NL2026954A - Experimental system and method for integrated simulation of sand production and reformation of natural gas hydrate reservoirs around wells - Google Patents
Experimental system and method for integrated simulation of sand production and reformation of natural gas hydrate reservoirs around wells Download PDFInfo
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 58
- 239000004576 sand Substances 0.000 title claims abstract description 56
- 238000000034 method Methods 0.000 title claims abstract description 43
- 238000004088 simulation Methods 0.000 title claims description 13
- NMJORVOYSJLJGU-UHFFFAOYSA-N methane clathrate Chemical compound C.C.C.C.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O NMJORVOYSJLJGU-UHFFFAOYSA-N 0.000 title description 5
- 239000007788 liquid Substances 0.000 claims abstract description 87
- 239000012530 fluid Substances 0.000 claims abstract description 65
- 230000008569 process Effects 0.000 claims abstract description 29
- 239000007787 solid Substances 0.000 claims abstract description 23
- 238000013508 migration Methods 0.000 claims abstract description 21
- 230000005012 migration Effects 0.000 claims abstract description 21
- 238000006073 displacement reaction Methods 0.000 claims abstract description 20
- 239000002184 metal Substances 0.000 claims abstract description 16
- 239000011148 porous material Substances 0.000 claims abstract description 14
- 238000000926 separation method Methods 0.000 claims abstract description 13
- 239000007789 gas Substances 0.000 claims description 70
- 239000000463 material Substances 0.000 claims description 36
- 238000011049 filling Methods 0.000 claims description 20
- 239000000523 sample Substances 0.000 claims description 18
- 239000013587 production medium Substances 0.000 claims description 15
- 238000007789 sealing Methods 0.000 claims description 13
- 238000002474 experimental method Methods 0.000 claims description 12
- 239000002609 medium Substances 0.000 claims description 10
- 238000012544 monitoring process Methods 0.000 claims description 9
- 239000011521 glass Substances 0.000 claims description 8
- 239000007791 liquid phase Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 238000009826 distribution Methods 0.000 claims description 6
- 229920006395 saturated elastomer Polymers 0.000 claims description 6
- 238000011161 development Methods 0.000 claims description 3
- 239000013049 sediment Substances 0.000 claims description 3
- 239000011435 rock Substances 0.000 claims 14
- 238000005336 cracking Methods 0.000 claims 7
- 238000009530 blood pressure measurement Methods 0.000 claims 1
- 238000007664 blowing Methods 0.000 claims 1
- 238000002407 reforming Methods 0.000 claims 1
- 238000000354 decomposition reaction Methods 0.000 abstract description 9
- 239000002245 particle Substances 0.000 abstract description 6
- 230000007246 mechanism Effects 0.000 abstract description 3
- 230000003993 interaction Effects 0.000 abstract description 2
- 238000005065 mining Methods 0.000 description 18
- 238000012800 visualization Methods 0.000 description 12
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 238000011068 loading method Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 206010017076 Fracture Diseases 0.000 description 4
- 150000004677 hydrates Chemical class 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
- E21B41/0099—Equipment or details not covered by groups E21B15/00 - E21B40/00 specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/34—Arrangements for separating materials produced by the well
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
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Abstract
The present disclosure relates to an experimental system and a method for simulating a 5 sand production process and reformation of a hydrate reservoir around wells. The experimental system includes a reactor, a gas-liquid mixed displacement and control sub-system, an overburden servo control sub-system, and a gas-solid-liquid separation sub-system. The reactor includes a top flange, a bottom flange, a ring-shaped metal frame, an overpressure piston, and a central well shaft. The top flange, the ring-shaped metal frame, and the bottom flange are 10 stacked along a top-down direction and are connected by evenly distributed screw rods. The overpressure piston is T-shaped, and a top of the overpressure piston is configured within the chamber of the reactor. A bottom of the overpressure piston passes through the bottom flange. A middle of the overpressure piston is configured with a fluid outlet passing through the reactor. The central well shaft is installed in the fluid outlet. Through the integrated application of the 15 reactor and the above system, the characteristics of the pore structure, the evolution of the fluid pressure in the process of sand production, and reformation in the decomposition zone of the hydrate reservoir can be observed. Thus, the migration of particle flow and fluid-solid transportation, and the mechanism of fluid-particle interaction during migration can also be observed.
Description
[0001] The present disclosure relates to the field of measurement technology for sand production and fracturing reformation during the development of natural gas-hydrate reservoirs, and in particular to an experimental system and method for integrated simulation of sand production and reformation of hydrate reservoirs around wells.
[0002] Natural gas hydrate is a potential alternative energy source due to its huge reserves, wide distribution, and high energy density. In addition, the natural gas hydrate combustion process is clean and pollution-free, which can effectively alleviate the bottleneck of energy and environment. The international community pays extensive attention to this high-quality unconventional energy. Up to now, major countries in the world, such as the United States, Japan, Canada, South Korea, India, Germany, Russia and China have conducted a large number of onsite investigations on it. Also, the United States, Japan and China are main representatives for successfully conducting relevant technology trial mining in permafrost and marine areas.
[0003] With trial mining experiments, research teams from various countries have verified the feasibility of hydrate mining technology, but a series of economic and safety problems are faced by hydrate mining. These problems have severely restricted the commercialization of hydrate mining. Sand produced by hydrate mining affects the safety of the area around the production well, and hydrates are mostly distributed in clayey reservoirs. Thus, it's difficult to extract the hydrate quickly, which affects the problems with respect to economics and continuous production. The hydrate resources in Nankai Trough in Japan are mostly sandy reservoirs. Although the economic indicators in the mining process are good, there are serious sand production problem in the first and second trial production stages. Although the second trial mining used a special Geoform material for sand control, on the basis of the first gravel pack sand control, it is still inevitable that the production will be interrupted early due to the continuous sand production problem. The hydrate resources in the China South Sea are dominated by clay reservoirs. As the trial mining period is relatively short compared with commercial mining time, and the solid particles produced with fluid migration are small, there is no obvious sand production problems causing safety hazards. However, the safety issue needs to be paid attention in the subsequent trial mining and further commercial mining. In addition, based on the analysis of the economic indicators, such as gas and water production, in the China South Sea, the clay hydrate reservoir may not be sufficient to support the requirements of commercial mining under the existing mining conditions. For daily gas production, corresponding reservoir transformation must be carried out on the basis of the original reservoir. The fracturing stimulation technology widely used in other energy exploitation fields is undoubtedly an option. It is necessary to carry out related fracturing stimulation research on hydrate reservoirs.
[0004] Specifically, in the actual mining process of hydrate reservoirs, there are undecomposed areas of hydrates, areas where hydrates are being decomposed and areas where hydrates have been decomposed. Due to the weakening of various properties after hydrate decomposition, the hydrate reservoir decomposition area around the well faces the most serious sand production problem compared with other areas, and the problems caused by the well wall safety and other issues need more attention. At the same time, the fracturing technology in the process of reservoir reformation also determines that the initiation and propagation of fractures develop from the hydrate decomposed areas around well. In view of the above, it is necessary to conduct an intuitive and in-depth study of the fluid-solid migration phenomenon in the decomposition area of the hydrate reservoir around the well. The three-phase distribution characteristics in the process of fluid-solid migration in hydrate reservoirs may be conceived in view of the hydrate reservoir reformation and fluid-solid migration during the mining process. Also, the mechanism affecting fluid-solid migration in hydrate reservoirs can be clarified. Thus, it is urgent to design a real-time visual observation of hydrate reservoir decomposition area around wells and a simulation system for regional sand production and reformation process.
[0005] In order to make up for the deficiencies of hydrate sand production and reservoir testing hardware, in one embodiment, an integrated experimental system and method for simulating sand production and reformation of hydrate reservoirs around wells is proposed. The safety and stability problems of reservoirs and well walls caused by sand production in the process of mineral exploitation can also be evaluated. In addition, the actual effect of hydrate reservoir fracturing technology can also be simulated. With respect to the hydrate sand production, not only the migration and distribution of fluid-solid during the mining process can be discussed, but also the gas, water, sand production rules, and the deformation and failure evolution characteristics of the well wall area. In view of the hydrate fracturing reformation problem, the crack initiation and propagation during the reformation process can be observed. Via the visual graphical observation and rigorous parameter monitoring, it provides theoretical reference for the actual mining plan of hydrate.
[0006] In one aspect, an experimental system for simulating a sand production process and reformation of a hydrate reservoir around wells includes: a reactor, a gas-liquid mixed displacement and control sub-system, an overburden servo control sub-system, and a gas-solid- liquid separation sub-system; the reactor including a top flange, a bottom flange, a ring-shaped metal frame, an overpressure piston, and a central well shaft, the top flange, the ring-shaped metal frame, and the bottom flange being stacked along a top-down direction, and being connected and locked by evenly distributed screw rods, the reactor being configured to be plate- shaped, and the reactor including a plate-shaped chamber; the top flange being embedded with a high-pressure visualization glass; the ring-shaped metal frame being configured with a plurality of fluid inlets evenly distributed on the ring-shaped metal frame along an annular direction, and the fluid inlets passing though the reactor; the overpressure piston being T-shaped, and a top of the overpressure piston being configured within the chamber of the reactor, and a bottom of the overpressure piston passing through the bottom flange, a middle of the overpressure piston being configured with a fluid outlet passing through the reactor; a central well shaft being installed in the fluid outlet; the bottom flange being configured with two overpressure inlets and outlets passing through the reactor; the gas-liquid mixed displacement and control sub-system being communicated with the fluid inlet and the central well shaft to provide the water-gas production medium required to the reactor or to provide fracturing fluid required to the central well shaft; the overpressure servo control sub-system being communicated with the overpressure inlet and outlet to apply overburden stress to sediment samples in the reactor; and the gas-solid-liquid separation sub-system being communicated with the central well shaft and being configured to separate an output of sand production experiment.
[0007] Wherein the central well shaft includes a sand producing well shaft and a fracturing well shaft, the sand producing well shaft is configured to collect solid, liquid, and gas produced during a simulated production process in the reactor, and the fracturing well shaft is configured to inject fluid into filling material in the reactor so as to simulate conditions of fractures in the reservoir during the process.
[0008] Wherein the overpressure piston is configured with a plurality of pressure measuring probes along a radial direction, the pressure measuring probe passes through the overpressure piston so as to insert into the chamber of the reactor; and the top flange is configured with a plurality of pressure measuring probes along the radial direction, and the pressure measuring probes pass through the top flange and are inserted into the chamber of the reactor.
[0009] Wherein the gas-liquid mixed displacement and control sub-system includes a gas source supply branch and a liquid phase supply branch; the gas source supply branch includes a gas cylinder, a one-way pressure reducing valve, a first valve, and a flow meter sequentially connected by at least one pipeline, a first pressure gauge is connected to a pipeline between the gas cylinder and the one-way pressure reducing valve, the liquid phase supply branch includes a variable frequency screw pump and a second valve, the pipeline between the variable frequency screw pump and the second valve is connected with a second pressure gauge; and the gas supply branch and the liquid supply branch merge into the mixer, the mixer is connected to the central well shaft in each fluid inlet, the pipeline between the mixer and each fluid inlet is configured with a third valve, and the pipeline between the mixer and the central well shaft is provided with a fourth valve.
[0010] Wherein the mixer connects to the pipeline including a fifth value for emptying medium in the mixer, and a third pressure gauge is connected to the pipeline between the mixer and the fifth valve.
[0011] Wherein the overpressure servo control sub-system is divided into an overpressure loading branch and an overpressure emptying branch, the overpressure loading branch includes a servo pump and a sixth valve that are sequentially connected through the pipeline, and the overpressure discharge branch is a pipeline configured with a seventh valve, the overpressure loading branch is connected to one of the overpressure inlet and outlet, and the overpressure discharge branch is connected to the other overpressure inlet and outlet, and a fourth pressure gauge is connected between the sixth valve and the overpressure inlet and outlet.
[0012] Wherein the gas-solid-liquid separation sub-system includes a solid-liquid separator, a back pressure valve, a gas-liquid separator, and a gas collector being sequentially connected by at least one pipeline, the gas-solid-liquid separation sub-system communicates to the central well shaft in the fluid outlet, a fifth pressure gauge is connected to the pipeline between the solid-liquid separator and the central well shaft.
[0013] Wherein the solid-liquid separator is connected to a pipeline having an eighth valve and a pipeline having a ninth valve, the solid-liquid separator is configured to empty liquid and gas in the solid-liquid separator, the gas-liquid separator connects to a pipeline having a tenth valve for emptying the liquid in the gas-liquid separator, the gas-liquid separator connects to a pipeline having a eleventh valve for exhausting the gas within the gas collector.
[0014] In another aspect, a method for simulating a sand production process of a hydrate reservoir around wells by adopting the above experimental system, the method includes:
[0015] S1: installing the sand production well shaft in a fluid outlet;
[0016] S2: before filling strata-simulation framework material into the reactor, checking airtightness of the experimental system to ensure sealing performance of sealing components, and checking the components are installed in place and performance of the components;
[0017] S3: filling the pre-selected strata framework material into the reactor, connecting valves and pipelines, and applying a vacuum pump to vacuum the system to ensure purity of the system; according to a saturated medium condition of the strata, filling the water-gas production medium into pores of the strata framework material through the gas-liquid mixing displacement and control sub-system so as to simulate actual strata;
[0018] S4: applying overburden stress through the overburden servo control sub-system, simulating actual submarine strata environment, and consolidating and compacting the strata framework material until a consolidated stable state is reached;
[0019] S5: providing water-gas production medium continuously by the gas-liquid mixed displacement and control sub-system into the reactor through the fluid inlet on the outer edge to simulate the water-gas production medium in the area around the well during a migrating process, collecting produced materials into the sand production well shaft to simulate the sand production experiment, and obtaining fluid pressure distribution inside the reservoir via at least one pressure measuring probe arranged radially on the overpressure piston;
[0020] S6: following the fluid migration process in the reservoir sequentially, the gas, liquid, and solid output materials enter the sand production well shaft, and pass through the solid- liquid separator, the gas-liquid separator, and the gas collector, and measuring changes of 5 various components in a real-time manner; and
[0021] S7: during steps S3-S5, through the visualization window in the top flange, monitoring and recording the changes in the pore structure of the reservoir in a real-time manner.
[0022] In another aspect, a method for simulating a reformation process of a hydrate reservoir around wells by adopting the above experimental system. The method includes:
[0023] S1: installing the fracturing well shaft in the fluid outlet;
[0024] S2: before filling the strata-simulation framework material into the reactor, checking airtightness of the experimental system to ensure sealing performance of sealing components, and checking the components are installed in place, and performance of the components;
[0025] S3: filling the pre-selected strata framework material into the reactor, connecting valves and pipelines, and applying a vacuum pump to vacuum the system to ensure purity of the system; according to a saturated medium condition of the strata, filling the water-gas production medium into pores of the strata framework material through the gas-liquid mixing displacement and control sub-system so as to simulate actual strata;
[0026] S4: applying overburden stress through the overburden servo control sub-system, simulating actual submarine strata environment, and consolidating and compacting the strata framework material until a consolidated stable state is reached;
[0027] S5: closing the fluid inlets evenly distributed on the reactor along an annular direction, and injecting fracturing fluid into the reservoir through the fracturing well shaft to simulate the migration of the fracturing fluid from the central well shaft to the chamber of the reservoir;
[0028] S6: monitoring pressure evolution along the radial direction of the reactor; and
[0029] S7: during steps S3-S5, through the visualization window in the top flange, monitoring and recording the real-time changes of a pore structure of the reservoir.
[0030] Through the structural design, component assembly and experimental testing of the above-mentioned experimental system, the claimed invention can achieve the following functions: 1. According to the size parameters of the central well shaft and the outer edge of the reactor, combined with the equal-proportion principle, the large-scale experiment can be applied to the hydrate reservoir well; 2. The consolidation simulation of the hydrate reservoir can be implemented by reducing the overlying strata stress of the hydrate reservoir through the control of the servo pump; 3. By combining the sand producing well shaft through the reactor, different production flow conditions, gas production, water production, and sand production process testing can be implemented in the decomposition area of the lower hydrate reservoir around the well; 4. Combining the reactor with fracturing well shaft, the evaluation of the fracturing reformation in the area around the well of the hydrate reservoir under different fracturing conditions may be performed.
[0031] Embodiments of the invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. Apparently, the accompanying drawings are only some embodiments of the claimed invention. Those of ordinary skill can derive other drawings from these drawings without creative efforts.
[0032] FIG. 1 is a schematic view of the experimental system in accordance with one embodiment;
[0033] FIG. 2 is a schematic view of the sand well shaft and the reactor in accordance with one embodiment; and
[0034] FIG. 3 is a schematic view of the fracturing well shaft in accordance with one embodiment.
[0035] In the figures, 1-gas cylinder, 2-first pressure gauge, 3-one-way pressure reducing valve, 4-first valve, 5-flow meter, 6-variable frequency screw pump, 7-second pressure gauge, 8- second valve, 9-mixer,10-thrid pressure gauge, 11-fifth valve, 12-third valve, 13-fourth valve, 14- servo pump, 15-sixth valve, 16-fourth pressure gauge, 17-seventh valve, 18-fifth pressure gauge, 19-solid-liquid separator, 20-eighth valve, 21-ninth valve, 22-back pressure valve, 23-gas-liquid separator, 24-tenth valve, 25-gas collector; 26-eleventh valve, 27-top flange, 28-glass pressure plate, 29-high-pressure visualization glass, 30-pressure measuring probe, 31-fluid inlet, 32-ring- shaped metal frame, 33-overpressure inlet and outlet, 34-well shaft pressure plate, 35-sand producing well shaft, 36-overpressure piston, 37-bottom flange, and 38-fracturing well shaft.
[0036] Embodiments of the invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.
[0037] Referring to Figs. 1-3, an experimental system is presented for simulating sand production and reformation of hydrate reservoirs around the well. The system including a reactor, a gas-liquid mixed displacement and control system, an overburden servo control system, and a gas-solid-liquid separation system. Through the integrated application of the reactor and the above system, the characteristics of the pore structure, the evolution of the fluid pressure in the process of sand production, and reformation in the decomposition zone of the hydrate reservoir can be observed. Thus, the migration of particle flow and fluid-solid transportation, and the mechanism of fluid-particle interaction during migration can also be observed.
[0038] In one embodiment, the reactor includes a top flange 27, a bottom flange 37, a ring-shaped metal frame 32, an overpressure piston 36, and a central well shaft. The top flange 27, the ring-shaped metal frame 32, and the bottom flange 37 are stacked along a top-down direction, and are connected and locked by the evenly distributed screw rods. As such, the reactor is configured to be plate-shaped. Also, the reactor includes a plate-shaped chamber.
[0039] The top flange 27 is embedded with a high-pressure visualization glass 29, which is fixed by a glass pressure plate 28 and screw. The ring-shaped metal frame 32 is configured with a plurality of fluid inlets 31 evenly distributed on the ring-shaped metal frame 32 along an annular direction, and the fluid inlets 31 pass though the reactor. The overpressure piston 36 is T-shaped, and a top of the overpressure piston 36 is configured within the internal chamber of the reactor, and a bottom of the overpressure piston 36 passes through the bottom flange 37. A middle of the overpressure piston 36 is configured with a fluid outlet passing through the reactor. A central well shaft is installed in the fluid outlet, and the central well shaft is fixed by a well shaft pressure plate 34 and screws. The bottom flange 37 is configured with two overpressure inlets and outlets 33 passing through the reactor.
[0040] In one embodiment, the central well shaft includes a sand producing well shaft 35 and a fracturing well shaft 38. The sand producing well shaft 35 is configured to collect the solid, liquid, and gas produced during the simulated production process in the reactor. The fracturing well shaft 38 is configured to inject fluid into the filling material in the reactor so as to simulate the conditions of fractures in the reservoir during the fracturing process.
[0041] In one embodiment, the overpressure piston 36 is configured with a plurality of pressure measuring probes 30 along the radial direction. The pressure measuring probe 30 passes through the overpressure piston 38 so as to insert into the inner chamber of the reactor. The T-shaped overpressure piston 36 facilitates the arrangement of the pressure measuring probe 30 so that the pressure measuring probes 30 can be directly inserted into the reactor. The top flange 27 is also configured with several pressure measuring probes 30 along the radial direction, and the pressure measuring probes 30 pass through the top flange 27 and are inserted into the inner chamber of the reactor.
[0042] In one embodiment, corresponding positions of the reactor need to be sealed with gaskets and sealing rings.
[0043] In one embodiment, an outer diameter of the reactor is configured as 1000 mm, the thickness is configured as 20 mm, and the inner diameter of the central well shaft is configured as 50 mm. The above-mentioned parameters are adopted to simulate a certain depth of underground well shaft and surrounding formation. The diameter of the high-pressure visualization glass 29 is 500 mm. The high-pressure visualization glass 29 may be configured with a camera device. The ring-shaped metal frame 32 is configured with a plurality of fluid inlets 31 evenly distributed along an annular direction.
[0044] The gas-liquid mixed displacement and control system is divided into a gas source supply branch and a liquid phase supply branch. The gas source supply branch includes a gas cylinder 1, a one-way pressure reducing valve 3, a first valve 4, and a flow meter 5 sequentially connected by pipelines. A first pressure gauge 2 is connected to a pipeline between the gas cylinder 1 and the one-way pressure reducing valve 3. The liquid phase supply branch includes a variable frequency screw pump 6 and a second valve 8. The pipeline between the variable frequency screw pump 6 and the second valve 8 is connected with a second pressure gauge 7.
[0045] The gas supply branch and the liquid supply branch merge into the mixer 9. The mixer 9 is connected to the central well shaft in each fluid inlet and each fluid outlet. The pipeline between the mixer 9 and each fluid inlet 31 is provided with a third valve 12, and a fourth value 13 is configured on the pipeline between the mixer 8 and the central well shaft. The mixer 9 connects to the pipeline having a fifth value 11 for emptying the medium in the mixer 9. A third pressure gauge 10 is connected to the pipeline between the mixer 9 and the fifth valve 11. The gas-liquid mixed displacement and control system is communicated with the fluid inlet 31 and the central well shaft so as to provide the water-gas production medium required for the experiment to the reactor or to provide the fracturing fluid required for the experiment to the central well shaft.
[0046] The overpressure servo control system is divided into an overpressure loading branch and an overpressure emptying branch. The overpressure loading branch includes a servo pump 14 and a sixth valve 15 that are sequentially connected through a pipeline. The overpressure discharge branch is a pipeline configured with a seventh valve 17. The overpressure loading branch is connected to one of the overpressure inlet and outlet 33, and the overpressure discharge branch is connected to the other overpressure inlet and outlet 33. A fourth pressure gauge 16 is connected between the sixth valve 15 and the overpressure inlet and outlet 33. The above-mentioned overpressure servo control system is connected to the overpressure inlet and outlet 33, and is configured to apply the overburden stress to the sediment samples in the reactor.
[0047] The gas-solid-liquid separation system includes a solid-liquid separator 19, a back pressure valve 22, a gas-liquid separator 23, and a gas collector 25, which are sequentially connected by pipelines. The gas-solid-liquid separation system communicates to the central well shaft in the fluid outlet. A fifth pressure gauge 18 is connected to the pipeline between the solid- liquid separator 19 and the central well shaft. The above-mentioned gas-solid-liquid separation system is communicated with the central well shaft and is configured to separate the output of the sand production experiment.
[0048] The solid-liquid separator 19 is connected to a pipeline having an eighth valve 20 and a pipeline having a ninth valve 21, which are respectively configured to empty the liquid and gas in the solid-liquid separator 19. The gas-liquid separator 23 connects to a pipeline having a tenth valve 24 for emptying the liquid in the gas-liquid separator 23. A pipeline with an eleventh valve 26 is connected to the gas collector 25 for exhausting the gas within the gas collector 25. The above pipelines can be connected to an external flow meter to measure the gas volume.
[0049] The highlights of the experimental system are: (1) The inner and outer diameters of the reactor are large enough to better simulate the area around the well in the actual formation,
which reduces the size effect of laboratory equipment in the analogy of the actual formation. Also, it's more close to the real formation conditions. At the same time, it can more completely reflect the fluid-solid migration and evolution in the area around the well, (2) The central well shaft is equipped with sand producing well shaft 35 and fracturing well shaft 38 at the same time. Through the conversion of the central well shaft, it can be simultaneously installed on a set of reactors. The sand production and reformation testing process may be performed simultaneously, which greatly improves the utilization efficiency of the equipment and speeds up the experiment process; (3) The top flange 27 is equipped with a large-size visualization window, which is used in the fluid- solid migration testing process, such as sand production and reformation. In addition to real-time monitoring of fluid pressure, flow rate, gas production, water production, sand production and other indicators, the evolution of the reservoir structure under corresponding conditions can also be observed through transparent windows. This is useful for evaluating reservoirs around the well under different sand production conditions. This contributes to establish the relationship between the visualization results and the experimental parameters of sand production or reformation, and to analyze the relationship between particles in the process of fluid-solid migration based on the intuitive visualization results, or the development of fractures in the area around the well under different fracturing conditions.
[0050] In one embodiment, the method for simulating a sand production process in a hydrate reservoir decomposition zone around the well includes the following steps:
[0051] S1: installing the sand production well shaft 35 in a fluid outlet;
[0052] S2: before filling strata-simulation framework material into the reactor, checking the airtightness of the entire experimental system to ensure that the sealing performance of the sealing components is good, and to ensure the components are installed in place and the working performance is normal;
[0053] S3: filling the pre-selected strata framework material into the reactor, connecting valves and pipelines, and applying a vacuum pump to vacuum the entire system to ensure the purity of an internal environment of the system, and then according to a saturated medium condition of the actual strata, filling the water-gas production medium into pores of the strata framework material through the gas-liquid mixing displacement and control system so as to simulate the actual strata;
[0054] S4: applying overburden stress through the overburden servo control system, simulating the actual submarine strata environment, and consolidating and compacting the strata framework material until a consolidated stable state is reached.
[0055] S5: the gas-liquid mixed displacement and control system continues to provide the required water-gas production medium, which is introduced into the reactor through the fluid inlet 31 on the outer edge of the reactor to simulate the water-gas production medium in the area around the well during production. During the migration process, the produced materials are collected into the sand production well shaft 35. During the sand production experiment, the pressure measuring probe 30 arranged radially on the overpressure piston 36 to obtain the fluid pressure distribution inside the reservoir;
[0056] S6: following the fluid migration process in the reservoir sequentially, the gas, liquid, and solid output materials enter the sand production well shaft 35. Afterward, the gas, liquid, and solid output materials pass through the solid-liquid separator 19, the gas-liquid separator 23, and the gas collector 25. In addition, a real-time measurement of the changes of various components are recorded in the process of the experiment;
[0057] S7: during steps S3-S5, through the visualization window in the top flange 27, monitoring and recording the real-time changes in the pore structure of the reservoir.
[0058] In the above process, the flow sequence of the overpressure liquid is: the servo pump 14, the sixth valve 15, the overpressure inlet and outlet 33; the gas flow sequence is: the gas cylinder 1, the one-way pressure reducing valve 3, the first valve 4, the flow meter 5, and the mixer 9; the flow sequence of liquid is: the variable frequency screw pump 6, the second valve 8, and the mixer 9; the flow sequence of water and gas output medium is: the mixer 9, the third valve 12, and the fluid inlet 31. The other valves of the gas-liquid mixed displacement and control system and the overpressure servo control system are closed.
[0059] In one embodiment, the method for simulating a reformation process of the hydrate reservoir decomposition area around the well includes the following steps:
[0060] S1: installing the fracturing well shaft 38 in the fluid outlet;
[0061] S2: before filling the strata-simulation framework material into the reactor, checking the airtightness of the entire experimental system to ensure that the sealing performance of the sealing components is good, the components are installed in place, and the working performance is normal;
[0062] S3: filling the pre-selected strata framework material into the reactor, connecting the valves and pipelines, and applying the vacuum pump to vacuum the entire reaction system to ensure the purity of an internal environment, and then according to a saturated medium condition of the actual strata, filling the water-gas production medium produced by the gas-liquid mixture into pores of the formation framework material through the gas-liquid mixing displacement and control system so as to simulate the actual formation environment;
[0063] S4: applying overburden stress through the overburden servo control system, simulating the actual submarine strata environment, and consolidating and compacting the strata framework material until a consolidated stable state is reached.
[0064] S5: closing the fluid inlets 31 evenly distributed on the reactor along an annular direction, and injecting the fracturing fluid into the reservoir through the fracturing well shaft 38 to simulate the migration of the fracturing fluid from the central well shaft to the chamber of the reservoir;
[0065] S6: monitoring the pressure evolution along the radial direction of the reactor;
[0066] S7: during steps S3-S5, through the visualization window in the top flange 27, monitoring and recording the real-time changes in the pore structure of the reservoir.
[0067] During the above experiment, the flow sequence of the overpressure fluid is: the servo pump 14, the sixth valve 15, and the overpressure inlet and outlet 33; the flow sequence of fracturing fluid is: the mixer 9, the fourth valve 13, and the fracturing well shaft 38. The other valves of the gas-liquid mixed displacement and control system, the overpressure servo control system and the gas-solid-liquid separation system are all closed.
[0068] It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.
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| CN201911276840.XA CN111022019B (en) | 2019-12-12 | 2019-12-12 | Experiment system and method for integrally simulating sand production and transformation of hydrate reservoir around well |
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| CN113092732A (en) * | 2021-05-07 | 2021-07-09 | 青岛理工大学 | Natural gas hydrate exploitation simulation and sand production and prevention experimental method |
| CN113250676A (en) * | 2021-06-25 | 2021-08-13 | 中国海洋石油集团有限公司 | Experimental device and method for capillary tube simulated displacement |
| CN116498279B (en) * | 2023-06-27 | 2023-09-15 | 中国地质大学（北京） | Experimental system and method for simulating sand production of argillaceous silt reservoir gas reservoir |
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| CN105301200B (en) * | 2015-11-12 | 2017-04-26 | 中国科学院广州能源研究所 | Testing apparatus for characteristics of sand production during mining of natural gas hydrate |
| CN105259003B (en) * | 2015-11-25 | 2018-02-02 | 中国科学院广州能源研究所 | A kind of experimental provision and method for synthesizing ocean gas hydrate sample |
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| CN109696360B (en) * | 2019-01-28 | 2023-10-31 | 中国地质大学（武汉） | Hydrate exploitation reservoir response and sand production simulation multifunctional reaction kettle |
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| CN109707377B (en) * | 2019-01-28 | 2023-06-06 | 中国地质大学（武汉） | Hydrate exploitation reservoir response and sand production comprehensive simulation experiment system and method thereof |
| CN110454146A (en) * | 2019-07-31 | 2019-11-15 | 中国地质大学（武汉） | The device and method to shake out in horizontal well with sand control in evaluation hydrate recovery process |
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