Method for measuring gas hydrate phase balance condition

A gas hydrate and phase equilibrium technology, applied in measuring devices, instruments, scientific instruments, etc., can solve the problems affecting the measurement accuracy, uncertain equilibrium temperature, sensitive hydrate formation, etc., to prevent hydrate blockage, and widely Application background, the effect of high measurement accuracy

Inactive Publication Date: 2009-03-04
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages of the constant volume curve method for determining the phase equilibrium conditions of hydrates are: the measurement period is long, the equilibrium temperature is uncertain and sensitive to the amount of hydrate formation, and the hysteresis of temperature or pressure measurement will also affect the measurement accuracy

Method used

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  • Method for measuring gas hydrate phase balance condition
  • Method for measuring gas hydrate phase balance condition
  • Method for measuring gas hydrate phase balance condition

Examples

Experimental program
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Effect test

Embodiment 1

[0035] Example 1: Device and method for measuring gas hydrate phase equilibrium conditions

[0036] Please refer to figure 1 As shown, the device includes a reactor 1, the reactor 1 is provided with a temperature measurement system (temperature sensor) 2, a pressure measurement system (pressure sensor) 3, and an exhaust system that can discharge the gas in the reactor 1 4. Wherein, the temperature measuring point of the temperature measuring system 2 is located in the reactor 1, which can directly contact the sample 5 to be tested in the reactor; and the reactor is provided with a piston 6, which connects the pressure transmission medium 7 and the experimental system ( The sample to be tested 5) is separated, and the piston 6 can be pushed by the manual pump 8 through the pressure transmission medium 7 to adjust the system pressure in the reaction kettle. In the device of this embodiment, both the pressure measuring equipment and the reactor are in the constant temperature a...

Embodiment 2

[0039] Embodiment 2: Determination of phase equilibrium conditions of methane+water system hydrate

[0040] In this example, the device in Example 1 is used to measure the phase equilibrium condition of the hydrate in the methane+water system.

[0041] Put pure water in the reaction kettle, maintain the system temperature at 0.5°C, vacuumize, and feed pure methane gas to 9.0MPa, so that a large amount of hydrates will be generated in the reaction kettle. After the hydrate is completely formed, push the piston to compact the hydrate, and then raise the temperature of the system to 4.0°C. Using the existing calculation model, it can be estimated that the equilibrium pressure of the hydrate formation condition of methane in the free water system is 3.80 MPa, the exhaust pressure is reduced to 3.50MPa, the exhaust system is closed, the reactor becomes a closed system, the timing is started, and the pressure change is recorded. After completing the measurement of a set of hydrate t...

Embodiment 3

[0042] Example 3: Determination of hydrate phase equilibrium conditions in methane+SDS aqueous solution (650ppm)+80-100 mesh quartz sand system

[0043] In this example, the device in Example 1 is used to measure the phase equilibrium conditions of hydrates in the methane+SDS aqueous solution (650ppm)+80-100 mesh quartz sand system (porous medium system).

[0044]The reaction kettle is built with sodium dodecylsulfonate (SDS) aqueous solution (SDS concentration 650ppm), and the porous medium sample (80-100 mesh quartz sand) is wrapped with a screen and placed in the reaction kettle to avoid exhaustion. When the medium particles enter the exhaust line. Maintain the system temperature at 0.5°C, vacuumize, and feed pure methane gas to 9.0MPa to form hydrates. Then push the piston to compact the hydrate; raise the temperature of the system to 4.0°C, the equilibrium pressure is estimated to be 3.90MPa at this time, and the exhaust pressure is reduced to 3.50MPa to close the exhaus...

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Abstract

The invention provides a method for determining the phase balance condition of gas hydrates, which mainly has the procedures: gas to be measured is caused to generate hydrates in a reaction kettle which is provided with a temperature measurement system, a pressure measurement system and an exhaust system; gas-phase space in the reaction kettle is compressed; system temperature in the reaction kettle is regulated to the temperature of the phase balance condition to be measured to exhaust the gas and lower the pressure, as well as the exhaust system is closed when the pressure in the reaction kettle rises at once because the exhaust is stopped, thus the reaction kettle is caused to become a closed system; the variation of the pressure in the reaction kettle is observed, if the pressure keeps invariant for a long time, three-phase balance is considered to be reached, at this time, the corresponding temperature and the corresponding pressure are a set of phase balance condition for the hydrates. The system temperature can further rise to the next balance temperature to be measured, the pressure variation is continuously recorded until the hydrates in the reaction kettle is completely decomposed, therefore, a series of phase balance condition data of the hydrates can be obtained. Adopting the method, the phase balance condition of the gas hydrates in a free water system or a porous media can be measured, and the measurement accuracy is high.

Description

technical field [0001] The invention relates to a method for measuring the phase equilibrium condition of gas hydrate. Background technique [0002] Gas hydrates are light hydrocarbons, CO 2 and H 2 A non-stoichiometric cage-like crystal substance formed by small molecular gases such as S and water. There are three main types of gas hydrate structures that have been discovered: structure I, II and structure H, each of which contains various holes of different sizes and numbers formed by water molecules connected to each other by hydrogen bonds , smaller gas molecules fill the pores and support the pores. [0003] With the application of gas hydrate technology in the exploration and development of natural gas, oil and gas pipeline transportation, bioengineering and environmental protection, the research on hydrate has attracted more and more attention. An important aspect and basic work. [0004] The possible coexisting equilibrium phases in the gas hydrate equilibrium s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N33/00G01N25/12
Inventor 孙长宇陈立涛陈光进
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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