Microbial technology modified hydrate reservoir sand prevention simulation evaluation device

Abstract

The utility model belongs to the technical field of hydrate reservoir modification, and particularly discloses a sand prevention simulation evaluation device for modifying a hydrate reservoir by a microbial technology, which comprises a reaction kettle, a microscopic CT (Computed Tomography) machine, a microbial liquid injection system, a gas injection system, a temperature control system, a simulation depressurization system and a data acquisition system, a liquid outlet of the microorganism liquid injection system is communicated with a liquid injection port of the reaction kettle through a pipeline, a microorganism bacterium solution and a cementation reaction solution are sequentially injected into reservoir sediments constructed in the reaction kettle, microorganisms generate urease to hydrolyze urea to form carbonate ions, the carbonate ions and metal calcium ions form calcium carbonate precipitates, the calcium carbonate precipitates are deposited in sand particle pores, and the solid-liquid separation effect is achieved. And filling the pores and bridging the sand particles at the same time. And the capability of the sand particles for resisting gas-water two-phase flow erosion caused by hydrate decomposition is greatly improved, so that the effect of reinforcing sand prevention is achieved. The method can truly reflect the modification process of the hydrate-containing reservoir by the microbial technology, and is used for evaluating the sand prevention effect after the hydrate reservoir is modified by the microbial technology.

Description

Technical Field

[0001] This utility model relates to the field of hydrate reservoir modification technology, and in particular to a simulation and evaluation device for sand control in hydrate reservoirs modified by microbial technology. Background Technology

[0002] Natural gas hydrate (NGH) refers to ice-like, cage-like crystalline compounds formed by natural gas and water molecules under specific low-temperature and high-pressure environments. As a clean and low-carbon geological energy source, it is characterized by its wide distribution, large reserves, and high conversion efficiency. Currently, NGH has attracted widespread attention from governments, related enterprises, and scholars worldwide, and possesses significant development and utilization value. my country has continuously invested substantial human and material resources in NGH development and research.

[0003] To date, hydrate extraction has not yet reached the standards for commercial development. Its extraction efficiency is constrained by multiple factors, and many problems remain to be solved. Among these, reservoir sand production is one of the key factors restricting the safe and efficient production of hydrates. Based on sand control experience in conventional oil and gas well production, researchers at home and abroad have proposed various methods and technologies for sand control in hydrate extraction. Field production test results show that conventional oil and gas well sand control methods perform well in onshore hydrate extraction, but for currently known marine hydrate reservoirs, they have reached their sand control limit. Current marine trial production periods are generally short, and the sand control technologies used have certain limitations. The contradiction between sand control and production enhancement has not been effectively resolved, and the hydrate extraction rate has not reached the requirements for commercial development. Therefore, it is still necessary to update sand control methods in parallel with the research progress on sand production mechanisms to accelerate the commercialization of hydrates.

[0004] Microbial induced carbonate precipitation (MICP) is an emerging microbial geotechnical technology characterized by high efficiency, environmental friendliness, and sustainability, and has been extensively researched and applied in the improvement of sandy soils. MICP based on the urea hydrolysis mechanism is the most common, generating calcium carbonate crystals through mineralization reactions to fill the pores of cemented sandy soils, thereby improving soil properties, retaining water and sand, and increasing soil strength. Furthermore, MICP technology can still improve sand strength in seawater environments, and its applicability can be improved through acclimatization. Considering the weakly consolidated characteristics of hydrate reservoirs, similar to conventional loose sandstone, applying MICP technology to sand control in hydrate reservoir mining has great application potential. This technology helps achieve efficient sand control in hydrate reservoir mining, ensuring long-term safe mining, and has significant theoretical guidance and engineering application value for promoting the commercial development of hydrates. However, at present, there is limited research on devices for using microbial technology to modify hydrate reservoirs, evaluating the sand control effect after modification, and exploring the mechanism of action. Utility Model Content

[0005] In view of this, in order to solve the above problems, this utility model provides a simulation and evaluation device for sand control in hydrate reservoirs modified by microbial technology, a device for simulating sand control in hydrate reservoirs modified by microbial technology, evaluating the sand control effect after modification, and exploring its mechanism of action, as well as its method of use.

[0006] This utility model provides a simulation and evaluation device for microbial technology modification of hydrate reservoirs to prevent sand control, including a reactor, a micro-CT scanner, a microbial injection system, a gas injection system, a temperature control system, a simulated depressurization system, and a data acquisition system. The micro-CT scanner has a rotating lifting platform inside, and the reactor is placed on the rotating lifting platform. The outlet of the microbial injection system is connected to the injection port of the reactor through a pipeline. The outlet of the gas injection system is connected to the inlet of the reactor through a pipeline. The outlet of the temperature control system is connected to the water bath circulation inlet of the reactor through a pipeline. The simulated depressurization system is connected to one of the injection ports of the reactor through a pipeline and is used to simulate hydrate depressurization mining. The data acquisition system is connected to the reactor and is used to collect temperature and pressure information in the reactor and each pipeline.

[0007] Furthermore, the reactor includes a first cylinder, a second cylinder, a first end cap, and a second end cap; the first cylinder and the second cylinder are arranged perpendicularly to each other, are of equal length and are hollow inside, and the second cylinder is placed outside the first cylinder, forming an annular sealed cavity with the first cylinder, which is used to provide a circulating water bath space for the temperature control system.

[0008] Furthermore, the first end cap and the second end cap are coaxially positioned on the upper and lower sides of the first and second cylinders. The inner sides of the first end cap and the second end cap are provided with annular grooves for connecting with the first and second cylinders. The inner sides of the first cylinder and the cylinders are provided with sealing structures in contact with the annular grooves. The first end cap is provided with a liquid outlet channel at its center. The second end cap is provided with a first liquid injection channel, a second liquid injection channel, and an air inlet channel that are independently provided. The first liquid injection channel and the second liquid injection channel are respectively connected to the liquid outlet of the microbial liquid injection system, and the air inlet channel is connected to the air outlet of the gas injection system.

[0009] Furthermore, the liquid outlet channel, the first liquid injection channel, the second liquid injection channel, and the air inlet channel are all equipped with sand-proof mesh to prevent sample particles from entering.

[0010] Furthermore, a groove is present inside the first cylinder near the second end cap for accommodating a sand-proof screen tube. A third cylinder is provided between the sand-proof screen tube and the second end cap to support the sand-proof screen tube. A sealing structure is provided between the third cylinder, the first cylinder, and the second end cap. The first cylinder, the first end cap, and the sand-proof screen tube form a first cavity for filling simulated reservoir samples and gravel. The second end cap, the sand-proof screen tube, and the third cylinder form a second cavity for providing space for outflowing sample particles.

[0011] Furthermore, the second cylinder has a water bath circulation inlet and a water bath circulation outlet at its bottom and top sides, respectively, which are connected to the temperature control system.

[0012] Furthermore, the microbial infusion system includes a first storage tank, a second storage tank, a third storage tank, a reversing valve, a first booster pump, a second booster pump, and a first back pressure valve. The first storage tank is used to store deionized water, the second storage tank is used to store microbial culture solution, and the third storage tank is used to store the cementation reaction solution.

[0013] The outlets of the first and second liquid storage tanks are connected to the inlet of the reversing valve. The outlet of the reversing valve is sequentially connected to the first booster pump, the first flow meter, and the first pressure sensor. The outlet of the third liquid storage tank is sequentially connected to the second booster pump, the second flow meter, and the second pressure sensor. The first back pressure valve is connected to the outlet channel. A third pressure sensor is connected between one end of the first back pressure valve and the outlet channel. The other end of the first back pressure valve is connected to the gas-liquid processing system.

[0014] Furthermore, the gas-liquid treatment system includes a gas-liquid separator, a liquid collector, and a third flow meter. The gas-liquid separator is connected to the third flow meter, and the liquid collector is used to collect the discharged liquid after separation.

[0015] Furthermore, the gas injection system includes a gas storage cylinder, an air compressor, and a pressure regulating valve. The gas storage cylinder is used to store methane gas, and the air compressor, the pressure regulating valve, a fourth flow meter, and a fourth pressure sensor are sequentially installed on the pipe connected to the outlet of the gas storage cylinder.

[0016] Furthermore, the simulated pressure reduction system includes a second back pressure valve, one end of which is connected to the outlet of the third liquid storage tank, and the other end is connected to the gas-liquid processing system.

[0017] Furthermore, a temperature sensor is provided on the inner wall of the first cylinder; the data acquisition system includes a data acquisition unit, and the temperature sensor is electrically connected to the data acquisition unit.

[0018] Compared with the prior art, the technical effects of this utility model are as follows:

[0019] (1) This utility model provides a simulation evaluation device for microbial technology to modify hydrate reservoirs for sand control. It includes a reactor, a micro-CT scanner, a microbial injection system, a gas injection system, a temperature control system, a simulated depressurization system, and a data acquisition system. The micro-CT scanner is equipped with a rotating lifting platform. The reactor is placed on the rotating lifting platform. The outlet of the microbial injection system is connected to the injection port of the reactor through a pipe. The outlet of the gas injection system is connected to the inlet of the reactor through a pipe. The outlet of the temperature control system is connected to the water bath circulation inlet of the reactor through a pipe. The simulated depressurization system is connected to one of the injection ports of the reactor through a pipe. It is used to simulate hydrate depressurization mining. The data acquisition system is connected to the reactor and is used to collect temperature and pressure information in the reactor and each pipe. The aforementioned simulation and evaluation device for hydrate reservoir modification using microbial technology and its operating method can realistically reflect the modification process of hydrate-bearing reservoirs by microbial technology. It can test the impact of microbial mineralization reactions in hydrate-bearing environments on reservoir porosity, permeability coefficient, and hydrate stability, providing experimental evidence for microbial seepage research in hydrate reservoirs. Furthermore, it can evaluate the sand control effect after microbial modification of hydrate reservoirs, explore the evolutionary laws of reservoir damage deformation and particle migration, and reveal the sand production mechanism under multiphase flow during hydrate decomposition and the sand control mechanism after microbial modification. This device and its operating method can guide actual field production, contributing to efficient sand control and optimal scheme selection in hydrate reservoir exploitation. It has significant theoretical guidance and engineering application value for promoting the commercial development of hydrates.

[0020] (2) Microbial-induced carbonate precipitation (MICP) technology is used to reinforce sand particles in hydrate reservoirs, thereby achieving a sand-prevention effect. The reinforcement principle is as follows: microbial inoculum and cementing reaction solution (urea + calcium source) are sequentially injected into the reservoir sediments. Microorganisms produce urease to hydrolyze urea to form carbonate ions, which react with metallic calcium ions to form calcium carbonate precipitate. This precipitate is deposited inside the pores of the sand particles, filling the pores and bridging the sand particles simultaneously. Under this action, the sand particles' ability to resist the erosion caused by the gas-water two-phase flow due to hydrate decomposition is greatly improved, thus achieving a sand-prevention and reinforcement effect. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the microbial technology-modified sand control simulation and evaluation device for hydrate reservoirs according to this utility model;

[0022] Figure 2 for Figure 1 Schematic diagram of the structure of the reaction vessel;

[0023] Figure 3 for Figure 2 Schematic diagram of the structure of the first end cover of the reactor;

[0024] Figure 4 for Figure 2 Schematic diagram of the structure of the second end cover of the reactor;

[0025] Figure 5 This diagram illustrates the morphological changes of sand particles, the characteristics of pore distribution, and the depth to which sand particles penetrate the gravel layer.

[0026] In the diagram: 1. Reactor; 11. First cylinder; 111. Temperature sensor; 12. Second cylinder; 121. Water bath circulation inlet; 122. Water bath circulation outlet; 13. First end cap; 131. Liquid outlet channel; 14. Second end cap; 141. First liquid injection channel; 142. Second liquid injection channel; 143. Air inlet channel; 15. Sealed cavity; 16. Sand screen tube; 17. Third cylinder; 18. Sealing structure; 2. Microscopic CT scanner; 21. Rotary lifting platform; 3. Microbial liquid injection system; 31. First storage tank; 32. Second storage tank; 33. Third storage tank; 34. Reversing valve; 35. First booster pump; 351, First flow meter; 352, First pressure sensor; 36, Second booster pump; 361, Second flow meter; 362, Second pressure sensor; 37, First back pressure valve; 371, Third pressure sensor; 4, Gas injection system; 41, Gas storage cylinder; 42, Air compressor; 43, Pressure regulating valve; 44, Fourth flow meter; 45, Fourth pressure sensor; 5, Temperature control system; 6, Simulated pressure reduction system; 61, Second back pressure valve; 7, Data acquisition system; 71, Data acquisition unit; 8, Gas-liquid processing system; 81, Gas-liquid separator; 82, Liquid collector; 83, Third flow meter. Detailed Implementation

[0027] To make the objectives, technical solutions and advantages of this utility model clearer, the embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0028] Sand production is one of the key issues restricting the safe and efficient production of natural gas hydrates. Current sand control technologies are insufficient to support long-term commercial sand control in hydrate extraction, and new technological solutions need to be explored to accelerate the commercial extraction process. Microbial-induced carbonate precipitation (MICP), as an emerging geotechnical engineering technology, has been extensively studied and applied in the reinforcement of conventional sandy soils. Hydrate reservoirs, similar to conventional loose sandstone, exhibit weak consolidation characteristics, making MICP technology a promising application for sand control in hydrate reservoir extraction. However, at present, there is limited research on the effectiveness and mechanism of using microbial technology to modify hydrate reservoirs for sand control, and related instrumentation is lacking. Therefore, this invention provides a simulation and evaluation device for sand control in hydrate reservoirs modified using microbial technology and its usage method.

[0029] Please refer to Figure 1-4 This invention provides a simulation evaluation device for microbial technology modification of hydrate reservoirs to prevent sand erosion, comprising a reactor 1, a micro-CT machine 2, a microbial injection system 3, a gas injection system 4, a temperature control system 5, a simulated depressurization system 6, and a data acquisition system 7. The micro-CT machine 2 has a rotating lifting platform 21 inside, and the reactor 1 is mounted on the rotating lifting platform 21. The outlet of the microbial injection system 3 is connected to the injection port of the reactor 1 via a pipe. The outlet of the gas injection system 4 is connected to the inlet of the reactor 1 via a pipe. The outlet of the temperature control system 5 is connected to the water bath circulation inlet of the reactor 1 via a pipe. The simulated depressurization system 6 is connected to one of the injection ports of the reactor via a pipe and is used to simulate hydrate depressurization mining. The data acquisition system 7 is connected to the reactor 1 and is used to collect temperature and pressure information from the reactor 1 and the various pipes.

[0030] In some embodiments, the reactor may include a first cylindrical body 11, a second cylindrical body 12, a first end cap 13, and a second end cap 14. The first cylindrical body 11 and the second cylindrical body 12 are arranged perpendicularly, of equal length, and hollow internally. The second cylindrical body 12 is positioned outside the first cylindrical body 11, forming an annular sealed cavity 15 with the first cylindrical body 11, which provides a circulating water bath space for the temperature control system 5. The temperature control system 5 may be equipped with a cryogenic circulating pump, which can adjust the temperature of the circulating fluid in the water bath to provide a low-temperature environment for the formation and stabilization of hydrates.

[0031] In some embodiments, the first end cap 13 and the second end cap 14 are coaxially positioned on the upper and lower sides of the first cylinder 11 and the second cylinder 12. The first end cap 13 and the second end cap 14 each have two corresponding annular grooves on the side in contact with the cylinder, used to place and fix the first cylinder 11 and the second cylinder 12. The first end cap 13 and the second end cap 14 are connected to the first cylinder 11 by a detachable threaded connection, facilitating cleaning of the vessel after use. The first end cap 13 and the second end cap 14 extend a certain distance into the cavity formed by the first cylinder 11. The inner diameter of the first cylinder 11 increases near the second end cap 14, and its annular cross-section contacts the circular sand-proof screen tube 16. A third cylinder 17 is provided between the sand-proof screen tube 16 and the second end cap, used to fix the sand-proof screen tube 16. The outer side of the third cylinder 17 is connected to the first end cap. A cylindrical body is tightly fitted, with its inner side tightly fitted to the extension of the second end cap 14. The inner diameter of the first cylindrical body 11 is the same as the inner diameter of the third cylindrical body 17. The diameter of the sand screen tube 16 is the inner diameter of the third cylindrical body 17 plus twice the thickness of the third cylindrical body 17. The first cavity formed between the first cylindrical body 11, the first end cap 13, and the sand screen tube 16 is used to place the sample. The second cavity formed between the first cylindrical body 11, the sand screen tube 16, and the second end cap 14 is used to provide space for the discharged sediment particles. There are sealing structures 18 between the inner sides of the first cylindrical body 11 and the second cylindrical body 12 and the two grooves of the first end cap 13, between the inner side of the second cylindrical body 12 and the outer groove of the second end cap 14, between the outer sides of the first cylindrical body 11 and the third cylindrical body 17, and between the inner side of the third cylindrical body 17 and the inner groove of the second end cap 14. These sealing structures 18 are used to ensure the sealing of the water bath environment and the reaction environment. The sealing structure 18 is a rubber sealing ring.

[0032] In the above embodiment, the first end cap 13 is provided with a liquid outlet channel 131 at its center, and the second end cap 14 is provided with a first liquid injection channel 141, a second liquid injection channel 142 and an air inlet channel 143 that are independently provided. The first liquid injection channel 141 and the second liquid injection channel 142 are respectively connected to the liquid outlet of the microbial liquid injection system 3, and the air inlet channel 143 is connected to the air outlet of the gas injection system 4. In the hydrate synthesis stage, the first injection channel 141 and the air inlet channel 143 serve as transport channels for high-pressure deionized water and high-pressure methane gas, respectively. In the microbial consolidation stage, the first injection channel 141 and the second injection channel 142 serve as transport channels for deionized water, microbial inoculum, and cementing reaction liquid, respectively. A certain back pressure is always maintained in the outlet channel 131. When the pressure inside the first cavity is greater than the back pressure, the excess gas-liquid mixture is discharged from the outlet channel 131, thereby ensuring the smooth formation and stability of the hydrate. In the simulated depressurization mining stage, the second injection channel 142 is equipped with a depressurization pressure to simulate hydrate depressurization mining. Replaceable sand screens are installed at the contact points between the outlet channel 131, the first injection channel 141, the second injection channel 142, and the air inlet channel 143 and the cavity to prevent sample particles from entering the pipes and causing blockage.

[0033] In some embodiments, the mesh size of the sand-control screen 16 can be changed according to the experimental plan. The first cavity can be filled with sediment or sediment + gravel according to the experimental plan. It is used to simulate reservoir sand production under different working conditions. The reactor 1 is 120mm long and 66mm in diameter. The inner diameter of the first cylinder 11 is 20mm. The height of the first cavity is 60mm. The height of the second cavity is 15mm. The first cylinder 11 and the third cylinder 17 are made of 7075 aluminum alloy. The second cylinder is made of plexiglass. The remaining parts are made of titanium alloy. The reactor 1 can carry out sand control experiments of hydrate reservoir modification using microbial technology under the conditions of temperature -5 to +80℃ and pressure 030MPa.

[0034] In some embodiments, the CT100 (equipment model Nano Vexel-3000) is equipped with an X-ray source, a rotating lifting platform, and a detector. The X-rays emitted by the X-ray source can penetrate the sample. The sample is irradiated multiple times during rotation, and a projection image is formed on the detector. After software processing, a three-dimensional data volume of the sample can be obtained. In the hydrate synthesis, microbial reinforcement, and simulated depressurization mining stages, the CT100 can scan the sample multiple times to obtain the spatial distribution of hydrates and calcium carbonate crystals, the influence of hydrate and calcium carbonate crystal formation on the pore throat structure of the sample, the decomposition of hydrates during depressurization mining, and the migration and evolution process of sediment particles. This allows for a comprehensive exploration of the effect and mechanism of microbial technology in sand control of hydrate reservoirs.

[0035] In some embodiments, the microbial injection system 3 includes a first storage tank 31, a second storage tank 32, a third storage tank 33, a reversing valve 34, a first booster pump 35, a second booster pump 36, and a first back pressure valve 37. The first storage tank 31 is used to store deionized water, and the second storage tank 32 is used to store microbial bacterial solution. The outlet channels of the first storage tank 31 and the second storage tank 32 are connected to the reversing valve 34, which is used to control the type of input liquid. The other end of the reversing valve is connected to the first booster pump 35, and the other end of the first booster pump 35 serves as a first discharge port connected to the first injection channel 141 of the second end cap 14. A first flow meter 351, a first pressure sensor 352, and a valve are connected to this pipeline. The third storage tank 33 is used to store the cementing reaction liquid, and the outlet channel of the third storage tank 33... A second booster pump 36 is connected to the second pump. The other end of the second booster pump 36 is connected to the second liquid injection channel 142 as the second discharge port. The second discharge port is connected to a second flow meter 361 and a valve. The second liquid injection channel 142 also serves as a simulated depressurization mining channel. During the simulated depressurization mining stage, the valve of the second discharge port needs to be closed. One end of the first back pressure valve 37 is connected to the liquid outlet channel 131. A third pressure sensor 371 and a valve are installed on its pipeline. The other end is connected to the gas-liquid treatment system 8. In the hydrate synthesis, microbial reinforcement and simulated depressurization mining stages, the first back pressure valve 37 maintains a certain back pressure. It is used to maintain the cavity pressure stability, discharge excess gas-liquid mixture and prevent gas-liquid backflow. In addition, the liquid outlet channel is connected to the first cavity. The third pressure sensor 371 is used to measure the pressure inside the first cavity.

[0036] In the above embodiments, the gas-liquid treatment system 8 includes a gas-liquid separator 81, a liquid collector 82, and a third flow meter 83. The gas-liquid separator 81 is used to separate the discharged gas-liquid mixture. The volume of the discharged gas is measured by the third flow meter 83, and the discharged liquid is collected by the liquid collector 82 for analysis and weighing.

[0037] In this invention, the gas injection system 4 includes a gas storage cylinder 41, an air compressor 42, and a pressure regulating valve 43. The gas storage cylinder 41 is used to provide methane gas for the synthesis of hydrates. Its outlet channel is connected to the inlet channel 143. The air compressor 42, the pressure regulating valve 43, the fourth flow meter 44, and the fourth pressure sensor 45 are connected in sequence on its pipeline. The methane gas is pressurized by the air compressor 42 and adjusted to a suitable pressure by the pressure regulating valve 43 before being injected into the first cylinder 11. The pressure regulating valve 43 mainly plays the role of regulating pressure and temperature. The fourth flow meter 44 and the fourth pressure sensor 45 are used to measure the gas flow rate and pressure in the outlet channel, respectively.

[0038] In the above embodiments, the booster pump can have a booster range of 0.30 MPa, and the pressure regulating valve can have a pressure regulating range of 0.15 MPa.

[0039] In some embodiments, the simulated depressurization system 6 includes a second back pressure valve 61, one end of which is connected to the outlet of the third storage tank 33. A second pressure sensor 362 and a valve are located between the second back pressure valve 61 and the second outlet channel. During the microbial reinforcement stage, the valve of the second outlet channel is opened, the valve of the second back pressure valve 61 is closed, and the second pressure sensor 362 is used to test the pipeline pressure during the injection of the cementing reaction liquid. During the simulated depressurization mining stage, the valve of the second back pressure valve 61 is opened, the valve of the second outlet channel is closed, and the second pressure sensor 362 is used to test the pressure during the simulated depressurization mining. This separates the microbial liquid injection channel from the cementing reaction liquid injection channel, thereby reducing the risk of calcium carbonate clogging the pipeline.

[0040] In some embodiments, the data acquisition system 7 includes a data acquisition unit 71, a first flow meter 351, a second flow meter 361, a third flow meter 83, a fourth flow meter 44, a first pressure sensor 352, a second pressure sensor 362, a third pressure sensor 371, a fourth pressure sensor 45, and a temperature sensor 111. The data acquisition unit 71 is used to collect test signals and convert them into data. The positions of the flow meters and pressure sensors are as described above. Their monitoring, collection, and processing of temperature and pressure information are all existing technologies, and their specific working principles will not be elaborated here. The temperature sensor 111 is placed inside the first cylinder, and three miniature temperature sensors are arranged from top to bottom. It is used to monitor the temperature changes inside the first cavity. The effects of hydrate synthesis and decomposition, and microbial mineralization reactions on the sample temperature can be measured. The data transmission line of the temperature sensor 111 passes through the first end cap 13 and is connected to the data acquisition system.

[0041] In the above embodiments, in order to prevent the pipeline from affecting the rotation of the sample during the CT100 scanning process, the microbial injection system 3, the gas injection system 4, the temperature control system 5, and the simulated depressurization system 6 are all connected to the reactor 1 by high-pressure hoses inside the CT100.

[0042] The method for using the microbial technology to modify hydrate reservoirs for sand control simulation and evaluation provided by this utility model mainly includes the following steps:

[0043] S1. After filling the first chamber with the sample and assembling the reactor, place the reactor 1 on the CT100 rotating lifting platform and fix it with the triangular claw, connect the pipeline, and perform a device self-test, including checking the airtightness and whether each system is working properly.

[0044] S2. Open the valves between the liquid outlet channel 131, the first back pressure valve 37, and the gas-liquid separator 81. Set the pressure of the first back pressure valve 37 to be higher than the preset hydrate synthesis pressure. Open the valve of the first liquid injection channel 141, start the first booster pump 35, and slowly inject high-pressure deionized water into the reactor. Then close the valve of the first liquid injection channel 141. At the same time, open the valve of the air inlet channel, start the air compressor 42 and the pressure regulating valve 43, and inject high-pressure methane gas into the reactor. Then close the valve of the air inlet channel and start the temperature control system 5 to cool down and synthesize hydrate. During this process, the data transmitted by the temperature sensor 111 and the third pressure sensor 371 are used to determine whether hydrate has been synthesized.

[0045] S3. After the hydrate synthesis is completed, the CT100 is started to test the microstructure of the sample inside the reactor. Specifically, the CT scanning software is opened, the X-ray source is turned on, and the sample inside the reactor is scanned. After the scan is completed, the X-ray source is turned off, the data is exported, and the data is analyzed and processed using image reconstruction software and Avizo software to obtain information such as the microstructure and spatial distribution of the hydrate deposits.

[0046] S4. Start the first booster pump 35, open the valve of the first injection channel 141, and slowly inject high-pressure deionized water into the reactor to saturate the sample until the value of the third flow meter 83 no longer changes. At this time, the difference between the fourth flow meter 44 and the third flow meter 83 is the methane gas consumed in the synthesis of natural gas hydrate, which can be used to calculate the hydrate saturation. Subsequently, adjust the reversing valve 34 to inject microbial liquid into the reactor. After the injection is completed, close the valve of the first injection channel 141 and open the valve of the second injection channel 142. Start the second booster pump 36 to cement the reaction liquid into the reactor body and carry out microbial mineralization reaction to modify the hydrate sample. The injection time, number of injections and reaction time can be arranged according to the experimental design. At the same time, during the microbial consolidation, the data transmitted by the temperature sensor 111 and the third pressure sensor 371 are used to determine whether the reaction will cause the decomposition of the hydrate.

[0047] S5. Start the CT100 test to examine the microstructure of the modified sample inside the reactor. Specifically, open the CT scanning software, turn on the X-ray source, and scan the sample inside the reactor. After the scan is completed, turn off the X-ray source, export the data, and use image reconstruction software and Avizo software to analyze and process the data to obtain the distribution of hydrates and calcium carbonate crystals after reinforcement.

[0048] S6. Keep the valves of the first injection channel 141 and the outlet of the microbial injection system 3 closed, set the pressure of the second back pressure valve 61, which is the pressure reduction pressure during simulated mining, open the valves before and after the second injection channel 142 and the second back pressure valve 61 to simulate hydrate depressurization mining; during this period, the valve of the second injection channel 142 can be closed multiple times, and the CT test can be started to test the microstructure of the sample during the depressurization process in the reactor to obtain the migration and evolution process of sediment particles under different degrees of reinforcement;

[0049] S7. After the simulated hydrate depressurization mining is completed, gradually reduce the pressure of the second back pressure valve 61 and the first back pressure valve 37 in sequence, remove the reactor, clean the reactor and pipelines, and carry out the next set of experiments.

[0050] Example 2

[0051] The apparatus of Example 1 was used to modify hydrate reservoirs using microbial technology and the sand control effect after modification was evaluated.

[0052] Evaluation indicators include:

[0053] 1. During the decomposition of hydrates, the morphological changes of sand particles, the characteristics of pore distribution, and the depth and extent of sand particles intruding into the gravel layer, such as... Figure 5 As shown.

[0054] 2. Quantitative indicators include: cumulative sand yield after hydrate decomposition, sample porosity, and permeability coefficient. The cumulative sand yield is obtained by weighing the sand particles inside the second cavity after the experiment, while the sample porosity and permeability coefficient are obtained from CT analysis.

[0055] Where there is no conflict, the above embodiments and features described herein can be combined with each other.

[0056] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for evaluating the sand control of a hydrate reservoir by microbial technology, characterized in that it comprises: The system comprises a reaction kettle (1), a micro-CT machine (2), a microbial liquid injection system (3), a gas injection system (4), a temperature control system (5), a simulated pressure reduction system (6) and a data acquisition system (7), the inside of the micro-CT machine (2) is provided with a rotating lifting platform (21), the reaction kettle (1) is arranged on the rotating lifting platform (21), the liquid outlet of the microbial liquid injection system (3) is connected with the liquid injection port of the reaction kettle (1) through a pipeline, the gas outlet of the gas injection system (4) is connected with the gas inlet of the reaction kettle (1) through a pipeline, the water outlet of the temperature control system (5) is connected with the water bath circulation inlet of the reaction kettle (1) through a pipeline, the simulated pressure reduction system (6) is connected with one of the liquid injection ports of the reaction kettle through a pipeline, which is used for simulating hydrate pressure reduction mining, and the data acquisition system (7) is connected with the reaction kettle (1) and is used for acquiring temperature and pressure information in the reaction kettle (1) and the pipelines.

2. The device for simulating and evaluating the sand control of the technically reconstructed water-saturated reservoirs according to claim 1, characterized in that, The reaction kettle (1) comprises a first cylinder (11), a second cylinder (12), a first end cover (13) and a second end cover (14), the first cylinder (11) and the second cylinder (12) are arranged vertically, are equal in length and are hollow inside, the second cylinder (12) is arranged outside the first cylinder (11) and forms an annular closed cavity (15) with the first cylinder (11), which is used for providing a circulating water bath space for the temperature control system (5).

3. The apparatus of claim 2, wherein the apparatus is configured to simulate the reservoir sand control using a microorganism technology. The first end cover (13) and the second end cover (14) are coaxially arranged on the upper and lower sides of the first cylinder (11) and the second cylinder (12), the first end cover (13) and the second end cover (14) are provided with annular grooves inside, which are used for connecting the first cylinder (11) and the second cylinder (12), the inner side of the first cylinder (11) and the second cylinder (12) is provided with a sealing structure (18) at the contact surface of the annular groove, the first end cover (13) is provided with a liquid outlet channel (131) at the center, the second end cover (14) is provided with a first liquid injection channel (141), a second liquid injection channel (142) and a gas inlet channel (143) which are arranged independently, the first liquid injection channel (141) and the second liquid injection channel (142) are connected with the liquid outlet of the microbial liquid injection system (3) respectively, and the gas inlet channel (143) is connected with the gas outlet of the gas injection system (4). The liquid outlet channel (131), the first liquid injection channel (141), the second liquid injection channel (142) and the gas inlet channel (143) are all provided with sand prevention nets inside, which are used for blocking the invasion of sample particles.

4. The apparatus of claim 2, wherein the apparatus is configured to simulate the reservoir sand control using a microorganism technology. 5 The first cylinder (11) is internally recessed near the second end cover (14) for placing a sand control screen (16), a third cylinder (17) is arranged between the sand control screen (16) and the second end cover (14) to support the sand control screen (16), a sealing structure (18) is arranged between the third cylinder (17) and the first cylinder (11) and the second end cover (14), the first cylinder (11), the first end cover (13) and the sand control screen (16) form a first cavity for filling simulated reservoir samples and gravel, and the second end cover (14), the sand control screen (16) and the third cylinder (17) form a second cavity for providing space for the outflow of sample particles.

5. The apparatus of claim 2, wherein the apparatus is configured to simulate the reservoir sand control using a microorganism technology. The side bottom and top of the second cylinder (12) are respectively provided with a water bath circulation inlet (121) and a water bath circulation outlet (122) connected with the temperature control system (5).

6. The apparatus of claim 3, wherein the apparatus is configured to simulate the reservoir sand control using a microorganism technology. The microbial injection system (3) comprises a first liquid storage tank (31), a second liquid storage tank (32), a third liquid storage tank (33), a reversing valve (34), a first booster pump (35), a second booster pump (36) and a first back pressure valve (37), the first liquid storage tank (31) is used for storing deionized water, the second liquid storage tank (32) is used for storing microbial liquid, and the third liquid storage tank (33) is used for storing cementation reaction liquid, The liquid outlets of the first liquid storage tank (31) and the second liquid storage tank (32) are communicated with the liquid inlet end of the reversing valve (34), the liquid outlet end of the reversing valve (34) is communicated with the first booster pump (35), a first flow meter (351) and a first pressure sensor (352) in sequence, the liquid outlet of the third liquid storage tank (33) is communicated with the second booster pump (36), a second flow meter (361) and a second pressure sensor (362) in sequence, the first back pressure valve (37) is communicated with the liquid outlet channel (131), a third pressure sensor (371) is connected between one end of the first back pressure valve (37) and the liquid outlet channel (131), and the other end of the first back pressure valve (37) is communicated with the gas-liquid treatment system (8).

7. The device for simulating the sand control of a microbially engineered aquifer according to claim 6, wherein, The gas-liquid treatment system (8) comprises a gas-liquid separator (81), a liquid collector (82) and a third flow meter (83), the gas-liquid separator (81) is connected with the third flow meter (83), and the liquid collector (82) is used for collecting discharged liquid after separation.

8. The device for simulating the sand control of a microbially engineered aquifer according to claim 7, wherein, The gas injection system (4) comprises a gas storage cylinder (41), an air compressor (42) and a pressure regulating valve (43), the gas storage cylinder (41) is used for storing methane gas, and the pipeline connected with the outlet of the gas storage cylinder (41) is sequentially provided with the air compressor (42), the pressure regulating valve (43), a fourth flow meter (44) and a fourth pressure sensor (45).

9. The apparatus of claim 6, wherein the apparatus is configured to simulate the reservoir sand control using a microorganism technology. The simulated pressure reduction system (6) comprises a second back pressure valve (61), one end of the second back pressure valve (61) is communicated with the liquid outlet of the third liquid storage tank (33), and the other end is communicated with the gas-liquid treatment system (8).

10. The apparatus of claim 4, wherein the apparatus is configured to simulate the effect of a microbial treatment on a sand control method for a hydrate reservoir. The inner wall of the first barrel (11) is provided with a temperature sensor (111); the data acquisition system (7) comprises a data acquisition unit (71), and the temperature sensor (111) is electrically connected with the data acquisition unit (71).

Images