Simulation device for producing methane by using CO2 through microorganisms in oil reservoir porous medium environment and application of simulation device

Abstract

The invention provides a simulation device for producing methane by using CO2 through microorganisms in an oil reservoir porous medium environment and application of the simulation device. The simulation device comprises a high-pressure-resistant sealed container, a gas injection port is formed in the top of the high-pressure-resistant sealed container, and an upper-end sampling port, a middle-end sampling port and a lower-section sampling port are sequentially formed in the side surface of the high-pressure-resistant sealed container from top to bottom; a piston is arranged at the bottom of the high-pressure-resistant sealed container, and the height of the piston is adjusted through a piston container injection opening formed in the bottom of the piston. And a porous medium is filled in the container. The simulation device provided by the invention is used for simulating a method for producing methane by using CO2 and residual oil through microorganisms in oil reservoir high-pressure and porous medium environments, and changes in physicochemical properties in a cultured oil-water phase, spatial distribution of communities in a porous medium, product properties and the like are calculated; and the growth metabolism mechanism under the high-pressure and porous medium environment of the oil reservoir can be researched and revealed.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and natural gas development, and in particular relates to a simulation device for microorganisms to produce methane by utilizing CO2 in a porous medium environment of an oil reservoir and an application thereof. Background Art

[0002] "Carbon peak and carbon neutrality" is the current mainstream trend, which will bring about a major change in the economy, society and environment caused by a scientific and technological revolution. The field of CO2 capture, utilization and storage (CCUS) refers to the industrial process of capturing and separating CO2 from industrial emission sources and utilizing it while achieving CO2 emission reduction. The Global Carbon Capture and Storage Institute (GCCSI) report shows that CO2 capture, oil recovery and storage (CCUS-EOR) is the main way to reduce carbon emissions. At present, there are 28 carbon reduction projects in the world, of which 22 are CCUS-EOR projects, accounting for 76.68% of the annual capture capacity. As of 2018, the total global CO2 utilization was less than 200 million tons per year, which is almost negligible compared with the total global anthropogenic CO2 emissions (more than 32 billion tons per year). Research on the utilization and conversion of CO2 after injection into oil reservoirs for oil recovery and storage has important scientific research value and social significance for CCUS.

[0003] The conversion of CO2 and crude oil into methane by reservoir microorganisms is one of the main phenomena of methane production in nature. The generation of methane from waste CO2 through biogeochemical reactions not only reduces carbon emissions but also achieves the generation of clean energy. On the one hand, methane dissolves in crude oil to promote fluidity, which can increase crude oil recovery; on the other hand, the density difference between methane gas and CO2 can produce gravity differentiation, forming methane enrichment in the high parts of geological structures, which can be developed at an appropriate time in the future. The use of CO2 by organisms to produce methane has the benefit of killing three birds with one stone. At present, research on the use of CO2 or crude oil to produce methane is mainly carried out in a normal pressure environment with oil and water as the reaction medium. The community structure and function, conversion pathway and conversion rate of anaerobic degradation of petroleum hydrocarbons into methane, as well as the progress of the functional bacterial community regulation mechanism have been obtained. However, the actual deep oil reservoir is a high-pressure and porous medium environment, and an oil-gas-water-rock multi-interface system is formed in the porous medium under high pressure. Early studies have shown that microorganisms from a variety of environments can adapt to high-pressure environments by changing cell membrane structure, intracellular lipid components, producing special enzymes, and reducing growth and metabolic efficiency. Song Zhiyong et al. found that under low permeability (1-40mD) porous media conditions in displacement experiments, reservoir microorganisms are difficult to break through the filtration effect of porous media; under high permeability (>1500-2500mD) conditions, large-scale water injection microbial channeling will occur, and it is also difficult to reflect the impact of porous media on the structure of microbial communities. For non-mobile mutualistic microorganisms, attachment to the surface of porous media can more stably carry out cooperative metabolism. The above shows that microorganisms in porous media environments under high pressure have special physiological characteristics that are different from those in normal pressure and oil-water two-phase environments. Therefore, it is necessary to develop research methods to simulate reservoir high pressure and porous media to produce methane using CO2 and residual oil. Summary of the invention

[0004] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a simulation device for microorganisms to produce methane using CO2 in a porous medium environment of an oil reservoir and its application. The simulation device provided by the present invention solves the technical difficulties of the methane production cultivation method in porous media on the basis of achieving good control of the cultivation temperature and high pressure, provides reliable guarantee for the long-term anaerobic cultivation of microorganisms under simulated reservoir pressure and porous media, breaks through the key research technical bottleneck of deep biosphere reservoir microorganisms and CCUS research, and is used for the method of microorganisms using CO2 and residual oil to produce methane under simulated reservoir high pressure and porous medium environment. By studying the changes in the physical and chemical properties of the oil-water phase after cultivation, the spatial distribution of the community in the porous medium, the properties of the product, etc., it can study and reveal the growth and metabolism mechanism under simulated reservoir high pressure and porous medium environment.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a simulation device for producing methane using CO2 by microorganisms in a porous medium environment of an oil reservoir, wherein the simulation device comprises a high-pressure resistant sealed container.

[0007] The top of the high-pressure resistant sealed container is provided with a gas injection port, and the side is provided with an upper sampling port, a middle sampling port and a lower sampling port in sequence from top to bottom.

[0008] A piston is arranged at the bottom of the high-pressure resistant sealed container, and the height of the piston is adjusted by a piston container injection port arranged at the bottom.

[0009] The container is filled with a porous medium.

[0010] The above-mentioned simulation device can effectively control the internal culture temperature and pressure, solve the technical difficulties of the methane production culture method in porous media, and has the ability of long-term culture and regular sampling. It provides a reliable guarantee for the long-term anaerobic culture of microorganisms under simulated reservoir pressure and porous media, breaking through the key research technical bottleneck of deep biosphere reservoir microorganisms and CCUS research; by setting liquid sampling ports at different depths, the fluid at different spatial positions in the porous medium can be taken out to conduct microbial community analysis and physiological and biochemical analysis in the fluid, which is conducive to studying the specific conditions of microbial metabolic activity at different distances from the oil-water interface in the reservoir; in the method for simulating the high pressure and porous medium environment of the reservoir for microorganisms to utilize CO2 and residual oil to produce methane, by studying the changes in the physical and chemical properties of the oil-water phase after culture, the spatial distribution of the community in the porous medium, the properties of the product, etc., it is possible to study and reveal the growth metabolic mechanism under the simulated high pressure and porous medium environment of the reservoir, and realize in situ simulation.

[0011] Preferably, the bottom diameter of the high-pressure resistant sealed container is 14-16 cm, the height is 8-10 cm, and the volume is 1.2-2 L, wherein the diameter can be 14 cm, 14.5 cm, 15 cm, 15.5 cm or 16 cm, etc., the height can be 8 cm, 8.5 cm, 9 cm, 9.5 cm or 10 cm, etc., and the volume can be 1.2 L, 1.3 L, 1.4 L, 1.5 L, 1.6 L, 1.7 L, 1.8 L, 1.9 L or 2 L, etc., but are not limited to the values ​​listed above, and other values ​​not listed within the above numerical range are also applicable.

[0012] Conventional culture experiments do not fully consider the physiological and biochemical effects of microorganisms at the oil-water interface, and the containers used have a small top-view surface area, which corresponds to a small oil-water interface area. The container with the above-mentioned specific parameters has the characteristics of a large top-view surface area, which helps to provide better reaction conditions for the reaction system and facilitates subsequent research based on efficient reactions.

[0013] Preferably, the porous medium comprises any one of quartz sand, glass beads, core chips or fine sand, or a combination of at least two thereof.

[0014] Preferably, the height of the porous medium inside the container is 5-7 cm, such as 5 cm, 5.5 cm, 6 cm, 6.5 cm or 7 cm, but is not limited to the above values. Other values ​​not listed in the above range are also applicable.

[0015] Preferably, a transparent window is provided on the side of the high pressure resistant sealed container.

[0016] The above-mentioned window design increases the accuracy of monitoring and sampling during the cultivation process.

[0017] In a second aspect, the present invention provides a method for simulating the production of methane by microorganisms using CO2 in a porous medium environment of an oil reservoir, the method comprising the following steps:

[0018] A typical terrestrial sedimentary non-calcium chloride water-type sandstone reservoir that has not been developed by gas injection was selected, and the oil-water mixed produced fluid was sampled. The oil phase and the water phase were then allowed to stand to separate. The oil phase and the water phase were respectively injected into the simulation device as described above containing porous media through the sampling port. The simulation device was then placed at the reservoir temperature, and the internal pressure of the simulation device was adjusted to the reservoir pressure through the gas injection port and the piston. Finally, the simulation experiment was carried out, and sampling and monitoring were carried out through the sampling port of the simulation device, and the experimental conditions and results were analyzed.

[0019] Preferably, the reservoir pressure is 5-25 MPa, such as 5 MPa, 10 MPa, 15 MPa, 20 MPa or 25 MPa, but is not limited to the values ​​listed above, and other values ​​not listed within the above numerical range are also applicable.

[0020] Preferably, the mesh number of the porous medium corresponds to the porosity of the oil reservoir, and the calculation method can refer to CN112461718A.

[0021] Preferably, the oil-water mixed produced fluid and the water phase and oil phase obtained after separation are under reservoir pressure environment throughout the entire process from sampling to injection into the simulation device.

[0022] Preferably, the aqueous phase is also mixed with the anaerobic culture medium before being injected into the simulation device.

[0023] The anaerobic culture medium is a conventional culture medium in the art and can be obtained from the market, and the present invention does not impose too many restrictions on this.

[0024] In a third aspect, the present invention also provides application of the above method in reservoir environment research.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a simulation device for microorganisms to produce methane by utilizing CO2 in a porous medium environment of an oil reservoir. The device can effectively control the internal culture temperature and pressure, solve the technical difficulties of the methane production culture method in porous media, provide reliable guarantee for the long-term anaerobic culture of microorganisms under simulated reservoir pressure and porous media, and break through a key research technical bottleneck in the study of deep biosphere reservoir microorganisms and CCUS. In the method for microorganisms to produce methane by utilizing CO2 and residual oil in a simulated reservoir high pressure and porous medium environment, the growth and metabolism mechanism in a simulated reservoir high pressure and porous medium environment can be studied and revealed by changing the physical and chemical properties of the oil-water phase after culture, the spatial distribution of the community in the porous medium, the properties of the product, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the appearance of the simulation device in Example 1;

[0028] Figure 2 is a schematic diagram of the longitudinal cross-section structure of the container of the simulation device in Example 1;

[0029] Figure 3 It is a schematic diagram of the internal structure of the container of the simulation device after the injection of crude oil and produced liquid water layer in Example 1. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0031] Example 1

[0032] This embodiment provides a method for simulating the production of methane by microorganisms using CO2 in a porous medium environment of an oil reservoir, and the specific steps are as follows:

[0033] Select a high pressure sealed container as the simulation device, the appearance of which is Figure 1 As shown, the bottom diameter is 15cm, the height is 8.5cm, and the volume is 1.5L. A transparent window is set on the side for easy observation. First, put the porous medium particles (quartz sand 100 mesh) into the container with a height of 6cm; close the container, connect the vacuum pump through the sampling port until it is evacuated to a vacuum state, and inject nitrogen into the upper gas injection end. Repeat the cycle 5 times to make the environment in the container anaerobic. Continue to add nitrogen until it reaches the reservoir pressure state. Close the gas injection end and the bottom sampling port valves, and wait for the experiment. The schematic diagram of the longitudinal section structure of the container is shown in Figure 2 shown.

[0034] A typical continental sedimentary non-calcium chloride water-type sandstone reservoir was selected. The selected block has not been developed by gas injection, and the reservoir pressure is between 5-25MPa. When sampling at the wellhead, first clean the wellhead valve of the oil production well with clean water, and then disinfect it with 75% alcohol three times. Open the wellhead valve, leave it empty for a while to let the dead oil flow away, and quickly align the sterilized container with the sampling port to collect the sample of the oil-water mixed produced fluid. After filling, quickly tighten the lid and seal it with tape. Use a pressure-resistant container to hold the oil-water produced fluid, and pressurize the pressure-resistant container to the reservoir pressure through a horizontal flow pump. Quickly transport the samples to the laboratory for experimental research.

[0035] The produced liquid in the pressure-resistant container is allowed to stand to allow the oil and water to separate, and then is taken out separately using a pump under pressure. NaHCO3 solution (final concentration not higher than 90mM), a small amount of fumaric acid (10mM), vitamins, trace elements, L-cysteine ​​(3mM), sodium sulfide (5mM), etc. are quickly added to the water layer. Vitamins: sodium phosphate buffer (10mM, pH 7.1), 4-aminobenzoic acid (40mg / L), biotin (10mg / L), niacin (100mg / L), calcium pantothenate (50mg / L), pyridoxine hydrochloride (150mg / L); trace elements: 25% HCl (100mM), FeSO4·7H2O (7.5mM), HBO3 (0.5mM), MnCl2·4H2O (0.5mM), CoCl2·6H2O (0.8mM), NiCl2·6H2O (0.1mM), CuCl2·2H2O (0.01mM), ZnSO4·7H2O (0.5mM), Na2MoO4·2H2O (0.15mM).

[0036] First, inject the separated crude oil into the bottom of the container through the sampling port (the height is the volume of 2 cm in the container). Then quickly put the water layer into the pressure-resistant container and inject it into the container under the push of the injection pump. The injection amount is 2 cm from the upper surface of the quartz sand. Among them, the injection amount of crude oil and produced liquid water layer is based on the amount injected into the same height of quartz sand under normal pressure in advance. At this time, the internal structure diagram of the container is as follows Figure 3 As shown. The container is placed in an incubator at reservoir temperature, and the container is connected to a piston container filled with nitrogen through a gas line for pressure regulation, so that the entire system reaches reservoir pressure at reservoir temperature. An experiment on the production of methane by microorganisms using CO2 and crude oil was carried out under simulated reservoir temperature, high pressure, and porous media environment.

[0037] Adjust to enter the static cultivation stage. Under the data collection of the pressure sensor and the indication of the pressure gauge, monitor the pressure changes in real time, and adjust the experiment in time if there are changes. Then enter the static cultivation stage, do a good job of experimental records and image acquisition.

[0038] Regular and continuous sampling and analysis during the static stage. Take liquid and gas samples according to the designed sampling time points (daily testing one week before cultivation, and once a week thereafter). Slowly open the corresponding sampling valve. Since the container is under high pressure, the operation must be slow. After the gas sampling is depressurized by the micro-regulating valve, it is collected with a 0.5L gas collection bag and then immediately loaded on the gas chromatograph for analysis. Liquid sampling is carried out through the upper, middle and lower sampling ports, and the sampling collection container is pre-pressurized to the reservoir pressure by the piston. The upper sampling port is located at the top of the porous medium (that is, the top of the oil phase culture layer) at a height of 6 cm; the middle sampling port is located in the middle of the water phase culture layer at a height of 4 cm, and the lower sampling port is located at the lower end of the water phase culture layer at a height of 2 cm. When sampling, the piston of the reactor moves upward to open and collect liquids in the upper, middle and lower sampling ports in turn. The superposition of multiple samplings at each sampling port cannot exceed a liquid volume of 2 cm high.

[0039] After sampling, record the pressure in the container. Observe from the window before sampling. When sampling, quickly push the piston upward to keep the pressure of the microbial anaerobic culture environment constant.

[0040] After the experiment, the pressure was slowly released. After the pressure was released, the upper cover of the autoclave was opened, and the upper, middle and lower porous media were taken out in layers for further DNA extraction and subsequent metagenomic analysis.

[0041] After experimental comparison, it was found that the culture environment with porous media has a shorter methane production time and higher yield than that without porous media, which can better reflect the actual reservoir conditions.

[0042] Table 1 The percentage concentration of methane in the gas products changes with time

[0043] 10 days 50 days 100 days Quartz sand 100 mesh 0.35％ 2.65％ 21.16％ No quartz sand 0 0.87％ 12.25％

[0044] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the simulation device and application of microorganisms producing methane using CO2 in a porous medium environment of an oil reservoir, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0045] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0046] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A simulation device for microorganisms to produce methane using CO2 in a porous medium environment of an oil reservoir, characterized in that: The simulation device comprises a high pressure resistant sealed container; The top of the high-pressure sealed container is provided with an air injection port, and the side is provided with an upper sampling port, a middle sampling port and a lower sampling port in sequence from top to bottom; A piston is arranged at the bottom of the high-pressure resistant sealed container, and the piston height is adjusted through a piston container injection port arranged at the bottom; The container is filled with a porous medium.

2. The simulation device according to claim 1, characterized in that The bottom diameter of the high-pressure resistant sealed container is 14-16 cm, the height is 8-10 cm, and the volume is 1.2-2L.

3. The simulation device according to claim 1 or 2, characterized in that: The porous medium includes any one of quartz sand, glass beads, core fragments or fine sand, or a combination of at least two of them.

4. The simulation device according to any one of claims 1 to 3, characterized in that: The height of the porous medium inside the high pressure sealed container is 5-7 cm; Preferably, a transparent window is provided on the side of the high pressure resistant sealed container.

5. A method for producing methane using CO2 by microorganisms in a simulated porous medium environment of an oil reservoir, characterized in that: The method comprises the following steps: A typical terrestrial sedimentary non-calcium chloride water-type sandstone reservoir that has not been developed by gas injection is selected, and the oil-water mixed produced fluid is sampled. The oil phase and the water phase are then allowed to stand to separate, and the oil phase and the water phase are respectively injected into a simulation device according to any one of claims 1 to 4 equipped with a porous medium through a sampling port. The simulation device is then placed at the reservoir temperature, and the internal pressure of the simulation device is adjusted to the reservoir pressure through the gas injection port and the piston. Finally, the simulation experiment is carried out by culturing, sampling and monitoring are carried out through the sampling port of the simulation device, and the experimental conditions and results are analyzed.

6. The method according to claim 5, characterized in that The reservoir pressure is 5-25 MPa.

7. The method according to claim 5 or 6, characterized in that: The oil-water mixed produced fluid and the water phase and oil phase obtained after separation are under reservoir pressure environment from sampling to injection into the simulation device.

8. The method according to any one of claims 5 to 7, characterized in that: The aqueous phase was also mixed with anaerobic culture medium before being injected into the simulation device.

9. Use of the method according to any one of claims 5 to 8 in reservoir environment research.

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