A light hydrocarbon collection device and method in a semi-enclosed thermal simulation experiment

Abstract

The application aims to provide a semi-closed thermal simulation experiment light hydrocarbon device and method, and belongs to the technical field of oil and gas exploration and development. The device comprises an oil and gas separation tank, a light hydrocarbon bottle one, a light hydrocarbon bottle two and an atmospheric bottle connected in sequence through pipelines. A valve one is arranged on the inlet pipeline of the oil and gas separation tank. Valves two, three and four are arranged in sequence on the pipelines between the outlet of the oil and gas separation tank, the light hydrocarbon bottle one, the light hydrocarbon bottle two and the atmospheric bottle. The device and method can not only ensure that the subsequent experiments are not affected by the oil produced, but also greatly improve the accuracy of light hydrocarbon quantification.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and development technology, specifically relating to a device and method for collecting light hydrocarbons in a semi-closed thermal simulation experiment. Background Technology

[0002] The theoretical basis of thermal simulation experiments is the principle of hydrocarbon generation through kerogen pyrolysis and the time-temperature compensation principle of organic matter thermal evolution. Hydrocarbon generation thermal simulation experiments are an important means of evaluating the hydrocarbon generation potential and resources of source rocks. They can reproduce the pyrolysis evolution process of organic matter in geological bodies, providing theoretical basis and experimental data for evaluating basin hydrocarbon generation potential, processes and mechanisms, and deriving hydrocarbon generation models and kinetics. Semi-closed thermal simulation experiments include a self-purging system and a compaction system. The pyrolysis system is connected to the product collection system to minimize the loss of pyrolysis products. The volume expansion of the pyrolysis products carries them out of the pyrolysis container. After collection, the gas / liquid products are analyzed to determine the relationship between pyrolysis temperature and pyrolysis products.

[0003] Currently, during the semi-closed thermal simulation experiment, for C8~C 12 The collection of light hydrocarbons is crucial for subsequent experiments. However, due to the high temperature of this experiment, a dilemma arises in the final step of collecting light hydrocarbons: if the valve is opened to collect light hydrocarbons at excessively high temperatures, some oil and water produced in the experiment will remain in the light hydrocarbon bottle as liquids. This not only hinders the subsequent quantitative analysis of light hydrocarbons but also reduces the mass of the oil produced, resulting in a lack of some lighter oils for later experiments. Conversely, if the valve is opened to collect light hydrocarbons after a period of time and a slight decrease in temperature, the temperature drops sharply as the gas passes through the pipeline (C8~C). 12 Some (highly volatile) hydrocarbons will change from a gaseous state to a liquid state at 150℃~200℃ and remain in the oil-gas separator. Since light hydrocarbons are highly volatile, the light hydrocarbons will be almost completely volatilized when the oil-gas separator is processed. This will not only affect the relative mass of each hydrocarbon in subsequent measurements, but also seriously affect the quantitative process of light hydrocarbons.

[0004] Due to the shortcomings and deficiencies in the equipment and methods for collecting light hydrocarbons, the experiment, despite consuming a great deal of financial, material, and human resources, still failed to achieve the desired quantitative goal for light hydrocarbons. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a semi-closed thermal simulation experiment device and method for collecting light hydrocarbons, which makes the subsequent quantitative analysis of light hydrocarbons more accurate, and thus allows for a more precise determination of the relationship between pyrolysis temperature and pyrolysis products.

[0006] The present invention adopts the following technical solution: A semi-closed thermal simulation experiment device for collecting light hydrocarbons includes an oil-gas separator, a light hydrocarbon cylinder 1, a light hydrocarbon cylinder 2, and an atmospheric cylinder connected in sequence by pipelines. A valve 1 is installed on the inlet pipeline of the oil-gas separator, and valves 2, 3, and 4 are installed in sequence on the pipelines between the outlet of the oil-gas separator, the light hydrocarbon cylinder 1, the light hydrocarbon cylinder 2, and the atmospheric cylinder.

[0007] A method for collecting light hydrocarbons in a semi-closed thermal simulation experiment includes the following steps: The first step is to install the pre-weighed light hydrocarbon bottle one and light hydrocarbon bottle two after the thermal simulation experiment ends and before the light hydrocarbon experiment ends, close all valves, and evacuate the entire pipeline, oil-gas separator, light hydrocarbon bottle one, light hydrocarbon bottle two and atmospheric gas bottle to ensure that there is no air in them. The second step is to shut down the heating system after the thermal simulation experiment. First, flood the light hydrocarbon bottle 1 and light hydrocarbon bottle 2 with liquid nitrogen, open valve 1 and valve 2, wait for 2-3 seconds, and then open valve 3 and valve 4. At this time, the oil and water part remains in the oil-gas separator, the light hydrocarbons will remain in light hydrocarbon bottle 1 and light hydrocarbon bottle 2 due to the liquid nitrogen, and the heavy hydrocarbons will go to the atmospheric gas bottle. Wait for 5-6 seconds and then close valve 2 and valve 4. The third step is that light hydrocarbon crystals will appear in light hydrocarbon bottle one and light hydrocarbon bottle two. There will be some oil and water in light hydrocarbon bottle one. Remove the liquid nitrogen, keep valve three open, and let it stand for a period of time. The crystals in light hydrocarbon bottle one and light hydrocarbon bottle two will form a gaseous state at room temperature. This state will be maintained for 30 seconds. At this time, there will be some liquid in light hydrocarbon bottle one. Close valve three. The fourth step is to immerse light hydrocarbon bottle one and light hydrocarbon bottle two again with liquid nitrogen for 2-3 minutes, so that solid crystals will reappear in light hydrocarbon bottle one and light hydrocarbon bottle two. Fifth step: If the temperature of light hydrocarbon bottle one and light hydrocarbon bottle two is too low, remove light hydrocarbon bottle one and light hydrocarbon bottle two, place them at room temperature, and wait until there is no solid crystal in light hydrocarbon bottle one and light hydrocarbon bottle two and no fog on the bottle wall, then weigh them.

[0008] The products of the thermal simulation experiment include three aspects: (1) the sample. Since the experiment uses high temperature and high pressure conditions to compensate for the long geological process, the samples after the experiment can be used to explore and evaluate the changes in maturity, porosity and permeability; (2) under high temperature conditions, oil shale, coal and other samples will generate a large amount of oil, especially at 350℃~500℃, a large amount of light oil will be generated; (3) the experiment will generate a large amount of gas, especially when the thermal simulation experiment reaches 500℃~600℃, including light hydrocarbons and heavy hydrocarbons. The present invention is based on a comprehensive evaluation of the device and method used to collect the oil and gas generated in the experiment. It can more accurately quantitatively evaluate light hydrocarbons and oil. Moreover, the present invention does not require more complicated steps, is easy to operate, and can be improved in a targeted manner according to the specific experimental focus.

[0009] The beneficial effects of this invention are as follows: This invention addresses the problem that high and low temperatures during light hydrocarbon collection after a semi-closed system thermal simulation experiment can negatively impact the quantitative analysis of subsequent light hydrocarbon collection experiments. It provides an apparatus and a novel method that not only ensures uninterrupted quantitative analysis of the produced oil in subsequent experiments but also significantly improves the accuracy of light hydrocarbon quantification. Furthermore, this invention considers the key aspects of later oil and gas experiments, proposing targeted improvements to the experimental scheme based on the new apparatus and method. In addition, this apparatus reduces the volatilization of light hydrocarbons, greatly benefiting subsequent light hydrocarbon GC-MS, carbon isotope experiments, and light hydrocarbon quantification. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the light hydrocarbon collection device in the semi-enclosed thermal simulation experiment of the present invention; Among them: 1-Oil-gas separator; 2-Light hydrocarbon cylinder one; 3-Light hydrocarbon cylinder two; 4-Atmospheric gas cylinder; 5-Valve one; 6-Valve two; 7-Valve three; 8-Valve four. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described in conjunction with these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0012] The device for collecting light hydrocarbons designed in this invention is as follows: Figure 1 As shown, it has two light hydrocarbon cylinders and multiple valve controls, including an oil-gas separator 1, light hydrocarbon cylinder 1 2, light hydrocarbon cylinder 2 3 and an atmospheric cylinder 4 connected in sequence by pipelines. The inlet pipeline of the oil-gas separator 1 is equipped with valve 1 5, and the outlet of the oil-gas separator 1 and the pipelines between the light hydrocarbon cylinder 1 2, light hydrocarbon cylinder 2 3 and the atmospheric cylinder are equipped with valve 2 6, valve 3 7 and valve 4 8 in sequence.

[0013] A method for collecting light hydrocarbons in a semi-closed thermal simulation experiment includes the following steps: a) After the thermal simulation experiment ends and before the light hydrocarbon collection experiment ends, light hydrocarbon bottle 1 2 and light hydrocarbon bottle 2 3 need to be installed (all weighed), all valves are closed, and the entire pipeline, oil-gas separator 1, light hydrocarbon bottle 1 2, light hydrocarbon bottle 2 3 and atmospheric bottle 4 are evacuated to ensure that there is no air in them. b) After the thermal simulation experiment, turn off the heating system and immediately begin collecting gas (high-temperature gas collection to maximize the collection of light hydrocarbons). First, submerge light hydrocarbon bottle 1 (2) and light hydrocarbon bottle 2 (3) with liquid nitrogen. Open valve 1 (5) and valve 2 (6), and hold for 2-3 seconds (the valve opening time can be longer because this invention is designed to solve the problem of oil and water consumption, so there is no concern about liquid in light hydrocarbon bottle 1). Then open valve 3 (7) and valve 4 (8) (to prevent any liquid from passing into light hydrocarbon bottle 2). At this time, the oil and water remain in oil-gas separator 1, and the light hydrocarbons will remain in light hydrocarbon bottle 1 (2) and light hydrocarbon bottle 2 (3) due to the liquid nitrogen (the bottle walls will fog due to the large temperature difference). The heavy hydrocarbons will flow into atmospheric bottle 4. Wait approximately 5-6 seconds (to reduce oil loss), and then close valve 2 (6) and valve 4 (8). c) Light hydrocarbon crystals will appear in the light hydrocarbon bottle. There will be some oil and water in light hydrocarbon bottle 1-2. Remove the liquid nitrogen, keep valve 3-7 open, and let it stand for a period of time. The crystals in light hydrocarbon bottle 1-2 and light hydrocarbon bottle 2-3 will form a gaseous state at room temperature. Maintain this state for 30 seconds (to allow the gases in the two light hydrocarbon bottles to reach equilibrium). At this time, you can see that there is some liquid in light hydrocarbon bottle 1-2 (due to the high temperature, some oil and water enter the light hydrocarbon bottle in a gaseous state. Due to the large temperature difference, this part of the liquid changes from a gaseous state to a liquid or solid state and remains in light hydrocarbon bottle 1). Close valve 3-7. d) Immerse light hydrocarbon bottle 2 and light hydrocarbon bottle 3 again with liquid nitrogen for 2-3 minutes to allow solid crystals to reappear in light hydrocarbon bottle 2 and light hydrocarbon bottle 3 (at this time, there may be no fog because the temperature difference is not as large as at the end of the experiment). e) While the temperature of light hydrocarbon bottle 1 (2) and light hydrocarbon bottle 2 (3) is too low (at this time, the loss of light hydrocarbon is the lowest), remove light hydrocarbon bottle 1 (2) and light hydrocarbon bottle 2 (3), place them at room temperature, and wait until there is no solid crystal in light hydrocarbon bottle 1 (2) and light hydrocarbon bottle 2 (3) and no fog on the bottle wall, then weigh them. f) Since there is liquid in light hydrocarbon bottle 2, light hydrocarbon bottle 2 can be further processed according to the specific experiments to follow, while light hydrocarbon bottle 3 can be removed for light hydrocarbon experiments.

[0014] Subsequent experiments focused on the relationship between oil composition, pyrolysis temperature, and oil production. These experiments required high precision in the collection and quantification of light oil. After weighing, the light hydrocarbons in light hydrocarbon bottle 2 could be discharged, weighed again, and the difference between the two weights obtained to determine the mass of light hydrocarbons in light hydrocarbon bottle 2. The oil-water mixture in the light hydrocarbon bottle was then washed with dichloromethane or formaldehyde to maximize the collection of oil and water produced in the thermal simulation experiment. Subsequent light hydrocarbon experiments were conducted using light hydrocarbon bottle 3. Subsequent experiments are quantitative experiments on light hydrocarbons, or if subsequent experiments require a large amount of light hydrocarbons, i.e., a high yield of light hydrocarbons is required. To avoid repeating experiments and wasting manpower, material resources, and financial resources, this method will increase the amount of light hydrocarbons collected. The light hydrocarbon bottle 2 can be used for the light hydrocarbon experiment first, and then placed in air to be weighed (however, this method takes a long time, and the volatilization of light hydrocarbons will have a certain impact on the quantitative analysis). Subtracting the mass from the mass after the light hydrocarbon collection is completed will give the mass of oil and water remaining in the light hydrocarbon bottle, and thus the mass of light hydrocarbons.

Claims

1. A method for collecting light hydrocarbons in a semi-closed thermal simulation experiment, characterized in that: The apparatus used in the method includes an oil-gas separator (1), a light hydrocarbon cylinder one (2), a light hydrocarbon cylinder two (3), and an atmospheric cylinder (4) connected in sequence by pipes. A valve one (5) is provided on the inlet pipe of the oil-gas separator (1), and a valve two (6), a valve three (7), and a valve four (8) are provided in sequence on the pipes between the outlet of the oil-gas separator (1), the light hydrocarbon cylinder one (2), the light hydrocarbon cylinder two (3), and the atmospheric cylinder (4). The method includes the following steps: The first step is to install the pre-weighed light hydrocarbon bottle one and light hydrocarbon bottle two after the thermal simulation experiment ends and before the light hydrocarbon experiment ends, close all valves, and evacuate the entire pipeline, oil-gas separator, light hydrocarbon bottle one, light hydrocarbon bottle two and atmospheric gas bottle to ensure that there is no air in them. The second step is to shut down the heating system after the thermal simulation experiment. First, flood the light hydrocarbon bottle 1 and light hydrocarbon bottle 2 with liquid nitrogen, open valve 1 and valve 2, wait for 2-3 seconds, and then open valve 3 and valve 4. At this time, the oil and water part remains in the oil-gas separator, the light hydrocarbons will remain in light hydrocarbon bottle 1 and light hydrocarbon bottle 2 due to the liquid nitrogen, and the heavy hydrocarbons will go to the atmospheric gas bottle. Wait for 5-6 seconds and then close valve 2 and valve 4. The third step is that light hydrocarbon crystals will appear in light hydrocarbon bottle one and light hydrocarbon bottle two. There will be some oil and water in light hydrocarbon bottle one. Remove the liquid nitrogen, keep valve three open, and let it stand for a period of time. The crystals in light hydrocarbon bottle one and light hydrocarbon bottle two will form a gaseous state at room temperature. This state will be maintained for 30 seconds. At this time, there will be some liquid in light hydrocarbon bottle one. Close valve three. The fourth step is to immerse light hydrocarbon bottle one and light hydrocarbon bottle two again with liquid nitrogen for 2-3 minutes, so that solid crystals will reappear in light hydrocarbon bottle one and light hydrocarbon bottle two. Fifth step: If the temperature of light hydrocarbon bottle one and light hydrocarbon bottle two is too low, remove light hydrocarbon bottle one and light hydrocarbon bottle two, place them at room temperature, and wait until there is no solid crystal in light hydrocarbon bottle one and light hydrocarbon bottle two and no fog on the bottle wall, then weigh them.

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