CN113029714B - Preparation method and preparation device of artificial rock core containing natural gas hydrate - Google Patents
Preparation method and preparation device of artificial rock core containing natural gas hydrate Download PDFInfo
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Abstract
The application provides a preparation method of an artificial rock core containing natural gas hydrate, which comprises the following steps: vacuumizing the artificial core, and fully contacting the artificial core with deionized water until the interior of the artificial core is in a water saturation state; draining water inside the artificial core to make the artificial core contain bound water; and adjusting the pressure and the temperature, and fully reacting methane gas and deionized water to obtain the artificial core containing the natural gas hydrate. The method performs reaction under the condition of simulating the state that the artificial core contains bound water in the stratum, so that the artificial natural gas hydrate core is more fit with the actual stratum environment containing the natural gas hydrate, the matching degree of physical property parameters of the artificial core and the stratum is improved, and the method has reference significance for the accuracy of a subsequent experimental test result based on the artificial core and the guidance of actual exploitation.
Description
Technical Field
The application belongs to the technical field of artificial core preparation, and particularly relates to a preparation method and a preparation device of an artificial core containing a natural gas hydrate.
Background
The natural gas hydrate is a novel clean energy, is rich in reserves, is widely distributed in marine sediments and land permafrost, is regarded as an effective alternative energy of conventional energy by various countries, and has great significance for relieving increasingly tense traditional fossil fuel crisis by successfully exploiting the natural gas hydrate. At present, the low technical level of exploitation and the potential safety hazard brought by the exploitation process are two key technical problems in the commercial exploitation process of the hydrate. Therefore, the change rule of the pore property, the permeability property, the mechanical property and the like of the natural gas hydrate stratum rock along with the exploitation of the natural gas hydrate and the mechanism influencing the physical property have important theoretical and practical significance for the use of the natural gas hydrate.
Due to the limitation of the problems of difficult acquisition of the natural core, high cost and the like, the artificial core is mostly adopted to simulate the natural gas hydrate formation in related researches at home and abroad. In the prior art, the in-situ generation of the natural gas hydrate in the formation core is not considered, so that the matching degree of the physical property parameters of the artificial core and the formation is not high, and the accuracy of a subsequent experimental test result based on the artificial core and the guidance for actual exploitation are limited.
Disclosure of Invention
The application aims to provide a preparation method and a preparation device of an artificial core containing a natural gas hydrate, and aims to solve the problem that the artificial core containing the natural gas hydrate cannot generate the natural gas hydrate in situ in the prior art, so that the artificial core containing the natural gas hydrate is not fit with an actual stratum containing the natural gas hydrate.
In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:
in a first aspect, the application provides a method for preparing an artificial core containing natural gas hydrate, comprising the following steps:
vacuumizing the artificial core, and then fully contacting the artificial core with deionized water until the interior of the artificial core is in a water saturation state;
draining water inside the artificial core to enable the artificial core to contain bound water;
and adjusting the pressure and the temperature, and fully reacting methane gas and deionized water to obtain the artificial core containing the natural gas hydrate.
In a second aspect, the present application provides an apparatus for preparing an artificial core containing natural gas hydrate, comprising: air supply system, water supply system, core reactor, exhaust system, drainage system, wherein, air supply system with core reactor intercommunication, water supply system with core reactor intercommunication, exhaust system with core reactor intercommunication, drainage system with core reactor intercommunication.
According to the preparation method of the artificial core containing the natural gas hydrate, the internal part of the artificial core is ensured to be in a water saturation state, then redundant water is discharged, the artificial core is in a state only containing bound water, and the state that the artificial core contains the bound water in a stratum is simulated; and then adjusting the pressure and temperature of the reaction cylinder, providing a natural gas hydrate generating and pressure stabilizing condition, simultaneously introducing deionized water and methane gas, providing a synthetic substance foundation of the natural gas hydrate, enabling the artificial core to generate the natural gas hydrate in situ, and simultaneously carrying out reaction under the condition of simulating the state that the artificial core contains bound water in the stratum, so that the artificial natural gas hydrate core is more fit with the actual stratum environment containing the natural gas hydrate, the matching degree of the artificial core and the stratum physical property parameters is improved, and the method has a reference significance for the accuracy of a subsequent artificial core-based experimental test result and the guidance of actual exploitation.
The utility model provides a preparation facilities that contains artificial rock core of natural gas hydrate that this application second aspect provided, this preparation facilities has included gas supply system, water supply system, core reactor, exhaust system, drainage system to through the pipeline intercommunication, this preparation facilities can simulate artificial rock core and contain the constraint water state in the stratum, be favorable to artificial rock core normal position to generate natural gas hydrate, this preparation facilities simple structure, degree of automation is high, be favorable to simplifying technology, and the cost is reduced, moreover, do not produce the discarded object, and is environment-friendly.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a diagram of an apparatus for preparing a natural gas hydrate-containing artificial core according to an embodiment of the present disclosure.
Fig. 2 is a schematic diagram of a preparation apparatus for a natural gas hydrate-containing artificial core provided in an embodiment of the present application.
Fig. 3 is a schematic view of a core holder preparation apparatus provided in an embodiment of the present application.
FIG. 4 is a temperature-pressure equilibrium diagram of the reaction process provided in example 1 of the present application.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In this application, the term "and/or" describes an association relationship of associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (one) of a, b, or c," or "at least one (one) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, and c may be single or plural, respectively.
It should be understood that, in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The weight of the related components mentioned in the description of the embodiments of the present application may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present application as long as it is scaled up or down according to the description of the embodiments of the present application. Specifically, the mass described in the specification of the embodiments of the present application may be a mass unit known in the chemical industry field such as μ g, mg, g, kg, etc.
The terms "first" and "second" are used for descriptive purposes only and are used for distinguishing purposes such as substances from one another and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the present application. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
The first aspect of the embodiments of the present application provides a method for preparing an artificial core containing a natural gas hydrate, including the following steps:
s01, vacuumizing the artificial core, and fully contacting with deionized water until the interior of the artificial core is in a water saturation state;
s02, discharging water in the artificial core to enable the artificial core to be in a state of only containing bound water;
and S03, adjusting the pressure and the temperature, and fully reacting methane gas with deionized water to obtain the artificial core containing the natural gas hydrate.
According to the preparation method of the artificial core containing the natural gas hydrate, the internal part of the artificial core is ensured to be in a water saturation state, then redundant water is discharged, the artificial core is in a state only containing bound water, and the state that the artificial core contains the bound water in a stratum is simulated; and then adjusting the pressure and temperature of the reaction cylinder, providing a natural gas hydrate generating and pressure stabilizing condition, simultaneously introducing deionized water and methane gas, providing a synthetic substance foundation of the natural gas hydrate, enabling the artificial core to generate the natural gas hydrate in situ, and simultaneously carrying out reaction under the condition of simulating the state that the artificial core contains bound water in the stratum, so that the artificial natural gas hydrate core is more fit with the actual stratum environment containing the natural gas hydrate, the matching degree of the artificial core and the stratum physical property parameters is improved, and the method has a reference significance for the accuracy of a subsequent artificial core-based experimental test result and the guidance of actual exploitation.
Further, the preparation method of the artificial core containing the natural gas hydrate comprises the following steps:
G01. providing a core clamping cylinder, placing an artificial core in the core clamping cylinder, covering a sealing cover, opening a gas exhaust valve, and vacuumizing by using a vacuum pump;
G02. providing a deionized water tank, and filling deionized water into the core clamping cylinder by adopting a second constant pressure pump to ensure that the interior of the artificial core is in a water saturation state;
G03. providing a methane gas bottle, and introducing methane gas into the core clamping cylinder by adopting a first constant pressure pump, so that the methane gas pushes deionized water of the artificial core to be discharged, and the artificial core is in a state of only containing bound water;
G04. and adjusting the temperature and the pressure of the core holding cylinder, and fully reacting methane gas and deionized water to obtain the artificial core containing the natural gas hydrate.
In step S01, the artificial core is vacuumized and then fully contacted with deionized water until the interior of the artificial core is in a water saturation state.
Wherein, a vacuum environment is provided to ensure that the reaction is in a vacuum state, which is beneficial to the subsequent reaction.
Specifically, as shown in step G01, a core holding barrel is provided, an artificial core is placed inside the core holding barrel and covered with a sealing cover, a gas exhaust valve is opened, and a vacuum pump is used for vacuumizing.
Further, the core holding barrel is mainly used for placing the artificial core, and meanwhile, a reaction chamber is provided for the subsequent preparation of natural hydrate. Wherein, the length of the artificial core is 100-120 mm, and the diameter is 30-40 mm; the porosity of the artificial rock core is 30-60%, and the permeability is 200-800 mD. The specification, porosity and permeability of the artificial core are controlled, synthesis of natural hydrate is facilitated, and meanwhile the provided artificial core is guaranteed to be beneficial to simulation; the artificial natural gas hydrate core and the actual stratum environment containing the natural gas hydrate are more fit, the matching degree of the artificial core and the physical property parameters of the stratum is improved, and the artificial natural gas hydrate core have reference significance for the accuracy of a subsequent experimental test result based on the artificial core and the guidance of actual exploitation.
In the specific embodiment of the invention, the artificial core is of a selected shape structure, the length of the artificial core is 100mm, and the diameter of the artificial core is 30mm; the porosity of the artificial rock core is 30-60%, and the permeability is 200-800 mD.
And further, opening a gas exhaust valve, and vacuumizing by using a vacuum pump to exhaust air in the core clamping cylinder to form a vacuum environment. Wherein, in the step of adopting the vacuum pump to carry out vacuum-pumping treatment, the vacuum pump is adopted to carry out vacuum-pumping treatment to achieve the vacuum degree not less than 0.067MPa. The vacuum degree is controlled to be not lower than 0.067MPa, which is beneficial to the subsequent reaction. If the vacuum is too low, subsequent core saturation may result.
Further, the artificial core was sufficiently contacted with deionized water until the inside of the artificial core was saturated with water.
Specifically, as shown in step G02, a deionized water tank is provided, and deionized water is filled into the core holding barrel by using a second constant pressure pump, so that the inside of the artificial core is in a water saturation state. And filling water into the vacuumized core holding barrel to enable the interior of the artificial core to be in a water saturation state, so that the state that the artificial core contains bound water in the stratum can be simulated after gas is introduced.
In the step S02, water in the artificial core is discharged, so that the artificial core is in a state only containing bound water, wherein the bound water is water which is in the artificial core and cannot move freely, the step can simulate the state that the artificial core contains the bound water in a stratum, so that the artificial core generates the natural gas hydrate in situ, the artificial natural gas hydrate core is more fit with the actual stratum environment containing the natural gas hydrate, and the matching degree of physical property parameters of the artificial core and the stratum is improved.
Further, water inside the artificial core is drained by applying a pressure difference, wherein the water inside the artificial core is drained by pressure generated by gas, optionally by introducing gas.
Furthermore, the introduced gas can be selected from inert gas or reaction gas, and the reaction gas for subsequent reaction is selected, so that impurity gas is avoided in the reaction process, the system is kept free of impurities, and the reaction efficiency is high.
Specifically, in step G03, a methane gas cylinder is provided, and methane gas is introduced into the core holding barrel by using a first constant pressure pump, so that the methane gas pushes deionized water of the artificial core to be discharged, and the artificial core is in a state of only containing bound water. And (3) introducing methane gas, completely driving out water in the pores of the rock core, enabling the rock core to be in a bound water-containing state in the stratum, and simulating the bound water-containing state of the artificial rock core in the stratum.
Furthermore, the purity of the methane gas is 99.90% -99.99%, the provided methane gas is high-purity methane gas, the introduced gas is high-purity methane gas, no gas is doped, the purity of the gas is improved, water in the pores of the rock core can be completely driven out, the rock core is in a bound water-containing state in the stratum, the bound water-containing state of the artificial rock core in the stratum is simulated, other impurity gases are not introduced, and the purity of the obtained natural hydrate can be ensured to be high in the subsequent reaction process.
Further, the ventilation amount of methane gas is 20 to 45mL. If the ventilation is too much or too little, the formation of hydrates in the pores of the core may be affected.
In the step S03, the pressure and the temperature are adjusted, and the methane gas and the deionized water are fully reacted to obtain the artificial core containing the natural gas hydrate.
Specifically, in step G04, the temperature and the pressure of the core holding cylinder are adjusted, and methane gas and deionized water are fully reacted to obtain the artificial core containing the natural gas hydrate. The pressure and the temperature of the reaction cylinder are adjusted, the generation pressure-stabilizing condition of the natural gas hydrate is provided, meanwhile, deionized water and methane gas are introduced, the synthetic substance foundation of the natural gas hydrate is provided, the artificial rock core generates the natural gas hydrate in situ, and meanwhile, the reaction is carried out under the condition that the simulated artificial rock core contains bound water in the stratum, so that the artificial natural gas hydrate rock core is more fit with the actual stratum environment containing the natural gas hydrate, the matching degree of the artificial rock core and the stratum physical property parameters is improved, and the method has reference significance for the accuracy of the follow-up experimental test result based on the artificial rock core and the guidance of actual exploitation.
Further, in the step of adjusting the pressure and the temperature, the temperature of the core holding cylinder is-10 ℃ to 10 ℃, and the pressure of the core holding cylinder is more than or equal to 3.5MPa. Regulating the temperature to-10 ℃, being beneficial to methane gas and deionized water to react to form natural hydrate at the temperature, and then controlling the pressure of the core holding cylinder to be more than or equal to 3.5MPa, so that the injection pressure is higher than the phase equilibrium pressure at the temperature, and being beneficial to the injection of reactants; and meanwhile, the pressure of the temperature of the core holding barrel is controlled, so that the temperature and pressure conditions reach the phase balance of the natural gas hydrate, the natural gas hydrate can react, and the generated natural gas hydrate is stable in state and not easy to decompose.
In the specific embodiment of the invention, in the step of adjusting the pressure and the temperature, the temperature of the core holding cylinder is-10-2.75 ℃, and the pressure of the core holding cylinder is more than or equal to 3.5MPa; the pressure and the temperature are controlled to ensure that the natural gas hydrate can react, and the generated natural gas hydrate is stable in state and not easy to decompose.
Further, fully reacting methane gas with deionized water to obtain an artificial core containing natural gas hydrate; in the step of fully reacting the methane gas and the deionized water, when the reaction time is more than or equal to 72 hours, the reaction generation time of the natural gas hydrate is ensured to be more than 72 hours, so as to ensure the complete reaction of the natural gas hydrate. The artificial core is enabled to generate the natural gas hydrate in situ, and meanwhile, the artificial core is enabled to react under the condition of simulating the state that the artificial core contains the bound water in the stratum, so that the artificial natural gas hydrate core is more suitable for the actual stratum environment containing the natural gas hydrate, the matching degree of physical property parameters of the artificial core and the stratum is improved, and the artificial core has reference significance for the accuracy of a subsequent experimental test result based on the artificial core and the guidance of actual exploitation.
A second aspect of the embodiments of the present application provides a preparation apparatus for an artificial core containing a natural gas hydrate, including: the reactor comprises an air supply system, a water supply system, a core reactor, an exhaust system and a drainage system, wherein the air supply system is communicated with the core reactor, the water supply system is communicated with the core reactor, the exhaust system is communicated with the core reactor, and the drainage system is communicated with the core reactor.
The utility model provides a preparation facilities who contains artificial rock core of natural gas hydrate, this preparation facilities has included gas supply system, water supply system, core reactor, exhaust system, drainage system to through the pipeline intercommunication, this preparation facilities can simulate artificial rock core and contain the constraint water state in the stratum, be favorable to artificial rock core normal position to generate natural gas hydrate, this preparation facilities simple structure, degree of automation is high, be favorable to simplifying technology, and reduce cost, moreover, do not produce the discarded object, and is environment-friendly.
Specifically, the gas supply system comprises a gas cylinder, a first constant pressure pump, a gas flowmeter and a gas valve; the gas cylinder is communicated with the core reactor through a first pipeline, and the first pipeline is provided with a first constant pressure pump, a gas flowmeter and a gas valve.
Specifically, the water supply system comprises a water tank, a second constant pressure pump, a water valve and a liquid flowmeter; the water tank is communicated with the core reactor through a second pipeline, and the second pipeline is provided with a second constant pressure pump, a water valve and a liquid flowmeter.
Specifically, the exhaust system comprises a gas exhaust valve and a vacuum pump; the vacuum pump is communicated with the core reactor through a third pipeline, and the third pipeline is provided with a gas exhaust valve.
Specifically, the drainage system comprises a liquid discharge valve, a flow meter and a water pump; the water pump is communicated with the core reactor through a fourth pipeline, and the fourth pipeline is provided with a liquid discharge valve and a flowmeter.
Specifically, the core reactor comprises a sealing preparation device and an artificial rock core arranged inside the sealing preparation device.
Further, as shown in fig. 2, the method includes: the device comprises a methane gas cylinder 1, a deionized water tank 8 and a core clamping cylinder 11, wherein the methane gas cylinder 1 is connected with the core clamping cylinder 11 through a first pipeline a, and the first pipeline a is provided with a first constant pressure pump 2, a gas flowmeter 3 and a gas valve 4; the deionized water tank 8 is connected with the core clamping cylinder 11 through a second pipeline b, and the second pipeline b is provided with a second constant pressure pump 7, a water valve 6 and a liquid flowmeter 5; the artificial rock core is placed in the rock core clamping barrel 11, and the rock core clamping barrel 11 is placed in the low-temperature incubator 9; the core holding barrel 11 is connected with a pressure gauge 10, a safety valve 12, a third pipeline c and a fourth pipeline d respectively, a gas exhaust valve 13 and a vacuum pump 14 are connected through the third pipeline c, and an exhaust valve 15, a flow meter 16 and a water pump 17 are connected through the fourth pipeline d.
Further, as shown in fig. 3, the core holding barrel 11 includes a sealing cover 18, a reaction barrel 19 and a base 21, wherein the reaction barrel 19 is disposed right above the base 21, the core 20 is disposed inside the reaction barrel 19, and the sealing cover 18 is disposed right above the reaction barrel 19.
Further, among the first pipeline a, methane gas cylinder 1 is connected with core holder 11 through first pipeline a, and, according to methane gas's direction of delivery, from methane gas cylinder 1, first pipeline a has set gradually first constant pressure pump 2, gas flowmeter 3 and pneumatic valve 4.
Further, the specification of the gas flow meter 3 is 1 to 10mL/min.
In some embodiments, in the step of delivering methane gas, the methane gas cylinder 1, the gas valve 2 and the first constant pressure pump 2 are opened to deliver methane gas into the core holding barrel 11, the methane gas is delivered from the methane gas cylinder 1 to the core holding barrel 11 through the first pipeline a, and the methane gas cylinder controls the input amount of the methane gas through the gas pump and the gas control valve.
Further, in a second pipeline b, the deionized water tank 8 is connected with the core holding cylinder 11 through the second pipeline b, and the second pipeline b is sequentially provided with a second constant pressure pump 7, a water valve 6 and a liquid flowmeter 5 from the deionized water tank 8 according to the conveying direction of the deionized water.
Further, the specification of the liquid flow meter 5 is 1 to 10mL/min.
In some embodiments, in the step of delivering deionized water, the water valve 6 is opened, the second constant pressure pump 7 is used to inject the deionized water tank 8 into the core holding cylinder 11, so that the core holding cylinder 11 is filled with deionized water, the water valve 6 is closed, wherein the deionized water controls the input amount of the deionized water through the constant flow pump and the liquid control valve, and the deionized water is used to prevent impurities and other ions in the water from affecting the synthesis of the natural gas hydrate.
Further, the artificial core is placed in the core holding cylinder 11, and the core 20 is sealed in the reaction cylinder 20 by the sealing cover 18, so that the core is in a sealing state, and methane gas and deionized water can react to generate natural gas hydrate.
Further, a core holding cylinder 11 is placed in the low-temperature thermostat 9; because the core holding barrel needs to be arranged in a low-temperature environment, the core holding barrel is arranged in a low-temperature incubator, and the temperature of the core holding barrel is controlled by adjusting the temperature of the low-temperature incubator.
In some embodiments, the low-temperature incubator is used in a range of-10 ℃ to 65 ℃ to ensure that the temperature inside the core holding cylinder can be thermostatically controlled.
In some embodiments, the low-temperature incubator controls the temperature inside the core holding cylinder, stably controls the temperature inside the core holding cylinder to be-10 ℃ to 10 ℃, and in the temperature range, the natural gas hydrate after the reaction process is stable in state and not easy to decompose.
Further, the core holding barrel 11 is connected to a pressure gauge 10, a safety valve 12, a third pipe c and a fourth pipe d, respectively, a gas exhaust valve 13 and a vacuum pump 14 are connected through the third pipe c, and an exhaust valve 15, a flow meter 16 and a water pump 17 are connected through the fourth pipe d.
In some embodiments, pressure gauge 10 sets up directly over core holding cylinder 11, and the pressure gauge shows pressure gauge junction department pressure in the core holding cylinder, adopts the pressure gauge can monitor the pressure condition in the core holding cylinder at any time.
In some embodiments, the safety valve 12 is disposed beside the core holding barrel 11, and is provided to open the safety valve in time for exhaust or drainage if the pressure gauge is abnormal during the reaction process, so as to ensure the safety of the equipment.
Further, the core holding barrel 11 is connected to a gas exhaust valve 13 and a vacuum pump 14 through a third pipe c.
In some embodiments, the gas exhaust valve is opened, and a vacuum pump is used for vacuumizing, so that the air in the core holding cylinder is exhausted, and a vacuum environment is formed.
Further, the core holding barrel 11 is connected to a discharge valve 15, a flow meter 16, and a water pump 17 through a fourth pipe d.
In some embodiments, in step G03, methane gas is provided, and the vent valve 15 is opened to allow the high pressure methane gas to push the deionized water in the core barrel 11 out, while the core 20 contains bound water.
In some embodiments, in step G04, adjusting the temperature and pressure of the core holding barrel, closing the gas valve 2 and the discharge valve 15, opening the water valve 6 and the second constant pressure pump 7 to continuously inject the deionized water in the deionized water tank 8 into the core holding barrel 11, opening the high pressure methane gas cylinder 1 and the gas valve 2 to introduce high pressure methane gas into the core holding barrel 11, and reacting as a reactant for generating natural gas hydrate to obtain the artificial core containing natural gas hydrate.
In some embodiments, the displayed quantities of the gas flow meter 3 and the liquid flow meter 5 are observed, and when the two are no longer changed, it is substantially determined that the natural gas hydrates are substantially reacted in the core 20.
The following description will be given with reference to specific examples.
Example 1
In this embodiment, a preparation apparatus shown in fig. 1 is used to prepare an artificial core containing natural gas hydrate, and specifically includes the following steps:
(1) Providing a core clamping cylinder, placing an artificial core in the core clamping cylinder and covering a sealing cover, wherein the length of the artificial core is 100mm, and the diameter of the artificial core is 30mm; the porosity of the artificial rock core is 30%, and the permeability is 200mD; opening a gas discharge valve, and vacuumizing by using a vacuum pump until the vacuum degree is 0.067MPa;
(2) Providing a deionized water tank, and filling deionized water into the core clamping cylinder by adopting a second constant pressure pump to ensure that the interior of the artificial core is in a water saturation state;
(3) Providing a methane gas bottle, and introducing methane gas into the core clamping cylinder by adopting a first constant pressure pump, wherein the purity of the methane gas is 99.90%, and the ventilation capacity of the methane gas is 20-22 mL; the methane gas pushes deionized water of the artificial rock core to be completely discharged, so that the artificial rock core is in a state of containing bound water;
(4) And (3) adjusting the temperature and the pressure of the core holding barrel, controlling the temperature of the core holding barrel to be-10 ℃ and the pressure to be 3.5MPa, fully reacting methane gas and deionized water, wherein the reaction time is not less than 72 hours, observing the display quantities of the gas flowmeter 3 and the liquid flowmeter 5, and basically determining that the natural gas hydrate basically reacts in the core 20 when the natural gas hydrate and the liquid flowmeter do not change any more to obtain the artificial core containing the natural gas hydrate.
Example 2
In this embodiment, the preparation apparatus shown in fig. 1 is used to prepare the artificial core containing natural gas hydrate, and specifically includes the following steps:
(1) Providing a core clamping cylinder, placing an artificial core in the core clamping cylinder and covering a sealing cover, wherein the length of the artificial core is 100mm, and the diameter of the artificial core is 30mm; the porosity of the artificial rock core is 40%, and the permeability is 400mD; opening a gas discharge valve, and vacuumizing by using a vacuum pump until the vacuum degree is 0.067MPa;
(2) Providing a deionized water tank, and filling deionized water into the core clamping cylinder by adopting a second constant pressure pump to ensure that the interior of the artificial core is in a water saturation state;
(3) Providing a methane gas bottle, and introducing methane gas into the core clamping cylinder by adopting a first constant pressure pump, wherein the purity of the methane gas is 99.95%, and the ventilation capacity of the methane gas is 27-29 mL; the methane gas pushes deionized water of the artificial rock core to be completely discharged, so that the artificial rock core is in a state of containing bound water;
(4) And adjusting the temperature and the pressure of the core holding barrel, controlling the temperature of the core holding barrel to be-5 ℃, controlling the pressure to be 4.0MPa, fully reacting methane gas and deionized water, observing the display quantity of the gas flowmeter 3 and the liquid flowmeter 5 when the reaction time is 80 hours, basically determining that the natural gas hydrate in the core 20 basically finishes the reaction when the two do not change, and obtaining the artificial core containing the natural gas hydrate.
Example 3
In this embodiment, the preparation apparatus shown in fig. 1 is used to prepare the artificial core containing natural gas hydrate, and specifically includes the following steps:
(1) Providing a core clamping cylinder, placing an artificial core in the core clamping cylinder and covering a sealing cover, wherein the length of the artificial core is 100mm, and the diameter of the artificial core is 30mm; the porosity of the artificial rock core is 60%, and the permeability is 800mD; opening a gas discharge valve, and vacuumizing by using a vacuum pump until the vacuum degree is 0.067MPa;
(2) Providing a deionized water tank, and filling deionized water into the core clamping cylinder by adopting a second constant pressure pump to ensure that the interior of the artificial core is in a water saturation state;
(3) Providing a methane gas bottle, and introducing methane gas into the core clamping cylinder by adopting a first constant pressure pump, wherein the purity of the methane gas is 99.99%, and the ventilation capacity of the methane gas is 41-43 mL; the methane gas pushes the deionized water of the artificial rock core to be completely discharged, so that the artificial rock core is in a state of containing bound water;
(4) And adjusting the temperature and the pressure of the core holding barrel, controlling the temperature of the core holding barrel to be 2.75 ℃, controlling the pressure to be 4.5MPa, fully reacting methane gas and deionized water, wherein the reaction time is 85 hours, observing the display quantity of the gas flowmeter 3 and the liquid flowmeter 5, and basically determining that the natural gas hydrate in the core 20 basically finishes the reaction when the two do not change, thereby obtaining the artificial core containing the natural gas hydrate.
Analysis of the reaction process:
when the reaction process of example 3 is tested, as shown in fig. 4, according to the phase equilibrium diagram of fig. 4, when the temperature is less than 276K and the pressure is greater than 4MPa, the natural gas hydrate reaches the phase equilibrium state, and it is considered that the natural gas hydrate stably exists under the current temperature and pressure environment condition.
In summary, according to the preparation method of the artificial core containing the natural gas hydrate, the artificial core is placed in the reaction cylinder, the interior of the artificial core is in a saturated water state, methane gas is introduced, water in pores of the core is completely driven out, the core is in a bound water state in a stratum, and the bound water state of the artificial core in the stratum is simulated; and then adjusting the pressure and temperature of the reaction cylinder, providing a natural gas hydrate generating and pressure stabilizing condition, simultaneously introducing deionized water and methane gas, providing a synthetic substance foundation of the natural gas hydrate, enabling the artificial core to generate the natural gas hydrate in situ, and simultaneously carrying out reaction under the condition of simulating the state that the artificial core contains bound water in the stratum, so that the artificial natural gas hydrate core is more fit with the actual stratum environment containing the natural gas hydrate, the matching degree of the artificial core and the stratum physical property parameters is improved, and the method has a reference significance for the accuracy of a subsequent artificial core-based experimental test result and the guidance of actual exploitation.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (6)
1. A preparation method of an artificial core containing natural gas hydrate is characterized by comprising the following steps:
providing a core clamping cylinder, placing the artificial core in the core clamping cylinder, covering a sealing cover, opening a gas exhaust valve, and vacuumizing by using a vacuum pump; wherein the length of the artificial core is 100-120 mm, and the diameter of the artificial core is 30-40 mm; the porosity of the artificial rock core is 30-60%, and the permeability is 200-800 mD;
providing a deionized water tank, and filling deionized water into the core clamping cylinder by adopting a second constant pressure pump to ensure that the interior of the artificial core is in a water saturation state;
providing a methane gas bottle, and introducing methane gas into the core clamping cylinder by using a first constant pressure pump, so that the methane gas pushes deionized water of the artificial core to be discharged, and the artificial core only contains bound water; wherein the ventilation volume of the methane gas is 20-45 mL;
adjusting the temperature and the pressure of the core holding barrel, providing a natural gas hydrate generation pressure stabilizing condition, fully reacting methane gas and deionized water, and generating the natural gas hydrate in situ by the artificial core to obtain the artificial core containing the natural gas hydrate;
wherein, in the step of adopting the vacuum pump to carry out vacuum pumping treatment, the vacuum pump is adopted to carry out vacuum pumping treatment to achieve the vacuum degree of not less than 0.067MPa.
2. The method for preparing the artificial core containing the natural gas hydrate as claimed in claim 1, wherein the purity of the methane gas is 99.90-99.99%.
3. The method for preparing the artificial core containing the natural gas hydrate as claimed in claim 1, wherein the temperature of the core holding barrel is-10 ℃ to 10 ℃.
4. The method for preparing the artificial core containing the natural gas hydrate as claimed in claim 1, wherein the pressure of the core holding cylinder is not less than 3.5MPa.
5. The method for preparing the artificial core containing the natural gas hydrate as claimed in claim 1, wherein in the step of fully reacting methane gas with deionized water, the reaction time is not less than 72 hours.
6. The preparation device for the artificial rock core containing the natural gas hydrate is characterized by comprising the following components: the preparation device comprises an air supply system, a water supply system, a core reactor, an exhaust system and a drainage system, wherein the air supply system is communicated with the core reactor, the water supply system is communicated with the core reactor, the exhaust system is communicated with the core reactor, the drainage system is communicated with the core reactor, and the preparation device is used for implementing the preparation method as claimed in any one of claims 1 to 5.
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Inventor after: Yu Qiannan Inventor after: Zhang Han Inventor after: Li Ning Inventor after: Zhang Kun Inventor after: Zhan Mingwang Inventor after: Sui Dianjie Inventor after: Zhao Fulei Inventor after: Yu Yang Inventor after: Wang Gang Inventor before: Yu Qiannan Inventor before: Zhang Han Inventor before: Li Ning Inventor before: Zhang Kun Inventor before: Zhan Mingwang Inventor before: Sui Dianjie Inventor before: Zhao Fulei Inventor before: Yu Yang |