulated temperatures. Figure 8 It is known that the thermal evolution of the hydrogen-rich source rock samples produced a large amount of valeric acid and acetic acid, especially at 400℃, where the acid production rate reached as high as 1.450 mg / g. Secondly, oxalic acid and glutaric acid were mainly produced, along with small amounts of formic acid, propionic acid, butyric acid, malonic acid, and pyruvic acid, among other organic acids.

[0079] The above embodiments are used to explain this application, not to limit it. Any modifications and changes made to this application within the spirit and scope of the claims shall fall within the protection scope of this application.

Claims

1. A method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks, characterized in that, The steps are as follows: Sample selection steps: Select source rock samples from the target area; Sample processing steps: The source rock sample is made into source rock powder and divided into multiple powder samples of equal weight; Simulation experiment steps: Mix each powder sample with distilled water according to the configuration ratio to obtain multiple mixtures. Place each mixture in the autoclave of the closed system autoclave thermal simulation experimental device to conduct a simulation experiment on the thermal evolution process of hydrocarbon source rocks. Detection steps: Measure the volume of liquid product in each simulation experiment, and determine the concentration of organic acid in the liquid product in each simulation experiment using high performance liquid chromatography; Acid production rate calculation steps: Calculate the acid production rate based on the powder sample mass, the volume of the liquid product, and the concentration of the organic acid.

2. The method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 1, characterized in that, In the sample processing step, the method for preparing the source rock sample into source rock powder is as follows: The source rock sample was cleaned; The cleaned source rock samples were air-dried. The dried source rock sample was crushed to obtain powder; Powder with a mesh size less than or equal to the set value is selected to obtain source rock powder.

3. The method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 1, characterized in that, In the simulation experiment steps, each simulation experiment uses a closed-system high-pressure autoclave thermal simulation experimental device to simulate the thermal evolution conditions of source rocks under real geological conditions.

4. The method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 1, characterized in that, In the simulation experiment step, after the mixture is placed in the autoclave, before the simulation experiment of the thermal evolution process of the source rock is carried out, the air in the autoclave is displaced by nitrogen, and the autoclave is evacuated after nitrogen displacement.

5. The method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 1, characterized in that, In the simulation experiment steps, when conducting the simulation experiment of the thermal evolution process of hydrocarbon source rocks, multiple set temperature points with equal temperature intervals are set between 200℃ and 450℃. Each simulation experiment corresponds to a set temperature point. During each simulation experiment, the temperature is raised to the set temperature point corresponding to that simulation experiment at a set heating rate, and the temperature is kept constant for a set time.

6. The method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 1, characterized in that, In the measurement step, the method for measuring the volume of liquid product in each simulation experiment is as follows: After each simulation experiment is stopped, when the autoclave is naturally cooled to room temperature, the solid products and liquid products generated in the simulation experiment are separated by a solid-liquid separator. The liquid product is aspirated using a pipette and transferred to a glass bottle with volume markings on its surface. The volume of the liquid product is read using a volume scale.

7. The method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 1, characterized in that, In the measurement step, the method for determining the concentration of organic acids in the liquid product of each simulation experiment using high-performance liquid chromatography is as follows: Prepare standard solutions of organic acids; The standard solution of organic acid was placed in a high performance liquid chromatograph, and a standard curve was plotted with the concentration of organic acid on the x-axis and the peak area of ​​organic acid in the high performance liquid chromatograph on the y-axis. The liquid products from each simulation experiment were subjected to high-performance liquid chromatography to obtain the peak area of ​​organic acids in the liquid products. The concentration of organic acids in the liquid product is obtained from the standard curve based on the peak area of ​​the organic acid in the liquid product.

8. The method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 1, characterized in that, In the acid production rate calculation step, the formula for calculating the acid production rate is expressed as: Y = m / (M * TOC) Where m = C * V; In the formula, Y is the acid production rate, in mg / g; m is the mass of organic acid, in mg; M is the mass of powder sample, in g; TOC is the organic carbon content, expressed as %; C is the organic acid concentration, in mg / L; and V is the volume of liquid product, in L.

9. A system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks, used to implement the method for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in any one of claims 1 to 8, characterized in that, include: The sample processing device converts selected source rock samples from the target area into source rock powder. A weighing device is used to divide the source rock powder into multiple powder samples of equal weight. A mixing container is used to mix each powder sample with distilled water according to the specified ratio to obtain multiple mixtures. A closed-system high-pressure autoclave thermal simulation experimental device is used to hold mixtures and conduct simulation experiments on the thermal evolution process of hydrocarbon source rocks; The detection device measures the volume of the liquid product in each simulation experiment and determines the concentration of organic acids in the liquid product. The calculation module calculates the acid production rate based on the powder sample mass, the volume of the liquid product, and the concentration of the organic acid.

10. The system for quantitatively characterizing the generation and excretion of organic acids during the thermal evolution of source rocks as described in claim 9, characterized in that, The closed-system autoclave thermal simulation experimental device includes: Autoclave, used for holding mixtures; Gas container, filled with nitrogen; A displacement pump is used to connect the autoclave and the gas container to fill the autoclave with nitrogen gas from the gas container, thereby displacing the gas in the autoclave. A vacuum pump is used to connect to the autoclave and evacuate the autoclave. A heating container is used to hold the autoclave and to heat the mixture inside the autoclave; A temperature control unit, connected to the heating container, is used to adjust the heating temperature of the heating container in order to regulate the reaction temperature of the mixture inside the autoclave.

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