Method and device for measuring methane adsorption quantity of hydrate-containing muddy silt

Abstract

The invention discloses a method and a device for measuring methane adsorption capacity of hydrate-containing muddy silt. The method comprises the following steps: controlling a methane adsorption quantity measuring device to carry out a hydrate generation experiment on a target test sample so as to completely convert water in the target test sample into methane hydrate; obtaining injection pressure, reference kettle pressure and balance pressure of the hydrate generation experiment; and determining the methane adsorption quantity according to the injection pressure, the reference kettle pressure, the balance pressure, the mass of the target test sample, the water content mass of the target test sample, the reference kettle volume and the free space volume of the sample kettle. According to the technical scheme, the problem of inaccurate measurement of the methane adsorption quantity of hydrate-containing muddy silt is solved, and the accuracy of measurement of the methane adsorption quantity is ensured by controlling generation of the methane hydrate and simulating gas adsorption characteristics in a methane hydrate reservoir environment.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and in particular to a method and a device for measuring the methane adsorption amount of hydrate-containing muddy silt. Background Art

[0002] Natural gas hydrates are ice-like crystalline substances formed by natural gas and water under low-temperature and high-pressure conditions. As a clean, unconventional energy source with vast reserves, they hold broad development prospects. Natural gas hydrate extraction is essentially a dynamically coupled process of in-situ hydrate decomposition, gas-water multiphase seepage, and production, which can be summarized as three key steps: decomposition and gas supply, seepage and gas transportation, and drainage and production. The seepage and gas transportation step directly influences gas migration efficiency, and methane adsorption in argillaceous silt reservoirs is a key factor influencing this process. During depressurization extraction, the hydrate decomposition front expands outward from the wellbore, and the resulting gas-water phases must flow through the porous medium of the argillaceous silt before extraction. During this process, methane molecules may adsorb on the pore surfaces of the argillaceous silt, reducing the effective gas permeability and thus limiting extraction efficiency. Therefore, studying the adsorption characteristics of methane in hydrate-bearing argillaceous silt is crucial for optimizing extraction processes and increasing production capacity.

[0003] Currently, gas isothermal adsorption testing primarily utilizes the volumetric method. Its core apparatus consists of a reference and sample reactor. The free volume of the system is calibrated with helium, and pressure changes are measured at constant temperature to calculate the adsorption capacity. However, existing gas isothermal adsorption measurement methods are primarily targeted at conventional reservoirs such as shale and coal seams. Natural gas hydrate reservoirs exhibit the unique coexistence of three phases: gas, liquid, and solid. The presence of hydrate ore bodies significantly alters the reservoir pore structure and gas storage state. Therefore, existing gas isothermal adsorption measurement methods are difficult to apply to measuring methane adsorption in hydrate-bearing muddy silt. Summary of the Invention

[0004] The present invention provides a method and device for measuring the methane adsorption amount of hydrate-containing muddy silt to solve the problem of inaccurate methane adsorption measurement of hydrate-containing muddy silt. By controlling the formation of methane hydrate and simulating the gas adsorption characteristics in the methane hydrate reservoir environment, the accuracy of the methane adsorption measurement is guaranteed.

[0005] According to one aspect of the present invention, a method for measuring the methane adsorption capacity of hydrate-containing muddy silt is provided, the method comprising:

[0006] Controlling the methane adsorption amount measuring device to perform a hydrate formation experiment on a target test sample to convert all water in the target test sample into methane hydrate; the target test sample is a water-containing sample prepared based on a muddy silt sample of a target reservoir; the particle size of the muddy silt sample meets a preset roughness condition;

[0007] Obtain the injection pressure, reference kettle pressure, and equilibrium pressure of the hydrate formation experiment; the injection pressure is the steady-state pressure in the reference kettle after methane gas is injected into the reference kettle, the reference kettle pressure is the pressure of the reference kettle at the end of the hydrate formation experiment, and the equilibrium pressure is the equilibrium pressure of methane hydrate at a preset temperature;

[0008] The methane adsorption amount is determined based on the injection pressure, the reference kettle pressure, the equilibrium pressure, the pre-acquired target test sample mass, the water content of the target test sample, the pre-calibrated reference kettle volume and the free space volume of the sample kettle; the reference kettle volume is the sum of the volumes of the reference kettle and the pipeline connected to the reference kettle; the free space volume of the sample kettle is the difference between the sample kettle volume and the target test sample skeleton volume; the sample kettle volume is the sum of the volumes of the sample kettle and the pipeline connected to the sample kettle.

[0009] According to another aspect of the present invention, a device for measuring the methane adsorption capacity of hydrate-containing muddy silt is provided. The device comprises a gas supply device and a gas adsorption balance device; the gas supply device is used to inject methane gas into the gas adsorption balance device during a hydrate formation experiment; the gas adsorption balance device is used to perform a hydrate formation experiment on a target test sample;

[0010] The gas supply device includes a first gas cylinder, a booster pump, a four-way valve, an exhaust port, a vacuum pump, and a three-way valve; the gas adsorption balance device includes a buffer container, a reference kettle, a sample kettle, a first pressure sensor, and a second pressure sensor; the gas adsorption balance device is located in a constant temperature space;

[0011] The first gas cylinder is connected to the booster pump through a pipeline and a first valve; the booster pump is connected to the four-way valve through a pipeline, the four-way valve is connected to the exhaust port, the four-way valve is connected to the three-way valve through a pipeline, and the three-way valve is connected to the vacuum pump through a pipeline; the four-way valve is connected to the buffer container through a pipeline and a valve; the buffer container is connected to the reference kettle through a pipeline and a valve, a T-shaped middle area is formed between the reference kettle and the sample kettle through a valve and a pipeline, the three-way valve is connected to the middle area through a pipeline and a valve, the reference kettle is connected to the first pressure sensor through a pipeline; the sample kettle is connected to the second pressure sensor through a pipeline;

[0012] The first gas cylinder is used to store methane gas, the booster pump is used to pressurize the gas adsorption balance device to the target reservoir pressure, and the vacuum pump is used to vacuum the gas adsorption balance device; the exhaust port is used to discharge the methane gas in the booster pump after the pressure in the buffer container reaches the target reservoir pressure; the first pressure sensor is used to measure the pressure in the reference kettle; and the second pressure sensor is used to measure the pressure in the sample kettle.

[0013] According to another aspect of the present invention, a system for measuring the methane adsorption amount of hydrate-containing muddy silt is provided, characterized in that the methane adsorption amount measurement system includes a control device and the methane adsorption amount measurement device described in any embodiment of the present invention; the control device includes a memory, a processor, and a computer program stored in the memory and executable by the processor, and when the processor executes the computer program, the methane adsorption amount measurement method described in any embodiment of the present invention is implemented.

[0014] The technical solution of an embodiment of the present invention controls a methane adsorption capacity measurement device to perform a hydrate formation experiment on a target test sample to convert all water in the target test sample into methane hydrate. The target test sample is a water-containing sample prepared from a silty silt sample of a target reservoir. The particle size of the silty silt sample satisfies a preset roughness condition. The injection pressure, reference kettle pressure, and equilibrium pressure of the hydrate formation experiment are obtained. The injection pressure is the steady-state pressure in the reference kettle after methane gas is injected into the reference kettle. The reference kettle pressure is the pressure of the reference kettle at the end of the hydrate formation experiment. The equilibrium pressure is the equilibrium pressure of methane hydrate at a preset temperature. The methane adsorption capacity is determined based on the injection pressure, the reference kettle pressure, the equilibrium pressure, a pre-acquired target test sample mass, a water-containing mass of the target test sample, a pre-calibrated reference kettle volume, and a sample kettle free space volume. The reference kettle volume is the sum of the volumes of the reference kettle and a pipeline connected to the reference kettle. The sample kettle free space volume is the difference between the sample kettle volume and the target test sample skeleton volume. The sample kettle volume is the sum of the volumes of the sample kettle and the pipeline connected to the sample kettle. This technical solution solves the problem of inaccurate methane adsorption measurement in hydrate-containing muddy silt. By controlling methane hydrate generation and simulating the gas adsorption characteristics in the methane hydrate reservoir environment, the accuracy of methane adsorption measurement is ensured.

[0015] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1This is a flow chart of a method for measuring the methane adsorption capacity of hydrate-containing muddy silt provided in Example 1 of the present invention;

[0018] Figure 2 2 is a schematic structural diagram of a device for measuring the methane adsorption capacity of hydrate-containing muddy silt according to a second embodiment of the present invention;

[0019] Figure 3 2 is a schematic structural diagram of a system for measuring methane adsorption of hydrate-containing muddy silt according to a third embodiment of the present invention;

[0020] Figure 4 2 is a schematic diagram of the structure of a control device provided according to embodiment 3 of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. The acquisition, storage, use, processing, etc. of data in the technical solution of this application comply with the relevant provisions of national laws and regulations.

[0023] Example 1

[0024] Figure 1 A flow chart of a method for measuring the methane adsorption of hydrate-containing muddy silt is provided for the first embodiment of the present invention. This embodiment is applicable to the methane adsorption measurement scenario of natural gas hydrate reservoirs, especially to the study of the adsorption law of methane in muddy silt. The method can be performed by a methane adsorption measurement device for hydrate-containing muddy silt, which can be implemented in the form of hardware and / or software and can be configured in a control device. Figure 1 As shown, the method includes:

[0025] S110. Control the methane adsorption amount measuring device to perform a hydrate formation experiment on the target test sample to convert all water in the target test sample into methane hydrate; the target test sample is a water-containing sample prepared based on a muddy silt sample of the target reservoir; the particle size of the muddy silt sample meets a preset roughness condition.

[0026] This solution can be implemented by a control device that controls a methane adsorption measurement device to conduct a hydrate formation experiment on a target test sample. Prior to conducting the hydrate formation experiment, the control device can obtain a muddy silt sample from the target reservoir and grind it to a particle size that meets a predetermined coarseness requirement, such as less than 80 mesh. The control device can then place the muddy silt sample, which meets the coarseness requirement, in a vacuum drying chamber for drying, for example, at 80°C for 12 hours.

[0027] For dried muddy silt samples, the control device can spray distilled water to produce test samples. Specifically, the control device can divide the muddy silt samples from the target reservoir into multiple groups, evenly spray different amounts of distilled water on each group of muddy silt samples, and stir them thoroughly. The mixed muddy silt samples are then placed in a vacuum drying oven filled with saturated potassium sulfate solution until the moisture balance is achieved, thereby obtaining each group of test samples.

[0028] Saturated potassium sulfate solution increases humidity in the air by releasing hydroxide and sulfate ions. When dissolved in water, these ions increase the water vapor content in the air, thereby regulating and controlling humidity levels. A vacuum drying oven filled with saturated potassium sulfate solution was used to control relative humidity to determine the maximum water absorption capacity of each group of muddy silt samples.

[0029] To determine whether moisture equilibrium has been achieved, the mass of each set of muddy silt samples is measured at preset intervals. For example, the muddy silt samples are weighed every 24 hours. If the mass change between two consecutive muddy silt samples is less than a preset mass threshold, moisture equilibrium has been achieved. Otherwise, moisture equilibrium has not been achieved. The mass threshold can be set to 2% of the mass of the dry muddy silt sample.

[0030] Based on the above experiments, the water saturation of each group of test samples can be calculated using the following formula:

[0031]

[0032] Among them, V w represents the volume of water, The unit can be cm 3 ; V b represents the apparent volume of the dry muddy silt sample, The unit can be cm 3 ; Indicates the porosity of dry muddy silt, which can be taken as 0.6; m w represents the water mass, ρ w Indicates water density, which can be 1g / cm 3 ;m b Indicates the mass of dry muddy silt sample, the unit can be g; ρ b The apparent density of dry muddy silt sample can be taken as 1.8 g / cm 3 .

[0033] In one feasible solution, before controlling the methane adsorption measurement device to perform a hydrate formation experiment on the target test sample, the method further includes:

[0034] A preset number of stainless steel balls of known volume are placed in the sample kettle, the temperature of the constant temperature space is adjusted to the preset temperature, and the vacuum pump is controlled to evacuate the gas adsorption balance device;

[0035] Based on the first inert gas expansion experiment, the reference kettle volume and the sample kettle volume were calibrated;

[0036] Take out the stainless steel balls from the sample kettle, put the target test sample into the sample kettle, adjust the temperature of the constant temperature space to the preset temperature, and control the vacuum pump to evacuate the gas adsorption balance device;

[0037] Based on the second inert gas expansion experiment, the free space volume of the sample kettle was calibrated.

[0038] In this scheme, the reference kettle volume is the sum of the volumes of the reference kettle and the pipelines connected to it, and the sample kettle volume is the sum of the volumes of the sample kettle and the pipelines connected to it. The sample kettle free space volume is the difference between the sample kettle volume and the target test sample skeleton volume. The control device can calibrate the reference and sample kettle volumes based on an inert gas expansion test. As will be readily understood, inert gases are chemically inactive and do not react chemically with muddy silt samples. Helium can be used in the inert gas expansion test.

[0039] The specific process of the first inert gas expansion experiment is as follows: the control device loads a preset number of stainless steel balls of known volume into the sample kettle, evacuates the gas adsorption equilibrium device using a vacuum pump, and adjusts the constant temperature space to a preset temperature, such as 30°C. The control device can then charge the reference kettle with inert gas from a gas cylinder. Specifically, the control device can open the valve in the pipeline between the inert gas cylinder and the reference kettle, pressurize the inert gas to a target reservoir pressure, such as 0-10 MPa, using a booster pump, charge the reference kettle with inert gas, and stop charging the reference kettle after the pressure in the reference kettle stabilizes. The pressure in the reference kettle, i.e., the injection pressure, is measured using a pressure sensor located in the reference kettle and recorded as a first pressure value. The control device can then open the valve in the pipeline between the reference kettle and the sample kettle to allow isothermal expansion of the inert gas into the sample kettle. If methane gas adsorption equilibrium is detected, the pressure in the sample kettle, i.e., the equilibrium pressure, is measured using a pressure sensor located in the sample kettle and recorded as a second pressure value.

[0040] The inert gas expansion experiment is repeated by varying the number of steel balls in the sample kettle to obtain at least two sets of pressure values. The reference kettle volume and the sample kettle volume are calculated using each set of pressure values ​​according to the law of conservation of mass. Specifically, the control device can determine the gas density values ​​corresponding to each set of inert gas expansion experiments, namely, a first gas density value and a second gas density value, based on each set of pressure values ​​and the inert gas state equation. The first gas density value is the gas density in the reference kettle at the injection pressure, and the second gas density value is the gas density at adsorption equilibrium conditions.

[0041] From the law of conservation of mass, we can get ρ1V ref =ρ2(V ref +V sam -ΔV); where ρ1 represents the gas density in the reference reactor under the injection pressure, and the unit can be kg / cm 3 ρ2 represents the gas density in the reference reactor under adsorption equilibrium conditions, and the unit can be kg / cm 3 ; V ref Indicates the reference kettle volume, V sam Indicates the volume of the sample kettle, ΔV indicates the volume of the steel ball in the sample kettle in the inert gas expansion experiment, and the volume unit can be cm 3 .

[0042] ρ1V ref =ρ2(V ref +V sam -ΔV) can be organized into a two-variable linear equation, with ΔV as "y", For "x", V sam For "b", we get the equation equation Can be expressed A straight line in a plane coordinate system with ΔV as the horizontal axis is drawn, and the slope and intercept of the line are the reference and sample kettle volumes, respectively. Therefore, the control device transforms the problem of "calculating the reference and sample kettle volumes" into the problem of "solving the slope and intercept of the line." Based on at least two known sets of gas density values, the values ​​of the reference and sample kettle volumes are obtained.

[0043] Similarly, the control device can determine the volume of the intermediate zone based on the inert gas expansion experiment, and the intermediate zone is the T-shaped connecting pipeline between the reference kettle and the sample kettle. The specific process is as follows: a preset number of stainless steel balls of known volume are loaded into the sample kettle, the gas adsorption balance device is evacuated by a vacuum pump, and the temperature of the constant temperature space is adjusted to a preset temperature, such as 30°C. The control device can fill the reference kettle with inert gas through a gas cylinder filled with inert gas. Specifically, the control device can open the pipeline valve between the inert gas cylinder and the reference kettle, pressurize the inert gas to the target reservoir pressure, such as 0-10MPa, through a booster pump, fill the reference kettle with inert gas, and stop filling the reference kettle with inert gas after the pressure in the reference kettle stabilizes. The pressure in the reference kettle, i.e., the injection pressure, is measured by a pressure sensor deployed in the reference kettle and recorded as the third pressure value. The control device controls the valve on the connecting pipeline between the reference kettle and the intermediate zone to open, so that the inert gas can expand isothermally into the intermediate zone. If adsorption equilibrium is detected, the pressure in the reference kettle is measured by the pressure sensor deployed in the reference kettle, that is, the equilibrium pressure, which is recorded as the fourth pressure value.

[0044] From the law of conservation of mass, we can get ρ3V ref =ρ4(V ref +V mid );wherein, ρ3 represents the gas density in the reference reactor under the injection pressure, and the unit can be kg / cm 3 ρ4 represents the gas density in the reference reactor under adsorption equilibrium conditions, and the unit can be kg / cm 3 ; V ref Indicates the reference kettle volume, V mid Indicates the volume of the middle area. The volume unit can be cm. 3 . Based on the obtained reference kettle volume and the third pressure value and the fourth pressure value measured by the inert gas isothermal expansion experiment, the control device can calculate the volume of the intermediate zone. Specifically, the control device can obtain the third gas density value and the fourth gas density value based on the third pressure value, the fourth pressure value and the inert gas state equation, that is, the gas density in the reference kettle under the injection pressure and the gas density in the reference kettle under the adsorption equilibrium condition. The control device can substitute the third gas density value, the fourth gas density value and the reference kettle volume into ρ3V ref =ρ4(V ref +V mid ), and the volume of the middle area V is obtainedmid .

[0045] The calibration of the free space volume of the sample kettle is also achieved based on an inert gas isothermal expansion experiment. The specific process of the second inert gas isothermal expansion experiment is as follows: the target test sample is loaded into the sample kettle, the gas adsorption equilibrium device is evacuated using a vacuum pump, and the constant temperature space is adjusted to a preset temperature, such as 30°C. The control device can fill the reference kettle with inert gas via a gas cylinder containing inert gas. Specifically, the control device can open the valve in the pipeline between the inert gas cylinder and the reference kettle, pressurize the inert gas to the target reservoir pressure, such as 0-10 MPa, using a booster pump, and then fill the reference kettle with inert gas. After the pressure in the reference kettle stabilizes, the inert gas injection is stopped. The pressure in the reference kettle, i.e., the injection pressure, is measured using a pressure sensor located in the reference kettle and recorded as the fifth pressure value. The control device can open the valve in the pipeline between the reference kettle and the sample kettle to allow the inert gas to isothermally expand into the sample kettle. If adsorption equilibrium is detected, the pressure in the sample kettle, i.e., the equilibrium pressure, is measured using a pressure sensor located in the sample kettle and recorded as the sixth pressure value.

[0046] From the law of conservation of mass, we can get ρ5V ref =ρ6(V ref +V sam -V frame );wherein, ρ5 represents the gas density in the reference reactor under the injection pressure, and the unit can be kg / cm 3 ρ6 represents the gas density in the reference reactor under adsorption equilibrium conditions, and the unit can be kg / cm 3 ; V ref Indicates the reference kettle volume, V sam Indicates the volume of the sample kettle, V frame Indicates the skeleton volume of the target test sample. The volume unit can be cm 3 . Based on the obtained reference kettle volume, sample kettle volume and the fifth pressure value and sixth pressure value measured by the second inert gas isothermal expansion experiment, the control device can calculate the skeleton volume of the test sample. Specifically, the control device can obtain the fifth gas density value and the sixth gas density value based on the fifth pressure value, the sixth pressure value and the inert gas state equation, that is, the gas density in the reference kettle under the injection pressure and the gas density in the reference kettle under adsorption equilibrium conditions. The control device can substitute the fifth gas density value, the sixth gas density value, the reference kettle volume and the sample kettle volume into ρ5V ref =ρ6(V ref +V sam -V frame ), and obtain the skeleton volume V of the target test sample frame , and then according to V sam -V frame, get the free space volume V of the sample kettle vp .

[0047] S120. Obtain the injection pressure, reference kettle pressure, and equilibrium pressure of the hydrate formation experiment; the injection pressure is the steady-state pressure in the reference kettle after methane gas is injected into the reference kettle, the reference kettle pressure is the pressure of the reference kettle at the end of the hydrate formation experiment, and the equilibrium pressure is the equilibrium pressure of methane hydrate at a preset temperature.

[0048] In this solution, the methane adsorption measurement device is controlled to perform a hydrate formation experiment on a target test sample, including:

[0049] Place the target test sample into the sample kettle, adjust the temperature of the constant temperature space to the preset temperature, and control the vacuum pump to evacuate the gas adsorption balance device;

[0050] Controlling the methane gas in the first gas cylinder to be pressurized to the target reservoir pressure by the booster pump and then entering the buffer container;

[0051] If it is detected that the pressure in the buffer container reaches a first pressure threshold, the methane gas in the booster pump is controlled to be discharged, and the methane gas in the buffer container is controlled to enter the reference kettle;

[0052] If it is detected that the pressure in the reference kettle does not change, the currently detected pressure in the reference kettle is used as the injection pressure, and the transfer of methane gas in the buffer container to the reference kettle is stopped;

[0053] Controlling the methane gas in the reference kettle to enter the middle zone; the middle zone is the T-shaped connecting pipeline between the reference kettle and the sample kettle;

[0054] If it is detected that there is no change in the pressure of the middle zone, the transfer of the methane gas in the reference kettle to the middle zone is stopped, and the methane gas in the middle zone is controlled to enter the sample kettle;

[0055] If it is detected that the pressure in the sample kettle is less than the second pressure threshold, the control returns to the reference kettle to allow the methane gas to enter the middle zone until the pressure in the sample kettle is greater than or equal to the second pressure threshold;

[0056] If the pressure in the sample kettle is detected to be greater than or equal to the second pressure threshold, the currently detected pressure in the reference kettle is used as the reference kettle pressure.

[0057] After calibrating the free space volume of the sample kettle, the control device can control the methane adsorption measurement device to perform a hydrate formation experiment on the target test sample. Specifically, the hydrate formation experiment process is as follows: the target test sample is placed in the sample kettle, the gas adsorption equilibrium device is evacuated using a vacuum pump, and the constant temperature space is adjusted to a preset temperature, such as 30°C. The control device can then charge the reference kettle with methane gas via a first gas cylinder containing methane gas.

[0058] Specifically, the control device can control the methane gas in the first gas cylinder to be pressurized by the booster pump and enter the buffer container through the four-way valve until the pressure in the buffer container reaches a first pressure threshold. The first pressure threshold can be set based on the target reservoir pressure. After the pressure in the buffer container reaches the first pressure threshold, the control device can control the exhaust port to open and discharge excess methane gas in the booster pump. The control device can open the pipeline valve between the buffer container and the reference kettle, control the methane gas in the buffer container to enter the reference kettle, and control the first pressure sensor deployed in the reference kettle to detect the pressure in the reference kettle according to a preset measurement cycle. If it is detected that the pressure in the reference kettle has not changed, the currently detected pressure in the reference kettle is used as the injection pressure, and the pipeline valve between the buffer container and the reference kettle is controlled to be closed, and the transfer of methane gas in the buffer container to the reference kettle is stopped.

[0059] The control device can control the valve in the pipeline connecting the reference kettle and the intermediate zone to open, allowing methane gas in the reference kettle to enter the intermediate zone. The control device can control a first pressure sensor deployed in the reference kettle to detect the pressure within the reference kettle according to a preset measurement cycle. Since the reference kettle is connected to the intermediate zone, the pressure within the reference kettle is equal to the pressure in the intermediate zone. The control device can use the pressure currently measured by the first pressure sensor as the pressure in the intermediate zone. If no change in the pressure in the intermediate zone is detected, the control device can control the valve in the pipeline connecting the reference kettle and the intermediate zone to close, stopping the transfer of methane gas from the reference kettle to the intermediate zone.

[0060] After shutting off the flow of methane gas from the reference kettle to the intermediate region, the control device can control the valve connecting the intermediate region and the sample kettle to open, allowing the methane gas in the intermediate region to enter the sample kettle. The methane gas entering the sample kettle can combine with the moisture in the target test sample to form methane hydrate. The control device can control a second pressure sensor located in the sample kettle to monitor the pressure within the sample kettle according to a preset measurement cycle. If the pressure within the sample kettle is detected to be less than a second pressure threshold, the control device returns to controlling the methane gas in the reference kettle to enter the intermediate region. After the pressure in the intermediate region stabilizes, the flow of methane gas from the reference kettle to the intermediate region is shut off, and the methane gas in the intermediate region is controlled to enter the sample kettle until the pressure within the sample kettle is greater than or equal to the second pressure threshold. If the pressure within the sample kettle is detected to be greater than or equal to the second pressure threshold, the currently measured pressure within the reference kettle is used as the reference kettle pressure. The second pressure threshold can be determined based on the equilibrium pressure of methane hydrate at a preset temperature. For example, to ensure sufficient combination of moisture and methane gas in the target test sample, the second pressure threshold can be greater than the equilibrium pressure of methane hydrate at the preset temperature, for example, equal to the sum of the equilibrium pressure of methane hydrate at the preset temperature and 0.5 MPa. If the pressure in the sample kettle is greater than or equal to the second pressure threshold, it means that all the water in the target test sample in the sample kettle is converted into methane hydrate.

[0061] S130. Determine the methane adsorption amount based on the injection pressure, the reference kettle pressure, the equilibrium pressure, the pre-acquired target test sample mass, the water content of the target test sample, the pre-calibrated reference kettle volume, and the sample kettle free space volume; the reference kettle volume is the sum of the volumes of the reference kettle and the pipeline connected to the reference kettle; the sample kettle free space volume is the difference between the sample kettle volume and the target test sample skeleton volume; the sample kettle volume is the sum of the volumes of the sample kettle and the pipeline connected to the sample kettle.

[0062] In this embodiment, determining the methane adsorption amount based on the injection pressure, the reference kettle pressure, the equilibrium pressure, the pre-acquired target test sample mass, the water content of the target test sample, the pre-calibrated reference kettle volume, and the sample kettle free space volume includes:

[0063] determining the gas density at the injection pressure, the gas density at the reference kettle pressure, and the gas density at the equilibrium pressure;

[0064] Determining a first gas volume according to the gas density at the injection pressure, a pre-calibrated reference kettle volume, and a pre-acquired target test sample mass; the first gas volume is the total volume of methane gas injected into the reference kettle;

[0065] determining a second gas volume based on the gas density at the reference kettle pressure, a pre-calibrated reference kettle volume, and a pre-acquired target test sample mass; the second gas volume being the remaining methane gas volume in the reference kettle at the end of the hydrate formation experiment;

[0066] Correct the pre-calibrated free space volume of the sample kettle according to the water content of the target test sample;

[0067] determining a third gas volume based on the gas density at the equilibrium pressure, the corrected free space volume of the sample kettle, and the pre-acquired target test sample mass; the third gas volume being the amount of methane gas not adsorbed in the free space volume of the sample kettle at the end of the hydrate formation experiment;

[0068] Determining a fourth gas volume based on the pre-acquired target test sample mass and the water content of the target test sample; the fourth gas volume is the methane gas volume consumed in the formation of methane hydrate;

[0069] A methane adsorption amount is determined according to the first gas amount, the second gas amount, the third gas amount, and the fourth gas amount.

[0070] The methane adsorption calculation formula is:

[0071] n ex =n1-n2-n3-n4;

[0072] Among them, nex represents the amount of methane adsorption, n1 represents the first gas volume, n2 represents the second gas volume, n3 represents the third gas volume, n4 represents the fourth gas volume, ρ inj represents the gas density at injection pressure, v ref Represents the pre-calibrated reference kettle volume, M c represents the molar mass of methane, m s represents the target test sample mass, ρ ref represents the gas density at the reference kettle pressure, ρ equ Indicates the gas density at equilibrium pressure, m w Indicates the water quality in the target test sample, M w represents the molar mass of water, v va represents the corrected free space volume of the sample kettle, and n represents the hydration number of methane hydrate.

[0073] As will be readily understood, the control device can determine the gas density at the injection pressure, the gas density at the reference reactor pressure, and the gas density at the equilibrium pressure based on the equation of state for methane gas. Based on the gas density at the injection pressure, the pre-calibrated reference reactor volume, and the pre-acquired target test sample mass, the control device can calculate a first gas volume. The first gas volume can be used to represent the total volume of methane gas injected into the reference reactor. The calculation formula for the first gas volume can be expressed as: ρ inj represents the gas density at injection pressure, v ref Represents the pre-calibrated reference kettle volume, M c represents the molar mass of methane, which is 16 g / mol; m s Indicates the mass of the target test sample, the unit can be g.

[0074] The second gas volume is determined based on the gas density at the reference kettle pressure, the pre-calibrated reference kettle volume, and the pre-obtained target test sample mass. The second gas volume can be used to represent the remaining methane gas volume in the reference kettle at the end of the hydrate formation experiment. The calculation formula for the second gas volume can be expressed as: ρ ref Indicates the gas density at the reference kettle pressure, v ref Represents the pre-calibrated reference kettle volume, M c represents the molar mass of methane, which is 16 g / mol; m s Indicates the mass of the target test sample, the unit can be g.

[0075] It should be noted that after the water in the pores of the target test sample is converted into methane hydrate, the volume of methane hydrate is greater than the volume of water, that is, the free space volume of the target test sample decreases after methane hydrate is generated. Therefore, the pre-calibrated free space volume of the sample kettle is corrected according to the water content of the target test sample.

[0076] After obtaining the corrected sample kettle free space volume, the control device can determine the third gas volume based on the gas density at equilibrium pressure, the corrected sample kettle free space volume, and the previously acquired target test sample mass. The third gas volume can be used to represent the amount of methane gas that is not adsorbed in the sample kettle free space volume at the end of the hydrate formation experiment. The calculation formula for the third gas volume can be expressed as: ρ equ represents the gas density at equilibrium pressure, M c represents the molar mass of methane, which is 16 g / mol; m s Indicates the mass of the target test sample, the unit can be g, v va Represents the corrected free space volume of the sample vessel.

[0077] Based on the pre-acquired target test sample mass and the target test sample water content, the control device can calculate the fourth gas volume. The fourth gas volume can be used to represent the methane gas volume consumed in the formation of methane hydrate. The calculation formula of the fourth gas volume can be expressed as: m w Indicates the water mass in the target test sample, the unit can be g, M w represents the molar mass of water, taking 18 g / mol, v va represents the corrected free space volume of the sample kettle, and n represents the hydration number of methane hydrate.

[0078] The methane adsorption capacity can be expressed as:

[0079] n ex =n1-n2-n3-n4;

[0080] Among them, n ex represents the methane adsorption capacity, n1 represents the first gas volume, n2 represents the second gas volume, n3 represents the third gas volume, and n4 represents the fourth gas volume. The gas volume unit can be mmol / g.

[0081] Based on the above scheme, the pre-calibrated free space volume of the sample kettle is corrected according to the water content of the target test sample, including:

[0082] The water volume of the target test sample is determined according to the water mass and water density of the target test sample, and the pre-calibrated free space volume of the sample kettle is corrected according to the water volume of the target test sample.

[0083] In a preferred embodiment, the calculation formula of the corrected sample kettle free space volume is:

[0084] v va =v vp -αv w ;

[0085] Among them, v vp Represents the pre-calibrated free space volume of the sample kettle, v w represents the water volume of the target test sample, α represents the coefficient, ρ w represents the water density, ρ h It represents the density of methane hydrate, which can be taken as 0.9g / cm 3 ;M h represents the molar mass of methane hydrate, which is 16 g / mol; n represents the hydration number of methane hydrate, M w To express the molar mass of water, take 18 g / mol.

[0086] It is understood that there is a certain quantitative relationship between water and methane hydrate, for example, 1 mole of methane hydrate is generated for every n moles of water. The molar mass of methane hydrate can be expressed as M h =M c +n·M w Among them, M h represents the molar mass of methane hydrate, M c represents the molar mass of methane gas, which is 16 g / mol; M w represents the molar mass of water, which is 18 g / mol, and n represents the amount of water contained in 1 mole of methane hydrate. The mass of methane hydrate can be expressed as m w represents the water mass, and the volume of methane hydrate can be expressed as ρ h represents the density of methane hydrate. The saturation of methane hydrate can be expressed as: V p Indicates the pore volume of the test sample, the unit can be cm 3 .

[0087] The corrected free space volume of the sample kettle can be expressed as: V va =V vp -(V h -V w ), where V w represents the volume of water, the volume of methane hydrate V h Can be V w Specifically, substitute the methane hydrate mass expression into V h Expression, get The water mass expression m w =V w ρ w Substitution get V va =V vp -(V h -V w ) can be expressed as V va =V vp -

[0088]

[0089] Normally, methane hydrate can be expressed as CH4·5.75H2O, that is, the hydration number n of methane hydrate is 5.75, and the density of methane hydrate is ρ h , take 0.9g / cm 3 ,

[0090] This scheme takes into account the impact of methane hydrate formation on the free space volume of the target test sample after the water in the pores of the target test sample is converted into methane hydrate. The pre-calibrated free space volume of the sample kettle is corrected using the water content of the target test sample, which is conducive to ensuring the accurate measurement of the methane adsorption amount.

[0091] The technical solution of an embodiment of the present invention controls a methane adsorption capacity measurement device to perform a hydrate formation experiment on a target test sample to convert all water in the target test sample into methane hydrate. The target test sample is a water-containing sample prepared from a silty silt sample of a target reservoir. The particle size of the silty silt sample satisfies a preset roughness condition. The injection pressure, reference kettle pressure, and equilibrium pressure of the hydrate formation experiment are obtained. The injection pressure is the steady-state pressure in the reference kettle after methane gas is injected into the reference kettle. The reference kettle pressure is the pressure of the reference kettle at the end of the hydrate formation experiment. The equilibrium pressure is the equilibrium pressure of methane hydrate at a preset temperature. The methane adsorption capacity is determined based on the injection pressure, the reference kettle pressure, the equilibrium pressure, a pre-acquired target test sample mass, a water-containing mass of the target test sample, a pre-calibrated reference kettle volume, and a sample kettle free space volume. The reference kettle volume is the sum of the volumes of the reference kettle and a pipeline connected to the reference kettle. The sample kettle free space volume is the difference between the sample kettle volume and the target test sample skeleton volume. The sample kettle volume is the sum of the volumes of the sample kettle and the pipeline connected to the sample kettle. This technical solution solves the problem of inaccurate methane adsorption measurement in hydrate-containing muddy silt. By controlling methane hydrate generation and simulating the gas adsorption characteristics in the methane hydrate reservoir environment, the accuracy of methane adsorption measurement is ensured.

[0092] Example 2

[0093] Figure 2 This is a schematic diagram of a device for measuring the methane adsorption capacity of hydrate-containing muddy silt provided in Example 2 of the present invention. Figure 2 As shown, the methane adsorption amount measuring device 200 includes a gas supply device 210 , a gas adsorption balance device 220 and a constant temperature space 230 .

[0094] The gas supply device 210 is used to inject methane gas into the gas adsorption balance device 220 during the hydrate formation experiment; the gas adsorption balance device 220 is used to perform a hydrate formation experiment on the target test sample;

[0095] The gas supply device 210 includes a first gas cylinder 211, a booster pump 212, a four-way valve 213, an exhaust port 214, a vacuum pump 215, and a three-way valve 216; the gas adsorption balance device 220 includes a buffer container 221, a reference kettle 222, a sample kettle 223, a first pressure sensor 224, and a second pressure sensor 225; the gas adsorption balance device 220 is located in a constant temperature space 230;

[0096] The first gas cylinder 211 is connected to the booster pump 212 through a pipeline and a first valve; the booster pump 212 is connected to the four-way valve 213 through a pipeline, the four-way valve 213 is connected to the exhaust port 214, the four-way valve 213 is connected to the three-way valve 216 through a pipeline, and the three-way valve 216 is connected to the vacuum pump 215 through a pipeline; the four-way valve 213 is connected to the buffer container 221 through a pipeline and a valve; the buffer container 221 is connected to the reference kettle 222 through a pipeline and a valve, a T-shaped middle area is formed between the reference kettle 222 and the sample kettle 223 through a valve and a pipeline, the three-way valve 216 is connected to the middle area through a pipeline and a valve, the reference kettle 222 is connected to the first pressure sensor 224 through a pipeline; the sample kettle 223 is connected to the second pressure sensor 225 through a pipeline;

[0097] The first gas cylinder 211 is used to store methane gas, the booster pump 212 is used to pressurize the gas adsorption balance device 220 to the target reservoir pressure, and the vacuum pump 215 is used to vacuum the gas adsorption balance device 220; the exhaust port 214 is used to discharge the methane gas in the booster pump after the pressure in the buffer container 221 reaches the target reservoir pressure; the first pressure sensor 224 is used to measure the pressure in the reference kettle; the second pressure sensor 225 is used to measure the pressure in the sample kettle.

[0098] In this solution, the control device can control the methane adsorption amount measuring device to perform a hydrate formation experiment on the target test sample. Specifically, the process of the hydrate formation experiment is: the target test sample is loaded into the sample kettle 223, the control device can control the four-way valve 213 to close, and control the three-way valve 216, valves a3, V1, V2, V3 and V4 to open, and the gas adsorption balance device is evacuated by the vacuum pump 215, and the temperature of the constant temperature space 230 is adjusted to a preset temperature, for example, 30°C.

[0099] The control device can control valves a1 and a3 to open, allowing the methane gas in the first gas cylinder 211 to be pressurized by the booster pump 212 and enter the buffer container through the four-way valve 213 until the pressure in the buffer container 221 reaches a first pressure threshold. This first pressure threshold can be set based on the target reservoir pressure. After the pressure in the buffer container 221 reaches the first pressure threshold, the control device can control valves a1 and a3 to close and the exhaust port 214 to open, exhausting excess methane gas from the booster pump 212.

[0100] The control device can open valve V1, allowing the methane gas in buffer container 221 to enter reference vessel 222. The control device can control first pressure sensor 224, located in reference vessel 222, to monitor the pressure within reference vessel 222 according to a preset measurement cycle. If no change in the pressure within reference vessel 222 is detected, the currently measured pressure within reference vessel 222 is used as the injection pressure, and valve V1 is controlled to close, stopping the transfer of methane gas from the buffer container to the reference vessel.

[0101] The control device can control valve V2 to open, allowing methane gas in reference vessel 222 to enter the intermediate zone. The control device can control first pressure sensor 224, located within reference vessel 222, to monitor the pressure within reference vessel 222 according to a preset measurement cycle. Since reference vessel 222 is connected to the intermediate zone, the pressure within reference vessel 222 is equal to the pressure within the intermediate zone. The control device can use the pressure currently measured by first pressure sensor 224 as the intermediate zone pressure. If no change in the intermediate zone pressure is detected, the control device can control valve V2 to close, stopping the transfer of methane gas from reference vessel 222 to the intermediate zone.

[0102] After shutting off the flow of methane gas from reference kettle 222 to the intermediate zone, the control device can control valve V3 to open, allowing the methane gas in the intermediate zone to enter sample kettle 223. The methane gas entering sample kettle 223 can combine with the water in the target test sample to form methane hydrate. The control device can control a second pressure sensor 225 located in sample kettle 223 to monitor the pressure within sample kettle 223 according to a preset measurement cycle. If the pressure within sample kettle 223 is detected to be less than a second pressure threshold, the control device returns to controlling the methane gas in reference kettle 222 to enter the intermediate zone. After the pressure in the intermediate zone stabilizes, the flow of methane gas from reference kettle 222 to the intermediate zone is shut off, and the methane gas in the intermediate zone is controlled to enter sample kettle 223 until the pressure within sample kettle 223 is greater than or equal to the second pressure threshold. If the pressure within sample kettle 223 is detected to be greater than or equal to the second pressure threshold, the currently measured pressure within reference kettle 222 is used as the reference kettle pressure. The second pressure threshold can be determined based on the equilibrium pressure of methane hydrate at a preset temperature. For example, to ensure that the water in the target test sample is fully combined with the methane gas, the second pressure threshold can be greater than the equilibrium pressure of methane hydrate at the preset temperature. For example, it can be equal to the sum of the equilibrium pressure of methane hydrate at the preset temperature and 0.5 MPa. If the pressure within sample kettle 223 is greater than or equal to the second pressure threshold, it indicates that all the water in the target test sample within sample kettle 223 has been converted into methane hydrate.

[0103] After the hydrate formation experiment is completed, the control device can obtain the injection pressure, reference kettle pressure, and equilibrium pressure of the hydrate formation experiment. The injection pressure is the steady-state pressure within the reference kettle after methane gas is injected into the reference kettle. The reference kettle pressure is the pressure of the reference kettle at the end of the hydrate formation experiment. The equilibrium pressure is the equilibrium pressure of methane hydrate at a preset temperature. The methane adsorption capacity is determined based on the injection pressure, the reference kettle pressure, the equilibrium pressure, the pre-acquired target test sample mass, the water content of the target test sample, the pre-calibrated reference kettle volume, and the free space volume of the sample kettle. The reference kettle volume is the sum of the volumes of the reference kettle and the pipeline connected to the reference kettle. The free space volume of the sample kettle is the difference between the sample kettle volume and the target test sample skeleton volume. The sample kettle volume is the sum of the volumes of the sample kettle and the pipeline connected to the sample kettle. This technical solution solves the problem of inaccurate methane adsorption measurement in hydrate-containing muddy silt. By controlling methane hydrate formation and simulating the gas adsorption characteristics in a methane hydrate reservoir environment, the accuracy of methane adsorption measurement is ensured.

[0104] On the basis of the above solution, the gas supply device 210 further includes a second gas cylinder 217, which is used to store inert gas. The second gas cylinder 217 is connected to the booster pump 212 through a pipeline and a valve;

[0105] The gas supply device 210 is also used to inject inert gas into the gas adsorption balance device 220 when calibrating the reference kettle volume and the sample kettle free space volume;

[0106] The gas adsorption balance device 220 is also used to conduct an inert gas isothermal expansion experiment to calibrate the reference kettle volume and the sample kettle free space volume; the reference kettle volume is the sum of the volumes of the reference kettle 222 and the pipeline connected to the reference kettle; the sample kettle free space volume is the difference between the sample kettle volume and the target test sample skeleton volume; the sample kettle volume is the sum of the volumes of the sample kettle 223 and the pipeline connected to the sample kettle.

[0107] In this embodiment, the gas supply device 120 may further include a second gas cylinder 217 for storing an inert gas, such as helium, so as to inject the inert gas into the gas adsorption balance device 220 when calibrating the reference kettle volume and the sample kettle free space volume.

[0108] It should be noted that the reference kettle volume is the sum of the volumes of the reference kettle 222 and the pipelines connected to the reference kettle 222, for example, Figure 2 The volume of the reference kettle 222, the connecting pipeline between the reference kettle 222 and the valve V1, the connecting pipeline between the reference kettle 222 and the first pressure sensor 224, and the connecting pipeline between the reference kettle 222 and the valve V2. The volume of the sample kettle is the sum of the volumes of the sample kettle and the pipelines connected to the sample kettle. For example, Figure 2 The volume of the sample kettle 223, the connecting pipeline between the sample kettle 223 and the valve V3, and the connecting pipeline between the sample kettle 223 and the second pressure sensor 225. The free space volume of the sample kettle is the difference between the volume of the sample kettle and the volume of the target test sample skeleton.

[0109] The control device can calibrate the reference kettle volume and the sample kettle volume based on the inert gas expansion experiment. It is easy to understand that the inert gas is chemically inactive and does not react chemically with the muddy silt sample. The inert gas used in the inert gas expansion experiment can be helium. The specific process is as follows: the control device loads a preset number of stainless steel balls of known volume into the sample kettle 223. The control device can control the four-way valve 213 to close, and control the three-way valve 216, valves a3, V1, V2, V3 and V4 to open. The gas adsorption balance device is evacuated by the vacuum pump 215, and the temperature of the constant temperature space 230 is adjusted to a preset temperature, for example, 30°C. The control device can control valves a2, a3, and V1 to open, and pressurize the inert gas in the second gas cylinder 217 to a target reservoir pressure, e.g., 0-10 MPa, via the booster pump 212. The inert gas is then fed into the reference vessel 222. Once the pressure in the reference vessel 222 stabilizes, valves a2, a3, and V1 are controlled to close, stopping the inert gas feed into the reference vessel 222. The pressure in the reference vessel 222, i.e., the injection pressure, is measured via a first pressure sensor 224 located within the reference vessel 222 and recorded as a first pressure value. The control device can control valves V2 and V3 to open, allowing the inert gas to isothermally expand into the sample vessel 223. If methane gas adsorption equilibrium is detected, the control device can measure the pressure in the sample vessel 223, i.e., the equilibrium pressure, via a second pressure sensor 225 located within the sample vessel 223 and record it as a second pressure value.

[0110] The inert gas expansion experiment is repeated by varying the number of steel balls in the sample kettle 223 to obtain at least two sets of pressure values. Using each set of pressure values, the reference kettle volume and the sample kettle volume are calculated according to the law of conservation of mass. Specifically, the control device can determine the gas density values ​​corresponding to each set of inert gas expansion experiments, namely, a first gas density value and a second gas density value, based on each set of pressure values ​​and the inert gas equation of state. The first gas density value is the gas density within the reference kettle 222 at the injection pressure, and the second gas density value is the gas density within the reference kettle 222 under adsorption equilibrium conditions.

[0111] From the law of conservation of mass, we can get ρ1V ref =ρ2(V ref +V sam -ΔV); wherein ρ1 represents the gas density in the reference kettle 222 under the injection pressure, V ref represents the reference kettle volume, ρ2 represents the gas density in the reference kettle 222 under adsorption equilibrium conditions, V sam represents the volume of the sample kettle, and ΔV represents the volume of the steel ball in the sample kettle 223 in the inert gas expansion experiment.

[0112] ρ1V ref =ρ2(V ref +V sam-ΔV) can be organized into a two-variable linear equation, with ΔV as "y", For "x", V sam For "b", we get the equation equation Can be expressed A straight line in a plane coordinate system with ΔV as the horizontal axis is drawn, and the slope and intercept of the line are the reference and sample kettle volumes, respectively. Therefore, the control device transforms the problem of "calculating the reference and sample kettle volumes" into the problem of "solving the slope and intercept of the line." Based on at least two known sets of gas density values, the values ​​of the reference and sample kettle volumes are obtained.

[0113] Similarly, the control device can determine the volume of the intermediate zone based on the inert gas expansion experiment, wherein the intermediate zone is the T-shaped connecting pipeline between the reference kettle 222 and the sample kettle 223, for example Figure 2 The T-shaped connecting pipelines between valves V2, V3, and V4 are shown. The specific process for calibrating the volume of the intermediate zone is as follows: a preset number of stainless steel balls of known volume are loaded into the sample kettle 223. The control device can control the four-way valve 213 to close and the three-way valve 216, valves a3, V1, V2, V3, and V4 to open. The gas adsorption equilibrium device is evacuated by the vacuum pump 215, and the temperature of the constant temperature space 230 is adjusted to a preset temperature, for example, 30°C. The control device can control valves a2, a3, and V1 to open, and the inert gas in the second gas cylinder 217 to be pressurized to a target reservoir pressure, e.g., 0-10 MPa, via the booster pump 212. The inert gas is then fed into the reference vessel 222. Once the pressure in the reference vessel 222 stabilizes, valves a2, a3, and V1 are controlled to close, stopping the inert gas feed into the reference vessel 222. The pressure in the reference vessel 222, i.e., the injection pressure, is measured via the first pressure sensor 224 located within the reference vessel 222 and recorded as the third pressure value. The control device then controls valve V2 to open, allowing the inert gas to isothermally expand into the intermediate zone. If methane adsorption equilibrium is detected, the pressure in the reference vessel 222, i.e., the equilibrium pressure, is measured via the first pressure sensor 224 located within the reference vessel 222 and recorded as the fourth pressure value.

[0114] From the law of conservation of mass, we can get ρ3V ref =ρ4(V ref +V mid ); wherein, ρ3 represents the gas density in the reference kettle 222 under the injection pressure, V ref represents the reference kettle volume, ρ4 represents the gas density in the reference kettle 222 under adsorption equilibrium conditions, V midRepresents the volume of the intermediate zone. Based on the obtained reference kettle volume and the third and fourth pressure values ​​measured by the inert gas isothermal expansion experiment, the control device can calculate the volume of the intermediate zone. Specifically, the control device can obtain the third gas density value and the fourth gas density value based on the third pressure value, the fourth pressure value and the inert gas state equation, that is, the gas density in the reference kettle 222 under the injection pressure and the gas density in the reference kettle 222 under adsorption equilibrium conditions. The control device can substitute the third gas density value, the fourth gas density value and the reference kettle volume into ρ3V ref =ρ4(V ref +V mid ), and the volume of the middle area V is obtained mid .

[0115] The calibration of the free space volume of the sample kettle is also achieved based on an inert gas isothermal expansion experiment. The specific calibration process is as follows: the target test sample is loaded into the sample kettle 223, the gas adsorption equilibrium device is evacuated via vacuum pump 215, and the constant temperature space is adjusted to a preset temperature, such as 30°C. The control device can control valves a2, a3, and V1 to open, and the inert gas in the second gas cylinder 217 is pressurized to the target reservoir pressure, such as 0-10 MPa, via booster pump 212. The inert gas is then injected into the reference kettle 222. After the pressure in the reference kettle 222 stabilizes, valves a2, a3, and V1 are controlled to close, stopping the injection of inert gas into the reference kettle 222. The pressure in the reference kettle 222, i.e., the injection pressure, is measured via the first pressure sensor 224 deployed in the reference kettle 222 and recorded as the fifth pressure value. The control device can control valves V2 and V3 to open, allowing the inert gas in the reference kettle to isothermally expand into the sample kettle 223. If the methane gas adsorption equilibrium is detected, the control device may measure the pressure in the sample kettle 223 , ie, the equilibrium pressure, through the second pressure sensor 225 disposed in the sample kettle 223 and record it as a sixth pressure value.

[0116] From the law of conservation of mass, we can get ρ5V ref =ρ6(V ref +V sam -V frame ); wherein, ρ5 represents the gas density in the reference kettle 222 under the injection pressure, V ref represents the reference kettle volume, ρ6 represents the gas density in the reference kettle 222 under adsorption equilibrium conditions, V sam Indicates the volume of the sample kettle, V frameRepresents the skeleton volume of the target test sample. Based on the reference kettle volume, sample kettle volume, and the fifth pressure value and sixth pressure value measured by the second inert gas isothermal expansion experiment, the control device can calculate the skeleton volume of the test sample. Specifically, the control device can obtain the fifth gas density value and the sixth gas density value based on the fifth pressure value, the sixth pressure value, and the inert gas state equation, that is, the gas density in the reference kettle under the injection pressure and the gas density in the reference kettle under adsorption equilibrium conditions. The control device can substitute the fifth gas density value, the sixth gas density value, the reference kettle volume, and the sample kettle volume into ρ5V ref =ρ6(V ref +V sam -V frame ), and obtain the skeleton volume V of the target test sample frame , and then according to V sam -V frame , get the free space volume V of the sample kettle vp .

[0117] This scheme can convert the water in the target test sample into methane hydrate through the methane adsorption measurement device, solving the problem of inaccurate methane adsorption measurement of hydrate-containing muddy silt. It simulates the gas adsorption characteristics in the methane hydrate reservoir environment and ensures the accuracy of methane adsorption measurement.

[0118] Example 3

[0119] Figure 3 This is a schematic diagram of a system for measuring methane adsorption of hydrate-containing muddy silt provided in Example 3 of the present invention. Figure 3 As shown, the methane adsorption measurement system 100 includes a methane adsorption measurement device 200 and a control device 300. The control device 300 communicates with the methane adsorption measurement device 200 and controls the methane adsorption measurement device 200 to perform a hydrate formation experiment on a target measurement sample.

[0120] Figure 4 A schematic diagram of the structure of a control device 300 that can be used to implement an embodiment of the present invention is shown. The control device 300 is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The control device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0121] like Figure 4 As shown, the control device 300 includes at least one processor 301 and a memory, such as a read-only memory (ROM) 302, a random access memory (RAM) 303, etc., which is communicatively connected to the at least one processor 301. The memory stores a computer program that can be executed by the at least one processor. The processor 301 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 302 or the computer program loaded from the storage unit 308 into the random access memory (RAM) 303. Various programs and data required for the operation of the control device 300 can also be stored in the RAM 303. The processor 301, ROM 302, and RAM 303 are connected to each other via a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0122] Multiple components in the control device 300 are connected to the I / O interface 305, including: an input unit 306, such as a keyboard, a mouse, etc.; an output unit 307, such as various types of displays, speakers, etc.; a storage unit 308, such as a magnetic disk, an optical disk, etc.; and a communication unit 309, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 309 allows the control device 300 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0123] Processor 301 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of processor 301 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any other suitable processor, controller, microcontroller, etc. Processor 301 executes the various methods and processes described above, such as the method for measuring methane adsorption in hydrate-containing muddy silt.

[0124] In some embodiments, the method for measuring the amount of methane adsorption by hydrate-containing muddy silt can be implemented as a computer program tangibly embodied in a computer-readable storage medium, such as storage unit 308. In some embodiments, part or all of the computer program can be loaded and / or installed on control device 300 via ROM 302 and / or communication unit 309. When the computer program is loaded into RAM 303 and executed by processor 301, one or more steps of the method for measuring the amount of methane adsorption by hydrate-containing muddy silt described above can be performed. Alternatively, in other embodiments, processor 301 can be configured to execute the method for measuring the amount of methane adsorption by hydrate-containing muddy silt using any other suitable means (e.g., via firmware).

[0125] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-chip systems (SOCs), programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0126] Computer programs for implementing the methods of the present invention can be written in any combination of one or more programming languages. These computer programs can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable device for measuring methane adsorption of hydrate-containing muddy silt, so that when executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer programs can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0127] In the context of the present invention, computer-readable storage media can be tangible media that can contain or store a computer program for use with an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. Computer-readable storage media can include but are not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, computer-readable storage media can be machine-readable signal media. More specific examples of machine-readable storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0128] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device that has: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the control device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0129] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0130] A computing system may include clients and servers. The clients and servers are typically remote from each other and typically interact via a communication network. This client-server relationship arises through computer programs running on the respective computers, creating a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host. This server is a hosting product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosting and VPS services.

[0131] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0132] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for measuring the methane adsorption capacity of hydrate-containing muddy silt, characterized in that: The method comprises: Controlling the methane adsorption amount measuring device to perform a hydrate formation experiment on a target test sample to convert all water in the target test sample into methane hydrate; the target test sample is a water-containing sample prepared based on a muddy silt sample of a target reservoir; the particle size of the muddy silt sample meets a preset roughness condition; Obtain the injection pressure, reference kettle pressure, and equilibrium pressure of the hydrate formation experiment; the injection pressure is the steady-state pressure in the reference kettle after methane gas is injected into the reference kettle, the reference kettle pressure is the pressure of the reference kettle at the end of the hydrate formation experiment, and the equilibrium pressure is the equilibrium pressure of methane hydrate at a preset temperature; The methane adsorption amount is determined based on the injection pressure, the reference kettle pressure, the equilibrium pressure, the pre-acquired target test sample mass, the water content of the target test sample, the pre-calibrated reference kettle volume and the free space volume of the sample kettle; the reference kettle volume is the sum of the volumes of the reference kettle and the pipeline connected to the reference kettle; the free space volume of the sample kettle is the difference between the sample kettle volume and the target test sample skeleton volume; the sample kettle volume is the sum of the volumes of the sample kettle and the pipeline connected to the sample kettle.

2. The method according to claim 1, characterized in that The controlling methane adsorption amount measuring device to perform a hydrate formation experiment on a target test sample comprises: Place the target test sample into the sample kettle, adjust the temperature of the constant temperature space to the preset temperature, and control the vacuum pump to evacuate the gas adsorption balance device; Controlling the methane gas in the first gas cylinder to be pressurized to the target reservoir pressure by the booster pump and then entering the buffer container; If it is detected that the pressure in the buffer container reaches a first pressure threshold, the methane gas in the booster pump is controlled to be discharged, and the methane gas in the buffer container is controlled to enter the reference kettle; If it is detected that the pressure in the reference kettle does not change, the currently detected pressure in the reference kettle is used as the injection pressure, and the transfer of methane gas in the buffer container to the reference kettle is stopped; Controlling the methane gas in the reference kettle to enter the middle zone; the middle zone is the T-shaped connecting pipeline between the reference kettle and the sample kettle; If it is detected that there is no change in the pressure of the middle zone, the transfer of the methane gas in the reference kettle to the middle zone is stopped, and the methane gas in the middle zone is controlled to enter the sample kettle; If it is detected that the pressure in the sample kettle is less than the second pressure threshold, the control returns to the reference kettle to allow the methane gas to enter the middle zone until the pressure in the sample kettle is greater than or equal to the second pressure threshold; If the pressure in the sample kettle is detected to be greater than or equal to the second pressure threshold, the currently detected pressure in the reference kettle is used as the reference kettle pressure.

3. The method according to claim 1, characterized in that Before controlling the methane adsorption amount measuring device to perform a hydrate formation experiment on the target test sample, the method further includes: A preset number of stainless steel balls of known volume are placed in the sample kettle, the temperature of the constant temperature space is adjusted to the preset temperature, and the vacuum pump is controlled to evacuate the gas adsorption balance device; Based on the first inert gas expansion experiment, the reference kettle volume and the sample kettle volume were calibrated; Take out the stainless steel balls from the sample kettle, put the target test sample into the sample kettle, adjust the temperature of the constant temperature space to the preset temperature, and control the vacuum pump to evacuate the gas adsorption balance device; Based on the second inert gas expansion experiment, the free space volume of the sample kettle was calibrated.

4. The method according to claim 1, wherein Determining the methane adsorption amount based on the injection pressure, the reference kettle pressure, the equilibrium pressure, the pre-acquired target test sample mass, the water mass of the target test sample, the pre-calibrated reference kettle volume, and the sample kettle free space volume includes: determining the gas density at the injection pressure, the gas density at the reference kettle pressure, and the gas density at the equilibrium pressure; Determining a first gas volume according to the gas density at the injection pressure, a pre-calibrated reference kettle volume, and a pre-acquired target test sample mass; the first gas volume is the total volume of methane gas injected into the reference kettle; determining a second gas volume based on the gas density at the reference kettle pressure, a pre-calibrated reference kettle volume, and a pre-acquired target test sample mass; the second gas volume being the remaining methane gas volume in the reference kettle at the end of the hydrate formation experiment; Correct the pre-calibrated free space volume of the sample kettle according to the water content of the target test sample; determining a third gas volume based on the gas density at the equilibrium pressure, the corrected free space volume of the sample kettle, and the pre-acquired target test sample mass; the third gas volume being the amount of methane gas not adsorbed in the free space volume of the sample kettle at the end of the hydrate formation experiment; Determining a fourth gas volume based on the pre-acquired target test sample mass and the water content of the target test sample; the fourth gas volume is the methane gas volume consumed in the formation of methane hydrate; A methane adsorption amount is determined according to the first gas amount, the second gas amount, the third gas amount, and the fourth gas amount.

5. The method according to claim 4, characterized in that The method of correcting the pre-calibrated free space volume of the sample kettle according to the water content of the target test sample includes: The water volume of the target test sample is determined according to the water mass and water density of the target test sample, and the pre-calibrated free space volume of the sample kettle is corrected according to the water volume of the target test sample.

6. The method according to claim 5, characterized in that The calculation formula of the corrected sample kettle free space volume is: v va =v vp -αv w ; Among them, v vp Represents the pre-calibrated free space volume of the sample kettle, v w represents the water volume of the target test sample, α represents the coefficient, ρ w represents the water density, ρ h represents the methane hydrate density, M h represents the molar mass of methane hydrate, n represents the hydration number of methane hydrate, M w Represents the molar mass of water.

7. The method according to claim 4, characterized in that The methane adsorption calculation formula is: <h2 style=";text-align:left;direction:ltr">n<h2 style=";text-align:left;direction:ltr"> ex <h2 style=";text-align:left;direction:ltr"> =n1-n2-n3-n4; Among them, n ex represents the amount of methane adsorption, n1 represents the first gas volume, n2 represents the second gas volume, n3 represents the third gas volume, n4 represents the fourth gas volume, ρ inj represents the gas density at injection pressure, v ref Represents the pre-calibrated reference kettle volume, M c represents the molar mass of methane, m s represents the target test sample mass, ρ ref represents the gas density at the reference kettle pressure, ρ equ Indicates the gas density at equilibrium pressure, m w Indicates the water quality in the target test sample, M w represents the molar mass of water, v va represents the corrected free space volume of the sample kettle, and n represents the hydration number of methane hydrate.

8. A device for measuring the methane adsorption capacity of hydrate-containing muddy silt, characterized in that: The methane adsorption amount measuring device includes a gas supply device, a gas adsorption balance device and a constant temperature space; the gas supply device is used to inject methane gas into the gas adsorption balance device during the hydrate formation experiment; the gas adsorption balance device is used to perform a hydrate formation experiment on the target test sample; The gas supply device includes a first gas cylinder, a booster pump, a four-way valve, an exhaust port, a vacuum pump, and a three-way valve; the gas adsorption balance device includes a buffer container, a reference kettle, a sample kettle, a first pressure sensor, and a second pressure sensor; the gas adsorption balance device is located in a constant temperature space; The first gas cylinder is connected to the booster pump through a pipeline and a first valve; the booster pump is connected to the four-way valve through a pipeline, the four-way valve is connected to the exhaust port, the four-way valve is connected to the three-way valve through a pipeline, and the three-way valve is connected to the vacuum pump through a pipeline; the four-way valve is connected to the buffer container through a pipeline and a valve; the buffer container is connected to the reference kettle through a pipeline and a valve, a T-shaped middle area is formed between the reference kettle and the sample kettle through a valve and a pipeline, the three-way valve is connected to the middle area through a pipeline and a valve, the reference kettle is connected to the first pressure sensor through a pipeline; the sample kettle is connected to the second pressure sensor through a pipeline; The first gas cylinder is used to store methane gas, the booster pump is used to pressurize the gas adsorption balance device to the target reservoir pressure, and the vacuum pump is used to vacuum the gas adsorption balance device; the exhaust port is used to discharge the methane gas in the booster pump after the pressure in the buffer container reaches the target reservoir pressure; the first pressure sensor is used to measure the pressure in the reference kettle; and the second pressure sensor is used to measure the pressure in the sample kettle.

9. The methane adsorption amount measuring device according to claim 8, characterized in that: The gas supply device further includes a second gas cylinder, the second gas cylinder is used to store inert gas, and the second gas cylinder is connected to the booster pump through a pipeline and a valve; The gas supply device is also used to inject inert gas into the gas adsorption balance device when calibrating the reference kettle volume and the sample kettle free space volume; The gas adsorption equilibrium device is also used to conduct an inert gas isothermal expansion experiment to calibrate the reference kettle volume and the sample kettle free space volume; the reference kettle volume is the sum of the volumes of the reference kettle and the pipeline connected to the reference kettle; the sample kettle free space volume is the difference between the sample kettle volume and the target test sample skeleton volume; the sample kettle volume is the sum of the volumes of the sample kettle and the pipeline connected to the sample kettle.

10. A system for measuring methane adsorption of hydrate-containing muddy silt, characterized in that: The methane adsorption amount measurement system includes a control device and a methane adsorption amount measurement device as described in any one of claims 8-9; the control device includes a memory, a processor and a computer program stored in the memory and executable by the processor, and when the processor executes the computer program, the methane adsorption amount measurement method as described in any one of claims 1-7 is implemented.

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